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Vlavsky
09-09-2013, 10:27 PM
K so I was driving kind of fast the other day (90-95) when someone going the speed limit (50) decided to switch lanes. Long story short I had to brake pretty hard and it scared the **** out of me. The car felt so wobbly and just unstable. I was extremely dissapointed by this experience and to be honest don't feel very confident behind the wheel anymore. Is this normal? Has anyone else experienced thks? Hoping there is a quick fix for this (lowering?) Thanks

Guest
09-09-2013, 10:34 PM
K so I was driving kind of fast the other day (90-95) when someone going the speed limit (50) decided to switch lanes. Long story short I had to brake pretty hard and it scared the **** out of me. The car felt so wobbly and just unstable. I was extremely dissapointed by this experience and to be honest don't feel very confident behind the wheel anymore. Is this normal? Has anyone else experienced thks? Hoping there is a quick fix for this (lowering?) Thanks

Dead easy fix mate....

Drive at a sensible speed for the safety of yourself and other road users and save this **** for the track!

Oh yeah, welcome to the forum!

DuckDodgers
09-09-2013, 10:35 PM
MY braking has been of a quality high varied due to road conditions. I drive acccordingly, and do not consider the berakes to be any worse than good...but they aren't great either.

Quick fix, change brake pads to a more performance pad...if you are willing to accept more brake dust, reduced pad and rotor life, and the need to properly warm the pads for best performance. Lowering would likely make braking worse, as it reduces suspension travel, and your wobble is probably road condition (crappy roads, uneven, etc) related.

Robert Nixon
09-09-2013, 10:41 PM
haven't noticed any issues in autcrossing or at the Abarth Experience, although neither one involves HARD braking from 95.

Top speed on the track at Abarth Experience was about 86 down to maybe 40 for a corner. No issues.

Felnus
09-09-2013, 10:53 PM
It's a short wheelbase car, the rear will unload under panic braking but the ESC and anti-lock brakes should keep you pointed in the right direction which is what you felt, the car battling physics to keep itself and you in one piece. 45 mph over the speed limit is asking for something bad to happen. Slow down before something life altering occurs and a squirrelly rear end is the least of your worries.

JoeB
09-09-2013, 11:54 PM
You were doing 95 in a 50, and the "dangerous little car" kept you going in the proper direction without plowing into an innocent person driving like an adult. It worked fine, and you need to cut that **** out.

AnthonyV
09-10-2013, 01:03 AM
Totally agree with what others have said about minding speed on the highway, and using caution to not put others lives in danger as well as your own.

That said, I think I've actually experienced the feeling OP is talking about, actually at much lower speeds as well. I think it's a issue of weight transfer. For me it's happened right at about the threshold of braking before a turn. Probably just short of engaging ABS. Being front weight biased and having a really short wheelbase definitely exacerbates the feeling. For me it wasn't a uncontrollable violent feeling or anything, just that the car felt like the rear got a little nervous feeling for a second, and still being a bit new to the cars handling characteristics at the time, was also a little nervous myslef for a second lol. The car sorted itself out though before any input on my part was necessary. But I could see how it might unsettle someone if they didn't expect it.

I think what's happening is the rear of the car is getting very unloaded under fast sharp braking. From my experience though, the rear only does it's little wiggle when it happens over uneven or somewhat rippled pavement. Since there's so little weight back there, the wheels are light for the second, and is easier for them to follow all the imperfections in the road.

Under normal driving, you'd just about never notice it. Under hard driving or in a panic situation on sort of grooved or rippled pavement is the only time it rears it's head. I would say the solution is dampers with more low speed rebound damping in e rear, or more low speed compression damping in front. I'd personally probably opt for low the low speed rebound in back, I like bump damping to be compliant. It would slow the weight transfer under extremely hard braking. i imagine any kind of uprated damper would probably sort this.

All that said, it's hardly any kind of deal breaker for me. This car handles excellently! Like I said, the car sorts itself for the most part before it ever really "gets out of shape". The only place I could see it being a issue is if the driver did something erratic, or over reacted when it happened. As is, nothing is really needed to compensate other then just keeping the steering wheel straight, which is what you want under threshold braking anyway.

djhace
09-10-2013, 01:34 AM
dude, you where driving too slow. if you would had gone faster. you would had pass the idiot. lesson learn. hah.

redred
09-10-2013, 02:04 AM
The speed issue aside, if you are that aggressive of a driver then some mods are a definite requirement. Better rotors & pads. Braided, stainless steel brake lines. Rear torsion bar. Lowering springs or coil-overs (good ones)

jguerdat
09-10-2013, 07:52 AM
I've never felt the car "wobble" under heavy braking until I went to the Abarth Experience which was my first track experience. Most folks were prolly doing more coasting than braking but I wanted to see what was up so I used my autocross braking (wait till you see God, then brake) or at least as much as I could with the instructor giving orders. The car was definitely moving around under heavy braking which wasn't unnerving to me, just a datapoint that a short, tall wasn't going to be as stable as a car with a different CG. It was also obvious that my huge rear torsion bar would be an issue on the track, since rotation was much easier than at autocross speeds.

