Trailing Arm Toe-In Shims

[Eric H.]

Technical Advisors -

The trailing arm shims on my 65 have fallen out on one side. This makes for an interesting handling characteristic. In fact probably dangerour.

These shims seem to fit "behind" a lip on the main frame. Is this all that is keeping them from working their way out? I have previously installed the aftermarket(?) SS shims which are slotted on one end.

The car is presently being realigned. Perhaps the shop will find an obvious answer as to why they fell out on this one side.

Also the AIM torque for the trailing arm bolt in my manual appears to be ?? - 75 ft-lbs. My manual is difficult to read. Any have these values handy?

Ric

[Joe L.]

Re: Trailing Arm Toe-In Shims

Ric-----

Originally, your trailing arm shims were of the "2 holer" variety, with elongated holes on either end. This provided a positive means of "secondary" retention. In late 1969/early 1970 the "slotted on one end" shims were phased into PRODUCTION. For these shims, a long cotter pin which passed through holes in the frame and the hole on the outer end of the shims provided the "secondary" means of retention. If you are not overly concerned with "correctness" you could add the cotter pin holes and pins.

However, generally, the cotter pins are really unnecessary, even with the slotted-on-one-end shims. IF THE SHIM PACK IS TIGHT AS IT SHOULD BE, the "ridge" on the frame you observed will provide all of the "secondary" retention necessary. The key is that the shim pack MUST be tight. That means that the last shim has to be driven in with a hammer, then the shim pack is driven down into the frame cavity.

By the way, the slotted-on-one-end shims are the ONLY WAY TO GO. Beyond that, the stainless steel shims are the ONLY WAY TO GO. In some cases, "correctness" just has to be foresaken.

[Joe L.]

Re: Trailing Arm Toe-In Shims

Ric-----

Originally, your trailing arm shims were of the "2 holer" variety, with elongated holes on either end. This provided a positive means of "secondary" retention. In late 1969/early 1970 the "slotted on one end" shims were phased into PRODUCTION. For these shims, a long cotter pin which passed through holes in the frame and the hole on the outer end of the shims provided the "secondary" means of retention. If you are not overly concerned with "correctness" you could add the cotter pin holes and pins.

However, generally, the cotter pins are really unnecessary, even with the slotted-on-one-end shims. IF THE SHIM PACK IS TIGHT AS IT SHOULD BE, the "ridge" on the frame you observed will provide all of the "secondary" retention necessary. The key is that the shim pack MUST be tight. That means that the last shim has to be driven in with a hammer, then the shim pack is driven down into the frame cavity.

By the way, the slotted-on-one-end shims are the ONLY WAY TO GO. Beyond that, the stainless steel shims are the ONLY WAY TO GO. In some cases, "correctness" just has to be foresaken.

[Dan White]

Re: Trailing Arm Toe-In Shims

The aftermarket kits that have the slotted shims usually come with long cotter pins, which after drilling both sides of the frame, is used to hold the shims in place. you might be able to get by if they are driven in very tight. If I remember right, the torque for the pivot bolt is 55 to 75 ft lbs. Good luck, Dan

[Dan White]

Re: Trailing Arm Toe-In Shims

The aftermarket kits that have the slotted shims usually come with long cotter pins, which after drilling both sides of the frame, is used to hold the shims in place. you might be able to get by if they are driven in very tight. If I remember right, the torque for the pivot bolt is 55 to 75 ft lbs. Good luck, Dan

[Michael W.]

Re: Trailing Arm Toe-In Shims

Rick,

Yours is the third case I have heard of slotted shims falling out. All could have been prevented by the auxiliary cotter pin as introduced in the 69 model year.

[Michael W.]

Re: Trailing Arm Toe-In Shims

Rick,

Yours is the third case I have heard of slotted shims falling out. All could have been prevented by the auxiliary cotter pin as introduced in the 69 model year.

[Patrick T.]

Re: Trailing Arm Toe-In Shims

When I installed new torque arms on my '67, which does not have holes drilled in the frame for cotter pins, as mentioned above, I used stainless slotted shims; they are the only way to go.

I loaded up the shim pack onto the forward bolt of the trailing arm and drove the last shim in with a light tap of a plastic hammer. Then I pushed the whole shim pack down into the frame, as far as it would go. The trick to keep them from coming out, is to lower the car down on the floor, so it's at riding height, then torque the bolts to 55 lbs.

I wasn't about to drill holes in my frame for cotter pins and the shims have stayed put, since I installed them 2 years ago.

[Patrick T.]

Re: Trailing Arm Toe-In Shims

When I installed new torque arms on my '67, which does not have holes drilled in the frame for cotter pins, as mentioned above, I used stainless slotted shims; they are the only way to go.

I loaded up the shim pack onto the forward bolt of the trailing arm and drove the last shim in with a light tap of a plastic hammer. Then I pushed the whole shim pack down into the frame, as far as it would go. The trick to keep them from coming out, is to lower the car down on the floor, so it's at riding height, then torque the bolts to 55 lbs.

I wasn't about to drill holes in my frame for cotter pins and the shims have stayed put, since I installed them 2 years ago.

[Keith B.]

Use the two hole -- With slight modification

I used stainless two hole shims but I cut a slanted slot into them the same size as the bolt that they rest on. With these I actually could hang the shims on one at a time until the last few which I tapped in. They can't fall off because of the angle. You have to push them up and forward to get them off of the bolt plus they you can not tell that they are slotted when installed.

[Keith B.]

Use the two hole -- With slight modification

I used stainless two hole shims but I cut a slanted slot into them the same size as the bolt that they rest on. With these I actually could hang the shims on one at a time until the last few which I tapped in. They can't fall off because of the angle. You have to push them up and forward to get them off of the bolt plus they you can not tell that they are slotted when installed.

[Gary B.]

Could you post a picture?

Keith,

Could you post a photo or drawing of exactly what your modified shim looks like?

Thanks,

Gary

[Gary B.]

Could you post a picture?

Keith,

Could you post a photo or drawing of exactly what your modified shim looks like?

Thanks,

Gary

[Terry M.]

Trailing Arm Toe-In Shims & cotter pin retainer *TL*

In spite of what the 1969 AIM shows, the cotter pin and slotted shims were not installed until the last week of 1970 production. The frame was drilled for the cotter pin during 1969 model year, but the shim style didn't change until much later. This is one of the real AIM mysteries, and I use it in training classes to emphasize how deceiving the AIM can be. Cars (before they are restored) tell the real story.

[Terry M.]

Trailing Arm Toe-In Shims & cotter pin retainer *TL*

In spite of what the 1969 AIM shows, the cotter pin and slotted shims were not installed until the last week of 1970 production. The frame was drilled for the cotter pin during 1969 model year, but the shim style didn't change until much later. This is one of the real AIM mysteries, and I use it in training classes to emphasize how deceiving the AIM can be. Cars (before they are restored) tell the real story.