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Topic: Unusual Wear on Half Shaft

in Forum: C3 Driveline Components

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Unusual Wear on Half Shaft (1/17)
7/13/08 8:08pm

jp75vette
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Bloomfield Hills, MI - USA

Vette(s):
1975 Corvette coupe, 4 speed manual, 383 ci 9.5:1,Edelbrock dual plane Air Gap intake, Alum Heads,Comp Cam, roller Rockers, PS,PB,Tilt

Joined: 6/29/2008
Posts: 199

My car is a 1975 Corvette with over 100,000 miles. I'm in the process of replacing the Passenger side U joints on my half shafts as I heard a noise and noticed that one U joint retaining clip was missing and the cup was working it's way out of the half shaft.

I noticed unusual war on the yoke of the inboard side of the half shaft (see photo 'Wear on Pass side Half shaft at Diff 2'. The half shaft is interferring with the differential yoke.
Pic 1

Looking from the rear at the differential and half shafts, I noticed that the driver side differential carrier yoke has a large gap to the differential vs the passenger side ( and this is the passenger side with the unusual wear).

Pic 2

One other thing that I notice is that the the differential trunion seats are not exactly 90 degrees to each other ( see photo Center view of Diff and Half Shafts (Medium))

Pic 3

Can anyone help me determine what is causing the unusal wear on the passenger side?

Also why is there a larger gap on the driver side of the differential?

(modified large images to links)Adams' Apple2008-07-13 18:47:47

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Unusual Wear on Half Shaft (2/17)
7/13/08 9:33pm

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CUYAHOGA FALLS, OH - USA

Vette(s):
1975 C3 Red, T-Tops, Black Interior. All I need is time and money! Getting there!

Joined: 12/2/2003
Posts: 6424

Oh boy, you got some more work to do.

First, keep in mind the drive shafts are also the support for keeping the rear tires upright. It used the links below the shafts and the shafts to maintain suspension position.

This means there is a lot of stress not only rotational, but in and out stress on the u-joints and shafts as well. The trunions, I call them yokes, have hardened ends inside the diff. These rest on a shaft in the center of the diff called the pinion shaft, not to be confused with the pinion gear.

As the end of the yoke shafts wear, the tops of the tires start to tilt inward when the weight is on the tires.

The wear you see is due to the joint allowing the shaft to hit the yoke due to the joint failing, and allowing play. That is the wear you see. That is cured by replacing the u-joints.

Game still on. The reason you see the gap on both sides of the diff is the fact the shaft ends are worn inside the diff. If you pull on them they will move out a bit. The cure is to replace the yoke/shafts. At least one of them has been replaced by a rookie. That is why they do not line up evenly. The really should line up. The way they are can create driveline vibration and result in more problems and wear. This may have an influence on the problem you have now. You can also get vibration throught the car under certain loads and shaft rpm.

So as you do the joints, it's a bandaid. You need to take the shafts out of the diff, and you will need at least one, if not both, along with the clips that hold them inplace. Replace the side seals in the diff housing at the same time. That also means a gasket and new fluid. Make sure it has the posi additive when refilled.

Yes it get worse. You need to take the spring out to take the diff out, to take it apart and get inside to do the work.

Not what you wanted to hear, but you should do it right to prevent more problems and grief in the near future.

kstyer2008-07-13 18:39:15

Unusual Wear on Half Shaft (3/17)
7/13/08 9:56pm

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Duncanville, TX - USA

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#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

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Ken is right on with all of the info...the u-joints are junk, and need replacing, as do the stub axles/yokes.
My opinion is the diff should be pulled and repaired/rebuilt, with new stub axles/yokes, as Ken says.

One thing I will add, tho...the yokes will rarely line up in use, unless the posi unit is locked/welded. The two half-shafts do spin at different speeds when turning corners, so even if the yokes start out perfectly aligned, they will not still be aligned after a trip around the block.

