[DIFFERENTIAL] Critique my pattern?
Thread Starter
Melting Slicks
Joined: Aug 2000
Posts: 2,961
Likes: 1
From: Sealy Texas
Cruise-In III Veteran
[DIFFERENTIAL] Critique my pattern?
This is on my '82 diff, so it's not quite exactly like the '63-'79 diff, but pretty much the same.
Backlash is at .009" - within the .008"-.010" spec. Pinion is moved up slightly from where it was for spec, will have to measure to be 100% sure by how much. Took me about 5 or 6 tries to get it to this point. Was too far up & out originally, got it in & down to this point now.
Drive side..
Coast side..
Backlash is at .009" - within the .008"-.010" spec. Pinion is moved up slightly from where it was for spec, will have to measure to be 100% sure by how much. Took me about 5 or 6 tries to get it to this point. Was too far up & out originally, got it in & down to this point now.
Drive side..
Coast side..
Tech Contributor
Joined: Aug 1999
Posts: 15,161
Likes: 3,965
From: Connecticut, USA
Drive side is deep. Coast looks close and to heel. You need to go with a thinner shim and load the gears as you pattern them. Thin out out the paste and get the yellow paste from any GM dealership.
Thread Starter
Melting Slicks
Joined: Aug 2000
Posts: 2,961
Likes: 1
From: Sealy Texas
Cruise-In III Veteran
I do load the gears when I pattern them - this grease sucks. I'll see if I can find a GM dealership for the yellow stuff. What should I ask for?
Thread Starter
Melting Slicks
Joined: Aug 2000
Posts: 2,961
Likes: 1
From: Sealy Texas
Cruise-In III Veteran
Got the yellow stuff at the dealership just the other day. Here's the results (though I can't tell much difference from the white stuff?) Am I doing something wrong? I'm loading the case up while I turn the pinion.. or do I turn the case while I load the pinion?
Drive side..
Coast side..
Drive side..
Coast side..
Drifting
Joined: Mar 2006
Posts: 1,526
Likes: 2
From: Oak Ridge NC
The pattern is much more "readable", but you need to clean that white crap off. Looks deep as Gary said. He wants you to put in a thinner pinion shim. What is the shim size that you are using?
Here is a link to Gary's post.
http://forums.corvetteforum.com/show...1236684&page=2
See the pinion shim in post 19 and pattern starting with post 24.
Is this a new set of gears? Or are you trying to reset an existing set after a fix of something? If it is the existing gear, did you do a pattern before taking it apart?
Here is a link to Gary's post.
http://forums.corvetteforum.com/show...1236684&page=2
See the pinion shim in post 19 and pattern starting with post 24.
Is this a new set of gears? Or are you trying to reset an existing set after a fix of something? If it is the existing gear, did you do a pattern before taking it apart?
Last edited by SmokinBBC; Jun 24, 2007 at 01:01 PM.
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Thread Starter
Melting Slicks
Joined: Aug 2000
Posts: 2,961
Likes: 1
From: Sealy Texas
Cruise-In III Veteran
New gears. Went from stock 2.87 to 3.23.
I'll disassemble and clean all the white crap off real good - might be a week before I can get back to it though, leaving out today for Virginia for the week.
I'll pull out some pinion shim, I've done it about 4 or 5 times already to get this result as it is. I thought you wanted it closer to the middle (heel to toe?)
I'll disassemble and clean all the white crap off real good - might be a week before I can get back to it though, leaving out today for Virginia for the week.
I'll pull out some pinion shim, I've done it about 4 or 5 times already to get this result as it is. I thought you wanted it closer to the middle (heel to toe?)
Drifting
Joined: Mar 2006
Posts: 1,526
Likes: 2
From: Oak Ridge NC
New gears. Went from stock 2.87 to 3.23.
I'll disassemble and clean all the white crap off real good - might be a week before I can get back to it though, leaving out today for Virginia for the week.
I'll pull out some pinion shim, I've done it about 4 or 5 times already to get this result as it is. I thought you wanted it closer to the middle (heel to toe?)
I'll disassemble and clean all the white crap off real good - might be a week before I can get back to it though, leaving out today for Virginia for the week.
I'll pull out some pinion shim, I've done it about 4 or 5 times already to get this result as it is. I thought you wanted it closer to the middle (heel to toe?)
What size shim you have in there now?
It is more important to have it centered between the face and flank.
Try PM to GTR1999 or TRACDogg2.
Melting Slicks
Joined: Jan 2006
Posts: 3,028
Likes: 2
From: North NJ
If my understanding is correct you have to load the pinion and turn the ring gear. Take a thick leather belt and wrap it around the pinion for load and then use a closed end wrench on the ring gear bolts to turn the gears.
I beleive your drive side should be more on the toe (inside) of the gears than the heel (outside). As you drive the car the gears will break in and the pattern will then cover the entire gear face. When setting it up your pattern should cover the full half of the gear toe.
Your coast side doesn't look too bad except you want it to leave a rectangle pattery not a triangle pattern like you have.
I can see the shiming, disassmble, reassemble of the diff the most frustrating rebuild on the car.
Don't ask me about shims. I only learned this stuff this weekend.
Definitely PM GTR1999 or TRACDogg2 like SmokinBBC advised.
I beleive your drive side should be more on the toe (inside) of the gears than the heel (outside). As you drive the car the gears will break in and the pattern will then cover the entire gear face. When setting it up your pattern should cover the full half of the gear toe.
Your coast side doesn't look too bad except you want it to leave a rectangle pattery not a triangle pattern like you have.
I can see the shiming, disassmble, reassemble of the diff the most frustrating rebuild on the car.
Don't ask me about shims. I only learned this stuff this weekend.
Definitely PM GTR1999 or TRACDogg2 like SmokinBBC advised.
Drifting
Joined: Mar 2006
Posts: 1,526
Likes: 2
From: Oak Ridge NC
Limping across the line
Joined: Oct 2002
Posts: 5,299
Likes: 109
From: Peoria Az
I bet Dollars to Donuts that if you measure the old pinion shim and install the same thickness on the new gear and set your backlash to .006
Your pattern will be good.
Give that a try.
If you were close I'd swing by and get you dialed in.
TO load the gears use the wooden handle of a hammer against the ring gear and turn the pinion by hand in the fwd direction,yoiu dont need alot of pressure just a good drag.
Thinning the marking compound with just a drop or 2 of oil helps also
Whos gears are you using?
Your pattern will be good.
Give that a try.
If you were close I'd swing by and get you dialed in.
TO load the gears use the wooden handle of a hammer against the ring gear and turn the pinion by hand in the fwd direction,yoiu dont need alot of pressure just a good drag.
Thinning the marking compound with just a drop or 2 of oil helps also
Whos gears are you using?
Last edited by AzMotorhead; Jun 26, 2007 at 09:03 PM.
Thread Starter
Melting Slicks
Joined: Aug 2000
Posts: 2,961
Likes: 1
From: Sealy Texas
Cruise-In III Veteran
Using Precision Gear gearset. Got back early from VA, will probably work on this tomorrow. I'll measure everything and clean during disassembly. Thanks for the tips so far! I was loading the carrier just with my hand, so I'll see if I can put some more pressure on it.
Melting Slicks
Joined: Nov 2001
Posts: 2,668
Likes: 43
From: Eastern US XX
To initially get as close to the original settings (i.e. pattern), you do have to factor in the measurement inscribed into the front/face of the pinion gear then use the appropriate thickness "shim" - it will probably be a little different size than the original.
