Shock to Trailing Arm clearance

[Michael M.]

On my '68 driver, I noticed that there is very little, if any, clearance between the shock absorber and the inside of the rear trailing arm.

How much distance should there be between the shock and trailing arm. I searched the archives with no luck. All of the components in the rear suspension are new or rebuilt. New trailing arms, newly rebuilt diff, new shocks, new strut rods, new rear spring liners, new spring bolts and bushings, etc.

Thanks for any replies.

[Joe L.]

Re: Shock to Trailing Arm clearance

On my '68 driver, I noticed that there is very little, if any, clearance between the shock absorber and the inside of the rear trailing arm.

How much distance should there be between the shock and trailing arm. I searched the archives with no luck. All of the components in the rear suspension are new or rebuilt. New trailing arms, newly rebuilt diff, new shocks, new strut rods, new rear spring liners, new spring bolts and bushings, etc.

Thanks for any replies.

Michael----


There is normally very little clearance between the shock and trailing arm----about 1/4" or less.

[Michael M.]

Re: Shock to Trailing Arm clearance

Thanks Joe.

What do you think about using some washers on the lower shock mount to create a little more clearance? Maybe 1 or 2 flat washers on each side to space it out. I know I shouldn't have to do this but it seems better than contact between the shock and trailing arm.

[Joseph K.]

Re: Shock to Trailing Arm clearance

If they are touching then a washer maybe necessary. If they do not touch I would leave it alone. Has the alignment been checked on the rear? If out, that may be the reason that they touch.

Joe

[Michael M.]

Re: Shock to Trailing Arm clearance

I will get the car aligned and see how it looks. Thanks for the suggestion.

[Dick W.]

Re: Shock to Trailing Arm clearance

If all the parts are properly installed and aligned there should be no need for extra washers

[Joe L.]

Re: Shock to Trailing Arm clearance

Thanks Joe.

What do you think about using some washers on the lower shock mount to create a little more clearance? Maybe 1 or 2 flat washers on each side to space it out. I know I shouldn't have to do this but it seems better than contact between the shock and trailing arm.

Michael-----


I agree with Dick; there should be no need for the addition of washers. If there is a need for washers, then something else is wrong and needs to be corrected. Three things to check for:

1) condition of the lower shock rubber bushings;

2) condition of the shock mount shaft. In other words, is it bent or otherwise distorted;

3) whether the upper shock bracket appears to have been "re-welded" to the frame at some point in the car's life.

[Terry M.]

Re: Shock to Trailing Arm clearance

One might also have a shock that is too fat if one is using a non-OEM shock, or if one is using the Heavy Duty shock with the non-HD lower shock mount bracket.

[Joe L.]

Re: Shock to Trailing Arm clearance

... or if one is using the Heavy Duty shock with the non-HD lower shock mount bracket.

Terry-----


I ABSOLUTELY agree.

[Michael M.]

Re: Shock to Trailing Arm clearance

I did see Joe's post on the differences between the lower shock mounts, so I'll check that first. I agree that something isn't right but all the components are new (although not original). For instance I am using Bilstein shocks on the car. I will check the upper shock mount location for signs of re-welding etc.

It would seem that the clearance on the shock should be pretty static, even if the car is out of alignment. I will get the car aligned and see if that fixes the issue and I'll report back. Thanks for the ideas and suggestions.

[Dick W.]

Re: Shock to Trailing Arm clearance

I have had HD Bilsteins on our '72 for over 15 years with no rubbing. If they are not rubbing, don' t worry about it. When they do, you will know immediately from the loud noises emulating from the rear of your car

[Terry M.]

Re: Shock to Trailing Arm clearance

I have my original shocks handy in the garage. When I get home tonight I can get a diameter off them. I would wager the Bilsteins are a larger diameter than the original shocks.

If you are really concerned the HD lower shock mounts are readily available (I think), but changing them is a lot of work for possibly little value.

[Joe L.]

Re: Shock to Trailing Arm clearance

I have my original shocks handy in the garage. When I get home tonight I can get a diameter off them. I would wager the Bilsteins are a larger diameter than the original shocks.

If you are really concerned the HD lower shock mounts are readily available (I think), but changing them is a lot of work for possibly little value.

Terry-----


Original standard suspension rear shocks have a tube diameter of 1.65-1.70". HD rear shocks have a larger tube diameter of 2.31" (1963-69) and 2.00" (1969-75+). When used with the standard suspension shock mount shafts, the minimal clearance of about 1/4" with standard shocks will be quickly reduced if larger OD shocks are used.

The HD shock mount shafts are very easy to come by; it's the standard suspension shafts that are difficult to find in NOS or good used condition. GM discontinued from SERVICE the standard suspension shafts many years ago and replaced them with the HD shafts for all SERVICE (although the standard suspension shafts were used in PRODUCTION right through to the end of the C3 run).

Also, all of the replacement shafts available in the aftermarket are of the HD configuration. As far as I know, the standard suspension shafts are not reproduced.

[Terry M.]

Re: Shock to Trailing Arm clearance

Thank you Joe. I went to the garage to look at AIMs, and completely forgot about measuring the shock diameter -- standard shocks only here. I think Michael now has all the information he needs to solve his "problem."

[Mike R.]

Re: Shock to Trailing Arm clearance

Can someone direct me to some photos showing the two different shock mounts?

Thanks

Mike

Terry-----


Original standard suspension rear shocks have a tube diameter of 1.65-1.70". HD rear shocks have a larger tube diameter of 2.31" (1963-69) and 2.00" (1969-75+). When used with the standard suspension shock mount shafts, the minimal clearance of about 1/4" with standard shocks will be quickly reduced if larger OD shocks are used.

The HD shock mount shafts are very easy to come by; it's the standard suspension shafts that are difficult to find in NOS or good used condition. GM discontinued from SERVICE the standard suspension shafts many years ago and replaced them with the HD shafts for all SERVICE (although the standard suspension shafts were used in PRODUCTION right through to the end of the C3 run).

Also, all of the replacement shafts available in the aftermarket are of the HD configuration. As far as I know, the standard suspension shafts are not reproduced.