C2 drive shafts and half shafts

[Mark P.]

I am having discussions with a local shop that specializes in drive shafts. They have a good reputation and have been around 20 years.

I am looking to have my drive shaft and half shafts rebuilt for my 65 small block. The Drive shaft has some pitting and has u-joints with zirc fittings so I know they have been changed.

I will bring the shafts to their shop and wanted to get some advice before I go.

I am planning to clean them in my parts tank this weekend then will de-rust them so I can avoid the need to bead blast them and change the finish.

They will wire brush them because they know I want an original natural finish. The owner told me about 40% of the drive shafts they see from this vintage need new tubing because they are twisted or need new yokes because they are bent from someone using a hammer to remove and replace u-joints.

If the tubing is bent or pitted they recommend replacing the tubing and can use seamless or seamed tubing very close to the original outside diameter.

I have heard the seamless is stronger but since the seamed is available then I am thinking it will look more original.

I have no plans to race this car but do plan to drive it fairly regularly.

Here are my questions ?

1. Should I go with seamed tubing if I need to change the tubing ?
2. Is light pitting acceptable from a safety perspective ?
3. Has anyone used their original yokes with new tubing successfully ?
4. Are reproduction or aftermarket yokes a good alternative if my yokes are bad or should I just buy reproduction drive shafts or half shafts from one of the large Corvette vendors ?

Thanks,

Mark

[Richard G.]

Re: C2 drive shafts and half shafts

1. Should I go with seamed tubing if I need to change the tubing?
After cleaning and polishing I couldn't find any seam marks in my original tubing. Likely I polished it off if was there. The picture below is of my half shaft mounted in the lathe with fixtures I made.




To me, seamed or no seam tubing would make little difference. Unless you are attempting to build a 100-point car I can't think of any reason to use one over the other. Strength wise they are comparable and will never give you an issue with stock size tires.

2. Is light pitting acceptable from a safety perspective?
This is a tough one. What is light pitting? I can only go by what is on the road and most have some pitting. Judgement call there. If it was more than light pitting, I would consider replacement for sure. Remember this is a wheel driver and a suspension member. Error on safety here.

3. Has anyone used their original yokes with new tubing successfully?
Yes, a shop can remove the original yolks from the tubing easily, that's what they do.

4. Are reproduction or aftermarket yokes a good alternative if my yokes are bad or should I just buy reproduction drive shafts or half shafts from one of the large Corvette vendors?
I would say 80% of the yolks, with replacement u-joints installed, have the ears bent. Mechanics just don't realize how easy the cast steel bends. I no longer purchase used yolks for this reason.
I have a 1-1/16 mandrel that I can check used one with. Occasionally I have drug it alone to swap meets, an eye opener for sure. Many used joints are bent to the extreme. I have straightened a few yolks in the past but it's never is as straight as a new one. Unless the yolks are rare style that isn't reproduced, I would recommend all new yolks. Or at the very least a close inspection of the used ones. After the U-joints have been removed you can check the bores for wear and alignment. I prefer a mandrel but a U-joint can be used. Just press one cap in and install the cross. See if the cross is centered in the other side. All used yolks seem to have the inside peaned over where the joints hits when pressing or driving the U-joint cross out of the yolk. Be sure to clean this area up before installing the new u-joint cross. Don't sand the bore. This will open up the fit. The contact between the u-joint cap and the yolk is what supports the bearing.

I would know the cost of vendor supplied complete shafts when i brought mine in. If they put it in a vise and use sockets to drive out the old joint you are in the wrong shop. If they are rusty a little heat goes a long way in keeping the yolks straight. Many shops will use one of these to keep from bending the yolk when pressing out the cross shaft/u-joint.



My post is long winded. The joints are so simple to repair, doing it correctly is often taken for granted.
After a close inspection of the driveshafts you may find the vendors replacement are a viable option.
Rick

[Mark P.]

Re: C2 drive shafts and half shafts

Thank you vey much Richard. I now feel like I a can make a better decision. After they are inspected and know what it will cost to fix them then so can compare that to reproduction shafts.

[Gary B.]

Re: C2 drive shafts and half shafts

Rick,

The original drive shaft on my '66 was unrestorable due to rust. There was no evidence of a weld seam when inspecting the outside, but when cutting the shaft in half and viewing the pristine tubing on the inside, the weld seam was clear as day.

Gary

[Joe L.]

Re: C2 drive shafts and half shafts

I am having discussions with a local shop that specializes in drive shafts. They have a good reputation and have been around 20 years.

I am looking to have my drive shaft and half shafts rebuilt for my 65 small block. The Drive shaft has some pitting and has u-joints with zirc fittings so I know they have been changed.

I will bring the shafts to their shop and wanted to get some advice before I go.

I am planning to clean them in my parts tank this weekend then will de-rust them so I can avoid the need to bead blast them and change the finish.

They will wire brush them because they know I want an original natural finish. The owner told me about 40% of the drive shafts they see from this vintage need new tubing because they are twisted or need new yokes because they are bent from someone using a hammer to remove and replace u-joints.

If the tubing is bent or pitted they recommend replacing the tubing and can use seamless or seamed tubing very close to the original outside diameter.

I have heard the seamless is stronger but since the seamed is available then I am thinking it will look more original.

I have no plans to race this car but do plan to drive it fairly regularly.

Here are my questions ?

1. Should I go with seamed tubing if I need to change the tubing ?
2. Is light pitting acceptable from a safety perspective ?
3. Has anyone used their original yokes with new tubing successfully ?
4. Are reproduction or aftermarket yokes a good alternative if my yokes are bad or should I just buy reproduction drive shafts or half shafts from one of the large Corvette vendors ?

