Are these the correct trailing arm shims???

[Michael L.]

Guys

im trying to install my trailing arms today and it looks to me that the shims are not correct. They are too long, and the lack of a notch at one end means the bolt has to be removed whenever I get a wheel alignment. I got these from Paragon and the label clearly says 63-69 but now I'm thinking they're wrong. I included a couple of pics to illustrate what I mean. Any advice?

Mike

[Bob W.]

Re: Are these the correct trailing arm shims???

Mike What year is your car? Long island corvette shows the 63 as notch and 64 to 67 like the ones you have .

Bob

[Domenic T.]

Re: Are these the correct trailing arm shims???

Michael,
I seem to remember, and I may be wrong , but the thicker shims don't have the notch because they always stay in. The thin shims are the ones that fine tune the spacing and are made to be removed or added.

Dom

[Joe L.]

Re: Are these the correct trailing arm shims???

Guys

im trying to install my trailing arms today and it looks to me that the shims are not correct. They are too long, and the lack of a notch at one end means the bolt has to be removed whenever I get a wheel alignment. I got these from Paragon and the label clearly says 63-69 but now I'm thinking they're wrong. I included a couple of pics to illustrate what I mean. Any advice?

Mike

Mike-----

This STYLE shim was used from 1964-69. However, this one does not appear 100% accurate in configuration to me. As far as length goes, they should be 4-1/2" long.

Regardless of the year car involved, I recommend that only the 1970-82 style SLOTTED shims be used. This is for exactly the reason you mention in that if the non-slotted shims are used it requires the removal of the bolt to remove or install shims. I also recommend that the shims be of stainless steel material.

[Michael W.]

Re: Are these the correct trailing arm shims???

Two holes shims as shown are correct for 63-69. Notched/slotted shims are correct for 70-82.

[Joe L.]

Re: Are these the correct trailing arm shims???

Two holes shims as shown are correct for 63-69. Notched/slotted shims are correct for 70-82.

Mike------


1963 used a slotted style shim but it was of a completely different configuration than the 1970-82.

[Michael L.]

Re: Are these the correct trailing arm shims???

Sorry the car is a 69. Also, the shock mtg shaft is listed as LH and RH in the AIM but how do I know which is which? Mine aren't currently labeled. I tried putting one on the first trailing arm I installed and it is a BITCH to get through the holes on the trailing arm. Is it supposed to be that hard? Should I take off the trailing arm and press them on along with the stabilizer strut shaft prior to install??? Finally, there is a pretty decent gap between the strut craft and the mounting points on the trailing arm. There are caps in the AIM for the differential side of the strut but nothing for the trailing arms side. Is this gap of almost 3/8 of an inch normal?

[Michael L.]

Re: Are these the correct trailing arm shims???

Thanks for te responses. Please see my above post for additional questions. As for the shims, these are 43/4" but they are just too long. Unless I'm reading my AIM wrong the shim has to align with the trailing arm bolt hole and the cotter pin hole. As you can see from the photo below that's impossible with these shims. The screw driver is in the cotter pin hole I believe. It's the only hole in the frame. You can see those shims are way too long.

[Joe L.]

Re: Are these the correct trailing arm shims???

Michael------

The shock shafts can only install one way due to the indexing flat on the end of the shaft and on the bearing support fork. The shock mount end of the shaft should be oriented INWARD on both sides of the car. Recognizing these two things, it's easy to figure out which shock mount goes on which side. Original shock mount shafts had forging numbers on the un-machined portion of the shaft. Later SERVICE shafts had no forged markings.

The clearance between the strut rod end and the spindle support forks is normal. However, the strut rod bushing tube should fit tightly against the forks.

I've never had any trouble, at all, INSTALLING the shock mount shafts into the spindle support fork and through the strut rod bushing. However, it may be necessary to rotate it so that the flat on the shaft aligns with the flat on the fork.

[Joe L.]

Re: Are these the correct trailing arm shims???

Michael-------


Actually, the 64-69 shims were 4-3/4" in length. The 4-1/2" I mentioned was the length of the 1970-82 slotted shims.

