1986 Carrera Targa 3.2 pulls left under accelleration

[travels68]

Hi All,

I've been scratching my head on this annoying issue for months now and so far have been unable to find the cause.

The problem:

When I accelerate on a straight flat road the car moves to the left and I have to correct with steering inputs, when decelerating the opposite is true and the car tends to move to the left.

Car alignment and handling was excellent until I had local shop performed top end engine rebuild and transmission refresh.

After I got the car back the shop mentioned my alignment was out and I should bring back for that service - I thought this odd as I had the local dealership do a complete alignment and ride height check prior and the car was perfect under acceleration (albeit less spirited given one of my plugs was constantly oil fouled).

Anyhow, after local shop lowered the car to Euro-height, replacing the tires, CV Joints, rear spring plates+bushings (with adjustable sway-aways), and multiple alignments, the car is still having problems. The alignment seems good as long as I'm at steady speeds but when power is applied the wandering/pulling begins.

In long sweeping corners (like highway clover-leafs) if I accelerate in the turn car really can't hold a constant turn angle (not sure if it's over or under steer... It just doesn't feel like it used to )

Any idea what's causing this?

More facts:

Car has a factory limited slip diff -> shop says that can't cause it but I've read it can on the newer cars so maybe?

In past 5k miles (prior to problem appearing):

New bilstein shocks and struts, rear and front.
New Front shock mounts
New Front sway bar bushings

What I haven't replaced:

sway bar drop-links
Front control arm bushings
rear control arm bushings

Bearings (front or rear)

Any help would be much appreciated - this is really making the car pretty annoyingto drive especially after the expense of the rebuild - it was more fun before $$$!

-Kale

[stomachmonkey]

Sounds like a trip back to the local shop to correct whatever they did is in order.

[gtc]

My guess is that your corner balance is way off.

[uwanna]

Originally Posted by gtc

My guess is that your corner balance is way off.

+++++ on what he said! Classic symptom of corner balance being WAY OFF!
Multiple "alignments" will not fix it, as most alignment shops don't do corner balance and if they do
it is a separate charge. Or perhaps they have no clue how to corner balance a 911.

[impactbumper]

Have them check your axles


Sent from my iPhone using Tapatalk

[BK911]

Originally Posted by travels68

When I accelerate on a straight flat road the car moves to the left and I have to correct with steering inputs, when decelerating the opposite is true and the car tends to move to the left.

I am a little confused by this. It pulls to the left under accel and decel? Or opposite under accel and decel? If opposite, check brake lines. My right front failed internally. Under braking, brake fluid was restricted to the rf brake and the car would pull to the left. After braking the brake fluid kept pressure on the rf brake and the car pulled to the right.

[travels68]

Sorry... should have been more clear.

Under acceleration the car goes left, let off the gas at high RPM and the car pulls to the right.

I had what appeared to be a sticking front right brake (the disk was getting very hot on right front disk and we replaced the front calipers and all the lines) but problem persists although not as pronounced as before (this was a definite contributor).

Regarding corner balance - Do the dealerships typically know how to do this?

Anyone in Tampa Bay area? Orlando?

-Kale

[DRACO A5OG]

They should but they usually sub it out.

I am sure Pelicans down yonder will chime in.

[ClickClickBoom]

Motor/trans mounts, loose or deteriorated? Sounds like a rear end steering issue. Proper corner balance will eliminate a lot of questions, any good PCar shop can do one.

[carreradpt]

Zotz Racing in Orlando.

[travels68]

So I had the car out for an extensive drive today and the behavior in long sweeping right hand turns (270 degree onto freeway) is that acceleration tends to 'push' the car out of the turn (understeer) and then let off gas and the car quickly snaps back to original arching carving of turn.

The front end seems to come up a bit when I'm pressing on gas too... I assume from rear end squat but seems like maybe the front end is too high to begin with (another corner balance resolution item).

Anyhow in left hand turns, the car does not exhibit such an extreme push-out behavior. Initially I thought it might actually over steer (in left hand turns) under power but it tends to also want to straighten out - I think this might be more of the soft sidewall Conti's I have on the car. The behavior is much less severe in the left turns. Also, from dead stop, left hand 90 degree take off turns snap around quickly. In right hand direction I have to muscle the car around due to the throttle pushing the car out of the turn...more or less consistent with the high speed turn behavior.

I'm leaning corner balance here but the shop told me they did check it... still highly possible it's bad as everything I've read seems indicate corner balance would explain all of this.

Engine mount and transmission mount - good theory based on the recent engine/tranny removal: checked the engine mount with floor jack under engine case and observed that body and engine moved up simultaneously when jacking, i.e. engine didn't move first. I'll check transmission.

So far no comments on the limited slip diff... judging by the silence, and my observations, it seems unlikely this would cause this behavior.

I'll keep the group posted. I really want my go-cart handling back!

[universeman]

If they checked the corner balance, they should be able to show you the sheet that gives you the details...

[travels68]

Unfortunately they never thought it necessary to give me the corner weights, or any alignment specs. I'm sure that info is long gone.

[darrin]

I'd posted on your other thread in the engine rebuilding forum -- I have continental extreme contact dw tires on my 911. While they aren't the stiffest tires in the world, my '86 targa handles quite well with them and I do not believe them to be the cause of your current issues. I echo others comments about getting this to a shop that specializes in and has expertise with these early 911s

[Mick_D]

If you lowered to Euro height, you may need a bump steer kit.

[bpu699]

There was an alignment book floating on here by Ray shrugs or something similar...

It stated that if the car goes to one direction under braking, corner balance is off...assuming brakes are fine.

Can be corrected by slowly raising the height of the front wheel that the car pitches towards using the height adjustment...

Worked for me...

Perhaps when you did the suspension work you indexed the torsion bars incorrectly...and screwed up corner balance...

[travels68]

Thanks for the comments - the feedback has been very useful. I'm developing a plan of attack with a focus on the corner weights, especially given the recent ride height change. I just think it's not weight-balanced at this point.

I think I'll try to find a generic (read - non specialist) auto shop willing to quickly grab weights while I wait so I can at least rule-in or out this issue.

Darrin - I appreciate the feedback regarding the Conti's - excellent to know you are happy and not having drive symmetry issues like me. Replacing them will be a last resort given I have about 800 miles on my set. I'm curious what tire pressure you run on these?

I'll keep the group posted so others might learn from my headaches.

Cheers!

-Kale

[qship510]

Amazing....

Doubtful that you have a corner balance issue. Extremely doubtful.

You have a rear control arm bushing issue

[JJ 911SC]

https://www.google.ca/search?client=safari&rls=en&q=porsche+911+Ray+scrugg+alignment+procedure&ie=UTF-8&oe=UTF-8&gfe_rd=cr&ei=qx1hV9uIMOmM8Qe6vZmwBw

[darrin]

kale: Running my contis at 32psi front and 36psi rear (on 16x7 fronts and 16x8 rears, which flatten the sidewalls a bit compared to 16x6 front and 16x7 rears)