'72 Trailing Arm Questions

[Terry M.]

[Timothy B.]

Re: '72 Trailing Arm Questions

Terry,

These are pictures of the spindles on my 63 that were purchased from GM circa 1981, the originals were shot. Is this a heavy duty spindle and what's the difference, I had no idea there was such a thing.

[Gary R.]

Re: '72 Trailing Arm Questions

I have to admit as well, I have rebuilt a LOT of arms from original to previously rebuilt covering all years 63-82 and never saw a HD spindle. I'm not saying they didn't exist but I just never saw one that appeared to be different. I have seen plenty of stock spindles break in use, abuse, or from dried out bearings. The only real deal HD spindle I trust are Tom's and they sure aren't stock looking. They run the same size cones inner and outer, have a huge flange, and are drilled for either 7/16 or 1/2" studs. I have used them with up to 1000hp setups. A GM spindle won't hold up to 1/2 of that.

[Terry M.]

Re: '72 Trailing Arm Questions

Terry,

These are pictures of the spindles on my 63 that were purchased from GM circa 1981, the originals were shot. Is this a heavy duty spindle and what's the difference, I had no idea there was such a thing.

Not like C3 spindles, much less HD -- at least as far as I can see from those pictures. I will get some C3 HD pictutres if I can. I too am not sure if there is any difference in the spindle itself or the bearings, but the new car features books talks about HD spindles. I have never seen anythign in the SERVICE parts biooks to indicate that HD spindles exist for SERVICE, but I have not spent my life in those books either.

[Jim T.]

Re: '72 Trailing Arm Questions

Patrick my 1970 does have the cap-type rear end yokes. I do not know how to identify a shot-peened half shaft. Mine are the original factory installed half shafts today. The rear end spindles and bearings were replaced before my 50,000 mile and 5 year warranty expired in 1975.

The largest Chevrolet dealership in Dallas, TX method of replacing the bearings and spindles created a lot of problems in my 1970 due to spindle/rotor disc run out causing my brake caliper pistons to pump air and loss of effective rear brakes.

[Joe L.]

Re: '72 Trailing Arm Questions

Not like C3 spindles, much less HD -- at least as far as I can see from those pictures. I will get some C3 HD pictutres if I can. I too am not sure if there is any difference in the spindle itself or the bearings, but the new car features books talks about HD spindles. I have never seen anythign in the SERVICE parts biooks to indicate that HD spindles exist for SERVICE, but I have not spent my life in those books either.

Terry------


There was never a difference in spindles as far as SERVICE was concerned. The only spindle ever available from GM for 1965-82 Corvettes (disc brake applications) was GM #3872476. Of course, it's possible that different spindles were used in PRODUCTION with only, presumably, the HD version available in SERVICE. I doubt it, but it's possible.

There was a difference between the trailing arm assemblies used in PRODUCTION for big blocks and most small blocks. What the difference was I do not know.

Correction: There was a different spindle used for early 1965 Corvettes with disc brakes. It was GM #3865904. It was discontinued from SERVICE in March, 1966 and replaced by the GM #3872476.

[Timothy B.]

Re: '72 Trailing Arm Questions

I am having a brain fart here but what's the difference in the disc vs drum brake spindles?

[Bob J.]

Re: '72 Trailing Arm Questions

Bob,
To my C3 knowledge the only way to tell is to look under the wheel cover at the end of the center shaft -- the one with the depression that has a bar across it. On C3s there is usually a white paint mark there. HD spindles have a cone shaped depression, much like a machinist’s centering mark.

As the car sits on the judging field there is no way I know of to identify HD spindles. If the trailing arm and spindle are disassembled I do not know what indicators, if any, there might be.

Thanks Terry
I've always heard that L88 used a unique spindle.
I'll take a few pics of the spindle ends when I get time and maybe you could point out the HD feature identifier in my pics. Bob

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[Timothy B.]

Re: '72 Trailing Arm Questions

Thanks Mike,

Yes, I guess the parking brake adjustment holes along with the rivet holes but I would think the length and bearing size is the same correct?

[Mike E.]

