How tight should the side bearings be

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challenger57

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I have viewed thread after thread after thread about setting up 8 3/4 rears but no one says how much torque should be applied to the side adjuster bearings. Everything else has a torque spec, what about them?? Also I have been trying to load pics of my contact pattern but the system keeps telling me the file is to big. I can not get the coast pattern in the middle. If I get it to start moving to the middle then my drive side is moving away from center. This is my second rear I have done, the first was easy but this one I have changed shim dim. 7 times. Ihave used from .035 to .052 changing about .003 at a time. I know pics would help. When it comes to computers my son calls me a ID10T. Yes I am!!! Help if you can???
 
Bad Sport said:
If I'm not mistaken he's talking about the bearings in the carrier itself.
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I was talking about the carrier bearings in the 8 3/4 pumpkin. Bearing Bolts should be torqued to 85-90 foot pounds and Adjuster locks should be 15-20 foot pounds.
 
I have not seen the spec for 8 3/4 because in the manual they use a spanner wrench instead of a socket. I made a socket to fit the adjuster and use the (75 ft lbs) spec from the 9 1/4 book.
 
66fs said:
I was talking about the carrier bearings in the 8 3/4 pumpkin. Bearing Bolts should be torqued to 85-90 foot pounds and Adjuster locks should be 15-20 foot pounds.
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Oh, I was confused when you said backlash and preload. I was thinking axle end play. :banghead:
 
The factory service manual is what you need.
 
I have a 73 challenger shop manual (not owners manual) and it does not mention any torque for the carrier bearings. It shows how to rebuild but no spec. Like 69mope said they use a spanner wrench. I have the specs for the bearing caps and adjuster locks just don't know tight to make the carrier bearing. I would think as stated 75 ft lb would be good if I can measure it.
 
If you follow the procedure for setting backlash the preload will be set. There is no torque other than preload for the carrier bearings. That is why there are adjusters and adjuster locks.
 
I think one of us is on the wrong track. The side adjusters don't "torque" they slide the cups in and out and set the bearing preload. You don't need the exact year manual. In the pdf I have for 73, it's page 3-29 and on for the 8 3/4 This is from page 3-42 of the manual: and is the gist of the preload part of the setup

So follow along: You get the caps set in place and snugged up, and you adjust them so that you have .0005 -- .0015 BACKLASH at the smallest backlash point. In other words you get the side bearings to "zero lash" and then move both adjusters equally one way or 't other to establish the backlash specified

Now read on.......Nex........you adjust ONLY the "tooth side" cap so that backlash is INCREASED out to .006--.008 at the smallest point. You are at this point ONLY adjusting the cap FORCING the ring AWAY from the pinion and simultaneously LOADING the two side bearings.
 

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Posting these for Mark.
 

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Del's right about how your setting the carrier bearing preload, not torque. I've set up several over the yrs. and every thing I've read says to start by snugging the adjusters up and setting the backlash to .001"-.0015" then tighten the adjuster on the side opposite the ring gear until you get the desired backlash and that preloads the bearings. I've also had a few experienced differential techs tell me this is the way to set the preload. I've been doing it for several yrs. now without a single failure.

Mark the pics Bruce posted show it's way too deep. Need thinner shim pack. That'll bring the patterns closer together and more oval. Right now the coast side is off the scale.

BTW: you won't always get the patterns perfectly centered from toe to heal. The main thing is to get a nice oval pattern on both sides that's pretty well centered from root to flank (top to bottom of the tooth). I have done some that were in the lower 1/3 (towards the toe or i.d.) but the pattern was a nice oval on both sides and they ran quiet.

Here's a you tube video where Carl Jantz explains the effects of pin depth and backlash changes

[ame="https://www.youtube.com/watch?v=nVb5WRUfM7Y"]Ring & Pinion Patterns explained, back lash vs pinion depth - YouTube[/ame]
 
67Dart273 said:
I think one of us is on the wrong track. The side adjusters don't "torque" they slide the cups in and out and set the bearing preload. You don't need the exact year manual. In the pdf I have for 73, it's page 3-29 and on for the 8 3/4 This is from page 3-42 of the manual: and is the gist of the preload part of the setup

So follow along: You get the caps set in place and snugged up, and you adjust them so that you have .0005 -- .0015 BACKLASH at the smallest backlash point. In other words you get the side bearings to "zero lash" and then move both adjusters equally one way or 't other to establish the backlash specified

Now read on.......Nex........you adjust ONLY the "tooth side" cap so that backlash is INCREASED out to .006--.008 at the smallest point. You are at this point ONLY adjusting the cap FORCING the ring AWAY from the pinion and simultaneously LOADING the two side bearings.
Click to expand...

Thank you, I didn't want to write all that down. Like RRR said you need the manual. You first have to set the pinion depth correctly per the manual, or you will still have a very bad outcome.
 
daredevil said:
Boy, the service manual line is beaten like a dead horse.
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I don't know why you would say that. This IS how these were put together from information provided by the people who designed and built them. Yes there ARE other ways to do things. But when you don't know those "other ways," or it turns out those other ways are incorrect, there's only one place to start from.

Even when I got my (much hated by the purists) Ford 9" I got busy on the www and searched around 'til I found downloads of sections of the original literature on how to set them up

I've only set up three 8 3/4 axles, ever. We did it exactly like "the book" says. They ran quiet, and held together. Can't say the same for the 10 bolt Chivvies a few years earlier!!!

So, OK!!! If you don't like the factory manual, here's an alternative from Yukon gear

[ame]http://selectric.org/manuals/rearend/yukoninstman.pdf[/ame]

And here's the Ferd way

http://selectric.org/manuals/rearend/indexford.html

Or, you can take the Muscle car magazine approach

http://www.moparmusclemagazine.com/howto/mopp_0308_mopar_rear_end_gears_set_up/viewall.html

What they claim is "as tight as you can get with a 12" long spanner" whatever that might mean.
 
Your pinion is too close. I would decrease the shim thickness 0.005" and re-check the pattern.

Get the spanner nuts as tight as possible with a 12" wrench when the cap bolts are finger tight. After adjusting back-lash to 0.008", torque the cap bolts to 90 ft lbs.

[ame]http://www.ringpinion.com/Content/Book/Reading-and-Adjusting-Ring-and-Pinion-Tooth-Patterns.pdf[/ame]

Note, the shape of the pattern is more important than where it lands on the gear tooth. You want a wide, wispy pattern that does not curve inward toward the peak or valley of the tooth. It must be centered between the peak and valley, but not necessarily between the inside and outside diameter of the ring gear.
 
daredevil said:
Boy, the service manual line is beaten like a dead horse.
Click to expand...

Sorry, that is the only way I know to do it, and it is not a short set of instructions. I do not have the experience to help using another method. I just wanted the OP to have a good gear set that would last when he was done.
 
The service manual is full of mistakes and the gear contact patterns depicted are not complete.

Ring gear bolt torque: 55 lbs

Pinion nut torque (10 spline with shims): 170 lbs
Pinion nut torque (29 spline with shims): 280 lbs

Cap torque: 90 lbs

Pinion bearing preload 741 case: 13-15 inch lbs rolling torque
Pinion bearing preload 489 case: 14-19 inch lbs rolling torque
Pinion bearing preload 742 case: 15-25 inch lbs rolling torque

Gear contact chart: [ame]http://www.ringpinion.com/Content/Book/Reading-and-Adjusting-Ring-and-Pinion-Tooth-Patterns.pdf[/ame]
 
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