Long story short, depending on speed, tires and road conditions (including smoothness and rain grooves) the car may very well move around/wobble under heavy braking.

P.S. Don't do that again.

deathshead
09-10-2013, 08:26 AM
This is what makes the car fun in stock form!
super light in the front + short wheelbase.

Braking late in a turn will kick out the ass.

If you want to fix it entirely pick up a set of springs such as the sportlines.
I have a VERY hard time trying to get my car to come loose in the back now.
even extremely hard braking, no problems...

One thing that IS a little sketchy are the stock **** balloon pirelli 16" tires.
get on a smooth highway in the rain and you have to white knuckle it, feels like your driving on an ice skating rink because the tires are TERRIBLE in the rain.

cmj912
09-10-2013, 08:39 AM
I've posted a few times that I've had to brake more than once in panic mode (on the highway, in bad weather, traveling maybe 45-50 MPH) and I felt the braking power of the car given its size and weight is not only superior but impressive.
In fact, on Sunday I was traveling in light traffic when a crazy person in front of me decided to stop suddenly to let someone in...I wasn't tailgating but I did have to brake harder than normal. Nice, smooth, controlled stop.
The Ford Focus behind me? Well. Let's just say I heard her laying down tire and she ended up going into the median to avoid hitting me. I haven't heard a modern car lock its brakes on dry pavement in a LONG time.
'Course this is the Sport and YMMV...but still.

trevc
09-10-2013, 09:43 AM
I never had this issue on the road but definitely had it on the track with the stock suspension. Heavy braking at high speed in anything except an exact straight line would make the rear try and come around.
Lowering the rear with Eibach pro-kit springs helped a lot.
I now have BC Racing coilovers and some good 215 tires and high speed, heavy braking is almost a non-issue now.

MAZ
09-10-2013, 10:07 AM
Rapid transitions will unsettle your car. Heavier cars will be more forgiving, as for light weight cars.. as OP found out, not so much.

I've experienced the 'unsettling' feeling from the rear under hard braking.
It's due to the rear of the car being very light (to begin with) and the rapid transfer of weight to the front of the car under heavy braking.
This is a geometry/suspension/weight issue.

The stock suspension is squirrelly to begin with.
I lowered the car and threw a spare tire in the trunk which seems to have helped.

JackandSue
09-10-2013, 10:53 AM
I do not drive over 5 miles above the speed limit now saying that my wife does! But only on the track. we discovered on our first track day that the Abarth does want to wobble at 100 plus so after some research with some of our vendors we added a extended rear spoiler and race performance brakes. Also had car race aligned and balanced and suspension added. The car now is a bullet and stops so much nicer but you still have to expect it to want to brake loose just as any car. Our biggest challenge is getting used to front wheel drive...a whole different animal :) Now for you guys that don't race just keep it under 80 and don't slam on brakes but pump them off and on firmly and always drive like the guy next to you is a nut!

Vlavsky
09-10-2013, 01:57 PM
Thanks for all the replies guys. I know I shouldn't drive that fast on public roads but I just hit the 1000 mile mark and couldnt resist the urge to finally push the car. That being said, I guess I learned my lesson. Anyway I think I'll start with some lowering springs and maybe a torsion bar and see how the car behaves then.

TubeDriver
09-10-2013, 02:07 PM
Thanks for all the replies guys. I know I shouldn't drive that fast on public roads but I just hit the 1000 mile mark and couldnt resist the urge to finally push the car. That being said, I guess I learned my lesson. Anyway I think I'll start with some lowering springs and maybe a torsion bar and see how the car behaves then.



First thing to do (other than slow down a bit on public roads) is to check your tires pressures. Uneven pressures can cause stability issues under hard braking.

I have felt the instability you describe at the track and on the street (but not really at autoX where speeds are lower). Interestingly enough, turning traction control off seemed to help somewhat. I actually think some of the instability/squirm is caused by traction control modulating brakes in an effort to keep the car pointed straight. With traction control off, the car certainly has issues with its short wheelbase and lose/soft suspension (leading to large weight transfer) but it feels more natural to me. I'll be at the track this weekend and will try to get some time to drive it and evaluate braking with traction control on/off.

Vlavsky
09-10-2013, 02:11 PM
First thing to do (other than slow down a bit on public roads) is to check your tires pressures. Uneven pressures can cause stability issues under hard braking.

I have felt the instability you describe at the track and on the street (but not really at autoX where speeds are lower). Interestingly enough, turning traction control off seemed to help somewhat. I actually think some of the instability/squirm is caused by traction control modulating brakes in an effort to keep the car pointed straight. With traction control off, the car certainly has issues with its short wheelbase and lose/soft suspension (leading to large weight transfer) but it feels more natural to me. I'll be at the track this weekend and will try to get some time to drive it and evaluate braking with traction control on/off.

