1968 upper control arms help

[james Kekeisen]

Having blasted, replaced the bushings, and painted the front control arms I can no longer remember of the two uppers which is the left and which is the right? Looking at it from the top one side of the triangle is straight and the other side cuts in and then around the upper ball joint. I think the straight side goes toward the front of the car?

Secondly the bolts which hold the arm shafts to the frame are bent slightly because of the alignment shims (and probably over tightening) should these be replaced? Do they have a part number?

Thanks, Jim

[Joe L.]

Re: 1968 upper control arms help

Jim-----

Neither side of the upper a-arms are really what I'd call "straight". However looking straight down at the arms you will note the curve that extends from bushing-to-bushing. One side of the curve has a greater radius than the other. The side with the greater radius goes toward the front. Actually, I don't think that it's possible to install the arms incorrectly since the spindle could not be attached.

The a-arm shaft retaining bolts have a serrated shank and are a press fit into the frame bracket. If damaged in any way, they should be replaced. The bolts for 68-82 Corvettes are available under GM #381909.

[Chuck G.]

Re: 1968 upper control arms help

The bolts can be a PIA to get out. You can put a nut on the end and try to tap them out if you can get some "swing" room with a hammer. As Joe said, they have a gnurled shank, and you cannot "screw" them out. I had to make a puller/pusher out of a 3 inch "C" clamp and a socket to press my bolts out. One more thing....and I don't know the when/where, and that is that the bolts come in both a fine and coarse thread. Seems I remember my 69 used fine, and my 63 used coarse. Some use the "TopLoc" nuts and some use "plain old" nuts. Hope this helps, and doesn't add to the confusion. Don't know if the bolts you get today from GM are coarse or fine thread. Chuck

[james Kekeisen]

Re: 1968 upper control arms help

Thanks Joe and Chuck. The front right upper arm shaft bolt is so long that the space between the end of the bolt and the radiator shroud prevents the control arm from coming off the bolt without a major pry bar (to bend in the shroud slightly) or removing the splined bolt (which I couldn't do with no space to hit it out). Chuck, your press trick sounds like the way to go.

My question do these splined bolts come in different lengths? What do you think about cutting an inch or so off then chasing the threads? There is plenty of length to insert any number of shims.

[Joe L.]

Re: 1968 upper control arms help

Chuck-----

I believe that the mid-years used the fine threaded bolts (7/16-20). These were last available under GM #3888248, but they've been discontinued for quite some time now. I think that they're available in reproduction, though. They were 2-1/4" long and exactly the same length as the 68-82 course thread (7/16-13)bolts.

1963 to 1965, and possibly early 1966, used a plain hex nut with a lockwasher on these bolts. 66-67 and all 1968-82 used a prevailing torque lock nut of the appropriate thread pitch.

[Joe L.]

Re: 1968 upper control arms help

James-----

The bolts available from GM are only of the 2-1/4" length. However, you could likely find a bolt of this type in an auto parts store and of different lengths. These bolts are similar to wheel stud bolts. However, I don't know that I'd recommend using shorter bolts. Corvettes often require a significantly thick shim pack on one or more of the bolts. I don't think that I'd "chance it" using shorter bolts.