Hello, I know I will open up a can of oil here but here goes. I replaced the rear spindles, strut rods, bushings and cam bolts(all after market). The rear camber needs to be reset and no shop will do just that. The 4- wheel align. was just done 500 miles ago. The specs call for Neg. 1/2 degree, +/-1/2 degree. I have found that one of the new cam bolts is NG. Cams don't turn when the bolt is turned. Is there a major difference in quality between the aftermarket bolts and GM bolts and can GM bolts still be obtained? From what I see the camber can only be acurately set with the weight of the vehicle on the wheels and leveled. This indicates that both wheels would have to be on dollies so that the tires will not drag during adjustment. Am I correct? Has anyone on this board tried this? One of the main reasons I am asking these questions is that most of the shops in my area cannot or will not touch this car. It's a 75 C-3. They don't even know how to program their machine with the specs. I guess they just don't need the hassle of messing with a 25 yr old car. If anyone can advise me I would appreciate it. Thanks, John
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Re: Rear Alignment
John,
I believe that the GM bolts are still available, but I have no way of knowing if your aftermarket bolts are better or worse than GM, there's lot's on the market. If you have doubts, why take a chance? Send them back.
You said:
From what I see the camber can only be acurately set with the weight of the vehicle on the wheels and leveled. This indicates that both wheels would have to be on dollies so that the tires will not drag during adjustment. Am I correct?
That's one way of doing it, but most places I have seen jack up the car, adjust without weight on wheels, and put it back down to measure. In theory, if this is the only adjustment you need to make, it can be done in your driveway if you have a good spirit level and a lot of patience.
I think you may want to start looking a little further afield for a competent alignment shop. It's true that a lot of them can't be bothered doing an older car, but setting the camber is one of the easiest adjustments to do. Maybe they're hoping not to get the business.
Mike
NCRS Quebec chapter -
Re: Rear Alignment
I gave up on alignment shops years ago. They have wonderful equipment, but the operators rarely understand suspension geometry and will never do it my way. All my cars are aligned somewhat different than factory specs as alignment is a chassis tuning device and can help dial the handling in.
Go out to a home supply store or Sears and buy an inclinometer - a good quality one. With a little practice I can pick off the readings within a quarter degree. Then you need a flat "surface plate", and a garage floor in a modern home will normally suffice. You can use the inclinometer to measure the floor slope and if it's within a quarter degree it should work out okay. Simply lay the incliometer against the tire or wheel rim flange, which is best. Take a reading or two then adjust the cam bolts. Roll the car back and forth a couple of times and then take another reading. Keep repeating this process until its dialed in. I'm not sure how to measure the rear toe on a Corvette, because you must know the true centerline. When I had the body off the frame of my SWC I measured the true CL of the frame and then hung a plumbob from a string set to the true CL. Then with the rear control arms set to the nominal ride height (spring not connected) I set each side to 1/32 toe in. Maybe someone can tell us how to properly set the rear toe with the body on the car. Make sure your spring link cushions are in good shape. If they are of indeterminant age I would replace them.
You can do the front end this way too. The inclinometer can be used to determine caster by computing the difference in camber readings with the wheels at extreme left and right lock, but it can be a little tricky to keep the signs straight to determine if caster is postive or negative, especially on a car with very little caster, but the Corvette should be about two degrees. Making adjustments is simply done by changing the shim pack on the upper control arm mounting studs. Simply loosen the nuts enough to remove or add shims. The shop manual should give an overview of what shims to change to make various changes in camber and caster. I also recommend the following specs on a C2/C3 assuming you want the best handling and are using radial tires
Front camber: -1/2 deg. (range -1 to 0)
Front caster: +2 deg. (range +1 to +3)
Total toe in: +1/16 inch (range 0 to +1/8)
Rear camber: -1 1/2 deg. (range -2 to -1)
Rear toe in: +1/16 inch (range 0 to + 1/8)
Caster and camber should be equal on both sides.