Let me know if that helps any. I'll check the tire pressure maybe that is part of the problem. I am a little bit dissapointed with the suspension however. I used to drive my wife's mini once in a while and feel like the mini set up was firmer and more controlled. Although the fun to drive factor definetly goes to the abarth

Giuseppe
09-10-2013, 02:41 PM
This is normal for a car with a wheel base that is this short. I have stabbed the brakes on track many times from 90 up to 130mph. The car feels very unstable. The ass end goes a little to either side. If you really get on the brakes, it may feel that it wants to roll over forward. This is the nature of the car. Just remember if it starts coming around, apply throttle and turn into the slide.

FTY
09-10-2013, 02:43 PM
Let me know if that helps any. I'll check the tire pressure maybe that is part of the problem. I am a little bit dissapointed with the suspension however. I used to drive my wife's mini once in a while and feel like the mini set up was firmer and more controlled. Although the fun to drive factor definetly goes to the abarth

The rear of the car has been known to dance a bit on these cars like many have said, whether its under hard braking or under hard cornering especially over rough pavement will cause the car to become somewhat unstable at times. Lowering the car to a degree and adding a rear torsion bar does dial most of this out. You know how people drive in Brooklyn, they don't pay attention just be careful, lots of knuckleheads out there!!

Indie500L
09-10-2013, 07:23 PM
1000 miles may have the engine some what broken in but the brakes are still new - if they were a little damp you made them steam at that speed and your tires are probably not gripping fully yet either. Rule of thumb from my motorcycle riding days "Don't go fast next to anything that can move!"

As for the 500L due to a slow GPS, like 1000 feet slow, I had to brake from 30MPH to avoid missing a drive way where I wanted to turn and I must say it hauled down to a stop very nicely. :encouragement:

melanzane
09-10-2013, 10:05 PM
So you don't have to be doing 90mph and brake to experience the wobble. I've had the same happen around 65mph under strong braking.

Adding spacers to your wheels helps. 15mm on the rears noticeably increases stability. But I've found that the torsion bar does the most magic - this is an easy upgrade. New springs also help. The combination of the 3 essentially eliminates the wobble.

The effect of spacers on this car is dramatic because of the narrow track.

deathshead
09-11-2013, 09:21 AM
Dancing - The equivalent to this.

http://i282.photobucket.com/albums/kk263/staceydodds/Cartech-Abarth-500-Coppa-Seitenansicht-Bremsmanoever-19-fotoshowImageNew-4053ac9e-565043_zps555da2f5.jpg
http://orgstories.files.wordpress.com/2010/03/davidleeroth.jpg

Indie500L
09-11-2013, 11:44 AM
heeeeeeeyyyyyy that's not stopping ... your rear wheels are still spinning - looks more like a jump and landing on your nose!!

DuckDodgers
09-11-2013, 03:36 PM
I'll note that sport shocks on stock springs will reduce some of the unloading...sport springs would help more. Again, lowering is not "the answer" to this, but will actually make it worse unless the spring/shock combination is properly matched.

A weight transfer issue will alway occur in a panic stopping situation. If you watch professional drivers, they begin loading up the suspension well before the corner to "set" for the corner. That avoids the transfer issues, but isn't possible in a panic stop.

Just remember, many torsion bars are lower than any other undercar component...and a big piece of metal that can be snagged, bolted directly to your rear suspension, is something to be aware of.

AnthonyV
09-11-2013, 05:42 PM
The lowering springs out there I've seen so far may or may not help with this depending on which we're looking at. I've actually seen a few that lower the car significantly but go to softer progressive rates. Those are not going to help with this, and actually create a few new problems. Aside from the other issues you get with a spring like that, softer progressive rates aren't going to better control that weight transfer moment, especially since they start out soft and get firmer as they compress. Increased spring rates could in fact help, but I'm not sure any of the one's out there yet have all the right ingredients. In fact other then a lower ride height, I don't know that there's anything to be gained from springs for this car, at least not cars that are running street tires still. Race tires different story, and for a different thread (the Abarth I'm talking about here, other models are different kettle of fish all together).

As for the larger rear torsion bar, it's not going to help with this either. At least not if we're talking about straight line braking. The torsion bar is designed to resist lateral twist, and reduce roll when the car is cornering. Straight line braking is a longitudinal force (fore and aft). Since this car has a beam rear suspension, and what we're talking about seems to occur on rough or rippled surfaces when the rear suspension is unloaded, the larger rear torsional bar will actually transfer more vertical force to both rear tires since it is more strongly tying them together. For example, with the rear unloaded under hard braking, if say the left rear tire hits a bump, the larger bar will actually transfer more of vertical force to both rear wheels, and in turn make the rear more loose. Keep in mind, I'm not saying more rear roll resistance won't help with this cars handling, just saying it won't for the situation we're discussing.

