1967 Leaf Spring replacement

[Donald H.]

My 67 has an import leaf spring and the car sits higher than I would like. I ordered a reproduction set from Eaton Detroit, so I will be installing the new set soon. I have read the instructions for removal and installation of the spring in the Chassis Service Manual. For installation, the manual says to align the spring bolt with the hole in the cover, then install the plate and 4 bolts and to tighten and torque the bolts.

I though I had read a thread that recommended not torqueing the 4 bolts until the weight was back on the wheels. I can't seem to find that comment now!

Is there any good reason not to torque these bolts as soon as they are installed?

Thanks,

Don

[Donald O.]

Re: 1967 Leaf Spring replacement

Don,
DO NOT TORQUE the 4 spring retaining bolts to the rear diff until it is on the ground. Doing otherwise can result in a broken diff carrier. Just snug them up amd when the car is back on the ground, then torque them to 55-75 lbs. ft. as shown in the 1967 AIM, UPC 4, Sheet B1.
DonO

[Richard M.]

Re: 1967 Leaf Spring replacement

Yes you've heard right and Don is correct.

Also a good idea to roll the car back 'n forth a few times to get the camber out level, or lower with tires on thin sheets of plywood cardboard or something that'll slide sideways when it comes down.

[Donald H.]

Re: 1967 Leaf Spring replacement

Thanks, I'll wait to torque

[Timothy B.]

Re: 1967 Leaf Spring replacement

Donald,

Also, double check the center bolt head to make sure it's not taller than the hole in the rear housing. Some center bolts zi have seen are to tall and you can crack the housing when the spring is tightened.

[John H.]

Re: 1967 Leaf Spring replacement

Thanks, I'll wait to torque

Don -

You didn't see that little tidbit in the Chassis Service Manual because it didn't get added to the CSM until 1971 or 1972, although it applied back to 1963.

[Bob R.]

Re: 1967 Leaf Spring replacement

You should also check the length of the bolts before installation. Not all springs are the same thickness and your bolts could be too long or too short. If too long and you torque them down you could brake the carrier if too short they just won't work. I think the Eaton spring is very close to the original in thickness but the one you are taking off may not be.

[Larry M.]

Re: 1967 Leaf Spring replacement

You should also check the length of the bolts before installation. Not all springs are the same thickness and your bolts could be too long or too short. If too long and you torque them down you could brake the carrier if too short they just won't work. I think the Eaton spring is very close to the original in thickness but the one you are taking off may not be.

This is VERY important. Info on this installation and fastener length etc should be available in the archives. I know I have posted a lot of info on this on either this forum or the Corvette Forum C2 Section. If you cannot locate, let me know. I know for a fact that I discussed this a few weeks back on CF. The Chevrolet Service Manual is very good, but additional info (based on experience) is also needed.

Many of the rear suspension bolts are not tightened or torqued until the wheels are on the ground and the ride height is stabilized. The AIM provides the proper height and torque necessary.

Larry

[Gary B.]

Re: 1967 Leaf Spring replacement

... The Chevrolet Service Manual is very good, but additional info (based on experience) is also needed.

Larry,

Can you elaborate on what additional info is needed?

Thanks,

Gary

[Donald H.]

Re: 1967 Leaf Spring replacement

Thanks all.

I think I found the thread that Larry reference. That thread suggested measuring and combining the depth of the hole, the thickness of the spring set, the retainer plate, and the cut washer on the bolts. Then use bolts that are about 1/8" shorter than this combined length. I got my spring set from Eaton today so I can now figure out whether my existing bolts are re-usable or not.

I certainly do not want to poke a hole in the diff case.

Don

[Larry M.]

Re: 1967 Leaf Spring replacement

Thanks all.

I think I found the thread that Larry reference. That thread suggested measuring and combining the depth of the hole, the thickness of the spring set, the retainer plate, and the cut washer on the bolts. Then use bolts that are about 1/8" shorter than this combined length. I got my spring set from Eaton today so I can now figure out whether my existing bolts are re-usable or not.

I certainly do not want to poke a hole in the diff case.

Don

Don: Does the Eaton spring come with liners, or must you buy and install new spring liners. If you purchase them, I recommend Quanta.

Larry

[Harry S.]

Re: 1967 Leaf Spring replacement

Thanks all.

I think I found the thread that Larry reference. That thread suggested measuring and combining the depth of the hole, the thickness of the spring set, the retainer plate, and the cut washer on the bolts. Then use bolts that are about 1/8" shorter than this combined length. I got my spring set from Eaton today so I can now figure out whether my existing bolts are re-usable or not.

I certainly do not want to poke a hole in the diff case.

Don

Not including the bolt head, 3.25 inches is the maximum length.

[Larry M.]

Re: 1967 Leaf Spring replacement

Larry,

Can you elaborate on what additional info is needed?

Thanks,

Gary

Gary: If I recall correctly, you wrote or co-authored two RESTORER articles on the Corvette rear spring. You should be giving Don and me the instruction.

I don't want to re-write today all of the things that I have been saying/telling others over the last few years. They should all be under my name in the archives (both here and on CF C2 Section……search under "Powershift" at CF)

However, a few things that I learned from experience that wasn't necessarily covered in the Chevrolet Service Manual are:

1. Better ways of spring unloading and removal from car. I think some of this was from your article.
2. Way to cleanup and then coat rear spring with available zinc coatings. Which ones are best.
3. Using your swage tool to install new main spring retainer cups
4. Learning all about spring liners. Who makes/sells the best ones . How they are different from OEM etc. I think I bought 3-4 pairs during this exercise.
5. Cautions regarding the head size of the small spring interconnecting bolt and cautions regarding the correct length spring retaining bolts to the rear carrier cover.
6. Cautions regarding torquing or not torquing various bolts until the weight of the car is on the wheels and the correct ride height has been established. I had to add extra ballast in the car to get this dimension correct prior to tightening some of the critical bolts.


There are probably more things than I listed. These are just a few. Some of these you have addressed in your work regarding rear springs and spring rates etc.

I feel fortunate to have folks like you and John H and others on the forum to help folks like me get it "almost right" the first time. At least I made no fatal errors.

Larry

[Larry M.]

Re: 1967 Leaf Spring replacement

Not including the bolt head, 3.25 inches is the maximum length.

Harry:

I found that I needed only 3-1/8 inch for the two bolts into the "blind" differential cover holes. 3-1/4 inch or slightly longer were okay for the other two "open" holes. The replacement Quanta liners that I used are thinner than original by about 1/8 inch overall for all the liners.

I used Chevrolet Parts Locator Service to try and find GM original liners. I was able to locate only two, and although they were genuine GM, they also were thinner than originals. Somewhere along the way, GM switched specs or suppliers. I finally settled on Quanta.

When you specify a bolt length for this application, you also need to specify spring and liner thickness if not ORIGINAL St Louis installed factory parts.

Larry

[Donald H.]

Re: 1967 Leaf Spring replacement

Larry,

The Eaton springs are assembled with liners. I'll take the springs apart, paint and reuse the liners that Eaton used.