1972 rear suspension

[Gary G.]

Good morning all,
I have a 1972 small block that I have been replacing bushings and shocks in. When I bought the car they were all shot. With that I was not able to get a accurate measurement to set the ride height. As I near completion of the project I am looking for advice on setting ride height.
I do not have the luxury of having a four post lift and thanks to the wifes great cooking I can not fit under the car without it being raised. My thoughts were to measure the distance from the quarter lip on each side to the center of the hub (rally wheels so just leave the caps off) with the car sitting on the ground after moving it the 15 feet and letting the suspension settle for a day.
My thought was to install the strut rod and swing arm bolts loose before I lower it then measure and then raise and tighten. The thought is to use the tall jack that I have to set the wheel at ride height while the car is raised. I will have it aligned after this work is completed.
Any input or hints would be greatly appreciated. Thank you in advance! Stay safe
Gary Goodyear 66059
72 Mille Miglia Red

[Mark E.]

Re: 1972 rear suspension

Gary,

Ride height is not adjustable. The service manual specifies proper ride height and how to check it from different points. Out of spec ride height is a symptom of worn or damaged suspension components, non-spec parts (e.g. different size tires, springs, rear spring bolts), collision damage (bent frame, suspension components or poor body repair), worn/damaged rubber body mounts (1973 or newer).

But it can't be changed by somehow adjusting the strut rod, trailing arm (these cars have a TA not a swing axle) or their fasteners. The strut rod cam bolts are for adjusting wheel camber.

[Patrick B.]

Re: 1972 rear suspension

As Mark said, the ride height is not designed to be adjustable. It is most influenced by the rear spring and the bolts that attach the trailing arms to the rear spring. Corvettes prepared for road racing were often lowered by using longer bolts at ends of the spring, but you should not need these if you have the original spring. Simply, assemble the rear suspension with the parts you have, and set the rear camber to about 1/2 degree negative. If it seems a little high with the original spring, that is good because it will probably settle down after it has been driven a for a while and rubber donuts on the spring bolt compress. Readjust the camber after it settles. If it seems too low, the spring is probably sagging. You can raise it by putting thick washers between the castle nuts and the stock washer at the ends of the spring, but that is not a good permanent solution. Replacement springs have a bad reputation for making the ride height too high, and there are lots of discussions of that problem you can find by searching the TDB.

[Joe L.]

Re: 1972 rear suspension

As Mark said, the ride height is not designed to be adjustable. It is most influenced by the rear spring and the bolts that attach the trailing arms to the rear spring. Corvettes prepared for road racing were often lowered by using longer bolts at ends of the spring, but you should not need these if you have the original spring. Simply, assemble the rear suspension with the parts you have, and set the rear camber to about 1/2 degree negative. If it seems a little high with the original spring, that is good because it will probably settle down after it has been driven a for a while and rubber donuts on the spring bolt compress. Readjust the camber after it settles. If it seems too low, the spring is probably sagging. You can raise it by putting thick washers between the castle nuts and the stock washer at the ends of the spring, but that is not a good permanent solution. Replacement springs have a bad reputation for making the ride height too high, and there are lots of discussions of that problem you can find by searching the TDB.

Patrick------


Yes, and in PRODUCTION during the period of 1975-82 GM actually used several slightly different length spring end bolts in order to "fine tune" the rear ride height. This was done to ensure that the bumper height conformed to requirements of FMVSS. However, none of these special length bolts were ever available from GM in SERVICE. For SERVICE, only the "standard" bolt length (same as all 1963-74) was available.

[Gary G.]

Re: 1972 rear suspension

Thank you for the replies! I was in another forum and read several posts about ride height being adjusted. I am using all stock parts so I should not have any issues. It is certainly a learning curve for me. coming from a Camaro family and turning to the bright side of life!