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Another Alignment Problem

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Old 10-18-2015, 12:00 AM
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vmaxpwc
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Default Another Alignment Problem

I have completely rebuilt the rear end in my 1966 roadster. Rebuilt differential, professionally rebuilt trailing arms, u-joints, bushings, brakes ect. ect. I noticed when I took it apart the trailing arms were both shimmed almost all the way to the passenger side. Only one small shim on the right side of the pockets.

Its now going back together and I am trying to do a home alignment in my shop. A picture of the set up is below. I am using a precision machined plug with a Sears laser level...Basically a high tech string system.

I was easily able to set the both rear wheels to 0 camber. The toe-in is a different story...to get 1/16 toe on each rear wheel I calculated what I would have to measure out from the center of the front hub taking into consideration the smaller front track, the extension of the plug and the distance to the laser beam on the level minus the extended toe-in distance at the front hub. Works perfect on the passenger side but on the drivers side with the trailing arm all the way to the right with no shims the best I can do is about 1/8 inch toe-out. That's my issue.

I checked the front toe-in and it is 1/8 of an inch total. I did notice that the front radius arm on the passengers side was adjusted about 1/2 longer than the drivers side but both wheels measured roughly the same to the center line of the car.

This is a west coast car with a very clean frame, small accident sometime in its life on the passenger front fender around the gills but no damage to the frame. Doors fit great, no other weirdness. Seems straight and honest. I have not driven it a lot since I have owned it but I don't remember any real issues with the steering.

Any ideas what might be going on and why the drivers rear wheel will only toe out compared to the front wheel? and at the same time the passenger side has plenty of adjustment both ways. Any help would be appreciated.

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Old 10-18-2015, 07:52 AM
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DansYellow66
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A couple things. Normally the rear tires should run a bit of negative camber - say a 1/4 degree of so. You are doing all of this with the full weight sitting on the tires - as the one picture sure seems to indicate the body is riding very high in comparison to the top of the tire???

Do you know anything about the condition of the side yokes in the differential? It's possible the driver side yoke has extensive wear and is riding deeper to the inside of the differential. That would throw your trailing arm and everything to the inside in trying to get to proper camber.

I'm not sure what you are calling the radius rod and being adjusted shorter on one side versus the other. Are you referring to the rear suspension strut rods from the differential bracket to the shock mounts? Is the difference in measurement from the shock mount bolt to the center of the camber bolt at the diff bracket? Or do you have aftermarket strut rods that are adjustable for length?

I'm not sure I completely understand how you are setting the rear toe but I understand enough to think you probably have something figured out. After ensuring the front is aligned and the front wheels pointed dead straight ahead, I stretch string line from the front knockoff to the rear knock off to establish a datum line. The line doesn't take into account the difference in track width but that won't affect it. Then I mark the same difference forward of the rear wheel on the stringline and I use a long straightedge laid against the sidewall to extend forward and I record the deviation on both sides. I have calculated the deviation I should have based on the difference in track width, distance forward of the rear center of tire, and with 1/16 inch toe in - but, it still boils down to checking overall rear toe in with a tram toe gage and wiggling it in with shims until the deviation to the string line is the same on both sides. Once you reach that point the rear should have proper toe in on each side and be aligned with the front suspension.

Don't know if any of this helps.

Last edited by DansYellow66; 10-18-2015 at 07:56 AM.
Old 10-18-2015, 09:15 AM
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vmaxpwc
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Dan thanks

Yes I am doing this will the full weight of the car on the tires. Tires are on the casters and can move freely on both ends of the car. I also noticed the car seems to be riding high. I rebuilt the original spring and I also installed new body mounts. I also noted the half shafts are not level with the weight of the car on the wheels. The new bolts on the rear spring are at the lowest point I can get the cotter pin in. Do the half shafts need to be level with the weight of the car on the wheels? Could this be the issue?

A well known guy in Tulsa rebuilt the rear. He said no issues. He has done many for our club members. I think the yoke is probably OK. Yes, I have new aftermarket adjustable strut rods in the rear. The rear strut rods are adjusted similarly to get 0 camber at each wheel.

