2edybrd

I was playing around with a Supra on some back roads the other day when we entered a rather hard sweeping turn at about 90. Visibility was great so we both saw the traffic up ahead with plenty of time to drift down to speed. HOWEVER, as soon as I let off the gas the rear end of the literally lifted up and became very unstable. As soon as I put some gas back into it, it tucked right in and was very stable.

Other than the slp kit I have on I also have poly rear LCA bushings as well as poly bushings and end links boith front and rear sway bars. front bar is 32 mm rear is stock. Oh, I also have a Global west Trac-link. What should I change to help with this floating at the limit? would a larger sway bar do it? Or maybe just a solid rear bar at the stock thickness?

NataSS Inc

iTrader: (9)

I think the trac link might be having some effect on that. I am not to familiar with it but if I remember right that is set up for straightline performance and doesnt handle side loads very well.

2edybrd

Actually, the Trac-Link took some of the problem away. Global west advertises it as an autocross and road course torque arm. I'm kind of wondering if this might just be a design flaw inherent in solid rear axles. I am hoping to eventually have a car that can handle auto cross style driving and raod course (these are the ranges of raods I drive everyday)

I guess you can't have it both ways.

If I go full on high speed cornering and control, I'll fishtail all over the really tight slow speed back roads, and if I go with an autocross type set up, I'll have control issues on high speed sweepers.

Cal

iTrader: (1)

It's your poly LCA bushings; those things bind-up under certain conditions. They aren't a problem for straight-line performance, but in cornering they can stick. Replace either the front or back with rubber (the stock ones or 1LE bushing work great.) Im not familiar with the trac link setup, but as NataSS said that can also cause problems in cornering, as can any really stiff LCAs. The reason is for your rear wheels to move independantly, the the LCAs must twist; therefore if you replace them with some that are very stiff, it can cause one rear wheel to leave the pavement. Yet another possibility would be if you have lowered your car; that messes up the angle of the LCA's until you install relocation brackets to correct this.

NataSS Inc

iTrader: (9)

I run my car in high speed events and have never experienced what you are describing. It could be a number of different things though. It almost sounds like when you let off the gas the car is nose diving on you making the rear end light.

but first of all at speed in a corner you should never make abrupt inputs into the cars stability, ie: totally lifting off throttle, hammering it, snapping the wheel or getting on the brakes. You should use steady throttle and smooth inputs. You should always "get your business done before the corner, not in it". So if this means waiting till your out of the corner tohammer the brakes thats fine. But lifting at speed will take weight off the rear end and make it dance a bit on you.

2edybrd

NataSS Inc. That is exactly what happens. Unfortunately I have to let off the gas quickly in the middle of a curve sometimes. So I guess I am just trying to figure a way to minimize that rear end float as much as possible. I'd hate to think what would happen if I had to slam on the brakes in that same situation.

titanium barchetta

Just buy a GT-2 Porsche and be done with it!

Eric 02z

A 911 will come around much faster if you lift mid-corner than the f-body.

Find a road course that hosts a Drivers Ed event, it will give you the chance to learn what to do and what not to do in those situations.

Never lift in a corner...

titanium barchetta

Are you ****** nutz?

I have driven a new turbo and you are incorrect my friend. It is one of the most stable cars I have ever driven through the twisties! If anything it has a slight push under power and neutral when lifting mid-corner.......if you so choose.

and your right, NEVER LIFT!

NataSS Inc

iTrader: (9)

As a suggestion, I would **** can the Level 1 suspension and upgrade to stiffer shocks and springs all the way around as well as put a larger front sway bar on the car.

If you are having to lift off the throttle quickly in a corner that means a couple of things
1) your entry speed was to fast
2) you picked the wrong apex into the corner and ran out of road on the exit
3) your on a public road and you about traded paint with someone else

On #2, 99% of the time the Apex of a corner is not where you think it is. The proper apex is usually MUCH later in the corner that most people would think.

