Differential Contact Pattern At 500 Miles

[66durgederp]

I'm a bit nervous on my drive side of the teeth at my 5/600 mile fluid change. I stuck a magnet on the cover to catch debris, there was hardly anything. however the tooth pattern has me worried, the section on the drive side that looks galled is where my main contact pattern was on setup. i cant not feel any difference over the entire tooth with my fingernail. for the friggin life of me I couldn't pull a perfect pattern. no matter what i did the contact pattern was ALWAYS heavy towards the root. i went .025-.045 pinion shims in .002 increments at .008 backlash and .010 backlash. the first pics are the best patterns i could pull. I spent DAYS on this thing, and set it as horseshoes and hand-grenades (close enough) or so I thought. the first pics are the best pattern I could pull with keeping the backlash and pinion pre-load within spec. i monitored the temps for the first 10 days of easy driving, the hottest it got was 146 degrees, once. most of the time it was 128-138 degrees. valvoline 80-90 conventional was used. nothing over 55mph for the first 300 miles. steady stop and go driving everyday. its motive gear 3.55's, all new bearings, and a 35,000 mile rear-end from a 74 dart. any opinions on this? is it normal? am i worrying over nothing? should I start $#!**!ng kittens? many thanks!!!

 

[66durgederp]

anyone?

 

[RustyRatRod]

Is it makin noise?

 

[CMcAllister]

Way deep. What rear? What shim's in it now?

 

[fishy68]

Way deep

Agreed. Pinion is way too deep. Did you measure the depth to get an idea where it was or just try different shims? It's possible that even the .025" was too much. Was it noisy?

 

[66durgederp]

I tried different shims in .002 increments. its a little noisy, but not nearly as noisy as I would expect with a sheisty pattern like that. what's killing me is no matter what shim pack I setup, that's the pattern I got. it just changed position on the tooth. I left it at .032, because it was at the best position toe-heel wise. there was a .072 shim between the inner race and the case itself, but I didn't have enough shims to run without it. what I failed to mention was that with no shims between the pinion and the bearing, the pattern was absolutely horrid. thanks for the responses. question now is, would it be worth my time to take it back apart and try this all again? and if not, should I bite the bullet and get a higher quality gear set and start over? or should I just run them?

 

[Hemioutlaw]

It's obviously not right and doesn't look too far gone so I would be redoing it if it were me. Not too far off from having to set one up myself. I will be starting with new gears though on a 742. I may buy an extra set of new setup bearings and hone em so I don't have to keep pressing them on and off.

 

[CMcAllister]

Heel to toe is not what counts. Depth is what we look at. Motive is not a bad gear, unless something has happened to them recently. I've had decent luck getting them right.

What rear is this? You have shims between the rear pinion bearing race and housing AND the rear bearing and pinion?

Moving the shim pack .002 at a time is ok when fine tuning. To get it close first, try moving it .005 or .006 to see the changes. In order to get an accurate pattern, everything need to be very close to being correct; pinion preload, backlash, etc.. As pinion depth is moved, backlash needs to be moved along with it.

Read this. See if it helps you.

[ame]http://www.ringpinion.com/Content/HowTo/TechnicalInstructions/Yukon_Installation_Kit_Instructions.pdf[/ame]

 

[66durgederp]

thanks!! that did help. its an 8.25. and the inner bearing had a shim between the case and the race. Chrysler still offers them for jeeps. they were used to correct the bearing position when the factory goofed up on the case.....fun stuff...

 

[Supershafts]

I'd pull .010 out of that

 

[oldkimmer]

............Where u say the first pics were where u could only get the bearing pre load right, if im understanding u right u had the crush sleeve in from the very start and collapsed it, if so that's where u went wrong right from the start, u will need a new crush sleeve now, set up the pinion where it needs to be then pull out the front bearing, install crush sleeve, front bearing, seal , yoke ,washer and nut and torque till u get the right preload.......u have to take some shim out or u will end up with paper weights in short order.......kim.....

 

[CMcAllister]

Pinion bearing preload, the amount of crush on the pinion bearings, has an effect on the pinion depth and the pattern. Less preload=deeper pattern. It is important to have the pinion at the correct preload (turning torque) when looking at the pattern.

I put it together using the bearings with no crush sleeve, no seal, a spacer to take the place of the yoke and the pinion nut and washer. Tighten the nut until you get the desired turning torque. Do this carefully. Banging on it with a half inch impact and no crush sleeve with damage parts. Once you are satisfied with the shim packs, do a final assembly with a new crush sleeve and the rest of the parts. Tighten the pinion nut to the same turning torque, or maybe a touch tighter to compensate for the seal drag, and the final check of the pattern should be good.