Beautiful day almost ruined...

[Leif A.]

Beautiful day here in the DFW area (68*) so, naturally, had to go for a drive. Took about an hour drive out around the lake and back. As is my custom, when I got home and pulled the car in the garage, I popped the hood to connect the battery minder and take a general look around the engine compartment for leaks or anything out of the way. Please review the pictures attached as this is what I noticed on the driver's side upper control arm shaft. I was able to easily re-install the bolt and before tightening went and got my 1967 shop manual to find out torque specs. Please review second picture, last three words in the instructions..."do not tighten". I guess whoever tightened these the last time (had to be over four years ago) took the instructions literally. How tight should these bolts be? And, yes, there is a lock washer in place.

[Joe L.]

Re: Beautiful day almost ruined...

Beautiful day here in the DFW area (68*) so, naturally, had to go for a drive. Took about an hour drive out around the lake and back. As is my custom, when I got home and pulled the car in the garage, I popped the hood to connect the battery minder and take a general look around the engine compartment for leaks or anything out of the way. Please review the pictures attached as this is what I noticed on the driver's side upper control arm shaft. I was able to easily re-install the bolt and before tightening went and got my 1967 shop manual to find out torque specs. Please review second picture, last three words in the instructions..."do not tighten". I guess whoever tightened these the last time (had to be over four years ago) took the instructions literally. How tight should these bolts be? And, yes, there is a lock washer in place.

Leif------


It means do not tighten it when the bushings are installed. However, they do need to be tightened after installation on the car and the car is at normal ride height . At that point, they need to be tightened to 40 lb/ft.

[Duke W.]

Re: Beautiful day almost ruined...

The reason the instructions say "do not tighten" is because the bushing bolts for both upper and lower control arms (and rear trailing arms and strut rods) should not be torqued until the car is at normal ride height. The plant frame assembly fixture compressed the suspension for this purpose.

The '63 Shop Manual and AIM are somewhat ambiguous on the upper control arm bushing bolts torque. The AIM lists the lower control arm bushing bolts at 45-55 lb-ft, but does not list a bushing bolt torque for the upper control arm - only the upper cross shaft nuts to frame studs, 65-75 lb-ft.

The Shop Manual jibes with the AIM on the upper cross shaft to frame stud nut torque and the lower control arm shaft fasteners to the frame.

The last listing is "control arm cross shaft 30-40 lb-ft."

The lower control arm bushing bolts are 7/16"-20, and the upper control arm bushing bolts are 3/8"-24, so it does make sense that the upper control arm bushing bolts would have a lower torque spec.

Maybe later years AIMs and service manuals are less ambiguous.

Hector Guzman had the same problem that he reported earlier this month on the TDB. One upper bushing bolt fell out on the road and he had to be towed, which turned out to be a very unpleasant experience. I think I now understand how a loose bushing bolt can happen depending on who installs the new bushing and who installs the control arm back on the frame.

Duke

[Joe L.]

Re: Beautiful day almost ruined...

The reason the instructions say "do not tighten" is because the bushing bolts for both upper and lower control arms (and rear trailing arms and strut rods) should not be torqued until the car is at normal ride height. The plant frame assembly fixture compressed the suspension for this purpose.

The '63 Shop Manual and AIM are somewhat ambiguous on the upper control arm bushing bolts torque. The AIM lists the lower control arm bushing bolts at 45-55 lb-ft, but does not list a bushing bolt torque for the upper control arm - only the upper cross shaft nuts to frame studs, 65-75 lb-ft.

The Shop Manual jibes with the AIM on the upper cross shaft to frame stud nut torque and the lower control arm shaft fasteners to the frame.

The last listing is "control arm cross shaft 30-40 lb-ft."

The lower control arm bushing bolts are 7/16"-20, and the upper control arm bushing bolts are 3/8"-24, so it does make sense that the upper control arm bushing bolts would have a lower torque spec.

Maybe later years AIMs and service manuals are less ambiguous.

Duke

Yes, I mis-typed, above. I have corrected it.

