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The last week there were some threads on rebuilding units, Differentials were one. Some may think I like to type the same info all the time on jobs but there usually is a lack of understanding or just misleading work performed in the automotive world these days, I know - nothing new, but if it helps just one guy in the future I'll continue to type.:crazy:

So for those that may care, below are pictures I was sent of a Differential rebuilt by a well known shop. Cost was $1000 I was told. I did not see this unit first hand and the owner was ony questioning why there was .025 endplay in a new rebuild with new yokes. I knew exactly why but this may help some of you in the future.

I am not naming owner or rebuilder. Not my intention to single out either although I'm sure both are on this and other forums. This is intended for the car owner who may be faced with this job in the future. I am not fishing for work either, TT pointed out I now hold up kids for their lunch money.:devil:- Not true as long as parking meters are still on the streets!!!:laughing:


So kid, you want a cheap job huh, well look at what this guy got for $1,000

Ring gear bolts reused, GM shims re-used, no detail or custom tuning, re-used posi springs, not sure what clutches were used- new or old???
It will work ok, I don't like the things I pointed out and would not use those procedrues in my work but it does cut corners customers can't see and won't - unless there is a failure. Adds to the bottom line- God how I have grown to hate that term.

Still think you get what you pay for??







 

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I did not see this unit first hand and the owner was ony questioning why there was .025 endplay in a new rebuild with new yokes.

So kid, you want a cheap job huh, well look at what this guy got for $1,000

Ring gear bolts reused Do they ever break? Mine aren't factory either.

GM shims re-used I doubt my current shims will even work.Ihave to buy the shim kit.

no detail or custom tuning Polishing the case is on me, I don't know of any custom tuning besides setting it up properly.

re-used posi springs How does toms not use them? http://www.tomsdifferentials.com/catalog.asp?pg=20

not sure what clutches were used- new or old??? I will get new metal ones


It will work ok, I don't like the things I pointed out and would not use those procedrues in my work but it does cut corners customers can't see and won't - unless there is a failure. Adds to the bottom line- God how I have grown to hate that term.

Still think you get what you pay for??
I don't even know if I'll be paying him. He will just show me how to do it. I have to walk 30 yards to see him.

More later. I have to go to bed. This is a crappy reply :crazy:

What is the quality on toms stock unit?
 

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Gary, was the .025 end play from the space between the circlip anf the gear?
 

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Gary, here's a dilema for ya. It seems like it's becoming more difficult to find a shop that will do a really good job on these things. However, I don't have the tools available to do much (if any) custom tuning myself. What are the minimum resources (namely tools/space) to properly rebuild a unit?

I'd love to tackle mine all on my own, but it seems like there are a lot of little things it would be easy to screw up. Especially for a guy that's never even seen the insides of one of these in person!

TIA
 

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Discussion Starter · #5 ·
The .025 endplay was in the new yokes after the rebuild. Apparently acceptable by the rebuilder.

Jason when you're ready look over my post above, it will outline a lot. I have walked a few guys through this for the first time as well. They wanted the parts I use so I supplied them and with some support they have done a great job. Think about it. If you're going to Carlisle I'll be at L116 and will go over the job with you.
 

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So whats wrong with using the original shims, hex nuts and ring gear bolts? If it was just a standard rebuild, wouldn't these work out fine? Were the ring gear bolts damaged? If so was he told and given the option for new? Did he ask for the HD cap to be installed on his rebuild? I honestly don't see anything wrong here except for the side yokes. The side yoke looks as if it almost a new yoke. It still has a good looking tip. Did you mic out the tip?
 

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Gary, here's a dilema for ya. It seems like it's becoming more difficult to find a shop that will do a really good job on these things. However, I don't have the tools available to do much (if any) custom tuning myself. What are the minimum resources (namely tools/space) to properly rebuild a unit?

I'd love to tackle mine all on my own, but it seems like there are a lot of little things it would be easy to screw up. Especially for a guy that's never even seen the insides of one of these in person!

TIA
Since you live in Lincoln Nebraska finding a good mechanic will be easy for you.