On a happier note tho...you do have the HD stub axles in there, with the bolt-on u-joint caps, instead of the straps/nuts.

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Unusual Wear on Half Shaft (4/17)
7/13/08 10:00pm

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CUYAHOGA FALLS, OH - USA

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Guess I was referring to the shaft not lining up on each end of each shaft. Not side to side of the diff. Perhaps I mistook what he said in that regard. If both u joints line up in each shaft, than okay. I thought he said they did not. Looking back I did not state that well.

Thanks Joel.

Unusual Wear on Half Shaft (5/17)
7/14/08 9:07am

sgm2004
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Falls Church, VA - USA

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1975, 4 speed, L48, NOW Silver mist, Oxblood inside 2003 50th Av Torch RED little brother to 75

Joined: 3/22/2006
Posts: 232

[QUOTE=kstyer]Oh boy, you got some more work to do.

First, keep in mind the drive shafts are also the support for keeping the rear tires upright. It used the links below the shafts and the shafts to maintain suspension position.

This means there is a lot of stress not only rotational, but in and out stress on the u-joints and shafts as well. The trunions, I call them yokes, have hardened ends inside the diff. These rest on a shaft in the center of the diff called the pinion shaft, not to be confused with the pinion gear.

As the end of the yoke shafts wear, the tops of the tires start to tilt inward when the weight is on the tires.

The wear you see is due to the joint allowing the shaft to hit the yoke due to the joint failing, and allowing play. That is the wear you see. That is cured by replacing the u-joints.

Game still on. The reason you see the gap on both sides of the diff is the fact the shaft ends are worn inside the diff. If you pull on them they will move out a bit. The cure is to replace the yoke/shafts. At least one of them has been replaced by a rookie. That is why they do not line up evenly. The really should line up. The way they are can create driveline vibration and result in more problems and wear. This may have an influence on the problem you have now. You can also get vibration throught the car under certain loads and shaft rpm.

So as you do the joints, it's a bandaid. You need to take the shafts out of the diff, and you will need at least one, if not both, along with the clips that hold them inplace. Replace the side seals in the diff housing at the same time. That also means a gasket and new fluid. Make sure it has the posi additive when refilled.

Yes it get worse. You need to take the spring out to take the diff out, to take it apart and get inside to do the work.

Not what you wanted to hear, but you should do it right to prevent more problems and grief in the near future.

[/QUOTE]

Ken, your right on the money what you just talked about. Above is what I'm going through right now. Left rear side yoke on my 75 just pulled out when I removed the half shaft. Almost got the differential carrier out now. I desided to replace and repair everything in the rear costing arm and leg but never have to mess with it again. Fix it right the frist time. Good luck Jack on yor repairs these guys and gals on this site are great help. Take care

Guy

sgm20042008-07-14 06:09:51

Unusual Wear on Half Shaft (6/17)
7/15/08 9:01pm

jp75vette
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Bloomfield Hills, MI - USA

Vette(s):
1975 Corvette coupe, 4 speed manual, 383 ci 9.5:1,Edelbrock dual plane Air Gap intake, Alum Heads,Comp Cam, roller Rockers, PS,PB,Tilt

Joined: 6/29/2008
Posts: 199

Ok, I moved the Corvette into intensive care and am ready to pull the differential and the half shafts and take it to someone who knows how to fix it right.

Anyone have instructions on how to pull the differential. I started to work at all the bolts I could see and they are all turning so that's good news.

Anyone know of a good Corvette diffential place in Detroit area?