[Leif A.]

Re: Beautiful day almost ruined...

Joe and Duke,
Thank you for your prompt and informative responses. I, ultimately, found the 40 lb ft spec in the back of the shop manual. When I went back to the garage to tighten the bolts, I noticed that my 9/16" six-point socket was not as fitted as I expected it to be. Out of curiosity, I tried a 14mm socket and it fit like a glove. I think whoever installed these cross shafts used the incorrect bolt. Out of an abundance of caution, I'm going to get four new (correct) bolts and lock washers. Hopefully, the threads in the cross shaft have not been wasted by the incorrect bolt(s).
Thank you, again, gentlemen and a very Happy New Year.

[Richard M.]

Re: Beautiful day almost ruined...

Leif, Keep an eye on all 8 bolts. Even after being torqued, I've seen them loosen over time. The bushings have "teeth" on the ends of the inner sleeves and if they get smoothed off from being loose, not until the bushing sleeves weld themselves to the shafts, will they stay tight.

Last car I took apart were loose after many years. Sleeve ends were smoothed.

Rich

[Leif A.]

Re: Beautiful day almost ruined...

Rich,
Always great to have your input, as well. I had actually been thinking to myself that the next time I had the car on the lift for an oil change (in about a month), had made a mental note to check everything over from underneath. Always a good practice to check these cars over on a regular basis...just glad I was doing my due diligence today and spotted a potential nightmare waiting to happen. Happy New Year Rich.

[Richard M.]

Re: Beautiful day almost ruined...

Rich,
Always great to have your input, as well. I had actually been thinking to myself that the next time I had the car on the lift for an oil change (in about a month), had made a mental note to check everything over from underneath. Always a good practice to check these cars over on a regular basis...just glad I was doing my due diligence today and spotted a potential nightmare waiting to happen. Happy New Year Rich.

Thanks Leif,

But even if the bolts fell out, the bushings would stay put for quite some time. By design, the ends of the control arms can't come off, the'd just rotate loosely on the shafts and wear them and the inner sleeve over time. You'd hear the metal to metal squeaking noises eventually. When everything is properly tight, only the rubber inside the bushing twists.....


I had the same problem not that long ago. After about 500 miles of driving with rebuilt arms with all new bushings, I went to check all 8 on the 67. All were torqued to spec with full weight of car on ground. I looked down at the top arms and could see the rubber behind the big washers was too thick, meaning the bolts were loose. On one, it was so loose I could see the lockwasher wasn't compressed. All 4 needed retightening.

The sleeve teeth are made to bite into the shaft flange and the big outer washer. A press is needed, well not always, but safer for the parts and arms, to install the bushings over the shafts using a tool made like a pipe to prevent the arm ends from bending. As you can see once the assembly is complete, it can't fall apart. You can see the teeth of the sleeve inside the bushing in the last pic. When bolt is tight, the bushing sleeve stays put and just the rubber moves.




The lower arm takes a different arm end support tool with a cutout due to the flanges on the shaft for the front bolts. I made the tools from steel pipe.


===

[Joe L.]

Re: Beautiful day almost ruined...

Rich,
Always great to have your input, as well. I had actually been thinking to myself that the next time I had the car on the lift for an oil change (in about a month), had made a mental note to check everything over from underneath. Always a good practice to check these cars over on a regular basis...just glad I was doing my due diligence today and spotted a potential nightmare waiting to happen. Happy New Year Rich.

Leif------


GM relied on split lockwashers to retain the bolts. Split lockwashers are near useless, though. Use Locktite 242 on the bolt threads. You can install the lockwashers, too.

[Leif A.]

Re: Beautiful day almost ruined...

Rich,
Thanks, as always, for your detailed and informative pictures...they never cease to amaze. When my new bolts are installed, I'll be checking all eight upper and lower bolts on a regular basis going forward.
Joe,
Thank you for the Loctite 242 recommendation...I'll probably remove one bolt at a time and put a bit of Loctite on all eight upper and lower cross shaft bolts.
Thanks so much fellas.