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I'm using C3 Trailing arm shims in my '66. I did not drill a hole in the frame for a cotter pin.
I don't drive it far or often. When I do drive it, afterwards I'll do a post-drive inspection. Sometimes I notice one or two of the shims moves just a little. (picture below)
When I see that, I'll push them back into place.
I saw in another post (which I can't find now) where somebody mentioned they had done the same thing but they used some kind of "glue" which they said was effective at holding them in place.
What have others done to hold the C3 trailing arm shims in place without drilling a hole in the frame and using a big cotter pin?
It may not be pretty, but what about aligning all of the shim holes on both sides and running a zip-tie through them and around the T/A? At the very least, they won't fall out completely and cause a rear-end steering condition.
Some guys just pound them down/rotate them, into the pockets so they can’t come out…..
others use at least one correct two hole shim at each location, and then use a little bit of mechanics wire through the exposed holes before placing them in the lowest position.
personally, I just use the correct shims, might as well do it right :-). When I have done major work back there that required a alignment, I’ve used the slotted shims…. that makes it easier for the alignment person to adjust, and then once I got the car back home, removed them, measured the thickness of the stacks, and replaced them with correct two hole shims.
Last edited by 66427-450; Sep 24, 2023 at 03:47 PM.
Some guys just pound them down/rotate them, into the pockets so they can’t come out…..
others use at least one correct two hole shim at each location, and then use a little bit of mechanics wire through the exposed holes before placing them in the lowest position.
personally, I just use the correct shims, might as well do it right :-). When I have done major work back there that required a alignment, I’ve used the slotted shims…. that makes it easier for the alignment person to adjust, and then once I got the car back home, removed them, measured the thickness of the stacks, and replaced them with correct two hole shims.
Certainly a bit more work but this is how I do mine, as well.
Last edited by leif.anderson93; Sep 25, 2023 at 10:13 AM.
Diabolical -
There are two common configurations of the slotted, stainless steel shims sold by the 'usual suspect' vendors. Those with deeper 1-7/8" slot index further forward to pivot bolt; they'll rotate down into the frame pocket pretty securely.
When you arrange the shim stacks, recall that the IB thickness is what sets the toe & the OB's are there only to tightly fill the gap. " ... use force as necessary ..." per the General when installing OB's. Try to arrange your OB stack with thicker shims outside, & thinner ones inside to make it easier to drift in without bending.
I prefer to lift & prop the TA ***'y upward to a near a 'weight-on-the-wheels' position before driving in the OB stack, torqueing the pivot bolt & declaring victory.
When I did the rearend rebuild 5 1/2 years ago, to be honest, I probably did not realize that the vendor had given me C3 shims when I received all the stuff (Trailing arms, half shafts, etc). I have driven it ~750 miles since then with no problems. Just a couple months ago, I did a 4-wheel alignment myself in my garage. I needed to change the PS shims. That's when I noticed one was slightly rotated up (above picture). I saw in another post somebody opined that if the bushings are installed correctly, and you torque the T-arm bolt/nut correctly, they should not move. I reckon that's more or less my experience. BUT now that I am fully aware of the risk I will want to "fix" it. Sounds to me, for my specific car and situation, probably the best overall solution is to drill the holes and use the big cotter pins. My car will never be a pristine museum car. No reduction in value by drilling those holes. I'm not sure I can do it with the body on. I'm planning to lift the body sometime in the future. Until then, I'm probably going to push them down into the pocket and then pull them rearward. That should keep them down for the short drives I do. I only drive <75 miles at a time. And, like I said, in 750 miles they hardly moved. I'll inspect them after every drive.
Just went through this. My 66 came to me with SS shims, all with the cotter pin holes but the pocket was not drilled. We drive ours 2-3K miles each year including 1-2 500-1000 mile road trips. Routine maintenance on the lift I noted the inboard shims on the passenger side were rotated up out of the pocket. No evidence they were working there way back out though. Using a punch and hammer I tapped them all down into the pocket and figured I was done. Night before we leave on the 1000 mile trip I am currently on it dawns on me to take a follow up look. Yup, they rotated back up out of the pocket. It's 11pm, were leaving at first light and I have read about what happens if you spill those shims on the road while driving. As a temporary fix I cut a narrow piece of steel to close off that side of the pocket without interfering with the TA function and put a #10 SS sheet metal screw in it to hold it. The pocket drills fairly easily. The shims can still rotate and probably have but they can not move aft and out. When I get home I will drill (probably a 12" extension 1/8" drill bit) and install the cotter pins. A dab of JB Weld will close the temporary sheet metal hole after I remove it.
Lesson learned, if it is a potential problem, just fix it.
using C3 T-arm shims
Certainly a bit more work but this is how I do mine, as well.
