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4/20/13 8:55pm - Original Message: 'Side yoke seals, and other questions...big job?'
persico Gold Member
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Long Valley, NJ - USA

Vette(s):
1972 454 Coupe, 4 speed, Targa Blue with blue interior, luggage rack

Joined: 3/21/2007
Posts: 253
OK  It's happening again "the dreaded while your at it syndrome".  Was under the car looking at frame, replacing the gas tank and I noticed that there is grease that looked like it was coming from the side yoke seals on the differential.  After dropping the strut rods and spring and half shafts I think it's actually from the universal joint.  They were replaced and have grease fittings so I think Bubba pumped them full and it was spraying all over the undercarriage!  Anyway, I want to drop the differential anyway (to replace cover - see below) so I will check the seals.  A few questions:

1.  Is it hard to replace the side yoke seals?  I don't want to mess with the diff internals, shims etc.

2.  I've read all the posts on dropping the pumpkin with the cross member still attached so thats how I'm going to go, (need to replace the "sombreros" too) BUT  how do you get he front bracket to frame mounting bolt off (the vertical one not the ones holding the bracket to the diff), I don't see how to get a wrench on top of the bolt? 

3.  Was also wondering what the best way is to disconnect the drive shaft, looks really tight, any suggestions?  (Half shafts are already off)

3. Finally I see Bubba also had to use a helicoil in the diff cover for one of the spring bracket retainer bolts.  This makes me uncomfortable so I am going to replace the cover.  My question is are the bolts that retain the spring supposed to all be the same length?  I have two at 4.5" and 2 at 5"??  Spring is 9 leaf 2 1/4" wide, is this the right spring for a big block?

Sorry for the lengthy post!




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4/20/13 10:54pm - Reply: 'Re: Side yoke seals, and other questions...big job?'
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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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To replace the seals, you must remove the yokes. If you are replacing the rear cover, you can get to the snap rings that hold the yokes in, and replace the seals.

If the heli-coil is installed properly, the threads in that are stronger than the cut threads in the diff anyway, so the use of a heli-coil in itself would not be a reason to replace the cover, for me.

Don't know exactly how long the bolts are for the spring mounting, but they should all be the same length, from what I can remember.

The front bolt on the diff bracket can be a little tough to get to, but you must remove the driveshaft first. That gives you more room to play with. Removing the bolts for the driveshaft can be done with a long extension and socket from the front.


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4/21/13 11:26am - Reply: 'Re: Side yoke seals, and other questions...big job?'
persico Gold Member
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Long Valley, NJ - USA

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Thanks Joel, so if I remove the side yoke snap rings and remove the yokes to replace the seal, do I need to worry about re-shimming or anything or just put back what came out?  The helicoil repair in this particular situation required a larger diameter bolt than the other three, the coil also appears to be part way out of the hole, that's why I'm leery.  I'll send a picture if I can figure how to upload a compressed shot!

PS the shop manual does have much info on this particular topic, it tells you how to remove the carrier but not the diff case.


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4/21/13 7:27pm - Reply: 'Re: Side yoke seals, and other questions...big job?'
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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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No shims, or other surprises when you remove the snap-rings and yokes. Fairly straight-forward...remove the snap-ring, slide the yoke out, replace seal(s), insert yoke, replace snap-ring. Be sure to keep the yokes on whatever side you take them out from....don't mix them up. They are the same, but they will have a wear pattern on the end that rides against the center shaft of the diff, and it's best to keep them in the original location.
I have been digging back thru my pic files, looking for something that shows the snap-rings, but so far...nuttin...Cry


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4/22/13 10:58am - Reply: 'Re: Side yoke seals, and other questions...big job?'
persico Gold Member
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Long Valley, NJ - USA

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OK got the crossmember and diff down, here are some pics:  The "somberos" don't look too good on the bottom but the other side not so bad! Guess I'll replace them "while I'm at it".  The yoke and pinion seals do not look to be leaking either (was probably too much grease in the universals) but I'll replace them as well to be safe.

 
 
 
Here are some pics of the helicoil in the cover plate.  As I said before it seems to be "hanging out" so I will replace the cover.
 
 
 
 
Here is the unit out of the car.  How much rust is too much?
Seals look good


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4/22/13 11:02am - Reply: 'Re: Side yoke seals, and other questions...big job?'
persico Gold Member
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Long Valley, NJ - USA

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1972 454 Coupe, 4 speed, Targa Blue with blue interior, luggage rack

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Also...not sure if I should have started a new thread for this, "while I'm at it" I was considering having the trailing arms rebuilt.  Any recommendations?  So far I've been told Bairs and Van Steel have good reputatuions.  Any others?  I'll go with the forum sponsor if all else is equal!  When replacing to I just keep the same number of shims on either side, any other tips?