Unusual Wear on Half Shaft (7/17)
7/15/08 10:08pm

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Hot Springs, AR - USA

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69 Conv #'s match 427, TKO-600/.64, 3.36HD-Posi, HT, T/T, PS, PB, PW, SP, Leather, Comp XE264HR & Roller Rockers & Lifters, Air-Gap RPM intake, Holley St Av 770 VS, MSD 6AL+Dist+Blaster SS, K&N, Jet-Hot Hooker Side-Pipes, Steeroids, Al Rad, Spal Fans

Joined: 4/24/2004
Posts: 3231

the part of this that I hate in replacing the yokes is the snap ring on the inside of the yoke.

i would bet the inner end of the yoke has worn off, causing the snap ring to fall off and then this lets the yoke slide ouf of the diff, which then allows a wierd angle.

also... im not sure what you mean about the 90 degrees thing. they will never stay lined up at 90 degree offset.

cthulhu2008-07-15 19:10:56

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Unusual Wear on Half Shaft (8/17)
7/16/08 12:17am

rraider1
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Woodland, WA - USA

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1977 T-Top,350,Auto Black Ruby Pearl,Steeroids R&P conversion

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When the repair is done Is it not better to replace the yokes with hardened ones, I beleive when mine was repaired that is what was done. a good check for this wear is when the car is jacked up you can grab the bottom and top of the wheel and it will rock back and forth as the yoke goeas in and out, which is bad

Unusual Wear on Half Shaft (9/17)
7/16/08 8:15am

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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

Joined: 11/8/2003
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[QUOTE=rraider1] When the repair is done Is it not better to replace the yokes with hardened ones,[/QUOTE]

It's always better to go with the best parts, but it really depends on how the car is used. A "driver", or a car that is used often, will benefit from the hardened yokes for sure. If you're working on garage art, or a car that rarely gets any long distance miles, it may not be all that worth-while.
In the long run, however, you really don't want to have to re-do a diff in a Shark more than once in a lifetime, so the better yokes would be money well spent.

______________

Joel Adams
C3VR Lifetime Member #56
My Link

(click for Texas-sized view!) NCRS

"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

Unusual Wear on Half Shaft (10/17)
7/16/08 8:38am

KeBo
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Kendall Park, NJ - USA

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1981 - 59 Beige over Cinnebar leather. Edlebrock top end, 2200 stall w/shift kit, 3:55s, Mufflex maniback exhaust, nice stereo, 16 in AREs w/BFGs

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Posts: 789

I just had my rear rebuilt from lug nut to lug nut. IT WAS EXPENSIVE! If you need to rebuild, I'd do the t-arm assms too. I didnt when I did mine and Im kicking myself..

Unusual Wear on Half Shaft (11/17)
7/16/08 6:54pm

sgm2004
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Falls Church, VA - USA

Vette(s):
1975, 4 speed, L48, NOW Silver mist, Oxblood inside 2003 50th Av Torch RED little brother to 75

Joined: 3/22/2006
Posts: 232

[QUOTE=Adams' Apple] [QUOTE=rraider1] When the repair is done Is it not better to replace the yokes with hardened ones,[/QUOTE]

It's always better to go with the best parts, but it really depends on how the car is used. A "driver", or a car that is used often, will benefit from the hardened yokes for sure. If you're working on garage art, or a car that rarely gets any long distance miles, it may not be all that worth-while.
In the long run, however, you really don't want to have to re-do a diff in a Shark more than once in a lifetime, so the better yokes would be money well spent.

[/QUOTE]

Your exactly right Adam in long run its worth it. Just got the 1ST T/A off going for secound tonight then Diff. Hope to head to Zips Saturday have to see. But I'm replacing with all new lug nut to lug nut. Like one of the members said its a once in a lifetime deal for us. Do it right and will not have to do it again (hopefully). Thanks

Guy

Unusual Wear on Half Shaft (12/17)
7/17/08 10:02am

sgm2004
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Falls Church, VA - USA

Vette(s):
1975, 4 speed, L48, NOW Silver mist, Oxblood inside 2003 50th Av Torch RED little brother to 75

Joined: 3/22/2006
Posts: 232

[QUOTE=jp75vette]Ok, I moved the Corvette into intensive care and am ready to pull the differential and the half shafts and take it to someone who knows how to fix it right.