Just go north to a little town called Bancroft. Find C&J Auto and talk to Chris. Tell him Morlok sent you. This guy is awesome. He is the only mechanic I will let touch my 2001 vette. He has also built a 350 and 496 for my friends 69 Vette. This guy is top notch and he will never try and screw you out of any money.

Good mechanics are hard to find, but I promise you, you will be happy with the work Chris does. He is about 50 miles from my hometown and I gladly made the drive to have him do the work.
 

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Discussion Starter · #8 ·
So whats wrong with using the original shims, hex nuts and ring gear bolts? If it was just a standard rebuild, wouldn't these work out fine? Were the ring gear bolts damaged? If so was he told and given the option for new? Did he ask for the HD cap to be installed on his rebuild? I honestly don't see anything wrong here except for the side yokes. The side yoke looks as if it almost a new yoke. It still has a good looking tip. Did you mic out the tip?
I don't think I know you, but you sure sound like a rebuilder. Will this setup work,yes. Is it the best way - no, is it worth what he paid - I don't think so.
In fact I think little of this type of work. Overpriced for little attention. Would I accept .025 endplay- no, chances are the rebuilder doesn't know or care about it.

There is a problem reusing those parts and for the cost of new ones just doesn't justify not replacing them.A good quality master kit will have most of them. Buying common parts, not the of the best quality is cheaper though. I've seen bearings sold in unmarked boxes, unwrapped- bulk purchased.

The cap bolts in this build are gr 8 but the earlier cars used a 5 line bolt. I replace them on every build for $5. The stock shims are cast and set in place with a spreader. Hammering them back in will break them and once out the backlash will change, hence new steel shims are in the kits. Again cut corners to save a dime. The backlash could be all over the place. I didn't mention a HD cap and I doubt this place would know how to fit one. They need to be machined to correctly fit, at least everyone I did required it but then I work to precision tolerences- not wide windows the books call out.

So if you honestly don't see anything wrong,ok you should use this rebuilder.Marketing is everything in this game but a big glossy ad doesn't give you the results you may expect. I'm selective in my work and would rather turn this job down then build it like this.

This is a good point though for those considering this work as it may give them some things to think about rather then follow the lead sheep.

The guys here and on the CF who I walked through the job for the first time built a better unit then any of the advetised jobs I see. Ask them what they think.
 

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I'm actually going to disagree with Gary just so everyone doesn't think we're joined at the hip. Only the part about the cast shims. I prefer to use a solid shim on the drive side. But (a) I've been doing these for a long, long time and know how to install them and (b) I have hundreds of them. The odds of the original shims that came out of a particular diff working with the new bearings is nil. It just won't happen if the backlash and preload are set right. The corvette gods were smiling when they invented the super shims.
80 vette guy. Take a close look at those ring gear bolts. They don't use lock washers. Instead they have a serrated face to contact the case. If you were in an aluminum boat in the middle of a lake during a lightning storm wearing an Ipod and holding up a 50' copper flag pole I would put my money on those bolts backing out before you got struck.
With that much end play in the yokes the backlash on the spyder gears has to be way out of range. Also in Gary's pics you can see the casting defect that needs to be addressed. Even if it's only a stock rebuild. Why would you want to re-install a factory defect?
Mike
 

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Gary, here's a dilema for ya. It seems like it's becoming more difficult to find a shop that will do a really good job on these things. However, I don't have the tools available to do much (if any) custom tuning myself. What are the minimum resources (namely tools/space) to properly rebuild a unit?

I'd love to tackle mine all on my own, but it seems like there are a lot of little things it would be easy to screw up. Especially for a guy that's never even seen the insides of one of these in person!

TIA
I was really nervous about doing mine, too. But with the help of Mike & Gary, who were both Johnny-on-the-spot when I had a question or confusion, and lots of downloaded info & a couple manuals, I got through it OK. It took me a couple weeks, and several times I had to just walk away from it for a while. I know my job was not as good as they would have done it, but I also know it's 1000% better than a "store bought" unit or rebuild job, and the satisfaction I got from doing it myself is 'priceless'.