Sorry I was referring to what I call the radius rods at the front end of the car that are unequal. My terminology maybe wrong but they are used to adjust the toe-in in front. The passenger side is noticably longer than the drivers side but the front wheels seem to point straight ahead and total front end toe is good.

I think our methods are similar. I just project the laser to the front wheel and take a measurement off the front hub that compensates for track difference and rear toe in. I thought this would get the thrust angle close to zero, but I get toe-out when I do this on the drivers side with the rear trailing arm fully to the right or passenger side.

I will try your method today. Do you measure or take your datum off the frame in front of the rear wheels? How far forward? I have a 6 ft level to do this off the rear tire. Thanks again.

Vmax
Old 10-18-2015, 02:23 PM
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What is typical on a car within GMs ride specs is for the half shafts to angle slightly down to the wheels - but not much. If you have a service manual or AIM, it includes instructions on how to check the suspension ride height. Sitting as high as it is right now will step the tires in a little and move your trailing arms in at the frame pockets. It's not unusual for a newly restored car to sit slightly high due to fresh body mounts and bushings and then settle slightly. Trying to get a perfect alignment where it's at right now is probably not worthwhile as it will probably settle a little in the first few miles and I suspect you will do something to otherwise get the height down to a lower level (longer spring end bolts possibly).

OK - referring to the yoke we are talking about the side yokes - correct? Even if he rebuilt the rear he may not have paid much attention to the condition of the side yokes. Do you know if he installed the "C" locks on the side yokes before installing the cover? If he was able to install them then they probably are not so worn as to cause an alignment problem.

Man - I hate to be dense but I'm drawing a blank on what you are calling radius rods. The arms on the rear suspension are trailing arms but you made reference to on the front. I'm suspecting that you are referring to the tie rod ends and sleeve units for adjusting front toe in. Yes, they should be fairly close to equal. If they are not then I suspect with the front wheels straight ahead, your steering box is not at center and your steering wheel if installed correctly, will not be centered. This would cause you problems with at least some play in the steering wheel and possibly inadequate range in one direction. The front steering needs to begin with centering the box - turning all one way and then the other and count the turns of the input shaft to do so. Then divide that by half and turn back to center. Make sure the steering column shaft is correctly inserted in the rag joint coupling and that the steering wheel is installed on the shaft in centered position. Hold the steering wheel and box in dead straight position and adjust the tie rod ends until the wheels are turned into straight ahead position. To make sure the wheels are straight I would pull an offset measurement with a straightedge on the sidewall (or laser level) to the side of the main frame rail. Then wiggle toe in to 1/16 to 1/8 inch.

Yes, I think your approach with the laser is good. I set the front wheels straight ahead but then use a straightedge and the stringlines from front hubs to rear hubs to align the rear wheels - pretty certain the front and rear will track with each other. It's easier to check to the stringline than to the frame so I did this as much to simplify things. But if you set front and rear by the same section of the main frame rail, then it should track straight.

Good luck
Old 10-19-2015, 12:39 PM
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Thanks again for your help Dan,

My half shafts are at about a 12 degree angle downward with the suspension settled. I ordered longer bolts this morning from VBP. I might be mistaken about the spring and it could be a replacement and I have heard they make the car ride high. Lowering the car and inch or so would get the half shafts close to horizontal and give me some more rear toe adjustment.

I'm sorry, you have the correct terminology. I had a mental block I think! I was talking about the tie rod ends and adjustment sleeves in front. I had a similar problem on my GTO so I will need to get that sorted out.

I did have a lot of play in the steering and I now know why. I am going to take a picture tonight and post it here of the rag joint and steering box to see if its clocked right.

I will give the differential guy a call about the C locks.

Vmax
Old 10-19-2015, 07:30 PM
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As near as I could read my angle finder in there, my half shafts are running at about 5 degrees down to the wheels. Last time I checked my suspension was within GM shop manual specifications on ride height. It has an original spring under it.

There is another thread running now that is discussing how long it could take for a new rear spring to settle down to final ride height. You may just have to square the wheels up as best you can and put 50 to 75 miles on it before dialing in the alignment to a precise degree.