Again that brings us back to dampers. Better dampers with more rear rebound damping will soften that motion we're talking about that causes the "wobble". I actually think uprated dampers are the answer to more then a few things here with this car, and would sort a lot of the inherent "nervousness" it has when getting driven flat out, but again that's for another thread. And again, not to say that the stock dampers are by any means bad, but I think here is one spot I'm fairly sure there's room for improvement. Not just for track built car's either but road cars as well.

Fiat500USA
09-11-2013, 08:24 PM
A rear set of Konis with adjustable rebound is just what the DR. ordered! gr_grin

SeaDawg
09-11-2013, 10:03 PM
A rear set of Konis with adjustable rebound is just what the DR. ordered! gr_grin

Do you have a set of those installed? If so, what setting are you using?

Robert Nixon
09-11-2013, 11:21 PM
"Just remember, many torsion bars are lower than any other undercar component...and a big piece of metal that can be snagged, bolted directly to your rear suspension, is something to be aware of. "

Are you saying that cars shouldn't have torsion bars? Or that the bar on a Fiat is too low? What I'm thinking is that even if you buy a larger bar than the stock Abarth bar, it adds maybe 5mm to the size of the bar, and assuming the bar is still centered the same, we're talking about the replacement bar being maybe 2.5mm lower to the ground.

Maybe I'm missing something but that doesn't sound like an issue to me.

Fiat500USA
09-12-2013, 12:08 AM
Do you have a set of those installed? If so, what setting are you using?

Yes, I'll have more about them on the blog, but I'm a big Koni fan for years. Konis out of the box are set up for a stock suspension and can be either softer or stiffer than stock shocks, depending on what the Koni development engineers determined was best. On the Koni Sports available for the 500, you can adjust the rebound settings to suit your preference. My preference in suspension setup is generally well controlled rebound, and not the slammed look. If the suspension is too stiff, it isn't going to work in the real world with the rotten north east roads we have here.

I installed the Konis one have turn stiffer than delivered because I also have lowering springs and wanted the rebound to keep up with the stiffer spring rate. Koni generally recommends installing the shocks on the softest setting and working your way up. The shocks aren't hard to take off and adjust, so that can be an option.

Fiat500USA
09-12-2013, 12:27 AM
"Just remember, many torsion bars are lower than any other undercar component...and a big piece of metal that can be snagged, bolted directly to your rear suspension, is something to be aware of. "

Are you saying that cars shouldn't have torsion bars? Or that the bar on a Fiat is too low? What I'm thinking is that even if you buy a larger bar than the stock Abarth bar, it adds maybe 5mm to the size of the bar, and assuming the bar is still centered the same, we're talking about the replacement bar being maybe 2.5mm lower to the ground.

Maybe I'm missing something but that doesn't sound like an issue to me.



This is the way I understand it. The car feels unstable when braking hard on uneven roads and adding a stiffer bar may not help because when one wheel hits a bump, the bar also effects the other wheel, and that is not really what you want. You want each wheel to stay in contact with the road and follow every nook and cranny.


http://youtu.be/RA0cKH0Z33k

AnthonyV
09-12-2013, 04:41 AM
This is the way I understand it. The car feels unstable when braking hard on uneven roads and adding a stiffer bar may not help because when one wheel hits a bump, the bar also effects the other wheel, and that is not really what you want. You want each wheel to stay in contact with the road and follow every nook and cranny.

Right, in the case of these car's more rear roll resistance will also translate into less wheel independence, which their isn't a lot of anyway since it'a a beam suspension. The larger the torsion bar, the more vertical force makes it to both wheels. But again, while that doesn't help with our wiggle under braking, there may still be benefits to the larger bar. The added roll resistance may still be beneficial under cornering load. And, if we have a damper that can better control wheel movement, they should be able to help us out with that as well.

The ideal suspension is one that is compliant enough to conform over road imperfections, and keep the tire's contact patch as uniform to the ground as possible under all types of loading, but........also be firm enough to control chassis motion (roll dive etc....) and keep any one end or corner from getting over loaded and overwhelming the tires. An easy enough idea, but much, much, more difficult to achieve in practice haha. Especially for a road car that has to meet a really diverse set of needs.

You mentioned the Koni rear's. That could very well lick the little problem we've been discussing here. Would be interesting to see somebody that has a set see if they've eliminated the "wiggle". I also like Koni, and have had good luck with getting the results I want with their stuff in the past. I'd say the dampers I've had my eye on though have been those B14 Bilstein's. Bilstein make a fine damper, and usually they also have a option to get their dampers as just a normal fixed perch strut. I probably would have gone with a set of those and the stock NA Abarth springs if they made them. I know they have the coilovers, I just wish we knew what the rates we're. I like the stock spring rates. I haven't measured to get the cars motion ratio, so I don't what wheel rate we're seeing, but just feel wise I think the engineers did a good job of not going much higher. I suspect the stock rates are right at just about the peak of what you would want for a street tire. Any more rate might have also ended up with a suspension frequency that might be on the harsh side even for a enthusiast.

