Hi Everyone,

Recently my U-joint on the Half-shaft went bad and I was wobbling down the road. Luckily I was able to drive home slowly and wasn't too far away.

I was just getting ready to work on removing the bolts to remove the half-shafts and what is that? Is this a spline bolt that is used on the straps? I don't have any spline sockets and have no ideal what size. I did some research and found replacement straps and bolts, but nothing concerning the type socket and size.

Anyone know what size and where I can purchase the socket? I've researched and local parts stores have been no help.

Thank you,

Jimmyiron

 

I think the term is "Serrated" sockets and Serrated wrenches. Those bolts are rusted so much that a standard socket will fit loosely.
you may have to use a Metric serrated socket by tapping it onto the bolt head with a small ball-peen hammer?

 

Those are just 12 point headed bolts. I think Auto has 1/4 fine thread bolts with 5/16 12 point head
Manual has 5/16 fine thread bolts with 3/8 12 point head

 

you may want to find a 9/32 12 point and hammer it on. same with a 9mm or 11/32 for the 3/8ths.

 

Pretty sure they're 5-16 12 points.....just did them in my 82.....not one of Chevy's better ideas.

Be VERY careful putting them in and torquing them. I found the torque rating (I forget now) was on the edge of what the socket 'liked'.

Pretty much by the time I was finished...so was the socket.

unkahal

 

FWIW, when I did this on my 80 (manual, so 1350 U-joints, and the larger bolt option), I had to cut two of the straps. That was fine, since I was sending the half-shafts out to be rebuilt with new Spicer 1350s. I used all new hardware when I reinstalled. @derekderek's advice above is spot on. You may need a 12 point socket hammered on, an impact driver, and a straight shot to get those bolts out. Start soaking in Kano Kroil now.

 

Lots of good info guys, thank you for sharing. I will update with resolution hopefully soon

 

Just an update, got a 1/4" 12 point socket and wrench to work on these bolts. Some of the bolts were very loose, going to be fun to torque these down right without stripping them.

 

I just replaced the u-joints on the half shafts in my 81 this weekend. Not difficult but definitely a test of patience. Tight spaces even with a lift. Did as much of the work as possible with a 12 point 1/4" socket and a universal joint, extension and ratchet. But most of it was done with a regular 1/4" combination wrench. I couldn't get the racheting wrenches to stay on if it was close to tightening up or beginning to loosen up. The u-joints themselves were not difficult. Put the half shafts was were patience is tested.

Suggestion: as you put the shafts back in, do each step little by little. Position the shaft, start all bolts, and then tighten them little by little. It is very tempting to tighten one side down. In a word: DON'T. Work 4 bolts a little, move to the other end of the shaft and work 4 bolts a little. You will save yourself a lot of headache.

 

Great advice !

 

@Hunt4run or anyone that knows.. which brand and part number did you use for your u joints? I purchased bought Moog 232 from RockAuto's catalogue... and these dang things do not fit. I went to Moog's website and they sell 231s for my 1981. If you look at other parts stores like Autozone they also recommend 232 or 231C(also too big) Caps seem to be too big and even getting the ujoint in the yoke is tough going? Ive done U joints before on other vehicles and these do not fit.. I've cleaned up the yokes and no rust they just do not fit.

Thanks,

Jimmy

 

I have a further question for the team.

Seems like EVERYONE hates the 12 point serrated bolts....Tom Falconer railed against them.

WHAT IS THE 'CROSS" (interchange part) for replacing them with bolts that ACTUALLY can take the torque rating. I believe the straps are fine.
Hex head grade 8

Unkahal

 

Manual or automatic?

I used Spicer 1350 U-Joints, and these U-Joint straps (6-point bolts) in my 80 4-speed. If your 81 is an auto, I think it uses 1330 U-Joints, and different straps. Someone posted the dimensions in a similar thread. Here's a table I found on a 4x4 site, with some common C3 sizes, but measure and be sure.

U-joint series Joint width (W) (inches) Cap diameter (D) (inches) Maximum Angle Continuous rating (lb-ft) Short Duration rating (lb-ft)
1310 3.219 1.062 30 130 800
1330 3.625 1.062 20 150 890
1350 3.625 1.188 20 210 1240
1410 4.188 1.188 37 250 1500

To get around the hateful 12-point bolts, I just cut the old straps. Then they were a lot easier to deal with.

I had Bairs rebuild the half-shafts for me, with the greaseless Spicers. They told me that the Spicers were a VERY tight fit, and needed the thinnest clips to secure them. So I'm very glad I farmed out that job.

 

Yeah these Moog do not fit, even tried the old stand by of deadhead to pop the caps into the yokes and no way. Love how these companies will put a different part number in there saying it still fits. .. they do not.

Thanks for the info... looking at the 1330 spicers.

 

You nailed it, the Spicer 1330 U-joints fit perfectly in the half shafts for my 1981 automatic corvette. Pressed them in and all four are now installed and ready to be re-installed into my corvette. The Spicer 1330 U-joints came with two different thickness clips and the copper colored ones worked better as they were thinner than the other clips.

Will be installing the half shafts back in one day this week... going to use the same straps and serrated bolts, as I did not find a good replacement that wasn't 8 dollars a bolt.

Thanks for your help,

Jimmy

 

I'm glad it worked out. Thanks for following up on the thread!

Please post a photo when it is all buttoned up.

 

Working on installing the half shafts back into the car and ran into a strange issue. I got the passenger side half shaft installed and tightened all the strap bolts down. I moved to the drivers side an installed the strap bolts onto the yoke/wheel bearing. When I went to install the strap and bolts on the side attached to the diff, noticed that there is a pretty good gap of maybe 1/4 inch or so... and the U-joint does not sit flush against the yoke on the diff side. Almost as if the half shaft is too short?

I then pulled the one on the passenger side that I just installed just to try to install on the drivers side and same problem, about a 1/4 " gap from the U-joint to the yoke.

Anyone experience this or has an idea what it could be? I go to both sides and wiggle the whole spindle assembly and a little play up and down not side to side, so suspension flex? I do the same on the spindle on the passenger side and doesn't move as much.

Frame is straight and it always drove straight and true for the ten plus years I have owned it? Seeing that the diff is bolted to the cross member, I don't see that it could have moved? Stumped...

Installed Spicer 1330X U-joints into the half shafts.

 

Is your spring still attached? I didn't attempt this job until everything else was disconnected. Even then, I had to fight the (new) trailing arm bushings to align everything. 1/4" is not much. Once it is all assembled on the ground, your rear alignment should still be whatever it was before, both camber and toe-in. Do you need new strut rod bushings, or heim-jointed strut rods?

 

I didn't detach the spring or trailing arm... didn't think I needed too. Then again I've never worked on the suspension on my Corvette before I checked the bushings on the strut rods and they look like good solid rubber.. must have been replaced before. These strut rods are non-adjustable ...

Will try again with spring and strut rod detached from spindle. Hopefully it will give me enough play to install the half shaft with no more issues.

Thank you for your advice, I really appreciate it!

Jimmy

 

I don't know that you need to, but with the spring pulling the trailing arms down, the geometry will be suboptimal. So that is probably the source of the gap. Detaching just the spring should be sufficient, as you can then raise the trailing arm up to neutral camber. Please be careful. If the spring is still loaded when relaxed, there is a lot of energy stored in it.

Trying to remove the outboard strut rod/shock bolts is exactly how I ended up doing a complete rear-end rebuild.