DukeComment
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Re: Rear Alignment
Duke,
I know what you mean about giving up on alignment shops. A few years ago when I first brought home my 66 the rear wheels looked like I was packing a ton of bricks. I found an alignment shop that was willing to clear their schedule and one bay for an entire morning with me. The night before, with the help of my level garage floor, I spent about a half hour lifting and lowering the rear end of the car after I adjusted the caster/camber each time. When I was satisfied with a perpendicular look to the wheels, I left it alone and took it into the shop the next day. When we finally got around to checking the rear wheel alignment the guy asked how I had adjusted for it. I told him, he measured the readings, and asked again if I was sure I had just "eyeballed" this. I told him again and he then asked me if I wanted a job. TBarr #24014Comment
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Re: Rear Alignment
To add to what Tom has said, I do the same thing. I have a "bubble level". I jack up the car one side at a time, play with the camber bolts, let it down, bounce on it a few times and check it again with my level. When the tires are "straight" or 1/4 or so of a bubble negative, I leave them alone. I might add that I measure from the rim of the wheel, not from the tire, as the tires bulge out when weight is on them. Chuck1963 Corvette Conv. 327/360 NCRS Top Flight
2006 Corvette Conv. Velocity Yellow NCRS Top Flight
1956 Chevy Sedan. 350/4 Speed Hot RodComment
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Re: Rear Alignment
I cut a piece of 2x4 at 15 inches. I checked with calipers that wood was parallel. Sit the car of a level floor and put a 2 ft level vertical with the wood against the rim(the only reason for the wood is so that the level won't hit the tire). Measure the difference to vertical at the end of the 2x4. Jack the car up and adjust the camber the same amount. Put the car down --roll it out and back in the garage and it is done. It is so easy that when I take any rear end parts apart, I don't even both marking the camber adjustments and have never had to redo it. Just my way. bobComment
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Re: Rear Alignment
I have a cheap alignment guage from J.C.Whitney. I put (2) 8x8 inch pieces of metal under each rear wheel with motor oil between them. After changing the settings, I push down on the back bumper before checking the result. Push straight down or the car will slip off the lower plates. I replaced my struts with adjustables that have hard inserts - it makes the job a lot easier. Also, I use 76 settings on my radial tired 66 - to prevent the front end from bump steering, and I set the rear wheels 1 or 2 degrees left of center instead of equal rear wheel toe-in. My car likes to change lanes (left) when I power shift, and the left of center setting counteracts the rotational precess of the rear end. I leave the front end to front end shops, but I always get a computer read out on the rear end (free with the front alignment) to check my rear end alignment work. - DaveComment
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Re: Rear Alignment
Dave----
Well, so there is someone else out there using the method that I use! I use the J.C. Whitney tools also. In fact, I have both the magnetic type and the "caliper" type, although I prefer the "caliper" type. The magnetic type is better, though, if you want to leave the trim rings on the wheels when you do this for ultimate convenience.
The "two plate" system which you described for facilitation of wheel movement while making the adjustment are called "grease plates". This is an old "shade tree" mechanics method and works very well. I use EP chassis grease on the plates, though, and I think that this works a little better than motor oil.
Using this method, I can set the rear camber "dead-on", every time.In Appreciation of John HinckleyComment
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There you go, 50 ways to love your camber
And you thought you would start a fight!
Quebec NCRS ChapterComment
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Re: Rear Alignment
Thought I'd mention that the final tightened and torquing of the nut should be done with the car at normal ride height. Otherwise the bushings will be stressed in torsion. The factory tighted all the bushing bolts front and rear with the springs compressed to normal ride height on the frame machine. This is tough to do with the car on the ground, but on a couple of other cars with cambolts on the front lower arms I tighten the nuts as much as possible with a 1/2 inch drive rachet, then jack the car up to get enough room to do the final pull with a torque wrench.
DukeComment
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Re: There you go, 50 ways to love your camber
Gentlemen, I thank you very much for all the great ideas to set my rear camber. I have tried with the 2x4 and a 2' spirit level but everytime I had the wheels at 0 degrees and drove the car and re-checked for 0 I found the wheels to be out again. That is why I asked about the dollies. Two metal plates with oil or grease makes more sense though. I know I can do this myself now that I have all the shade tree tricks. I will also try the measurement method that was suggested. Sounds very interesting. Wasn't trying to start a comotion just get the knowledge of some with more experience than myself. Thanks again for all the useful information. JohnComment
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Now that's a different fettle of kitsh!
If you find that the settings are changing after a drive, that's a different story.
The camber bolts need a good strong torque on them to start with, and if the bolts are in any way worn or just junk, then they may be slipping while you drive.
In your first post you asked if the GM bolts were available. Why not replace them with new parts, set them as per the above posts and see if they hold the settings. I had a worn GM bolt that would slip a good 5 degrees at the first bump!
Mike
Quebec NCRS ChapterComment
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P.S.
The torque spec for the camber cam bolts ('63 shop manual) is 55-70 ft-lbs. What fight?
DukeComment
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