DuckDodgers
09-12-2013, 11:58 AM
"Just remember, many torsion bars are lower than any other undercar component...and a big piece of metal that can be snagged, bolted directly to your rear suspension, is something to be aware of. "

Are you saying that cars shouldn't have torsion bars? Or that the bar on a Fiat is too low? What I'm thinking is that even if you buy a larger bar than the stock Abarth bar, it adds maybe 5mm to the size of the bar, and assuming the bar is still centered the same, we're talking about the replacement bar being maybe 2.5mm lower to the ground.

Maybe I'm missing something but that doesn't sound like an issue to me.

What I'm saying is remember that installing an item on the bottom of the car is something to think about.

As for your example, you would want to consider each model on it's own merits and measurements. There is no assurance that each bar is centered up on the same position, therefore back of the envelope calculations (e.g. 5mm/2=2.5mm lower) are suspect. Some bars use alternate mounting or non-centric design.

I'm just saying that if you lower the clearance on your car, you might have problems. For example, slam the car with lower shocks and springs and then put on a bar that's quite a bit thicker, and suddenly you have a lot less clearance than you might expect from the specifications.

Onto the other point made...a larger anti-sway (or torsion) bar will flatten cornering attitude, but might actually increase wheel hop or wiggle in a high speed panice stop. You are tying the two rear wheels together with a thicker piece of metal, making them react in a more uniform manner...if the handling you are complaining about is caused by the wheels wandering, will it be better or worse with the wheels locked together?

Indie500L
09-12-2013, 12:10 PM
Might be a good idea to test to see if it was the ABS kicking in at high speed that caused the wiggle or in fact some tire / traction issues. If the front tires were locking up and releasing then it would cause the wiggle and have nothing to do with the back end at all.

Vlavsky
09-13-2013, 07:44 PM
I drove by the site of this incident today. The road is actually fairly smooth. After reading all the replies I came to the conclusion that it's just a weight distribution issue as many have mentioned. I still think that a stiffer suspension set up would at least eliminate some of that wobble. Am I the only one tsht thinks the stock set up is on the softer side?

redred
09-13-2013, 07:59 PM
Yes I believe a better suspension setup, especially the rear, would help

Abarth Five O
09-13-2013, 09:04 PM
64/36 nose heavy weight distribution and high COG makes this platform tippy w/ roll over tendencies at high speeds. I agree, a combination of improvements, including suspension upgrades, would significantly improve this tendency, but good wheels, tires and tire pressure should not be overlooked. I know when I replaced the stock 17" wheels and P zeroes w/ NeuSpeed wheels, Falken Azenis tires w/ the correct tire pressure, it greatly improved handling at low and high speeds and made the car feel much more planted and stable.

AnthonyV
09-13-2013, 09:12 PM
I drove by the site of this incident today. The road is actually fairly smooth. After reading all the replies I came to the conclusion that it's just a weight distribution issue as many have mentioned. I still think that a stiffer suspension set up would at least eliminate some of that wobble. Am I the only one tsht thinks the stock set up is on the softer side?

Stock spring rates are 195/210. Stock Abarth weighs about about 2500 lbs, by comparison looking at a stock Subaru STi that weighs 3,384 lbs and has stock spring rates 188/173 (also a performance car keep in mind). The FIAT which is nearly 900lbs lighter, yet still has higher spring rates. Granted both car's have different motion ratios and weight distribution, but just for comparison sake, the Abarth is hardly a softly sprung car for it's weight. Especially for a road car! For driving enthusiasts, this is good news. It basically means the manufacture took care of that part for us.

Again the problem that I'm seeing (and it's just barely a problem at that) comes from what I think is probably a tid bit soft low speed rebound in the rear's. The car's came with damn good dampers out of the box, but it's in this aspect I think there's a little room for improvement. I think better dampers would help tame just about all the little bit of nervousness the car's handling has.

Fiat500USA
09-13-2013, 11:22 PM
The 500e feels better, a benefit of the 600lbs battery and 57/43 weight distribution.

Abarth Five O
09-13-2013, 11:50 PM
The 500e feels better, a benefit of the 600lbs battery and 57/43 weight distribution.

Perhaps I should add some ballasts in the rear end? lol

jguerdat
09-14-2013, 07:31 AM
Trailer hitch! :-)

FTY
09-14-2013, 10:33 AM
Its a combination of things, including a higher stock COG/weight dist, rear dampers/wheel frequency as stated prior. To stabilize/lessen this it will be a combination of things. Lots of people have great results from the performance rear struts and Coilovers. Springs will help to a degree but is not the answer to the equation but can be part of it. I don't have this issue....rough pavement in a turn, the car is much more stable than stock(this was my main concern). Straight line panic braking I still do get a twitch from the rear but it is less than in stock form.

http://www.racingaspirations.com/apps/wheel-frequency-calculator

This is pretty interesting, as you play with spring rate you can see the effects of the wheel frequency cpm.

http://www.racingaspirations.com/apps/weight-distribution-calculator

No means an expert at all...but find this stuff really interesting, really like how this stuff equates to real world performance.

