SUSPENSION PROBLEM? Rear is breaking loose at high speeds.

[blackbombshell95]

Why does the rear of my car break loose? I mean, when i'm taking high speed turns and gunning the throttle and as soon as i release the throttle the rear of the car breaks loose.

 

Now one time it got so out of control that i slid several feet. I was going on a free on ramp. Its one of those on ramps where you drive in a half circle to get on the freeday. I got up to 50 when the posted speed limit was 20. As I finished the turn at 50mph and released the gas and the rear end broke free and starting to slid to the left. I immediately turned my steering wheel hard to the left to gain control. Luckily i gained control and didn't kill anyone. I almost went into the right lane of traffic.

 

While i have the gas down to the floor in a turn its fine. But as soon as i release it, it looses control(when i finish the corner). What is happening is that i'm putting too much power down in the turns, when I feel that i'm putting too much power down and release the gas the rear brakes free and starts to slide.

 

Now I have one concern with the rear addco sway bar. The outer bushings that come with the bar doesn't snug the bar down. The rear bushings/brackets are nice and tight. I'm using the monte carlo 22mm bushings there with stock center brackets. Real tight fit there. But it seems that the outer sway bar bushings aren't right. That is the only thing I can think of there.

 

 

Mods are: Note: less than 15k on everything below

KYB strut mounts

KYB GRII struts. all 4 corners

RSM front and rear strut tower bars

ADDCO rear swaybar with custom center brackets

245/50/16 fuzion ZR tires

ffp dogbones

FFP coilovers #250 springs

Front ST-lowering springs

GMPP rear trailing arms

[Prospeeder]

its because of understeer i think, when u let off the gas, the speed lowers, and it hits right in its little band where its right below understeer and it will turn too sharp and skid would be my guess, or mabye ur rear tires are worn, or mabye when it says 20 u dont go 50 wbodies arnt THAT great

[Justin]

When you are on the gas the weight is transferred more towards the rear. You let off the gas and that momentum goes over the front tires, your rears lose traction and they slide. My CS does the same thing, FE3 suspension, totally stock except for a front strut tower brace.

[Prospeeder]

When you are on the gas the weight is transferred more towards the rear. You let off the gas and that momentum goes over the front tires, your rears lose traction and they slide. My CS does the same thing, FE3 suspension, totally stock except for a front strut tower brace.

 

that makes more sense

[mihela816]

Those magazine articles from the other day mentioned the drivers being able to induce oversteer by letting off the throttle. It's probably even more possible with the upgraded components we have available today.

[AWeb80]

dang corey, i have everything yoiu have except my tires are 235/50's, not 345/50's...but they are 18's so that might make difference....

 

I've never had that problem.

[blackbombshell95]

My tires are brand new. Sticky as hell. hmm. I hope it is just the sway bar

[GnatGoSplat]

Addco rear sway bar is the cause.

The rear is staying too flat, causing the tires to break loose. The Addco adds oversteer which is what you're experiencing.

[bartonmd]

The anti-roll bar and strut tower braces are the cause... They make a car handle better on COMPLETELY smooth surfaces, like a racetrack, but make it handle mid-corner bumps worse, so in the real world, if you go too stiff, it'll handle worse than stock... stock vehicles of all kinds have what is called "tuned flex" which you are messing up when you mess with the suspension...

 

Mike

[blackbombshell95]

I think i might try to downgrade my sway bar to the lumina police bar. which is 3/4'' wide.

 

 

 

Also i have a Frame guy who owns a nice shop by where I live. He builds race cars and cars for autocross. He is going to test drive my car and adjust my camber and toe for autocross. For a price of course.

[bartonmd]

I'm suprised nobody's said this yet, but: SLICKS SUCK for the street! Reasons:

 

1. Slicks are made of different compounds than street tires... Street tires grip at "normal" temperatures, but slicks (and drag radials) only grip when the rubber is at VERY high temperatures (meaning they're as slick as snot at normal, street temperatures)... This is why you do a burnout to heat up slicks before a drag run, but burnouts do nothing for you on street tires. Motorcycle "squids" do this kind of thing all the time... in fact, I've seen 2 guys go down because they were on "race" compund tires that weren't all the way heated up

 

2. On a standard street tire, when you go over things like sand and small gravel, the tire slips until the sand makes it into the treads, or at least until the biting edges of the tire make contact with the road... With a slick, you have to slide completely out of the gravel before before it will gain any signigifigant amount of traction again: Unsafe.

 

3. Does it rain where you live? Ever tried driving in the rain on bald street tires? Try that, THEN consider that your tires are more cold in the rain than they are when the pavement is dry at the same temperature... Then see #1 above...

 

Get sticky street tires!

 

Mike

[blackbombshell95]

good point mike. i wasn't thinking lol. And i know all those things too. somebody slap me

[z34Phoenix]

[88Regal Limited]

What size rims? 15? 16? If so try Dayton daytona SR tires. My friend witha 1976 TA 455/4sp 50th anniversery. Beutiful car. (check my cardomain, page 6) His car is set up with koni springs/shocks/swaybars all around and routeenly take corners at over 100MPH with them. Give em a try. You'll like em.

[blackbombshell95]

if u noticed at the top, i have 245/50 on a 16. Fuzion tires. If you already don't know, the fuzions are the newer version of the Dayton Datona tires I believe. From Bridgestone.

[94CutlassSLCoupe]

If your car isn't a 3.4 DOHC...then i'm totally going to blame it on the rear sway bar. A 3100 car will have a 30mm front bar as opposed to a 34mm in a DOHC car. A stock rear one would be 12mm on a Non DOHC Car (if it had one) and 14mm on a DOHC car.

 

I have a 3100 Car with a front STB from a vert and a DOHC 14mm rear bar from a 92 Z34. I've actually had the backend kick out like you say but only in the extreme situation at an autocross event.

 

12mm~0.47"

14mm~0.55"

7/8" Addco=.875"

 

Clearly there is a lot of extra stiffness in the rear given by the Addco bar. I personally think it is too much for the car. The transverse leaf spring cars need much less rear bar than a car with the McPhearson Struts like a gen 1.5 or gen 2

[blackbombshell95]

does it matter if it is dohc or not? FE3 is what matters right?

[bartonmd]

I believe FE3 is different actual springs and anti-roll bars for the different engines...

 

Mike

[94CutlassSLCoupe]

My Dad's DOHC car is FE3 and FE9. I believe FE9 may be the 34mm front bar/14mm rear bar. We had an '88 FE3 Cutlass...only had a 30mm bar but it was a 2.8L, with the 12mm rear

[blackbombshell95]

I wonder if a larger front swaybar might help

[AWeb80]

A larger front will give you more understeer.....so ya, it might.

[94CutlassSLCoupe]

The super duper weight gain from having a 3.4 DOHC increases understeer too lol

[pwmin]

that's why if youre taking a corner and you think you're going to fast, don't let off. power through it. i had the same thing happen when i was on a windy road and hit a bump. car went way out of the turn and i thought i was going to lose it. luckily nothing happened and no one was coming.

 

without the leaf (w/ coilovers), you need a larger sway bar. this is what i am coming to believe after some thought and discussion. is the addco bar too big for a daily driver on crappy roads? maybe (sounds like it at least).

[blackbombshell95]

With the swaybar i have absolutely ZERO LEAN. even at high speeds. Maybe its too much.... I remember for the few weeks when i had the coilovers and the factory swaybar that the car would lean a considerable amount. I might try to downgrade to the lumina police bar. with is 3/4 i believe. compared to 7/8 addco

[pwmin]

if you do that, let us know how it comes out.