Rear Toe-in alignment with the body off the frame HELP!

[Louis C.]

Re: Rear Toe-in alignment with the body off the frame HELP!

I believe the weight of the assembly is pulling them outward. I can move each but the return to the outboard position. I had a straight edge on the tire perpendicular to the frame and was able to see the excessive toe-in; moving the wheel assembly inboard did not change the toe.

[Louis C.]

Re: Rear Toe-in alignment with the body off the frame HELP!

I will post a pic of the camber adjusters as set. I believe the are well within the limits. Camber adjusted to zero with ease. The photo of the level was the beginning of this journey as that was an initial setting that was necessary to begin. My initial attempts to set the toe-in were done with the rotors flipped. Since then the wheels have been on and off a number of times trying different methods to measure and adjust. At this point the wheels are on as I understand the measurement is retaliative to the wheel diameter..

I will have to remove the wheels again to get the measurements from the spindle flange to the casting adjacent to the inboard yoke. I don't know if I am clear on the "casting adjacent to the inboard yoke" part. In any event It doesn't look like I will be able to get to that today. I did take some quick photos.. As the wheels are on and I didn't have the time to do more, I took a couple of photos of the measurement of the back of the rotor to the edge of the trailing arm. Not a very accurate guide but all I could do this morning. The left and right looked about the same; perhaps an eighth over five inches. i also tried to photo the spindle support as attached to the trailing am. It all looks good to me.

http://s186.photobucket.com/user/chip6565/library/

[Steve G.]

Re: Rear Toe-in alignment with the body off the frame HELP!

I had another thought about this. We should take a measurement from the top centre of tire to top centre of tire and from outside frame pocket for arm to outside frame pocket. I will take those same measurements on the 67 to compare. The spindle supports are on backwards on the 67, but the track distance should be the same. I think the 69 should be the same, so I will take those as well.

You should correct the yoke end play problem while you are doing all this, but it is not enough to cause the amount of toe problem you have.

Steve

[Steve G.]

Re: Rear Toe-in alignment with the body off the frame HELP!

Scratch the centre of tire to centre of tire measurement. We would have to know that the wheel offsets are the same for that to be right and I'm pretty sure the 69 is different and I know the 67 is off because they have washers under the wheels to keep them from rubbing on the trailing arm. We would need to do wheel mount face of rotor to wheel face of rotor which makes it difficult for me to take a same measurement with the springs installed.

Take your measurements from the wheel face mount and I will figure out how to get a smimilar measurement here.
Steve

[Michael W.]

Re: Rear Toe-in alignment with the body off the frame HELP!

moving the wheel assembly inboard did not change the toe.

If the front of the trailing arm is a pivot point and the opposite end is moved towards the centre of the frame, why would toe-in not decrease?

[Louis C.]

Re: Rear Toe-in alignment with the body off the frame HELP!

Moving the trailing arm pivot point does change the toe. I must have made a typo.

when I started I had about an inch total toe. After swapping shims and more swapping I found myself with all shims inboard and still with too much toe-in.

[Duke W.]

Re: Rear Toe-in alignment with the body off the frame HELP!

Normal static and dynamic loads keep the halfshafts in compression, so tie them together to ensure that the side yokes are hard gainst the diff. pinion shaft inside the axle housing.

Also, it's time you took some frame measurements to see if the frame is out of spec.

Duke

[Steve G.]

Re: Rear Toe-in alignment with the body off the frame HELP!

Normal static and dynamic loads keep the halfshafts in compression, so tie them together to ensure that the side yokes are hard gainst the diff. pinion shaft inside the axle housing.

Also, it's time you took some frame measurements to see if the frame is out of spec.

Duke

According to GM published material, that is so only 85% of the time. 15% of the time the dynamics will pull the yokes out. In order to maintain proper alignment 100% of the time the yoke end play should be as close to 0 as possible. The same reason and circumstance that we like to see spindle bearing end play as close to the lower end of the spec rather than the higher.

Steve

[Michael W.]

Re: Rear Toe-in alignment with the body off the frame HELP!

Moving the trailing arm pivot point does change the toe. I must have made a typo.

when I started I had about an inch total toe. After swapping shims and more swapping I found myself with all shims inboard and still with too much toe-in.

Correct.

If now you were to move the opposite end of the trailing arm (the rear) towards the centre of the car, the toe will decrease.

[Louis C.]

Re: Rear Toe-in alignment with the body off the frame HELP!

Normal static and dynamic loads keep the halfshafts in compression, so tie them together to ensure that the side yokes are hard gainst the diff. pinion shaft inside the axle housing.

Also, it's time you took some frame measurements to see if the frame is out of spec.

Duke

I'm starting to wonder if the trailing arms could be out of spec. So I called Pat Ikert and we agree that it is highly unlikely but am running out of ideas. I have done some preliminary frame measurements and I have no signs of previous damage.

[Michael W.]

Re: Rear Toe-in alignment with the body off the frame HELP!

I'm wondering if the trailing arms could be out of spec. I called Par Ikert and agree that it is highly unlikely but am running out of ideas. I have done some preliminary frame measurements and I have no signs of previous damage.

I have seen bent arms resulting in crazy toe angle, but this was usually from Bubba not bracing the spindle assembly properly in a press while removing/installing bearings.

As Joe R. pointed out above, Ikert is a class act.

[Louis C.]

Re: Rear Toe-in alignment with the body off the frame HELP!

When building the spindle assemblies I measured end play and came up with .002 on one and .004 on the other. Now that they are greased and assembled, when you "wiggle" the wheel seems like more that I would have expected.

I built the rearend years ago. I don't recall dealing with yoke end play or adjusting lash out? There is a bit of lash present on both sides.

[Louis C.]

Re: Rear Toe-in alignment with the body off the frame HELP!

So I'm thinking that something is pushing/holding the back of the trailing arms outboard?

[Steve G.]

Re: Rear Toe-in alignment with the body off the frame HELP!

So I'm thinking that something is pushing/holding the back of the trailing arms outboard?

Yes, that's my suspicions as well. I think there are only three possibilities, really. If we measure from frame pocket to frame pocket and compare to a known good frame, that's one. Another would be wheel face of rotor to wheel face of rotor. Changing either of those dimensions changes toe.

The third would be the angle between centre line of spindle support and the trailing arm.

Of those three, the track distance between the rear wheels would seem most likely.

Steve

[Michael W.]

Re: Rear Toe-in alignment with the body off the frame HELP!

So I'm thinking that something is pushing/holding the back of the trailing arms outboard?

Yes, gravity

With the car sitting on it's wheels, the diff yokes are loaded inwards by virtue of the pivot at the junction of the lower strut and spindle housing. Rough calculation puts the static compressive load at around 300lbs per side.