MAZ
09-16-2013, 11:44 AM
Perhaps I should add some ballasts in the rear end? lol
a spare tire.

NORCAL SS
09-16-2013, 06:43 PM
Wilwood brakes fixed all of my problems with braking.

James Hunt
09-16-2013, 07:03 PM
Wilwood brakes fixed all of my problems with braking.

Same here

shagghie
09-16-2013, 07:27 PM
I fixed mine as soon as I got rid of the stock rubber. The Direzza ZII's don't exhibit any of the twitchy ESC induced madness when breaking from 70mph+ quickly. The car is about as planted as any car I've ever driven, and certainly better than all of the VAG cars I've been driving and modding since late 90's.
I'm also running Neu-F springs and Koni yellows in the rear, as well as the rear torsion bar...so it is a whole different ballgame now.

I originally had some low-grade C.O.'s on the car but I still had the twitchy feeling breaking hard because I was on the stock rubber still. Once I went to ZII's and the springs/koni's ... everything is completely dialed out. Hope that helps!

SeaDawg
09-16-2013, 09:00 PM
Same here

Do you happen to be exceptionally mechanically inclined and installed the Wilwoods yourself or did you get someone to do the work? If someone else, who? The box with my front set is in my entryway and hopefully the rear set will be here soon.

James Hunt
09-16-2013, 09:06 PM
Do you happen to be exceptionally mechanically inclined and installed the Wilwoods yourself or did you get someone to do the work? If someone else, who? The box with my front set is in my entryway and hopefully the rear set will be here soon.

A novice could do it.

Crazy Otto
09-18-2013, 09:36 AM
Street cars come with heavy bias to front for braking power. I suspect this is the issue. If I end up keeping the abarth (just bought a e46 m3 ) I may try to source more aggressive rear pads. Brake proportioning valve a more complex fix. The wilwood kit fixes the issue by the same fundamental principle.

ripper
09-18-2013, 01:49 PM
Street cars come with heavy bias to front for braking power. I suspect this is the issue. If I end up keeping the abarth (just bought a e46 m3 ) I may try to source more aggressive rear pads. Brake proportioning valve a more complex fix. The wilwood kit fixes the issue by the same fundamental principle.

I agree. Brake biasing is a good point that should not be overlooked as a means to improve the braking on our little Abarths. The Abarth appears to have its braking power naturally biased to the front. I am not an expert on the best solution; but, as with any track or race car, brake biasing (to attempt to transfer more braking force to the rear of the car) can be aimed at obtaining increased braking force while still getting the car to track straight when in straight line threshold braking situations (e.g., prior to entering a corner at high speeds). I put my Abarth (with all stock suspension and original P-Zeros) on the big track (High Plains Raceway, 2.6 mile road course) a couple of weeks ago. I was studying the track prior to putting our race car out (a modded RX7 with RWD). Felt the same "wiggle" tendency on a number of occasions with the Abarth when I came in too hot and set the brakes too hard coming into a corner--especially the downhill corners. The track surface was very smooth and the "wiggle" was managable but unsettling (to me and the car). As I put in more laps, I found that I had to pay attention to keeping the fore-aft weight shift under braking (i.e., to the front of the car) from getting excessive (e.g., by squeezing down on the brakes a bit slower at the onset of braking, and gradually increasing brake pressure to threshold as my speed decreased) in order to minimize the "wiggle" and get throught the corners faster. This kept the car more settled under braking and more planted entering the corners. With our race car, we have the brakes biased more to the rear and I get no such "wiggle" tendency in the car at all--even with higher entry speeds and even harder braking than with the Abarth. While this is the goal, brake biasing can probably only achieve somewhat of an improvement on a front wheel drive car (with a proportioning valve and/or alternative front and/or rear brake combinations). Braking in the Abarth can likely be improved with some rear-biasing, but only to the point where too much rear bias begins to reduce the overall braking capacity of the car, since the resulting reduction in weight on the rear tires under hard braking will only lock them up if the fore-aft weight shift is still too excessive for the bias setting. May be worth playing with though to see if this can be optimized to obtain higher overall braking performance, as lower lap times would be worth it. Finding the optimum with brake biasing may become even more feasible when combined with the other reasonable options being discussed in this forum (improving shocks, tires, etc.). In the meanwhile, I have installed a stiffer torsion bar on the rear and a set of stiffer vertical chassis braces on the front to see if this helps (although this was primarily aimed at improving cornering). Also, I am planning to change to the Direzzas as soon as I burn up the Priellis. I will report after my next track experience. But I may be looking at the brakes next....