If you have an excessively worn side yoke you may be able to tell from how much clearance the gravel shield on the yoke has to the differential case. A worn yoke will probably be right up against the case and in severe cases even wearing into it.
Old 10-19-2015, 08:39 PM
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I will check the gravel shield. Thanks for the tip.
Old 10-19-2015, 09:20 PM
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Originally Posted by vmaxpwc
I will check the gravel shield. Thanks for the tip.
Can you tell much from this picture. The gravel shields look ok to me?
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Old 10-19-2015, 09:23 PM
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Originally Posted by vmaxpwc
Can you tell much from this picture. The gravel shields look ok to me?
Here is another
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Old 10-19-2015, 09:35 PM
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Originally Posted by vmaxpwc
Here is another
Installed in car sorry about the quality of the pic
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Old 10-19-2015, 09:37 PM
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Originally Posted by vmaxpwc
Installed in car sorry about the quality of the pic
Drivers side
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Old 10-19-2015, 09:40 PM
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Originally Posted by DansYellow66
What is typical on a car within GMs ride specs is for the half shafts to angle slightly down to the wheels - but not much. If you have a service manual or AIM, it includes instructions on how to check the suspension ride height. Sitting as high as it is right now will step the tires in a little and move your trailing arms in at the frame pockets. It's not unusual for a newly restored car to sit slightly high due to fresh body mounts and bushings and then settle slightly. Trying to get a perfect alignment where it's at right now is probably not worthwhile as it will probably settle a little in the first few miles and I suspect you will do something to otherwise get the height down to a lower level (longer spring end bolts possibly).

OK - referring to the yoke we are talking about the side yokes - correct? Even if he rebuilt the rear he may not have paid much attention to the condition of the side yokes. Do you know if he installed the "C" locks on the side yokes before installing the cover? If he was able to install them then they probably are not so worn as to cause an alignment problem.

Man - I hate to be dense but I'm drawing a blank on what you are calling radius rods. The arms on the rear suspension are trailing arms but you made reference to on the front. I'm suspecting that you are referring to the tie rod ends and sleeve units for adjusting front toe in. Yes, they should be fairly close to equal. If they are not then I suspect with the front wheels straight ahead, your steering box is not at center and your steering wheel if installed correctly, will not be centered. This would cause you problems with at least some play in the steering wheel and possibly inadequate range in one direction. The front steering needs to begin with centering the box - turning all one way and then the other and count the turns of the input shaft to do so. Then divide that by half and turn back to center. Make sure the steering column shaft is correctly inserted in the rag joint coupling and that the steering wheel is installed on the shaft in centered position. Hold the steering wheel and box in dead straight position and adjust the tie rod ends until the wheels are turned into straight ahead position. To make sure the wheels are straight I would pull an offset measurement with a straightedge on the sidewall (or laser level) to the side of the main frame rail. Then wiggle toe in to 1/16 to 1/8 inch.

Yes, I think your approach with the laser is good. I set the front wheels straight ahead but then use a straightedge and the stringlines from front hubs to rear hubs to align the rear wheels - pretty certain the front and rear will track with each other. It's easier to check to the stringline than to the frame so I did this as much to simplify things. But if you set front and rear by the same section of the main frame rail, then it should track straight.

Good luck

Dan,

The steering box in the straight ahead position. Does this look right?
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Old 10-20-2015, 01:22 PM
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Originally Posted by vmaxpwc
Here is another
Well, the picture didn't copy into the response - this is in response to post #9.

This is about the only picture I tell much from. It does appear the passenger side yoke is sitting in closer to the case than the driver side - but it could be the angle of the picture. The gravel shield space isn't going to tell you anything definate one way or the other, but if one side is sitting in noticeably further than the other side then it could be an indication of wear on that side.

You would also notice more in-out play on that side too indicating the tip is pretty worn down. You can jack the car up and move the top of the tire to check for in-out movement of the yoke. If it's got a C-clip installed and you only have say less than an 1/8 inch of play at the case then it's probably not real worn.

Last edited by DansYellow66; 10-20-2015 at 01:24 PM.
Old 10-20-2015, 01:26 PM
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Originally Posted by vmaxpwc
Dan,

The steering box in the straight ahead position. Does this look right?
Not sure - I may have to study mine in comparison when I get home.
Old 10-20-2015, 06:05 PM
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Vmax - Here are top and bottom photos of my pitman arm and steering coupler with the wheels straight ahead. I'm pretty sure everything is clocked correctly.