Re: '72 Trailing Arm Questions

Thanks Mike,

Yes, I guess the parking brake adjustment holes along with the rivet holes but I would think the length and bearing size is the same correct?

Haha...You're too fast...I deleted my post because when I looked at replacement 63-64 spindles they had rivet holes and parking brake adjustment holes. They are shown as different parts...I'm not sure why...I think the half shaft flange is different on at least a 1963. It might be the spline is different. I'm sure Gary would know.

Mike

[Dick W.]

Re: '72 Trailing Arm Questions

Terry, how does a person know HD rear spindles by sight?
Thanks, Bob

This discussion got me to thinking and researching. I looked back at some paperwork and catalogs that I received in 1969-'71 concerning performance and performance parts. The only reference I could find to shot peening was for Camaro rear axle flanges, nothing about the Corvette spindles. Plenty of reference to frame mods, headers, etc, but not the spindles. Makes one wonder if ALL spindles were not shot peened? A lot of information came from Sport Equipment booklet, the predecessor to the Chevrolet Power booklet.

[Patrick B.]

Re: '72 Trailing Arm Questions

The picture on the left is the original rear spindle of my 70 LT-1. An NCRS judge told me that the circular mark on the left protrusion indicated the heavy duty spindle used on all big blocks, LT-1s, and apparently Turbo 400 small blocks. I imagine heat treatment or alloy differences made it heavy duty rather than any dimensional difference. The other two photos are rear spindles from a 67 427. I cannot be positive they are the original spindles. However, one has a circular mark on the left outer surface and the other has an "X" mark on the right outer surface. Maybe these marks relate to their use in a big block, but I'm less sure of it than the mark on the C3 LT-1.

My theory about why the LT-1s and Turbo 400 sb had the rear sway bar holes in the trailing arms was that the big block trailing arms were equiped with the HD spindles, so when those spindles were used on a small block the trailing arms with holes came with it despite the lack of need for a rear sway bar.

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[Terry L.]

Re: '72 Trailing Arm Questions

I have a 70 LT1 that I restored a couple of years ago and I am currently restoring another 70 LT1. The LT1 I finished a couple of years ago did not have the holes drilled in the trailing arm for the sway bar. It appeared at the time the trailing arms were original to the car and unmelested, (54,000 mile car), it still appeared to have the original un-slotted shims, original rear diff with dated ring gear, shot peened half shafts and HD caps etc... I checked tonight and the spindles do have the dimples on the protruding portion of the spindle end. I assumed this is how the trailing arms came from the factory. My current LT1 restoration did have the holes drilled in the trailing arms and someone did installed a aftermarket rear sway bar. Based on the first LT1, I sold the trailing arms on the second LT1 for a pair of trailing arms with out the holes. Did I make a mistake on the trailing arms? Could it be possible the LT1 came with out the holes drilled in the trailing arms with the HD spindles? I know I can drills holes in the trailing arms but I want to be sure before I do this.

[Patrick B.]

Re: '72 Trailing Arm Questions

I have a 70 LT1 that I restored a couple of years ago and I am currently restoring another 70 LT1. The LT1 I finished a couple of years ago did not have the holes drilled in the trailing arm for the sway bar. It appeared at the time the trailing arms were original to the car and unmelested, (54,000 mile car), it still appeared to have the original un-slotted shims, original rear diff with dated ring gear, shot peened half shafts and HD caps etc... I checked tonight and the spindles do have the dimples on the protruding portion of the spindle end. I assumed this is how the trailing arms came from the factory. My current LT1 restoration did have the holes drilled in the trailing arms and someone did installed a aftermarket rear sway bar. Based on the first LT1, I sold the trailing arms on the second LT1 for a pair of trailing arms with out the holes. Did I make a mistake on the trailing arms? Could it be possible the LT1 came with out the holes drilled in the trailing arms with the HD spindles? I know I can drills holes in the trailing arms but I want to be sure before I do this.

I am the second owner of my LT-1 and I bought it with 8,000 miles on it in 1972. It and every LT-1 I was sure was legit had the trailing arms with holes. Since you had one with HD spindles and no holes, I guess less than 100% had holes. However, I think the holes were prevelent, and I would drill the holes if I had your car. My car has a July 3 build date.