So today I stumbled across a big empty parking lot to practice some "emergency maneuvers..." yeah that's right... "emergency maneuvers." Haha anyway I noticed that my car under steers badly on sharp turns at higher speeds.

Lets say I'm doing about 35 mph and I take a sharp left, I jab the brakes at the last moment and then punch the gas to [hopefully] kick the rear end out. Instead all I got was my front tires screaming and my tail barely kicked out.

And while my front tires were screeching like mad, the whole car was vibrating very badly; almost like a very rapid shaking. And I noticed that my sidewalls are showing wear about 3/4 of an inch from the outer edge or the tire and the little "hairs" at the outer edge are almost gone too.

I checked the tire pressure and they were each about 34 psi at the gas station pump; less than a minute after driving normally for about 15 minutes. I put in a few more pounds to compensate for the warm tires.

I only got to try again once since I got chased out by some angry little Chevy Cobalt that came flying out of nowhere. Not sure what his problem was but the whole parking lot is already covered with tire marks... probably from stupid kids like me lol. Although it was hard to tell, I think I MIGHT'VE felt a slight improvement after adding a little air... I might be wrong though.

The car is a 91 Trans Am WS6 convertible with a rebuilt front end with about 2000 miles on it. Stock specs with KYB GR-2 struts and all Moog steering links and ball joints. The tires are also new Riken Raptors with the same mileage. LB9 engine, 700r4 trans, and stock 2.73 (worn) posi rear end.

I'm thinking of getting a wonderbar for my car though. You think that might affect this? And were WS6 Trans Ams supposed to come with those from the factory?

Maybe I just sound like a total idiot since perhaps I was doing something terribly wrong with my driving but I'm still learning and I'm still not sure what to expect! Thanks guys!

 

what tires and what condition, how old?

if the car oversteers, you can increase the rear bar size, or decrease the front bar size, or play with spring rates, ect.

the front strut mounts are rubber, and make the front end sloppy, and other things. Sounds like the tires are rolling over a bit, probably combined with other older parts that need replacing.

not totally sure what you were doing, but turning, stabbing the brakes, then the gas can upset the car and make it react poorly.

 

"The car is a 91 Trans Am WS6 convertible with a rebuilt front end with about 2000 miles on it. Stock specs with KYB GR-2 struts and all Moog steering links and ball joints. The tires are also new Riken Raptors with the same mileage. LB9 engine, 700r4 trans, and stock 2.73 (worn) posi rear end."

I doubt that worn parts could be my culprit, since I replaced everything in my front end that's usually replaceable, except for the control arm bushings (where they connect to the k-member) and springs.

And rubber strut mounts? I replaced those too and they seemed pretty metallic to me, then again I didn't inspect them very closely when replacing them.

And what I was doing was this:

35 mph in a straight line, then stab the brakes, turn, and punch the gas during the turn.

 

yeah, sounds like somebody needs driving lessons.. lol

you're car doesnt exactly have the power, nor the gearing to overpower the grip it will have..and kick the rearend out..

that said, stop driving like an idiot before you hurt yourself, or others. take it to a track, go through some lessons, and put the car on a REAL track.

 

It was a huge empty parking lot like I mentioned earlier... Jesus. I don't do this on the road.

 

I know that the car is kinda underpowered, especially with those highway gears but I thought it was weird how the car would just understeer like crazy. I assumed that pegging the brakes would result in the weight falling forward, taking some of the weight off of the rear end while the nose dipped down and then as a result the rear end would swing out easier.

 

The following is from How to Tune and Modify your 1982-1998 Camaro by Jason Scott. Though the quote deals with slow speeds, I wonder, since your front tires were screeching and the car was shaking (your car, BTW, wouldn't be equipped with a Wonderbar) if this is what you're experiencing:

"The problem stems from high forces transmitted from the steering box to the chassis, especially under low-speed cornering, such as when maneuvering around a shopping mall parking lot. Fat performance tires present a great deal of resistance at low speeds, which imparts considerable stress into the steering system, and ultimately attempts to rip the steering box from its mounting surface--especially during "full-lock" turns, where steering torque is greatest. Over time, these forces weaken the chassis surface around the steering box and can result in torn metal.