Here is a picture of my rear leaf spring arch and half shaft orientation. I just installed new rubbers at the spring end links. This is my old original spring and it's not too far from flat but the last time I checked my ride height it was in GM shop manual specs. I'll add a side shot of the car's stance down below.



Here is a picture of my side yoke and the gravel shield. These yokes have about 2500 miles on them. Again, this is probably not a very good comment since unless yours are really shot you probably would not know it from this.





Hope this helps a little.

Last edited by DansYellow66; 10-20-2015 at 06:13 PM.
Old 10-20-2015, 08:51 PM
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Dan,

Thanks so much for your help. It looks like my steering gear in front was way off. Another job for this weekend. My rear is too high also and my angle is easily twice yours with the wheels on the ground. I have a hunch I do not have the original rear spring but others say I do. I ordered new longer bolts yesterday from VBP and should have them this week. That should get me in the ballpark. I will check the free play on the half shafts as you suggest. If you get to Tulsa look me up. About 15 corvettes in my neighborhood a couple are top flight cars.

Your car is just outstanding.
Old 10-20-2015, 10:10 PM
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Thanks - I rebuilt my car before the internet so it's a bit amateurish in some areas but it's held up well.

It's important to get your steering box clocked correctly because they are manufactured to have kind of a high spot at dead center - minimal lash. When the box is turned anywhere off dead center, the lash is greater and so is the play.

This all got visited in a recent thread that should have some useful information. It kind of seems that my box had a mark on the input shaft for center but it's been so long I can't be sure.

https://www.corvetteforum.com/forums...on-1966-a.html

Your spring looks like either an original or an Eaton reproduction which are supposed to be dead on for the originals. But, it may need to get a few miles on it to settle back down. I know coil springs take a few weeks to settle to their stable height so I guess the same can be true for the rear spring.

Good luck - sounds like you have some good support in your neighborhood so I'm sure you'll get it all worked out. Kudos for doing your own alignment. I think with some effort the results can be just as good as at a high price shop.

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Old 10-20-2015, 10:18 PM
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Originally Posted by DansYellow66
Thanks - I rebuilt my car before the internet so it's a bit amateurish in some areas but it's held up well.

It's important to get your steering box clocked correctly because they are manufactured to have kind of a high spot at dead center - minimal lash. When the box is turned anywhere off dead center, the lash is greater and so is the play.

This all got visited in a recent thread that should have some useful information. It kind of seems that my box had a mark on the input shaft for center but it's been so long I can't be sure.

https://www.corvetteforum.com/forums...on-1966-a.html


Your spring looks like either an original or an Eaton reproduction which are supposed to be dead on for the originals. But, it may need to get a few miles on it to settle back down. I know coil springs take a few weeks to settle to their stable height so I guess the same can be true for the rear spring.

Good luck - sounds like you have some good support in your neighborhood so I'm sure you'll get it all worked out. Kudos for doing your own alignment. I think with some effort the results can be just as good as at a high price shop.
Dan,

I just went out to the workshop and the clocking on my steering gear is way off compared to yours. Bubba at his best. I also looked at some pictures of mine before I refurbished the rear spring and it indeed sat at least an inch lower. Thanks for the help.

Vmax
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Old 10-21-2015, 11:13 AM
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Not sure if I missed it but you need to drive your car (not lower with a jack) onto whatever you are using to allow the wheels to move freely, in your case the casters, so the suspension is sitting correctly. Also, I'm sure you know the rear suspension needed to tightened with car on the ground.

Last edited by narlee; 10-21-2015 at 02:53 PM.
Old 10-21-2015, 06:50 PM
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Originally Posted by vmaxpwc
Dan,

I just went out to the workshop and the clocking on my steering gear is way off compared to yours. Bubba at his best. I also looked at some pictures of mine before I refurbished the rear spring and it indeed sat at least an inch lower. Thanks for the help.

Vmax
Yes, that certainly looks off - at least compared to mine. Just for grins I measured my tie rod assemblies on the front from grease zerk to grease zerk and mine are within 1/4 inch of each other in length. Not sure that has any significance as in a 50 year old car any number of things could be very slightly tweaked by now.

Dan


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