Anyone have instructions on how to pull the differential. I started to work at all the bolts I could see and they are all turning so that's good news.

Anyone know of a good Corvette diffential place in Detroit area?

[/QUOTE]

Jack, one of the best books I have found and what is helping me now is a soft cover book called "How to Restore and Rebuld Your Covette". I think the authors last name is Newton, cant remember first, book at home. It's very good reading and the author really does a good job of giving information on rebuild and Mods. One or two tips from me before you start are Buy yourself a good pair of mechanics gloves like Craftsman from Sears and if you can afford it or rent it. A 1/2 electric impack drill w/tempered sockets (DEEP WALL) trust me it will help you GET ER DON. Thanks

Guy

sgm20042008-07-17 07:03:57

Unusual Wear on Half Shaft (13/17)
7/19/08 8:50am

jp75vette
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Bloomfield Hills, MI - USA

Vette(s):
1975 Corvette coupe, 4 speed manual, 383 ci 9.5:1,Edelbrock dual plane Air Gap intake, Alum Heads,Comp Cam, roller Rockers, PS,PB,Tilt

Joined: 6/29/2008
Posts: 199

I pulled the differential last night and found out that the Yoke retainer clip had come off. I'm not sure how that happened as the clip and the groove in the yoke look OK to me. I see that the splines on the yoke have twisted a little. Is this normal and is the yoke OK?

Unusual Wear on Half Shaft (14/17)
7/19/08 9:44am

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Hot Springs, AR - USA

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69 Conv #'s match 427, TKO-600/.64, 3.36HD-Posi, HT, T/T, PS, PB, PW, SP, Leather, Comp XE264HR & Roller Rockers & Lifters, Air-Gap RPM intake, Holley St Av 770 VS, MSD 6AL+Dist+Blaster SS, K&N, Jet-Hot Hooker Side-Pipes, Steeroids, Al Rad, Spal Fans

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if the splines have twisted then the yoke isnt ok...

you need to replace it.

how about the other side and its yoke and clip?

cthulhu2008-07-19 06:45:04

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Unusual Wear on Half Shaft (15/17)
7/19/08 2:56pm

jp75vette
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Bloomfield Hills, MI - USA

Vette(s):
1975 Corvette coupe, 4 speed manual, 383 ci 9.5:1,Edelbrock dual plane Air Gap intake, Alum Heads,Comp Cam, roller Rockers, PS,PB,Tilt

Joined: 6/29/2008
Posts: 199

The other side clip was still on, I removed it and noticed that the was wear on the end of the yoke shaft, so much that there were burrs on the splines. The splines were straight on this side.

Unusual Wear on Half Shaft (16/17)
7/20/08 12:52am

sgm2004
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Falls Church, VA - USA

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1975, 4 speed, L48, NOW Silver mist, Oxblood inside 2003 50th Av Torch RED little brother to 75

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Posts: 232

All, yoke came completly out on mine only thing holding mine together was rear supention. Got it all out took it to Zips today T/As and diff. I'm replacing just about everything from wheel to wheel. keep ya posted. Thanks

Guy

Unusual Wear on Half Shaft (17/17)
7/20/08 6:41am

jp75vette
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Bloomfield Hills, MI - USA

Vette(s):
1975 Corvette coupe, 4 speed manual, 383 ci 9.5:1,Edelbrock dual plane Air Gap intake, Alum Heads,Comp Cam, roller Rockers, PS,PB,Tilt

Joined: 6/29/2008
Posts: 199

I talked to a Corvette shop that repairs differentials and when I reviewed my situation, over the phone he said it was the springs that caused all these problems. I believe he is right as my car had extra wide tires (P295 50R 15's), spacers to prevent these wheels from rubbing on the ebrake cable and also was riding high. I will take it to him to rebuild and have him give me advise on a new spring.

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