carrier bearing cap torque...what if?

[fosgate3]

What would happen if the carrier bearing cap bolts were torqued too much?

I recently rebuilt my differential but I think I may have used the wrong torque specs. Yukon called for 75 ft. pounds but I think I torqued them to 100 or 110. I keep trying to find where I got that number from...at first I thought it was my Haynes manual but I can't find it in there.

Basically, my gear pattern is perfect, preload is right on but I get a noise when I accelerate and it goes away about a second after letting off the gas pedal. If I accelerate again, it comes back. It's not a loud roar or anything....more like a "tone"; and it doesn't seem noticeable until I hit 40mph and higher.

Maybe I'm being paranoid and it's all normal. I took a picture of the ring gear after putting 700 miles on it and sent it to Yukon. The guy there said it looked great so all that's going well. Just this one thing keeps nagging at me. What do you guys think?

 

[Redtruck-VA]

Of course this is all just guessing. But a humming is often incorrect backlash. Noise on acceleration, front pinion bearing. Decel, rear pinion bearing. What did you set backlash at? .005-.008. Main caps should torqued to 100-110ft/lbs. Measure the temperature of the cover
Should be 160-240 degrees after getting to running temp.

 

[fosgate3]

Thank you for the reply. My backlash was just over 0.007. I checked it several times as I adjusted everything, and then made sure of it again before moving on to the next step. As for the front and rear pinion bearings, they are both brand new and Timken (the ring and pinion are Yukon). The preload was right at 17 inch pounds, if I remember correctly. I used the specs for the 9.25 differential that were provided in the Yukon manual (found here). I took my time on the rebuild and my pattern was posted on here and uploaded to Yukon. The only place where I deviated from the Yukon manual was with the bearing caps: Yukon states the caps should be torqued to 75 and I'm pretty sure I went to 100 or 110 with them. I don't know why I didn't stay with the manual on that.

Your description of the sound---"humming" is pretty accurate for what I am hearing but it only seems to be noticeable when I hit 40mph and over. It doesn't get loud and I can't detect it when I am going over 55 but that could be due to road noise, etc. It goes away when I let off of the accelerator. When I give it gas again (and going over 40), it comes back.

I recall reading something about worn carrier bearings making a noise when driving over 20mph but these bearings are also brand new. That's why I am wondering if I over-torqued them and if that could be causing the noise. Perhaps I should drain it and check the torque this weekend...

 

[Redtruck-VA]

The 75 ft/lb is the carrier bearing preload. The bearing cap 100ft/lbs is the cap holding the bearing. I suspect you have the carrier bearing preload set too high. What is the differential temperature?

 

[fosgate3]

I haven't checked the temperature yet but I will.

The 75 foot pounds I mentioned is what is listed for torquing the caps. See the highlighted part in the picture below. I will have to read about the carrier preload. I do not recall what I set it to. At first, I didn't think the manual mentioned it but after re-reading it, I found it mentioned on page 11. Yukon calls for 150-200 foot pounds for the carrier preload. I think I may drain it this weekend, check it and see where it stands and then report back.

 

[Redtruck-VA]

As I read your install sheet it ommits carrier preload. I would loosen the cap bolts to something around 35 ft/lbs. Back the passenger side bearing collar off a little. Driverside collar back a turn, then slowly turn in until there is zero backlash. Then turn in the passenger side collar until about 60 ft/lbs. Check backlash. It should be very close to .007". If it is above .007. Turn in the driver side to 75ft/lbs and check backlash. Tighten passenger side to 75 ft/lbs. Check backlash. When correct, tighten caps to 100ft/lbs and do a final backlash check.

 

[fosgate3]

Will do. On page 11 of that manual, it states the carrier preload should be 150-200 foot pounds for axle assemblies with a screw adjuster like ours ("Set the carrier bearing pre-load to approximately 150 to 200 pounds/feet. It is difficult to damage bearings with excessive carrier bearing preload on a screw-adjusted differential.") I call myself doing this but maybe I didn't. I don't know. It is parked now and I have another truck to drive until I get time to open it up this weekend. I am hoping this is something I can do with the axle still on the truck as I don't want to have to pull it all back off again. I have three quarts of Royal Purple 75w140 on the way and a new pan gasket. It all should be in Thursday. I may take off Friday just to have extra time to relax and go slow with it.

Thank you for your help Redtruck. I will post some updates as I get into it.

 

[Redtruck-VA]

Our 9.25 calls for 75ft/lbs .
https://dodgeforum.com/forum/2nd-gen-ram-tech/310559-carrier-adjustment-chrysler-9-25-a.html

 

[fosgate3]

Thank you. I got this.

 

[lharrell79]

Just to double check, this is for a 9.25 Chrysler? If so, the following was taken from the 2004 factory service manual:

 

[lharrell79]

Also, this is the installation procedure of the carrier:

INSTALLATION
(1) Apply a coating of hypoid gear lubricant to the differential bearings, bearing cups, and threaded adjusters. A dab of grease can be used to keep the adjusters in position.
(2) Install differential assembly into the housing.
(3) Install differential bearing caps in their original locations (Fig. 38).
(4) Install bearing cap bolts and tighten the upper bolts to 14 N·m (10 ft. lbs.). Tighten the lower bolts finger-tight until the bolt head is seated.
(5) Perform the differential bearing preload and adjustment procedure.
NOTE: Be sure that all bearing cap bolts are tightened to their final torque of 136 N·m (100 ft.lbs.) before proceeding.
(6) Install axle shafts.
(7) Apply a bead of orange Mopar Axle RTV Sealant or equivalent to the housing cover (Fig. 39).

 

[fosgate3]

Well I opened her up and found that I did not torque the adjusters down on each side of the carrier. I also discovered that I lost my pinion preload. So, I redid the preload and made sure I used a lot of locktite this time. I set the preload to 9 inch-pounds on the advice from Yukon (the representative said to use the "used" specs in the installation book instead of the "new" specs--so 6-9 inch pounds instead of 14-19). My blacklash is set right around 0.007 and was checked again after everything was properly torqued.

My gear pattern is below. How does it look?




View attachment 165959

 

[lharrell79]

The first picture looks like the ring gear is too far away from the pinion. The second picture looks perfect. How does the pattern look on the coast side of the gear?

 

[fosgate3]

I just realized I put on an old picture and a current picture in my last post. I apologize for that. Here are the two pictures of the drive and coast:






The first picture is the drive, the second picture is the coast.

 

[lharrell79]

That looks pretty dang good. If anything, the pinion gear might be a little low (needs another shim), based on the drive pattern. Coast looks great. I would torque everything down and run it like that. That looks better than what most shops would do.

 

[fosgate3]

Awesome! And that's quite a compliment there! This is only my 2nd one to do...hopefully last one too!

 

[Redtruck-VA]

A step not often mentioned when torquing the pinion and setting it's preload is to hit the pinion end with a shop hammer a couple times while tightening. This insures the bearings are securely seated. Not seating the pinion bearings most likely what caused you to lose your pinion preload. Not torquing the collars properly I have no explanation for.

 

[fosgate3]

Thank you for the tip. I did not hit the pinion with a hammer when setting it. If I have to redo it, I will remember to do so. I drove it a little yesterday and it sounds much better now. I appreciate everyone's advice and help.