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4/22/13 3:03pm - Reply: 'Re: Side yoke seals, and other questions...big job?'
JohnRR
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Mario,
After you removed the half-shafts, did you check the end play of the side yokes?  The half-shafts are the upper control arms of the suspension.  Some guys say that the end play doesn't matter, but I think it does.  Mine were about .200 before Van Steel rebuilt the rear.  Now the end play is around .015.   

"While I was at it", I bought new offset trailing arms from Van Steel.  They came assembled complete with new spindles so now the rear wheels ought to be pretty good.

Another "While you're at it" would be to replace that heavy steel spring with a light weight fiberglass piece.  Or, go with a coil-over system from Van Steel.

Have you looked at "Smart Struts" yet?

John


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4/22/13 3:34pm - Reply: 'Re: Side yoke seals, and other questions...big job?'
persico Gold Member
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Long Valley, NJ - USA

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1972 454 Coupe, 4 speed, Targa Blue with blue interior, luggage rack

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JohnRR said: Mario,
After you removed the half-shafts, did you check the end play of the side yokes?  The half-shafts are the upper control arms of the suspension.  Some guys say that the end play doesn't matter, but I think it does.  Mine were about .200 before Van Steel rebuilt the rear.  Now the end play is around .015.   

"While I was at it", I bought new offset trailing arms from Van Steel.  They came assembled complete with new spindles so now the rear wheels ought to be pretty good.

Another "While you're at it" would be to replace that heavy steel spring with a light weight fiberglass piece.  Or, go with a coil-over system from Van Steel.

Have you looked at "Smart Struts" yet?

John

John,
 
I seem to be headed down that path with the trailing arms.  Actually found there is a guy near me that people have said good things about, Glenn at Hillside Corvette in Martinsville NJ - anyone have any experience with them? (am I allowed to name names??)
 
I didn't check the end play on the side yokes, how do you measure it?? Confused
 
I did order adjustable strut rods if thats what you mean by "smart".
 
What is the advantage of the lightweight fiberglass spring?  It looks like my 9 leaf steel spring was rebuild recently so I was hoping top save some money there.  I see there are so many sizes (300, 320, 340, 360 etc.)  How do you tell which you need?


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4/22/13 9:29pm - Reply: 'Re: Side yoke seals, and other questions...big job?'
Jeffm Gold Member
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Sebago Lake, ME - USA

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1978 Silver Anniversary L82 4spd (M21) Red Leather. -1978 Pace Car L82 4spd (M21) 20k miles.

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I replaced my side yokes myself and that was totally new territory for me. Didn't get into anything beyond side yokes, seals and cleaning up the inside as best I could. My '78 was 1 of the years that the side yokes wore down pretty quick which created a lot of end play. Picture shows the "C" clips and the mushroom effect of the ends wearing.That was at about 48,000 miles. You can see how much end play I had there on the left as the yoke end wore down. Replaced them, put it back together and its been great since, and no leaks. Didn't measure end play but it was a whole lot tighter after.
Also did a VB&P composite spring i picked up at Carlisle at the same time. I think it was the touring rating , can't remember the lbs. Never told the wife I bought a new spring and within 2 miles she asked me what I did to make the car ride better.

http://i159.photobucket.com/albums/t132/JeffsVette/DSC03587-1.jpg

|UPDATED|4/22/2013 6:29:30 PM (AZT)|/UPDATED|


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4/23/13 12:52pm - Reply: 'Re: Side yoke seals, and other questions...big job?'
Adams' Apple Lifetime Member
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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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Great pic, Jeff! Thanks for posting that...I'll be stealing it for future reference.....Embarrassed

The yoke on the left is definitely mushroomed, the one on the right has just about worn all the way down to the snap-ring. Once they wear down that far, the snap-ring can pop off, and fall down in the gears, doing some major damage....as well as allowing the yoke to slide out on hard turns....Censored


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Joel Adams
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4/24/13 2:23pm - Reply: 'Re: Side yoke seals, and other questions...big job?'
persico Gold Member
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Long Valley, NJ - USA

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1972 454 Coupe, 4 speed, Targa Blue with blue interior, luggage rack

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Adams' Apple said: Great pic, Jeff! Thanks for posting that...I'll be stealing it for future reference.....Embarrassed

The yoke on the left is definitely mushroomed, the one on the right has just about worn all the way down to the snap-ring. Once they wear down that far, the snap-ring can pop off, and fall down in the gears, doing some major damage....as well as allowing the yoke to slide out on hard turns....Censored

OK Sorry for being so dense.  But in the photo I see the mushrooming and the worn right side yoke, but...are they supposed to be flush against the vertical shaft in the middle?  Is that the pinion?  I'll open 'er up and take a pic this weekend.
 
Also any advice on how to tell when the trailing arms need to be rebuilt.  Mine look pretty crusty but seem to spin OK.  Do I disconnect half shafts and check spindle end play somehow.  Scope creep again!
Joel what did you think of that helicoil repair in the pics above!