"Whether the chassis is weakened or torn at the steering box, the result is the same--steering actions are delayed while the chassis flexes, leading to unresponsive and erratic steering. Ironically, though the damage stems from low-speed steering, the resulting problem is far more serious at high speeds than low ones.

"It is possible to repair the damaged area, though the best solution is to avoid the problem in the first place by installing a brace [Wonderbar] that reinforces the steering box mounting area."

JamesC

 

Thanks James! More reason for me to try that wonderbar. That explanation kinda makes sense, but I wouldn't consider what I was doing to be "low speed."

And guys, check this video out:
http://www.youtube.com/watch?v=E6Z63CyMCrU
At around 3:07 the host said "hit hard on the throttle in a corner, and the tail breaks loose easily." Granted, that car was a 5-speed but I don't think that the difference would be that big. If I'll do the same in mine, the car will just go straight regardless of where the front wheels are pointing.

 

That aint right... if you dont have a wonderbar and are trying to make the car handle in any way, you are going to destroy it.. Install this steering brace (aka wonderbar) immediately. As James quoted above, it will tear the area around the steering box and you don't want cracks there because it will take alot of work to fix a cracked frame. I have the TDS one, it seems to be the most compatible with most cars.

 

the narrator of that video put me to sleep.

your gears are whats's keeping you from kicking the rear end out.
You have so much weight pushing forward and the 2.73 gears are causing the back tires to grab and just causes to much understeer.

 

Maybe I'm misinformed, but I thought most cars come from the factory with under steer so it doesn't "J" hook and spin out of control.

Experimenting like you're doing can be done on a more slippery surface like a dirt track with crappy tires. That way you get the idea of the way it will handle at slower speeds with less stress on the car. Either way, I wouldn't hit the brakes after going into a turn. That seems to be the makings of a roll over. Jacking the brakes and throttle like that aren't really going to teach you anything either as far as I know.


Yes, I believe a WS6 should have come with the wonder bar. If it doesn't have it, then you should also verify the sway bars as well. The insides of the strut mount are rubber, it's in-cased inside the metal shell.

 

Only IROCs were originally equipped with the Wonderbar.

JamesC

 

musclecar70sfan, go out to the parking lot after or during rain. The wet surface will make it easier to slide the car around, and at lower speeds. This is better for the initial learning process.

RBob.

 

As I said earlier, I jabbed the brakes before the turn while still straight. And how can I flip this car anyway? Maybe if I hit something... I don't think too many have flipped their thirdgens on a smooth surface.

Good idea... I'm gonna go get that wonderbar too.

 

Really? I was under the impression that the performance components were identical. Is this also for the 1LE as well?
Thanks for the info BTW.

 

When I read the second quote it looked like you were hitting the brakes after initiating the turn.

Edit: I'd never be overconfident that any car is incapable of rolling over. A higher performance vehicle only allows the driver to put the car in a situation of more potential energy.

 

My bad, I should've been a little clearer... sorry!

 

That's what I was thinking too. I started to get worried since my car is a WS6 according to compnine lol.

And what are you thoughts on this? I'm guessing a wonder bar is a wonder bar but just thought I'd ask. Decent price?
http://www.summitracing.com/parts/UPI-2030-B/

 

The cheapest I've found is a stock one through here, Ebay, Cl etc. I haven't looked for a while but you should be able to find a stock one for $20 give or take depending on how long you have to find a good price.

WS6 should be on the RPO list on the inside of the center console glove box or the rear locked compartment on the drivers side.

 

Oh ok, I know a guy with a ton of third gen parts so I'll give him a call. And my RPO sticker was missing before I even got the car a year ago... good thing I found compnine!

 

Ahh good thing you were able to find the info then!

Sounds like you have a nice ride, a rare convertible with high performance options.

 

I think those are the biggest contributing factors for why your rear axle won't "kick out". Lack of power and lack of gearing & good posi.

If you try just a standing still brake stand (burnout) can you light up both tires?

