73sbvert

Hey guys,

I'm in the midst of upgrading my front end suspension with the Performance Plus system from VB&P and while fitting the arms in place, I noticed that the upper and lower ball joints are not in line. The upper seems like it's about an inch or so behind the lower, yet the spindle openings for the ball joints are in line. I have not put any of the shims in place yet.

My questions are: Is this how the caster is adjusted? Via the fore/aft tilt of the spindle? Do the shims adjust this tilt, or some other method?
Also, if this is how it's done, how should I shim it to begin with, so the spindle is straight up? Tilted back? Tilted forward? I don't have any experience with alignments other than bringing my cars to the shop!!

Thanks for any assistance!

0grandmastercorvette

Fisrt question. How many shims were in the upper control arm area before you removed the factory a-arms. This is important. If you had a decent thickness of shims, (i.e. 1/4" to 1/2"+) that is good. IF you have no shims or teh shims are really thin in some of the mounting locations. You may have another problem on your hands. It is called cradle collapse. Itr is common on many vettes that have seen alot of hard miles.

The VB&P upper control arms have an off-set shaft made into it. If you have no shims or very few shims BEFORE you removed the a-arms, the shaft needs to be rotated to aid in gaining more adjustment in the a-arm due to the cradle collapse. I install these systems and sometimes the shaft may not be correctly positioned right out of the box. Call their tech line and they will tell you how to "read" the off-set and install the a-arm.

If you had no shims or very few, you MAY need to take your car to a frame shop and have the cradle stretched. Over time, your cradle begins to sag or collapse inward. So the upper a-arms are getting closer to each other. The alignment shop will then REMOVE shims to get the a-arms back in the correct position for alignment. This goes on and on until one day, they have NO shims to remove to get the a-arm back into its needed position. When the shaft of the upper a-arm is contacting the cradle brqacket, you have no alignment capabilities. The option(s) is to install an off-set upper a-arm shaft (like what you have in the a-arms you have nowfrom the kit) or to have the cradle pulled apart so shims can be installed and the process starts all over again...unless you install the VB&P spreader bar. This bar keep the upper a-arms in their position and prevents the sag or collapse of the cradle.

As for your question, I put in about 1 inch of shims with four diffeerent thicknesses so when ti is going to be aligned, the mechanic will pull out what is needed to get the camber /caster as it should be. And as you know it requires q FOUR wheel alignment. not just a front end alignment. This is because the rear has to be aligned and then the front get aligned to it. SO... if your rear is shot or worn out, the front will be aligned to components in the rear that will move and change under driving conditions because the alignment is prefromed when the car is at rest. this may give you a "steering wheel in the rear effect" or stagecoaching. Just put teh shim in and have it flatbedded to teh alignment shop or drive it....depending on how far you have to go and how it feels in the neighborhood.
"DUB"

calwldlife

do you have the arms on the proper side of the car?
upper should be infront of the lower.

73sbvert

Thanks guys for the input!

There were some shims in all the locations, about 1/2" (+/-) on the left side and about 1/4" (+/-) on the right. I did put the ones I had in the same locations just for a starting point.

I figured I'm making so many changes, I'll HAVE to flatbed it to the shop! No worries, I'm not going to drive it until then!

I thought about that calwldlife, but the uppers literally would NOT fit on the opposite sides. I shrugged and just put them on!

My only other problem which has reared its ugly head now, is the right side lower A-arm ball joint just spins in the socket.
I can't even get the castle nut off of the ball joint stud, it's pretty tight on there. I'm guessing it will need to be replaced since now that it spins, there's nothing to oppose the torque wrench when I tighten it.

Back to VB&P Tech, again! These guys know me on a first name basis now! Gary is a very patient and knowledgeable man! Their customer service is top notch!

Buddy1980

The upper ball joint should be to the rear of the lower joint if caster angle is correct. You can measure this youself with a angle finder. Just level the car on a surface such as garrage floor (I use 1/4" plywood pieces under the wheels where needed.) Then turn the front wheels 20 degrees to the right and measure the camber angle. Now turn the front wheels to the left 20 degrees and measure the camber angle. The difference between these 2 measurements is the caster angle. To increase caster angle put shims at rear location or remove shims at front location. Set the caster first, when it is correct then set camber by removing or adding equal amount of shims at both front and rear locations. By removing or adding equal amount of shims to set camber you will not change the caster angle setting. Lastly set the toe in and you will be real close to good alignment. I have a very accurate angle finder that I align all my vettes with and I have never been to the shop to have it done. All my cars track well I have never had any problem doing it this way. You can also do the rear camber and toe in but it takes a little more work to set the toe in properly.

calwldlife

yeah, upper is behind, I was screwedup