Mrmerlin

My 84 Euro with auto trans seems to want to wag its tail when under full throttle upshifts , almost as if the right wheel is toeing out, the back end is very unsettled, I had the car aligned and all 4 corners were IN the Green on the machine. It seemd to be doing this before the alignment as well.
I am wondering has one of the Weissack links failed or its worn to the point of flexing?
My 88 doesnt do this and the 84 still has the normal size tires all the way around 225/60-16.. Anyone with some thoughts or cures??.
All of the links are tight, the lower link pins are tight and straight. Shocks are good, ride height is good.

SharkSkin

Tire pressures even?

Mrmerlin

tires are all set at 36.
Dave this feels like the rear wheel is being defleced when the power is put to it.
I would really like to have somone drive the car while I watch the rear wheel from another car.
My guess is that there is something thats loose or worn

SharkSkin

Well, you've covered the obvious stuff... how about some less obvious stuff. Corner balance could be an issue if one tire has a lot less weight on it than the other. If you were around here I'd take you around the block to the 24/7 accessible public scale and weigh each wheel separately looking for gross issues. This approach would introduce enough error that I wouldn't attempt to corner balance the car this way but I think it would show a 50lb+ error. Try to find such a scale near you and try weighing with one rear swaybar droplink disconnected.

Try the same test(Not weighing, I mean WOT & shifting) with no change other than having the rear swaybar droplink disconnected on one side.

Also, many tires have a soft compound initially to make you glad you bought them, but at some point they wear down and expose a harder compound so that they can list a high treadwear rating. A similar effect may result if the car was parked for a long time in such a way that one tire was exposed to more sunlight. Switch the rears side-to-side to see if it feels any different.

IcemanG17

What type of differential...open or LSD.....maybe there is problem with the diff only sending power to 1 wheel?

Vlocity

That was my thinking exactly. Before I converted my Automatic without LSD to manual with LSD there was a huge difference in red line shifts... You just about had to anticipate the shift with the non-LSD because the tire would spin/slip and "wag the tail".

Much different with the LSD even with the power adder.

Ken

John Speake

I don't think it is the reason for yor issue, but rears should be 42psi, fronts at 36.

I would suspect tyres.....

mark kibort

If you are pushing your car on purpose and plan for this kind of driving, 32psi all the way around is a good place to start. tire temps will confirm this. I told you the story about the NSX boys that I helped on the track at Buttonwillow one weekend. all 6 of them were spinning all over the place. 3 of them at one time! 44psi cold settings for all of the them. after they reluctantly reduced the pressures to 32psi cold, they were all very happy. (no more spinning)

mk

SharkSkin

To Ken & Brian's points -- there is not much that could go wrong with an LSD or open diff to cause this kind of imbalance IMHO. With a live axle, sure -- the right side tire will tend to lift and break free because of the way that the torque operates against the suspension. With a transaxle though, this effect is much less and the tendency is to just break loose one or both rear wheels(without/with LSD respectively) without much drama.

What is more likely IMHO is something else that is causing one side of the car to have less traction than the other.

IMHO tire pressure is only relevant insofar as it should be the same side-to-side, though I agree with Mark's point that many(most?) people use way too much air for good traction.

PorKen

My LSD '86.5 usually corkscrews the 265s to the right when it shifts from 1st to 2nd @ WOT, on dry pavement.

'87-up have a pressure sensor which tells the EZK to retard the ignition briefly when it shifts to save the bands.

Mrmerlin

OK I will try the reduced air pressure, the tires are in fact 225/50-16 and are old Michelin pilots . Anyway i went back and removed the right lower link pin and all things looked OK. So i buttoned it back up .. The only thing that i did do was recheck the torque of the bolts and i found the eccentric for the right inner link to the rear crossmember was not tight. SB 146ft/lbs so i retorqued everything.
Brian the rear is open and its a diconcerting feeling to be gassing it and then know that the rear is going to go cata wampus when its time to shift..
Are there any instructions on how to pin the rear ?? Has anyone done this ?? what is the result and what did it stop from happening?

SharkSkin

Stan, the 32v cars I've driven lately - an 86(I think, borrowed it while in Washington a while back), an 86.5 and an 89, all with open diff, simply squatted down and took off going into 2nd. I'd say leave the tire pressure for the moment and swap the tires R <-> L on the rear and see how it behaves... if it's the same, check the other issues I mentioned.

When you say you disconnected the link pin and it looked OK... I take it you were only checking for preload/bias on the swaybar? That's not particularly conclusive WRT corner balance.

Marine Blue

Watch out for old tires. My 87 had old S02 that looked fine visually but the cars tail was loose as hell. The tires not only affected traction during acceleration but also during hard braking. New owner replaced the tires and said it made a night and day difference in the handling and traction. Do you have another set of wheels/tires you can try to rule this out?

Mrmerlin

the link pin I am referring to is the pin that goes through the hub and lower shock mount and the control arm, I was thinkining that possibly a bevelled washer was left out or some other thing, but everything looks good,
Now about the tires they are directional, I guess for a test it would be OK this car also has the sucked in wheels look I was going to add some bolt on bolt on spacers but they wont fit the 16 in Phone dials the webs between the bolt holes hit the lug bolts. I will leave the tire pressue alone till I swap the tires and test em, then i will swap them back and then reduce the pressure then i will test with the pressure raised and then with the sway bar link disconnected.
I dont really have any way to corner balance the car the levels look good, and i have a set of 87 S red Boges and springs on the car. It had Black Boges and 84 S Springs

JEC_31

IMO: bingo.

- Josh