Unable to get proper rear toe-in alignment
 

My alignment guy and I are stumped on our inability to dial in any rear toe-in on the right rear. When the eccentric is at the end of its range, we are still at a toe out situation. The eccentrics have been 180'ed to see if it would help - no luck. All of the other wheels are spot on.

Any suggestions on why we can't get the toe set correctly?

Btw, the reason for the alignment is installation of new polybronze bushings and monoballs.

--Mike

You need to set camber first.

IIRC you need about negative 1.0 degree (sometimes more) to get toe, especially if it's lowered.

Good luck.

We had the camber at negative 1.8 degrees with no luck.

Is it close?

My alignemnet guy(s) said to try and hollow it out, but I was afraid of that.

I am out of ideas then, unless it the ride-height is REALLY low, or too high?

Now what I understand is that they are running out of room where the spring plate meets the swing arm. He said it seems like the swing arm is too long.

Mike, did you notice this before the rear mono ball install? You've got aluminum trailing arms right?

I will have to go through the PO documentation to see if I can find any old alignment info. I didn't take any toe measurements prior to dismantling to install the monoballs and bushings. I didn't notice any odd handling characteristics while driving the car, but it was mostly highway and around town driving.

Yes, the trailing arms are Al.

--Mike

I don't think the ride height is too low, or too high. I measured it at 25.25" prior to the alignment.

--Mike

You've got an SC suspension on a 71 chassis right?

Perhaps someone out there who has done the conversion can tell you what is up. I can't think of anyhting off the top of my head right now....wish it were a Friday afternoon, I'd run over too Jms and get greasy just to find out why...I'm intrigued!

Its a Carrera rear suspension on a '71. Jim and Joe are both working on it now. I'm about the head out of work now and go on over.

--Mike

I wonder if your problem exisited before and you just didn't notice.

On an 80's 911 when you crank in a lot of negative rear camber (more than 1.5deg for example) it causes the suspension to toe out. At some point the there isn't enough adjustment in the spring plate to get toe back (in) where you want it. The fix is to lengthen some holes in the spring plate. I can't remember which ones.
-Chris

spring plate

http://forums.pelicanparts.com/uploa...1085541275.jpg

The problem exists on the passenger side only? Could be a bent trailing arm.

Is the toe eccentric freely rotating 360 degrees? or is it limited in travel due to the rear bolt holes Ron is referencing above? You can test this by removing one of the bolts, or replacing it temporarily with a smaller diameter bolt. If so, use a file to elongate the slotted holes.

Are you make the adjustment with the weight off the wheels? You'll find more range if you unweight it.

If none of that works, some clever work with a welder and a file and you can move the toe hole forward a bit on the spring plate.

Or some clever work with a welder and lathe and you can accentuate the eccentric adjuster a small bit.

There is always a solution.

My car has the same problem and I put to down the the previous owner parking it againsts a guard rail at Watkins Glen. I attributed it to bent chassis, although I haven't been able to confirm it with measurements. I opened up the hole that you described, but I also had to do the same thing to the slotted adjuster hole to give it enough travel.

Since the problem existed with the original steel bananas and the aluminum bananas that I have since installed, I still believe that it is the chassis or torque tube.

You may find here that the problem already existed. Perhaps you can make some basic measurements across the underside of the car and see if the torsion tube is swept back on the right side from impact.
Good luck-

What would have the highest margin of safety, using a smaller bolt or enlarging the hole?

It concerns me a bit to start shaving off metal from connection points or using non-spec bolts.

--Mike

An old 70T I previously owned had exactly that problem. Half an hour on the frame rack cured it and dialed right in afterwards.

Tim

Just talked to the alignment guy. It looks as if the aluminum trailing arm is bent, the rest of the frame is spot on.

Off to the classifieds to find a trailing arm. Thanks for everyone's help with this issue.

--Mike

That must be a relief... Call Parts Heaven, they should have one.

alignment
 

porta-power the lower shock mount until the alignment comes back. You have to go to extreme measures to repair bent Porsches.

Re: alignment
 

Great idea. And while you're at it Porta-Power the front shocks mounts together to get some extreme negative camber. Who cares if the hood gaps close up?

Its just a bent part, not a bent Porsche. The t-bar tube, frame, trailing-arm brackets are all in spec. Replace the part, fix the problem.

The rear suspension is from a Carrera and was installed by the PO. It was most likely bent when he installed it. There are no signs of crash damage on the vehicle.

--Mike

Mike: If the arm is not too much bent, some heat and a little pressure could bring it back. Otherwise, I would prefer to stay with the right size bolt and file out the hole.
Tim Polzin: Shovel the snow in front of the garage and come to the Canyon Drive: http://members.shaw.ca/zielke/schedule.html

Re: Re: alignment
 

Or you could just attach the front fenders with spacing washers and pull the towers together with a strut bar like the F Stock guys do. ;)
-Chris

bent
 

You haven't worked on many bent Porsches.

to my understanding the rear control arms are designed to be flexable.. meaning that it's not being stressed for small adjustments like Otto performs.

Otto;
I'm just trying to picture the details of what you described without doing something stupid like I usually do.

Option one: Brace axis of the spring plate (through the access hole) up against an immoveable object. Then use pull the lower shock mount out until the car aligns This will basically pivot the triangle created by the banana, spring plate out around the front pivot point.

Option Two: Push the lower spring plate out (by pushing against what???) to accomplish the same result.

Any good ideas that people have used to brace the car without resorting to a complete alignment table?

What does half an hour on a frame rack cost? Can it cure anything?

when my car was aligned the front camber was just on the edge of being in spec, and they said the front shock towers over time move sag inwards.

Is it worth it to try bending the control arm if everything else is in spec? How long would it take a shop to do this? I can just buy a *new* used arm for $100 and install it myself.

--Mike

Mike, just buy a good used one. Doing anything to straighten the arm while it's on the car is likely to twist or bend something else. Your chassis is straight...do fuch! with it.

EASY has a good rep.

Hi Bill:

Mine was an easy fix. Somewhere in the life of the vehicle, it took a hard hit to the left rear wheel and bowed the rear torsion tube to the front of the vehicle. The guys with the frame rack were able to pull the tube back in position. It was straight forward, although they were really surprised how much force it took to do it. They honestly thought they were going to break something on this "fragile" car. Remembering that I live in a small town in Northern Alberta, the whole thing cost $75 cash and a six-pack of beer.

Tim