Abarth Five O
09-18-2013, 02:37 PM
I agree. Brake biasing is a good point that should not be overlooked as a means to improve the braking on our little Abarths. The Abarth appears to have its braking power naturally biased to the front. I am not an expert on the best solution; but, as with any track or race car, brake biasing (to attempt to transfer more braking force to the rear of the car) can be aimed at obtaining increased braking force while still getting the car to track straight when in straight line threshold braking situations (e.g., prior to entering a corner at high speeds). I put my Abarth (with all stock suspension and original P-Zeros) on the big track (High Plains Raceway, 2.6 mile road course) a couple of weeks ago. I was studying the track prior to putting our race car out (a modded RX7 with RWD). Felt the same "wiggle" tendency on a number of occasions with the Abarth when I came in too hot and set the brakes too hard coming into a corner--especially the downhill corners. The track surface was very smooth and the "wiggle" was managable but unsettling (to me and the car). As I put in more laps, I found that I had to pay attention to keeping the fore-aft weight shift under braking (i.e., to the front of the car) from getting excessive (e.g., by squeezing down on the brakes a bit slower at the onset of braking, and gradually increasing brake pressure to threshold as my speed decreased) in order to minimize the "wiggle" and get throught the corners faster. This kept the car more settled under braking and more planted entering the corners. With our race car, we have the brakes biased more to the rear and I get no such "wiggle" tendency in the car at all--even with higher entry speeds and even harder braking than with the Abarth. While this is the goal, brake biasing can probably only achieve somewhat of an improvement on a front wheel drive car (with a proportioning valve and/or alternative front and/or rear brake combinations). Braking in the Abarth can likely be improved with some rear-biasing, but only to the point where too much rear bias begins to reduce the overall braking capacity of the car, since the resulting reduction in weight on the rear tires under hard braking will only lock them up if the fore-aft weight shift is still too excessive for the bias setting. May be worth playing with though to see if this can be optimized to obtain higher overall braking performance, as lower lap times would be worth it. Finding the optimum with brake biasing may become even more feasible when combined with the other reasonable options being discussed in this forum (improving shocks, tires, etc.). In the meanwhile, I have installed a stiffer torsion bar on the rear and a set of stiffer vertical chassis braces on the front to see if this helps (although this was primarily aimed at improving cornering). Also, I am planning to change to the Direzzas as soon as I burn up the Priellis. I will report after my next track experience. But I may be looking at the brakes next....

Good point. I was planning to upgrade the front w/ Wilwood BBK, but will instead upgrade all rotors, brake pads, and lines for the front and rear. Direzzas are also an excellent choice.

Robert Nixon
09-18-2013, 03:11 PM
thanks for the comments above on your real track experience, that is certainly more useful than hitting the brakes on a freeway!

But, on a street car, HOW do you bias your brakes front/rear? As far as I know there is no built in way to do it like a F1 car or whatever.

I've read one tip where for track or even autocross you might affect the Front/Rear bias by say putting top of the line pads on the rear and medium line pads on the front, in an effort to increase braking in the rear! That at least is understandable to me, and since it was in a book I'm sure it works!

My interest in brake performance right now is based on autocrossing this year, so if there was a simple way to drop times by better braking running stock, then that would really get my interest!

EDIT: Just went back and caught what Crazy Otto said, so sorry for repeating his comment about pads!

Crazy Otto
09-18-2013, 03:49 PM
Robert As I mentioned you can look into rear pads with more bite more friction.

Ripper - agreed that more rear bias only goes so far to reduce stopping distances. The issue being addressed is the back end wanting to overtake the front end.

All street cars have enough brake power to overcome tire traction. If you want to shorten braking distances then you have to increase tire grip. Only in repetitive applications of max brake will a typical car run into difficulty with brake fade due to thermal overload. I run stock calipers rotors with race pads motul600 and stinless lines on my race car and they are fine even without ducting. But car weighs 2700 lbs only.

In general there is a lot of focus on brake power for race track but the typical driver will do much much better by attention on how the brakes are released and carrying more speed through the corner. Where the abarth is concered you will gain very little by the increase in max retard Going to a bbk. Pedal feel thermal management and esthetics are separate considerations.

ripper
09-18-2013, 05:44 PM
Robert As I mentioned you can look into rear pads with more bite more friction.

Ripper - agreed that more rear bias only goes so far to reduce stopping distances. The issue being addressed is the back end wanting to overtake the front end.

All street cars have enough brake power to overcome tire traction. If you want to shorten braking distances then you have to increase tire grip. Only in repetitive applications of max brake will a typical car run into difficulty with brake fade due to thermal overload. I run stock calipers rotors with race pads motul600 and stinless lines on my race car and they are fine even without ducting. But car weighs 2700 lbs only.

In general there is a lot of focus on brake power for race track but the typical driver will do much much better by attention on how the brakes are released and carrying more speed through the corner. Where the abarth is concered you will gain very little by the increase in max retard Going to a bbk. Pedal feel thermal management and esthetics are separate considerations.