The only particularly special tools you'll need would be a vernier caliper, 1" micrometer, and a dial indicator w/magnetic base. You should be able to get these at a pawn shop, but do get good ones. You probably won't use them very often, but they are invaluable when you need them and you'll find you use them more often on other various jobs if you have them. I did not use a dial torque wrench, I decided I could fake that close enough for the cost, but I will pick one up someday if I see a good one I can afford.
Same for bearing puller & splitter, torque wrench, dead blow hammer,--You should have these in your tool box anyway. And a 4" bench vice.
The motor stand made it very easy to work on, you should be able to borrow one if you don't have your own.
I have some air tools--die grinder, wrenches, etc. but these are not 'necessary' just nice. Same for a solvent tank.
I borrowed a press, but I will be buying my own someday soon (Actually, I was going to buy one anyway for this job, but the only store locally who had them was closed for remodeling, so my hot rod buddies said I could take theirs home for the weekend).

You can do it.

John
 

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I have built a few diffs in my day and I always use the solid shims that come out of the diff. As long as you keep the left side on the left and rebuild it with the same gears, I found that I had no issues. When gears are replaced, it's a different story.

Lets be honest, how many times have you seen posi springs go bad. I can tell you I have seen very few. When I called up a couple differential shops, they only had 800# springs which would be way to hard for street driving.

Yeah, the ring gear bolts should have lock washers but I have seen the aluminum diffs without any at all. Like the pic posted above.

I'm sure the rebuilder would care. Not everyone is out to just make a quick buck. There are people out there who still care about what they put their name on and I'm sure they would want to know about the problem. I agree they may not put as much attention into a diff basic diff rebuild as Gary but your not paying $1500 either. I think the going rate is about $600 for a standward rebuild wether it's from Zip, Bairs or any of the other people.

Where do you see the casting defect?
 

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Mike you disagree- ok you're buying the beer:rolling:

Yeah you can use the cast shim on the left but I don't. You have to change the backlash with new gears and even with old ones.Using a solid shim requires grinding to change the backlash. It is easier to use the steel shims on both sides to dial in the backlash- I still grind them parallel.

The early diff's require using solid shims, ground to size. They take longer to setup.

The ring gear bolts were changed to the flange heads around 1976. The 63-76? used shoulder bolts and hardened lock washers. Some of them backed out but not as much as the flange head bolts did. These bolts are under load-I replace them every time.

I do not set up posi's with springs, I toss them out. Now as far as replacing them if you do want them, why not? They come in 3 or 4 ratings,most will hammer if the backlash is not right.

The 80-82 are not the same, I often refer to them as junk but that is biased as I was told!:laughing: I refer those to Mike, I want nothing to do with them. He likes the abuse.

As for rebuilders who care, yes there are some still out there. Mike, Tom's, Bair's are all places I deal with and are good people. This work was not done by one of them. The things I pointed out were done either for money savings on parts/increased profit or just lack of craftsmanship. It could have been done better for little outlay. This was a std in/out job, nothing more. The problem is their procedures in this case, not 1 bad job in particular. This is probably typical of their work and no one called attention to it but me. No, I'll never buy into that one.

Again it will work,but is this what you want for your car? If so, good deal - any of the vendors will handle it.Cost wise you can't compare jobs until all the parts and services are listed. Remember the thread title- "Think all rebuilds are the same" I'm still waiting to see vendors post their jobs online.

So without turning this into a pissing match, I think I made my point. Now do you want to talk about rebuilding rear bearings or boxes. I've seen a lot of similar procedures with those as well.
 

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Gary or all,

Is there a standard for what items are required to be replaced in a rear diff rebuild?

What is the significance of you pointing out the 0.025" endplay? What is it supposed to be? Will the 0.025" get worse over time for a normal driver?

Thanks,
 

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Mike you disagree- ok you're buying the beer:rolling:

Yeah you can use the cast shim on the left but I don't. You have to change the backlash with new gears and even with old ones.Using a solid shim requires grinding to change the backlash. It is easier to use the steel shims on both sides to dial in the backlash- I still grind them parallel.