And yes, slamming on the brakes in a corner at speed can potentially be a life threatening situation. On the road course last time I had a new RX-8 in front of me nail his brakes entering turn 2 at pacific raceways. I am normally coming off of turn 1 into turn to 2 around 140+mph. When he did this I was forced to dive into turn 2 WAY to early to avoid trading paint. Luckily he stayed high and I dove inside of him, but still had to be all over the brakes because I didnt get the right entry into the corner. It took everything I had to keep the car on the track. if I would have paniced and nailed the brakes the car would have more than likely spun off the track and into the very large fir trees on the side of the track.

mitchntx

iTrader: (14)

You are definitely over driving the car, if lifting is a must.

Slow in fast out is the rule.

With almost 2 tons and 400hp, all the neat stuff needs to happen when in a straight line, unless you are Joe Stud.

2edybrd

This is true. I need to slow down around here. There is just no such thing as empty backroads anymore. NataSS, you say a larger front bar. Does that help at all with nose dive? And I am saving up for a better suspension. Maybe Coil-overs are in the future.

NataSS Inc

iTrader: (9)

it will help with handling, but nothing willhelp if you enter a turn to fast.

Sam Strano

iTrader: (41)

The part about your lifting off the gas, and the car getting squirrely is telling. Like 99% of the stability issues with the 4th gen, it's a lack of rear rebound damping, and a lack of front compression damping..... I know you have Bilstein's, but the parts you have do have a lack (IMHO) of rear low-speed rebound damping, which is what's in play when the body pitches and rolls. Better rear shock damping will dramatically slow the pitch rate down, so it won't unload as quickly. As for the front, SLP takes 10% of the compression damping out of a standard HD shock, this also leads to more pronouned weight transfer..... however, the majority of the issue you want to fix is the rear shocks.

distortion_69

iTrader: (20)

I have had that happen too when lifting gas.. the rear gets sorta light and it feels almost like your either gonna go left or right, and you have to keep the car straight.. Because like it doesn't grip the curb anymore and it goes in the opposite direction usually of the curb your in. Then you have to try not to over correct because it'll scare you when it gets that light.

Sam,

How will setting up your damping in the rear so that this effect is lessened have an effect on a car that is used primarly for drag racing?

Thanks,

Sam Strano

iTrader: (41)

That depends.... I don't really think it'd have much bad effect, and very possibly do some good. More low-speed rebound would hold the tail down more upon launch and even on upshifts, which could very well hlep traction. Or the alternative is to run an adjustable shock so that you can turn the damping up or down @ will.

2edybrd

So, as far as shocks are concerned, go with a new set or just get my current ones revalved? The springs if I recall the SLP specs correctly, are progressive rates with 375 to 390 up front and 180-195 in the rear. Oh, by the way, Thanks for jumping into this thread Sam. Exactley the guy I was hoping to hear from.

Cal

iTrader: (1)

I have one word for you "Koni's!" They make more difference than you would think if you have never tried a set of them.

samz28

im not into racing, but my stock 65K 00 z28 suspension has this "flighty" feel when you gas it then let off, the suspension tends to go left or right. Something im not used to coming from german heritage.

Without compromising drag traction, what can be done to fix this? It's like i gas the car, then looking back to make sure ive got no one in the blindspot, then when im in the lane , i need a bit of correction. Mah bimmer certainly doesn't behave this way. I suspect its worn out suspension, but it appears others have seen this phenom. I'd like to retain drag capability, but have the car center without correction on an acceleration and let-off pass movement on the freeway.

What do you guys suggest? Again keeping in mind i dont want to sacrifice hook. I just ordered a strut brace, lca's, panhard, hoping it will Help some, but i suspect the suspension may be too "Stock" or the steering system is not very good quality.

Suggestions?

Rice Burner

I didnt really feel like reading through every post but, you unloaded your rear end, you probably knew that. when you hit the brakes, did you hit them very hard and sudden? like everyone says, try to get your braking done before a turn. drastic inputs, especially at high speeds are very bad. braking to the perfect entry speed on a turn will take some practice to figure everything out. everything meaning timing, proper entry speed, apex, when your brakes start to fade, when to start the turn...when you brake hard, less force on the rear end, so when you go into a turn it is very light like you described. stiffer springs may help. so the stiffer springs on the front will help prevent the force from transfering to the nose, and the stiffer in the rear will help hold the wheels on the road and help keep the force back there.