The cotter pin is not used with the "2 hole" shims. The cotter pin is 100% superfluous with the 2 hole shims. Some 1969 frames (such as yours) do have the cotter pin holes but no cotter pins were originally installed. If you use the 1970-82 style slotted shims, you will be able to install cotter pins if you wish. However, if the slotted shims are properly installed with a TIGHT shim pack and tucked down into the frame pocket, I really think the cotter pins are unnecessary.

[Joe R.]

Re: Are these the correct trailing arm shims???

Michael,

You need to call Bair's at 1 800 421-9644 and ask for Brian. Tell him you are an NCRS member and tell him I referred you.
He has what you need and its NCRS correct.

JR

[Michael L.]

Re: Are these the correct trailing arm shims???

Ok thanks Joe. Will do.

[Michael L.]

Re: Are these the correct trailing arm shims???

Michael-------


Actually, the 64-69 shims were 4-3/4" in length. The 4-1/2" I mentioned was the length of the 1970-82 slotted shims.

The cotter pin is not used with the "2 hole" shims. The cotter pin is 100% superfluous with the 2 hole shims. Some 1969 frames (such as yours) do have the cotter pin holes but no cotter pins were originally installed. If you use the 1970-82 style slotted shims, you will be able to install cotter pins if you wish. However, if the slotted shims are properly installed with a TIGHT shim pack and tucked down into the frame pocket, I really think the cotter pins are unnecessary.

Joe,

if the 69 shims were all two holes why does my 69 AIM show the slotted shims and a cotter pins? I would like to order the 70-82 slotted shims but wanted to make sure that they would be judged as correct. Also, for the two hole shims what would the second hole be for? As you can see in the picture the shim is so long it is sticking out of the frame. Just curious.

Mike

[Terry M.]

Re: Are these the correct trailing arm shims???

Joe,

if the 69 shims were all two holes why does my 69 AIM show the slotted shims and a cotter pins? I would like to order the 70-82 slotted shims but wanted to make sure that they would be judged as correct. Also, for the two hole shims what would the second hole be for? As you can see in the picture the shim is so long it is sticking out of the frame. Just curious.

Mike

In production the slotted shims did not start until the last week of 1970 model year. Why the holes in the frame for the cotter pin started a year earlier is one of the great Corvette mysteries. I use this example often in my Advanced Judging Seminar to illustrate the danger of relying on only the AIM in restoring your car. One also needs the TIM&JG as well as spending a lot of time looking at original un-restored cars built around the time of yours.

[Joe L.]

Re: Are these the correct trailing arm shims???

Joe,

if the 69 shims were all two holes why does my 69 AIM show the slotted shims and a cotter pins? I would like to order the 70-82 slotted shims but wanted to make sure that they would be judged as correct. Also, for the two hole shims what would the second hole be for? As you can see in the picture the shim is so long it is sticking out of the frame. Just curious.

Mike

Mike------


Well, the change to the slotted shims happened late in the 1969 model year. In fact, my original owner, September, 1969 built convertible originally had a combination of shim types-----some of the "2 hole", some slotted. However, while there were cotter pin holes in the frame, no cotter pins were originally installed. Some (or, many) judges might regard the "2 hole" shims as the only correct type for any 1969. They're right for early 1969 but not correct for late 1969. So, when did the change occur? I'd say, it STARTED about the time my car was built (that's why mine had a mixture of shims). However, I believe that, either way, the outer hole for 1969 (and, maybe, early 1970) should be round and not oblong.

As far as what the purpose of the second hole is for the "2 hole" shims, all I can figure is that it was to make the shims installable either way OR there was some PRODUCTION-utilized function. It was certainly not for a cotter pin retainer since 1963-E1969 frames did not even have the cotter pin holes.

By the way, the late 1969 slotted shims were not the same as the 1970-82 slotted. The late 1969 shims were GM #3965192 through 3965195. These were also available in SERVICE until 1972 when they were replaced by the 1970-82 shims, GM #3983392 through 3983395. So, what was the difference between the two sets? The earlier set was 4-3/4" long and the latter was 4-1/2" long and the hole in the earlier shim was round while the hole in the latter was oblong. The oblong hole might have made it easier for cotter pin insertion.

Whether your 1969 was originally equipped with "2 hole" shims or slotted shims, I recommend the slotted type (for 1963-E69, too).