Upper A Arm bolts (alignment adjustment)

[Mike R.]

Can anyone tell me the length of the bolts that attach the upper A-Arm cross shaft to the frame. Mine are 2" and don't seem long enough for much caster/camber adjustment. Also, what is the correct head marking. Thanks!

[Joe L.]

Re: Upper A Arm bolts (alignment adjustment)

Can anyone tell me the length of the bolts that attach the upper A-Arm cross shaft to the frame. Mine are 2" and don't seem long enough for much caster/camber adjustment. Also, what is the correct head marking. Thanks!

Mike-----


The original bolts were 7/16-20 X 2-1/4".

[Mike R.]

Re: Upper A Arm bolts (alignment adjustment)

Thanks Joe, just to confirm, the 2.25" is the length under the head, which would be about 2.5" total length(?).

Mike

Mike-----


The original bolts were 7/16-20 X 2-1/4".

[Joe L.]

Re: Upper A Arm bolts (alignment adjustment)

Thanks Joe, just to confirm, the 2.25" is the length under the head, which would be about 2.5" total length(?).

Mike

Mike-----


Yes, bolt lengths are almost always specified as the length as measured from under the head. As far as I know, the specifications for this bolt are on that basis. However, I have not actually measured the bolt length.

[Dick W.]

Re: Upper A Arm bolts (alignment adjustment)

If your car has been "run hard and put up wet", it is not uncommon to see the front crossmember rolled in, pulling the mounting for the upper control arm with it. That is the reason that race cars used a spreader bar. It creates problems trying to align the front end if that happens. Only practical way that I know of to correct this is to send it to a competent frame shop.

[Mike R.]

Re: Upper A Arm bolts (alignment adjustment)

Thanks Dick and Joe. I am taking the car to the alignment shop today and noted that there was no more for more shims on the rear bolt. My bolts are 2". I have ordered the correct bolts but hopefully I can get the car aligned with the bolts currently installed. We will see in a couple hours....

[Joe L.]

Re: Upper A Arm bolts (alignment adjustment)

If your car has been "run hard and put up wet", it is not uncommon to see the front crossmember rolled in, pulling the mounting for the upper control arm with it. That is the reason that race cars used a spreader bar. It creates problems trying to align the front end if that happens. Only practical way that I know of to correct this is to send it to a competent frame shop.

Dick-----


A "band-aid" solution is using offset upper control arm shafts. These are available from Moog but were never available from GM, although Delco might offer the Moog product in Delco boxes..

[Terry M.]

Re: Upper A Arm bolts (alignment adjustment)

I have found a gradual closing of the upper control arm supports on all my "old" LASA (Long Arm Short Arm) cars. I could enumerate all of them, but they range from a 1967 Chevelle to my 1995 Caprices. My belief is it comes from just the weight of the engine on the frame over time. Although at getting close to a quarter million miles on the Caprices and a long gone 1972 Chevelle might have something to do with it. Does that many miles count as "rode hard and put away wet" Joe?

Two solutions, both of which have been mentioned: Frame tweaking -- had that done to the 1972 Chevelle -- I don't think you want to watch that process. it involved two large hooks, chains and large hydraulic cylinders. They literally pulled the frame supports apart by the upper control arms. The sound it made was even worse than it looked. The process put fairly large dents in the upper control arms from where the hooks grabbed the UCA, but they pulled it exactly right. I needed to add nor take away no shims when they were done, and it lasted another 150K miles.

Or the offset UCA shaft. I did that to one of the Caprices, and soon expect to have to do it to the other. I'll do it when I replace the upper inner control arm bushings. It is easy to do then. I suspect it has some suspension advantages in that one is lengthening the upper control arm by the length of the offset. This has the negative potential in that a sharp-eyed judge could catch it during judging.