Thanks,

Mark

Mark------


Personally, I would not even consider re-using any driveshaft or half shaft that suffers from any PITTING type corrosion. I would also not use any shaft that has been machined down to remove any pitting type corrosion or other damage.

[Richard G.]

Re: C2 drive shafts and half shafts

Just to be clear, the shaft in the lathe has only been polished with 220 grit paper. No cuts were made. The Judging manual states to watch for turned down shafts with tool markings.
Joe gives the better advice on this issue.
Rick

[Mark P.]

Re: C2 drive shafts and half shafts

I am not too optimistic my drive shaft is going to be usable due to rust. Will see what the shop says and maybe they can just change the pipe and use the yokes, replace the u-joints then balance.



Anyone notice that the trailing arm pivot bolts from CCare too long ? These are 5" long and the Chassis Restoration Guide says they should be 4 and 9/16". I don't want to add 3/8" of washers just to use these. Will call around Monday to see who has the correct length bolts.

Lastly, any advice on how to set-up the shims for the initial installation ? I will use the string alignment approach before driving the car but would appreciate any experience with shim set-up. Should I use a 1/4" shim on each side of the trailing arm then add a .125 next to each 1/4" shim then use the 1/32nd to bring it up to interference fit ?

[Edward J.]

Re: C2 drive shafts and half shafts

Mark, if your dealing with a low horse power car and don't really plan on drag racing the car some pitting after a clean up is ok. I myself don't trust any of the reproduction parts including drive or half shafts. if your car drove smoothly with old shafts why risk it. I see your in California where there are likely some used ones that can also be found ,likely the surface rust is only minor, just another option for you. Your through bolts on the trailing arm are a good example of what you find with some of the parts. I also believe that the washers you have are to thin, factory washers were much thicker. you can use the string to get you in the ball park for the shimming. depending on the year of car the shims were not slotted myself I would use the slotted shims, its much easier to align.

[Gary R.]

Re: C2 drive shafts and half shafts

Hi Mark
I am going to take a guess on those longer bolts. I don't have one in front of me right now but the TA bolt and the Diff front bracket bolts look the same but the diff bolt is longer. Maybe you were shipped Diff bolts instead of the TA bolts?

Your DS appears to have just surface rust on it. If there is no pitting or dents I would blast it and use it in a driver.

[Gene M.]

[Mark P.]

Re: C2 drive shafts and half shafts

Thanks Edward and Gary - I will try to clean-up the rust with a rust dissolver then wire brush it or media blast it.

The bolts the package came in were clearly marked as TA bolts but the front differential bolt does look just like this. I will call them and ask them.

[Mark P.]

Re: C2 drive shafts and half shafts

Gene - thanks for confirming the length issue and providing a work around. The service replacement bolts I removed were .200 too long. I continue having issues with reproduction bolts being the wrong length or wrong finish. When I get a cad bolt that is supposed to be be black phosphate I strip the finish with Muriatic acid then blacken them. Makes things rather slow. I appreciate your experience as this helps with the journey I am on. Mark

[Joe L.]

Re: C2 drive shafts and half shafts

Gene - thanks for confirming the length issue and providing a work around. The service replacement bolts I removed were .200 too long. I continue having issues with reproduction bolts being the wrong length or wrong finish. When I get a cad bolt that is supposed to be be black phosphate I strip the finish with Muriatic acid then blacken them. Makes things rather slow. I appreciate your experience as this helps with the journey I am on. Mark

Mark-----


The original bolts were 4-9/16" in length. That's the length you need now. The original bolts were GM #3846867 and were zinc plated. These bolts were GM 280M material grade (SAE grade 5; 3 radial lines). The GM replacement bolt, GM #458984 and also used in PRODUCTION from 1977-82, was black phosphate finish and GM 300M material grade (SAE grade 8; 6 radial lines). The latter was discontinued about 10 years ago.

The original slotted nuts were 11/16" across the flats, 29/64" thick, and GM 301M material grade (SAE grade 8). GM #3774712. Discontinued.

The original flat washers were 15/32" ID, 15/16" OD, 3/32" thick and zinc plated. GM #3693853. Replaced by GM #475359 which is long-since discontinued.

The original lock washers were 29/64" ID, 49/64" OD, 9/64" thick and natural finish. GM #103328. Discontinued.

[Gary B.]

Re: C2 drive shafts and half shafts

....

The original lock washers were 29/64" ID, 49/64" OD, 9/64" thick and natural finish. GM #103328. Discontinued.

Joe,

GM #103328 is the sol-called "hi-collar" lock washer used at multiple locations on C2s and C3s, including the bumper attachments starting in 1965. I'm just curious where you found the information about the natural finish. I agree that's correct based on another NOS lock washer I have that starts with the same 103xxx part number. The finish is quite dark, which I presume comes from its heat treatment.to achieve HRC 38-46.

Was 103328 ever available as a service replacement part? I've been searching eBay for years for an NOS example and have not yet found one.

Gary

[Gene M.]

Re: C2 drive shafts and half shafts

Gene - thanks for confirming the length issue and providing a work around. The service replacement bolts I removed were .200 too long. I continue having issues with reproduction bolts being the wrong length or wrong finish. When I get a cad bolt that is supposed to be be black phosphate I strip the finish with Muriatic acid then blacken them. Makes things rather slow. I appreciate your experience as this helps with the journey I am on. Mark

Mark
The original trail arm bolts @ the shims were zinc plated on mid years up to and into 68. After that I don’t know. This is one of the cases where GM didn’t use phosphate on a graded bolt.