7.5 Ring and Pinion Pattern

Status
Not open for further replies.

pontiacgp

blank
Mar 31, 2006
29,270
20,391
113
Kitchener, Ontario
The reason I asked about the crush sleeve is that if it not collapsed enough that would be the reason for a pattern that is too deep with no shims. The bearings would also not be seated properly........
Crush-Sleeve.jpg
 

64nailhead

Goat Herder
Dec 1, 2014
5,659
1
12,059
113
Upstate NY
The reason I asked about the crush sleeve is that if it not collapsed enough that would be the reason for a pattern that is too deep with no shims. The bearings would also not be seated properly........
Crush-Sleeve.jpg

I agree. Crushing the crush sleeve is with the differnetial and housing in the car is, borderline, an art, but definitely a PITA. But no matter of the situation, that should and can be addressed later as the crush sleeve should not be installed during rear end setup. The crush sleeve is the needed on the final step of the setup.
 
  • Agree
Reactions: 1 user

Rocket Powered

Not-quite-so-new-guy
Nov 4, 2017
24
11
3
Nebraska
I set up without the crush sleeve during inspections. I tried setting preload to summit spec, 25in lbs. I could not turn the yoke. Drag was severe. Did research, found for a Gm 7.5 preload 12-15 In lbs. Turned great, had some drag as it should. Thanks for all of your input. Looks like it' all coming apart to reevaluate...ugh! Rather be done right though
 

Pontiac455

Master Mechanic
Jun 8, 2010
470
73
28
The Master Housing Dimension (MHD) is the distance between the axle centerline and the back of the pinion head. This equals Pinion Head Thickness + Pinion Depth. Since your factory gears were installed using the MHD method from the factory, you know that your pinion depth was properly setup with the correct pinion shim. Since we are changing the pinion, we must now calculate the correct pinion shim thickness. For an example, if Pinion Head Thickness was 1.781 and the shim was .019” thick, doing the math: (4.415-1.781=pinion depth of 2.634) The .019” shim was used to reach that pinion depth of 2.634. If our new pinion head is now 1.770” thick, doing the math: (4.415-1.770=2.645 pinion depth). Since the difference in pinion thickness is .011 less on the new gear, we must ADD .011 to the existing .019 shim to get the correct pinion depth. This leaves us with a .030 shim for the new thinner pinion gear. If the new gear was 1.792, .011” thicker than the old gear, we would subtract .011 from .019 and use a .008” thick pinion shim. Using this method, I have double checked the MHD with my pinion depth checker and found it within .001” of my calculations on both installs. This is the easiest way to do it, and will save a lot of time in installing, measuring, disassembling, and changing shims; not to mention re-installing and measuring all over again.
 
  • Like
Reactions: 1 user

Pontiac455

Master Mechanic
Jun 8, 2010
470
73
28
The crush sleeve is for bearing pre load only. It has nothing to do with pinion depth. I only install the crush sleeve during final assembly.
 
  • Agree
Reactions: 1 user

Bonnewagon

Rocket Powered Basset Hound
Supporting Member
Sep 18, 2009
10,536
14,217
113
Queens, NY
Pontiac455 I like your method but I am confused. What does the 4.415 represent? Is that a constant? Is the pinion depth of 2.634 a constant? If the 1.781 is the pinion thickness, where is the .019 in the formula? 1.781 plus .019 is 1.80, 1.770 plus .030 is 1.80, and 1.792 plus .008 is 1.80- is pinion gear plus shim thickness of 1.80 what we should be seeking always? Where is that in the formula? Pardon my ignorance but if there is a formula to get the shim thickness I want to learn about it.
 

Rocket Powered

Not-quite-so-new-guy
Nov 4, 2017
24
11
3
Nebraska
After much thinking I forgot to mention this. During the several times of assembling the rearend to check pinion depth the results as followed. I first used the stock .032" pinion shim. Read it should be close. Set preload, checked pattern, it was darn near hitting the root. Next I tried .022" shim. This time pattern was a little further away from the root. Then I tried .010" shim. A little better. I removed that shim, didn't install a shim. Pattern was a little better toward the top of the gear. No shims is what I have pictured in my post. If I add more shims, pattern goes more toward the root. So I question, is this the best it' gonna get? Nothing stock in the rearend at all other than bearings and races. Carrier preload is tight as it should. Diff won't just "fall" out. Idk...had that thing together and apart at least 7 times. I' m a perfectionist
 

pontiacgp

blank
Mar 31, 2006
29,270
20,391
113
Kitchener, Ontario
The crush sleeve is for bearing pre load only. It has nothing to do with pinion depth. I only install the crush sleeve during final assembly.

If you don't crush the sleeve enough the pinion will sit too deep to get a good pattern and the bearings will not be seated. I have seen a first time builder make that mistake. In this case I have not seen what is being done so I'm just throwing my 2 cents but I have never seen a pinion sitting too deep when there is no shims installed. Perhaps the bearing race isn't seated
 

Rocket Powered

Not-quite-so-new-guy
Nov 4, 2017
24
11
3
Nebraska
Also forgot to mention, during all assemassembly and disassembled the crush sleeve was never used. Pattern looks the same with or without the sleeve. Pattern in pics is with sleeve installed
 
Status
Not open for further replies.

GBodyForum is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to amazon.com. Amazon, the Amazon logo, AmazonSupply, and the AmazonSupply logo are trademarks of Amazon.com, Inc. or its affiliates.

Please support GBodyForum Sponsors

Classic Truck Consoles Dixie Restoration Depot UMI Performance

Contact [email protected] for info on becoming a sponsor