The early diff's require using solid shims, ground to size. They take longer to setup.

The ring gear bolts were changed to the flange heads around 1976. The 63-76? used shoulder bolts and hardened lock washers. Some of them backed out but not as much as the flange head bolts did. These bolts are under load-I replace them every time.

I do not set up posi's with springs, I toss them out. Now as far as replacing them if you do want them, why not? They come in 3 or 4 ratings,most will hammer if the backlash is not right.

The 80-82 are not the same, I often refer to them as junk but that is biased as I was told!:laughing: I refer those to Mike, I want nothing to do with them. He likes the abuse.

As for rebuilders who care, yes there are some still out there. Mike, Tom's, Bair's are all places I deal with and are good people. This work was not done by one of them. The things I pointed out were done either for money savings on parts/increased profit or just lack of craftsmanship. It could have been done better for little outlay. This was a std in/out job, nothing more. The problem is their procedures in this case, not 1 bad job in particular. This is probably typical of their work and no one called attention to it but me. No, I'll never buy into that one.

Again it will work,but is this what you want for your car? If so, good deal - any of the vendors will handle it.Cost wise you can't compare jobs until all the parts and services are listed. Remember the thread title- "Think all rebuilds are the same" I'm still waiting to see vendors post their jobs online.

So without turning this into a pissing match, I think I made my point. Now do you want to talk about rebuilding rear bearings or boxes. I've seen a lot of similar procedures with those as well.
I'm not here to get into a pissing match either. Just asking questions in to learn more. Like I said I rebuilt a lot but new info is always good. Your posts are great for a lot of people. Why don't you pay to be a supporting member?

Sure we can talk about steering boxes and bearing assemblies. I have done many but I farm them out to Van Steel now like I mentioned in a previous thread(medical issues). They have access to all the parts if anything is bad and I have had zero issues plus offer me a 5 yr warranty. Not bad.
 

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Gary or all,

Is there a standard for what items are required to be replaced in a rear diff rebuild?

What is the significance of you pointing out the 0.025" endplay? What is it supposed to be? Will the 0.025" get worse over time for a normal driver?

Thanks,

Don't mean to horn in on Gary, but yes they do wear out a bit over time....if you get out to over 1/8 inch end play on those yokes,....you are pushing your luck pretty bad there, it needs come down for O'haul...there be a differance between that and just 'fixing'.....

I have done my diffy long time ago, and left it with somewhat less then 1/16th inch....thats 0625 end play on the output yokes....some of that was the cross shaft as new ones were not available...not that I found anyway....

the Yokes came from Bairs....that's about all I remember....
 

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Me? Buy the beer?:rolling: :rolling: You so funny!
I use the cast shim when I can if I have the size needed. I have over a hundred shims ranging from .230 to .250. But I use the super shims for set-up. So far it has never been the same shim I took out.
The casting defect is in the big window where it starts to turn near the ring gear. It's where the two sand castings were put together.
Mike
 

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At least my auburn didn't allow my yokes to get torn up at all. They look brand new.


And how does toms eliminate the springs?

Also do you have a price on there stock unit.


Basically all I need is the internals and the posi case from toms and I can build my own right?

http://www.tomsdifferentials.com/catalog.asp?pg=29

They will build it for 85 dollars more also. That put it around 400 for a brand new quality posi.

But the I need the rebuild kit and that is another hundred.
 

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At least my auburn didn't allow my yokes to get torn up at all. They look brand new.


And how does toms eliminate the springs?

Also do you have a price on there stock unit.


Basically all I need is the internals and the posi case from toms and I can build my own right?

http://www.tomsdifferentials.com/catalog.asp?pg=29

They will build it for 85 dollars more also. That put it around 400 for a brand new quality posi.

But the I need the rebuild kit and that is another hundred.
http://www.tomsdifferentials.com/catalog.asp?pg=20

I think someone is reading the wrong page...........or do you have an 80-82 diff??
redvetracr
 
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