Rear toe out of adjustment range - possible fixes?

[Chuck Moreland]

Originally Posted by Jim Williams

Oh, and I almost forgot to mention, the bottom line...! The toe can now be adjusted from (+) to zero and on to (-) through the spec range! Camber too...

Glad to hear you got it sorted out.

The porta power on the shock bolts was very creative. Though I'd be cautious doing this with a set of steel trailing arms that I planned to use. I'd be concerned about bending the arms as well.

Good job

[Jim Williams]

Originally Posted by lateapex911

Nice write up. So am i to understand you onlu needed to modify the right (passenger) side of the rear engine crossbrace?

I am jealous of your toe situation. I think I need to print out this tread, take a highlighter to it, and spend a long weekend in the shop under the car!

Jake, yes, I only modified the right side. I think the right side of the car must have taken a lick at some point it's life before I acquired the car. None of the little evidences to this effect were apparent when I bought the car. All the measurements I made and compared to the shop manual that gives underbody dimensions between points indicated that the points most out of kilter were in the right rear. Pulling them out would have required chassis work that would have also included outer body work, which had already apparently repaired well enough that underbody wrinkles were not apparent.

For info to all, some things I read in the workshop manual did not make much sense until I experienced them first hand while doing the camber and toe manipulations. I don't think they really soak in until you encounter them. These concerned having to reposition the adjusters in the spring arm if you run out of adjustment room. For example it is possible to get the camber eccentric adjuster in a position that it won't further move in the direction you are trying to go. This could be due to the toe adjuster being in a certain position. In the case one runs across this, you will need to remove the adjuster, keeping the lockdown bolts at the end of the spring plate tight, and reposition the adjuster to the opposite end of the slot, which will allow it to continue in the desired direction. Then loosen the locking bolts and proceed. This will make more sense when you are confronted with the problem. Just stop and think through what the adjusters are doing, and need to do to make the banana arm move in the proper way.

BTW, I should mention that there is a copy of Ray Scrugg's Alignment book posted here on Pelican. Do a search for Ray Scruggs. It has an error in describing the direction the banana arm must move to get more negative camber. I don't have the patience right now to relocate it, but if someone is willing find it, I'll point out the error.

I have made some drawings to help me remember all this the next time I do an alignment. I looked back and the last time I did this was in 1999, on an SC. I took notes then and they didn't cover this problem, as I didn't run into it.

[Jim Williams]

Originally Posted by Chuck Moreland

Glad to hear you got it sorted out.

The porta power on the shock bolts was very creative. Though I'd be cautious doing this with a set of steel trailing arms that I planned to use. I'd be concerned about bending the arms as well.

Good job

Chuck,

I can see the reason for concern, and I don't plan on using the steel arms, that's true. But I don't think they were deformed in the least. Best as I can figure the stresses in the whole geometry, the bananas were in tension, the spring plates were in compression (the member I was afraid might be the weak link and bend in all this) and the torsion bar tube had a bending moment applied, the member I hoped would actually bend somewhat. One thing that apparently wasn't affected in the least was those damn delrin bushings!

[christians]

Morning gents, I had reason to search the web for possible solutions to an excessive rear toe out problem beyond the eccentric adjustment range. After some thinking and basic by eye checking it seemed that the torsion beam was bent. once i started thinking along this line ,a quick check of the tube by gazing straight up at it from about two meters away confirmed that it was obviously bent roughly in the middle by quite an amount, it had a distinct V shape to it.
Jims thread was the only one i could find that had any answers to fix the problem without going the chassis jig and or replacement route. I decided to "do a Jim" and apply pressure to the rear of the semi trailing arms ,as Jim said they are a decent lump of steel and tracing the arc from the inner mounting points on the beam (by the transmission mounts) to the damper mounting points, they are quite substantial. Thinking the other approaches would be time consuming and expensive ,i would risk damage to the arms . The engine and trans was removed and the chassis put on to a two post lift, out with the porta power and a quick application of pressure to the trailing arms, confirmed that the beam did flex back towards the rear of the car. Whilst keeping the pressure applied i sighted the beam by eye until it looked straight, it appeared to be not quite uniform in its straightness, so i borrowed a length of stout oak post and blocked it down from the underside of the rear chassis legs, so that it was resting against the rear of the tyres and inline with the direction that i wanted to pull the beam in(straight towards the rear). I held the wood in place with a transmission jack whilst i looped a ratchet strap around the beam at the exact point of the bend and than around the wood and wound up some tension to it. It appeared to make a difference and the beam looked better for it. Wondering exactly how much to pull and for how long, to effect a repair i left it for an hour or so, then as it was at the end of the working day decided to remove the porta power but leave the wood under tension overnight. Relieving the considerable tension on the wood was accomplished by deflating the tyres and then releasing the strap. Good news! the beam looked straight to the eye, i didn't really see how far it relaxed, but at one point in the process the beam was certainly curved beyond straight for a while.
The next job was to re-install the running gear roughly( I had no trouble aligning the four mounting bolts and without any real tension on the rear engine carrier to get the bolts in) and put it on the alignment machine to see if it was roughly in the right place.
Before the surgery the best figures i could achieve were camber in spec (-55 mins ) and right rear toe out of negative 20 mins and a left rear figure of negative 50 mins.
After the work and before driving and settling(bit of ballast added to rough compensate) the figures had turned to a positive toe in (per side) of around one degree but with the eccentrics still in "max toe in" setting. Result! By eye the beam looks good but i think that according to the positions of the eccentrics required to achieve the correct figures i went a bit too far. Easy to do when you have no reference points and of course you have no idea what figures you will get when you eventually get the car back together an settled out.
I believe i have passed the "Jim Williams alignment module" and completed the practical exam with merit!

[christians]

A few more shots of the work in progress.
Photo one is the beam with a distinct bend towards the front of the car, clearly the gap between the rear bulkhead and beam is reducing in the center of the chassis.




Photo two shows some of the equipment in use.





This photo shows the rear beam with a more uniform distance between the bulkhead and the beam ..


Thanks Jim for your bravery! Christian.....................

[matt demaria]

Just to make a note:
In post #15 with the drawn setup, the definition of rear toe should be

(i+j)-(k+l) - = toe value, where
positive values are defined as toe in and
negative values are defined as toe out.

Same theory applies to the front.