CO:
Agreed, the issue is certainly the back end wanting to overtake the front end under heavy braking.
I think that we agree that an improvement to rear brake stopping power, relative to the front brake stopping power, would only help reduce this tendency. Assuming that the tires are the same front and back, regardless of whether they are street stock or stickier racing tires, the situation would still require stronger rear braking relative to the front brakes to attempt to reduce the tendency of the back end wanting to overtake the front end. (In my experience I had no signs of brake fade with the Abarth on the track, and yeah, the Pirellis are part of the problem in my opinion.)
Agreed that rear brakes with more friction appears to be the most obvious way to make an improvement of the car's handling under braking. This would be far easier than putting in a proportioning valve to separate the front brake lines from the rear brake lines so as to adjust the relative input to each from the master cylinder. (Although the latter is easier to tweak to taste after the mod.)
Agreed, if you want to shorten braking distance you have to increase tire grip.
Very much agreed that the best way to decrease lap times is to concentrate on carrying more speed into and out of the corner by attention to how the brakes are engaged and released. It would be nice, however, if the car didn't have the tendency for the back to overtake the front when I get a bit too aggressive or inconsistent--which appears to be happening even when I am not losing tire traction under braking. As you mentioned, braking power is otherwise generally overrated (or, at least a much lesser factor) as a means to go faster on the track.
I am still on the fence on what I will do, if anything. All of the input from the forum is helpful and encouraging. I think I'll wait and see what the stickier tires do to my braking performance (and car stability under braking) before I commit to a plan. I am expecting that the stock Abarth will still have plenty of braking force to overcome tire traction with the Direzzas, unless others on the forum have experienced otherwise.

mjanowich
09-19-2013, 04:55 PM
K so I was driving kind of fast the other day (90-95) when someone going the speed limit (50) decided to switch lanes. Long story short I had to brake pretty hard and it scared the **** out of me. The car felt so wobbly and just unstable. I was extremely dissapointed by this experience and to be honest don't feel very confident behind the wheel anymore. Is this normal? Has anyone else experienced thks? Hoping there is a quick fix for this (lowering?) Thanks

As others have said, upgrade the springs to something with a higher spring rate to help control the weight transfer from back to front. There are other ways to control front/back weight transfer but springs would most likely be the cheapest. A little toe-in on the back wheels may help too.

Robert Nixon
09-20-2013, 09:49 AM
I'm not a physicist, but I read an entire book on braking, and one of the points they made is that changing the energy (heat) of forward motion is what stops the car, basically the ability of the braking system to absorb and get rid of the heat from braking. So while tire grip, pad performance, rotor interaction, etc are all factors, the biggest limitation is on having enough MASS in the system (rotors mostly I guess) to dissipate the heat.

I'm not arguing either way since I'm not a scientist or in Formula 1 and NASCAR, but that's what the book was talking about.

TubeDriver
09-20-2013, 02:30 PM
I was at Summit point last weekend.

Braking and especially trail braking is somewhat twitchy feeling.

A couple points to consider.

Mass and ability to absorb heat has nothing to do with this. That only is important on the track with repeated braking and relates to the vehicles ability to repeatedly brake without experiencing pad fade, cracked rotors and/or fluid boiling. On the street you will probably never have this issue and it has nothing to do with twitchy feeling.

Increasing rear pad friction (adjusting brake bias towards the rear) will generally increase the chances that the rear will rotate. However, it is not that simple because with the lose suspension in the Abarth, weight transfer during braking also plays a role and increased rear bite might reduce forward weigh transfer.

Couple easy suggestions to fix lose feeling under threshold braking include:

1) alignment (zero or slight tow in at the rear)

2) sticky tires will increase grip/traction in general and may reduce instability. Of course, sticky tires are also going to increase braking power and increase weight transfer forward which is not what you want to do.

3) Suspension changes (shock and springs). Rear swaybar should not really do much here unless you are trail braking.


I found the stock pads completely inadequate for track use (no surprise here). I got 4 laps before experiencing some fad, when I pitted in they were smoking terribly. Probably should have done longer cool down lap. Pad material was smeared all over the front rotors. Rear pad/rotors look fine. I generally never use street pads at the track but CarboTech has not yet made pads for the Abarth. Need to pull them and get some pics so they can start making these.

My short term plans are better tires and track pads. The twitchy feeling might feel a little weird but the car generally does not want to rotate (even with the Neuspeed bar). I think that a short wheel base, narrow car with a high center of gravity is just never going to be the beast braking or handling car.

satural
09-26-2013, 09:07 AM
"Increasing rear pad friction (adjusting brake bias towards the rear) will generally increase the chances that the rear will rotate"
"I think that a short wheel base, narrow car with a high center of gravity is just never going to be the beast braking or handling car."

I completely agree with above statements

I would expect that the reason of instability is just proportions (wheelbase vs track + height) and probably soft rubber bushings (you may improve it a little - at least in theory - changing into polyurethane one or uniball type, at the cost of comfort)