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4/24/13 5:19pm - Reply: 'Re: Side yoke seals, and other questions...big job?'
Jeffm Gold Member
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Sebago Lake, ME - USA

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1978 Silver Anniversary L82 4spd (M21) Red Leather. -1978 Pace Car L82 4spd (M21) 20k miles.

Joined: 2/15/2007
Posts: 962
The yokes are suppose to ride against the center pin.If the yokes were not worn so badly the "C" clip would be much closer to the metal plate just to the outside of it that the blue springs are against. As Joel stated the one on the right is much worst. The camera was a little off center so it's hard to see the space behind the "C" clip.

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4/24/13 10:53pm - Reply: 'Re: Side yoke seals, and other questions...big job?'
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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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persico said: OK Sorry for being so dense.  But in the photo I see the mushrooming and the worn right side yoke, but...are they supposed to be flush against the vertical shaft in the middle?  Is that the pinion?  I'll open 'er up and take a pic this weekend.


The yoke ends should butt right up against the center pin, yes. These yokes are worn bad enough to have too mech clearance between the snap-ring, and the side gear of the diff.

The amount of metal you see in between the two red vertical lines here is how much metal is worn off of the OTHER side of the snap-ring. With good yokes, the snap-rings would actually be snugly up against the side gears, instead of close to the center pin. This wear will allow the yokes to move in/out of the diff, and when they do, the tops of the tires/wheels will also move in-out, which effects handling and alignment.


On the heli-coil repair...yeah...that's kinda messed up right there! I see now why you want to replace the cover.
Checking for wheel bearing play on the t-arms is normally easier with the suspension still in the car, but, the general rule is if you can FEEL any play in the bearings, they are too loose.


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4/25/13 9:05am - Reply: 'Re: Side yoke seals, and other questions...big job?'
persico Gold Member
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Long Valley, NJ - USA

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Thanks guys, heres a pic of mine.  It is off center as well but now I know what I'm looking for.  There is end play but what is the tolerance supposed to be?  And how do you measure it?  Hate to have to buy new yokes (couple hundred here, couple hundred there pretty soon we're talkin' real money!) but then again, don't want to drop the diff again anytime soon!  Also in second picture why would my carrier have those gear marks on it?  Is that common?  It's not rubbing against the pinion nor does anything seem out of whack when I turn it, maybe from a prior incident?  I can tell Bubba has had this open before (found three different length bolts holding the cover on!)






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4/25/13 12:50pm - Reply: 'Re: Side yoke seals, and other questions...big job?'
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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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The gouges on the carrier are obviously from previous damage. It is where the pinion bearing took a doo-doo, and the pinion ran back into the carrier. You would know if there was a problem with it now, so it has to be from a previous encounter of the closest kind.

Hard to see in the pics, but it doesn't appear that the yokes have much wear. As far as how much is too much? Dat's a gud kweschun.....You should have some play, around .040" or so. I've never really seen any specs on it, but .040" is pretty good for new, unworn yokes and posi clutch packs. The play is adjustable to an extent by using different thickness snap-rings, and shims on the clutch packs.

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4/25/13 5:38pm - Reply: 'Re: Side yoke seals, and other questions...big job?'
Jeffm Gold Member
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Sebago Lake, ME - USA

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Posts: 962
Mario,
Your yokes look a whole lot better than mine. When I was doing research on how to do this differential stuff I found out that later C3's, including '78 had bad yokes. Soft metal wore quickly. My oil was like a metallic paste.
Joel, That's pretty cool the way you can put notes on a picture. Someday i learn how to do that stuff. Use the pic anytime you like.  


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4/26/13 10:58am - Reply: 'Re: Side yoke seals, and other questions...big job?'
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Just a quick note to say thanks for all the great information here... One day I too will be tackling rebuilding the back mechanicals and love to read all I can. 


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4/28/13 1:11pm - Reply: 'Re: Side yoke seals, and other questions...big job?'
persico Gold Member
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Long Valley, NJ - USA

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1972 454 Coupe, 4 speed, Targa Blue with blue interior, luggage rack

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Yes this forum is a wealth of info, thanks to all ...I find myself accessing regularly....now an update.  Trailing arms off to be rebuilt, need new cores since the old ones were pretty beat up by previous owners, but  "while I'm at it", anyone have experience with rebuilding calipeers?  Mine look pretty good but thinking of switching to O rings, any thoughts?  Sorry if this off topic.  Also should I flush the differential before refilling?  What would one use?

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4/29/13 12:13pm - Reply: 'Re: Side yoke seals, and other questions...big job?'
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I just did all 4 on the white vette last fall. O-ring kits from bairs and new rebuild kit for master cylinder. Easy job just time consumming. I have lots of pictures need to turn them into a tech article.....ebo

|UPDATED|4/29/2013 9:13:13 AM (AZT)|/UPDATED|


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4/29/13 12:37pm - Reply: 'Re: Side yoke seals, and other questions...big job?'
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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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ebo said:I have lots of pictures need to turn them into a tech article.....ebo


...And put it in the next installment of "Shark Bytes", right? Big smile


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