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Discussion Starter #1 (Edited)
Ok I know a lot of you have followed my threads on diff's over the years and a question I get a lot is " Why are your's different then any of the others out there"

That is a very good question, so here I present something for those of you who want to play along. Let me know if you see anything odd here. I'll go over what I was told before I opened it up. I won't mention the owner or the well known rebuilder. I will say the shop is South of the Mason/Dixon.

Ok this was "rebuilt" recently and has only 800 miles on it. The gears were whining from day one and the pinion seal leaking like an open tap.

What you can't see, 020" backlash, 030 pinion endplay.

So anyone want to take a shot? Win a no-prize!

The main purpose is to use this as a tool to inform and educate the average vette owner. Anyone in the rebuilding business would or should know this.









 

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Are they located around Farmers branch TX
 

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Speaking of iron differentials.... I still want to do a swap in my car at some point! I want it to be able to hold up to slicks and some hard launches at the strip:thumbsup: I've got to get more details from you at some point so I can start planning it.
 

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this is just a stab in the dark, but does it have to do with the lock-washers? Split lock washers seem out of place on a ring gear. :huh:
 

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this is just a stab in the dark, but does it have to do with the lock-washers? Split lock washers seem out of place on a ring gear. :huh:
Thats funny, those jumped out at me too. I dont know much about the internals of a diff, and I definitely don't know a lot about rebuilding one, but they just seemed out of place.
 

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I'm just guessing, but I don't see any clutch disks, maybe they are there but I don't see them. I know that some people tune them to not need the springs somehow, and that wasn't done here.

And was the carrier rubbing the case? I'm interested to learn and see what was going on. I also know that I have heard horror stories about rebuilders. But I have heard tons of success stories from gtr1999. (Gary isn't it?)
 

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looks like the case is cracked to me especially in the last picture.

I also dont know about those washers, they do look out of place but im not a rear end builder and i know some custom things can be done to them, gary is a prime example of that. but still just looks out of place.
 

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Have not had the pleasure of seeing the internals of a Vett diff in over 10 years, but my first guess is the end caps are on backwards (tang pointed out not in) and causing a cracked housing?
 

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Discussion Starter #12 (Edited)
You guys are sharp but no cracks seen yet. The posi is a loaded Eaton. I want to mention I like and use Eaton posi's. They are my first choice, I just mod them somewhat for my own taste.

Ok here's what I found.
First look at the carrier( housing) and you see it's a 1965, stamped for a 65 396 in fact. NCRS guys might want it,but I already ground off the ears. Then look at the bearing caps, not correct for this year,they're 71-79 with cast in tab. What's that mean? They were not fit to the carrier, the caps originally were line bored so the caps are matched to each carrier. I was able to loosen them by hand with a 3/8 ratchet. The case came out without any resistance and NO preload- Not good.

The Ring gear bolts are std grade 8's,they're ok but I only use them in very mild applications. They are part of the common master kits sold many of which include the cheap side yoke bearings which I also don't use.
I use ARP RG bolts.





The back lash was way off and the wrong shims used. The 63-66 housings are narrow and no one sells a master kit with the correct shims in it. The kits use shims for the wider 67-79 housing- vendors please note. I grind shims to size when rebuilding these.





I've made my feelings known about using certain posi parts. This is just my opinion, only the way I do them, others think otherwise - generally motivated by money.
Here are the fiber coated clutches.



HD springs with less clutches per side and once the springs were removed there was 030" endplay in the side gears- also not good.





The diff leaked from lousy setup - 030 endplay in the pinion yoke and CHEAP parts, in this case the pinion seal used. Also no sealant on the splines - only under the washer completely useless and shows complete lack of experience with this work.







Other things, the crush sleeve was over crushed,the cross shaft had wear on it already- I use HD shafts, I didn't care for the R&P set, the pattern was all over the place.

So I hope this helps answer some questions, if you need a diff make up your own mind and ask questions before you decide.
You all passed!!
 

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Looks like a casting seam to me. :cheers:
Yeah, like Gary said above there have been no cracks. I was just agreeing that I thought it was one at first :thumbsup:
 

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Really appreciate all the critical details explaining how and why things are being done. It really goes to show what makes the difference between a truly long lasting professional job and just some guy slapping **** together hoping it will last.
 

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I know who it is. I'm not getting myself in trouble though.
I have an idea of who it might be...

Before I was aware of Gary and his amazing work, I bought a "rebuilt" 1980 differential with 3.70 gears from a well-known company down south.... what a mistake. After a few thousand miles of pretty easy cruising the things already got a significant leak from the front seal, and small leaks from the side yoke seals.... and that all happened BEFORE I put in the 383 stroker.:down:

Im planning on going to Gary sometime in the future for a much more solid unit.:thumbsup:
 

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I have an idea of who it might be...

Before I was aware of Gary and his amazing work, I bought a "rebuilt" 1980 differential with 3.70 gears from a well-known company down south.... what a mistake. After a few thousand miles of pretty easy cruising the things already got a significant leak from the front seal, and small leaks from the side yoke seals.... and that all happened BEFORE I put in the 383 stroker.:down:

Im planning on going to Gary sometime in the future for a much more solid unit.:thumbsup:
If you want to beef up you aluminum diff, contact tracdogg2 (Mike Dyer). He's the only one I know of who installs steel caps in the aluminum housings.



Sorry for stealing your thunder Gary:rolleyes:
 

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Discussion Starter #20 (Edited)
For those that think this is a bolt in job, forget it. You need more then a drill press to correctly fit them. BTW, today I put in about 7 hours into machine fitting the posi and housing, I figure the original builder (not mentioned by me) would have about 2 diff's done in that time, maybe 3!:surprised
 
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