 

Thanks! The funny thing is, when I was looking for a third gen a year ago, I was expecting to buy a t-top car. But I stumbled across this 91 'vert on the board! And initially I didn't really like the 91-92 birds but for some reason I just fell in love with this one and the rest grew on me a lot. It was a little rougher than I would've liked, but I took the leap of faith and now have no regrets. And you know what else? The PO was trying to sell it for a year. I though that this car would've been gone in a couple weeks.

Yeah, only if its a good clean surface. It'll do a peg-leg if one tire has a little more traction than the other.

 

Here is a spinout with my race tires on, jump to 25 seconds to see it,
http://www.youtube.com/watch?v=Kxy2NZ8Sh_k

and here is an in car spinout, jump 55 seconds to see it since it is really shaky,
http://www.youtube.com/watch?v=R1e5_v3kVZg
oh and if you watch it, at 30 seconds the car is pushing real hard so I had to throttle it to kick the rear out.

I like this vid of me spinning out,
http://www.youtube.com/watch?v=0GAKToH464U

I had 315/35/17 tires up front that I was testing that day. 275/40/17 were in the rear.

 

hahaha that looks like fun. I gotta try autocross sometime.

 

Sounds about right. These cars, like many, understeer significantly from the factory. If you are going fast enough and crank the wheel as much as you can as fast as you can in one direction the car will continue straight. With the wheels turned to the side the tires are no longer rolling but rather they're sliding and thats the noise and shaking you experienced. I'm going to call that completely normal behavior for a V8 thirdgen. Next time you're out messing around and it does that, turn the wheels slowly back to straight and you might find the noise vanishes about the same time the car decides to turn. Do what you can to reduce the understeer issue and it will help. And as far as power and posi and gearing helping to kick out the back end, I have a small truck with less power than an Iron Duke with an open diff but I guess you could argue better gearing and I can overpower the back tires in a turn fairly easily in fact I did just that about half an hour ago with it (not the first time). There are a lot of factors involved in it (like how sticky your tires are), but the right amount of throttle and steering angle and you should have no problem sending the back sideways.

I too think you should wait for a rainy day and hit the same parking lot again. Wet pavement is going to make sliding a lot easier, and easier on your car and tires too. Just dont hurt yourself or your car... or anyone else.

 

Something to think about........... a tire can only do 1 thing at a time and give it's best performance. If you are still braking and start turning, the tire must comprimise and do both partially. This is one reason that you can cause understeer under heavy breaking.
For the best cornering, do not add brake input. For the best stopping grip, keep the steering wheel straight.

If you do have the wheel turned sharply to one side under extremely heavy braking, and then let off the brakes, the sudden restoration of total turning capability could cause the car to quickly "dart" to that side, maybe roll the tire off the bead, dig the rim into the ground and possibly cause a rollover. This would be much like a "highside" on a motorcycle.

 

racecars are on the brakes as they begin turning into a corner all the time. Neither of which inputs is extreme. Even if you are trying to hang the rear end out, you need to enter a corner under control...let the front end stick. Then, stand on the throttle. Probably, as stated, going to be difficult with the 305 and 2.73 gear.
Typically the lighter end of the car will stick better. The weight will push the heavier end in a straight line. Front end heavy (in our case, especially with a v8), car is more likely to understeer. Rear end heavy, oversteer will be predominant.
One thing that, surprisingly, hasn't been asked...what size tires are you running?
Not sure what you meant when you said you added some air pressure to compensate for warm tires... as they build heat, they build air pressure.

 

There's finite traction available, if you're braking as you enter a turn, it isnt much. Even if you're trail braking, the inputs are pretty delicate.

 

My cousin can debunk that myth. He was on a dry road missed the road going to his house. He made a hard left turn and rolled the car 4 times! The T-Top stayed in place too. You can roll any car under the right conditions and they may be without warning!

 

Stock size... P245/50R16
And what I meant by that was that I checked my pressure and it was reading a little low, at least for being warm (about 32 psi) so I added a few more pounds since 32 psi is the cold pressure if I'm not wrong.

Holy crap that's nuts. Was he ok?

 

He walked away with just a few cuts. Actually he walked to his house and called a wrecker to get the car. It was an IROCZ the totaled I'm not sure of the year.