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Greg
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19,974 Posts
Discussion Starter · #1 ·
I am not impressed with the 9.25 rearend. I guess it's been 3 years since I had a DTT and OEM 4:10 gear installed with a Timkem Master Install kit. I had it done at a defunk Dodge dealer. Took the mechanic 4 hours start to finish to do. Ran perfect without issues. Did a little TnT and to be honest it started to have a little backlash. I don't abuse my ride, but will make a few passes and of course this means spinning the wheels. I was going to adjust the backlash this morning and got to looking at everything and the bearings have a look of running under heavy load. I use mobil 1 75-145 gear oil. Normally I would expect the bearings to have a burnished look, this are lightly scored. This includes the pinion bearing which still maintained a rotational drag of 20in/lbs. The Timken bearings should have held up better IMO. What's the best quality Master Rebuild available?
Thanks,
 

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Greg
Joined
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19,974 Posts
Discussion Starter · #2 ·
I am not impressed with the 9.25 rearend. I guess it's been 3 years since I had a DTT and OEM 4:10 gear installed with a Timkem Master Install kit. I had it done at a defunk Dodge dealer. Took the mechanic 4 hours start to finish to do. Ran perfect without issues. Did a little TnT and to be honest it started to have a little backlash. I don't abuse my ride, but will make a few passes and of course this means spinning the wheels. I was going to adjust the backlash this morning and got to looking at everything and the bearings have a look of running under heavy load. I use mobil 1 75-145 gear oil. Normally I would expect the bearings to have a burnished look, this are lightly scored. This includes the pinion bearing which still maintained a rotational drag of 20in/lbs. The Timken bearings should have held up better IMO. What's the best quality Master Rebuild available?
Thanks,
 

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I'd like to know as well...all I've seen are timkens Greg... my bearings are fairly new but i can hear and feel them...then again, I'm still doing breakin and it seems that the gears are getting more quiet every day.. now that i understand this i might redo them if someone can suggest a better setup...
 

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Greg
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19,974 Posts
Discussion Starter · #4 ·
Fred, I'm being told Timken is the best. There are some other manufactures of bearings available. Also, the kits are made up using different levels of parts, including some that have Timken bearings. It's a steep learning curve and there are likely different levels of Timken bearings also available. I really don't have the opportunity to do many of these so I took the easy way out by going to NAPA and ordered a true Timken kit and asked for the best quality available. When I first installed the gears I ran them 500 miles on dyno gear oil, drained the oil and filled with Mobil 1 (75-145). The original break-in oil looked contaminated. I'm thinking this may have been the source that scored the bearings. The ring and pinion are now broken in so I'm going to carefully flush the housing before installing the new bearings. This should be as good as it gets. I hope...
 

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Greg
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19,974 Posts
Discussion Starter · #5 ·
Man, I'm learning alot with doing this overhual. First it isn't easy getting what you want even when you are eyeball to eyeball with parts guy. NAPA got me a pieced together master install kit. It's has Timken bearings, but they pieced in other parts trying to make it a Master kit. I was out of time and took it, but it was over priced and not the true kit I ordered. So get your parts ahead of time and that way you can get what you need. Finally got it worked down to the Truetrac differential is were the slop is. I talked the Matt at Moe's who attempted to help me and he did helped me get ahold of the right people to talk to. I've had this unit for a little more tha 3 years so I wasn't expecting warranty but more advice /source for repair parts. But I learned quick when you talk to Eaton they were quick to tell you what you did to cause the problem. First, he told me that all Trutrac's develop backlash, even his personal truck has backlash. 2nd, don't use synthetic lubricate as it does't transfer heat and traps heat in the unit. He recommended using 70-90 dino oil in colder climates, but said I would be ok with 80-140 gear oil in Virginia. I asked for a rebuild kit and was told there wasn't one. I specifically stated that I didn't like having backlash and was told there was nothing to be done. So as much as I like how the Trutrac operated before it developed slop, I won't accept having backlash. This is a real disappointment and the first I have heard about Trutrac's slop issues. My opinion is if I spend good money then I expect a good product. Anyway cleaned everything up and stuck the pinion and Trutrac back together with the r/p backlash set at .009, tried for .008 but kept leap frogging and final said enough. The pinion is set at 25 in/lbs using an impact wrench. Still got the axles to install, but ran out of gas, Wanted to go racing tonight, but it ain't going to happen.
 

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Greg
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19,974 Posts
Discussion Starter · #6 ·
Finished it up and filled iup with Advance Auto 75-140 dino gear oil. Fired it up and let it run for awhile with the wheels off the ground. Very quiet. Took her for a roll around the block (10 miles). Quiet and vibration free. Good to have the old girl running good again. Obviously still have a little backlash from the Trutrac. Will see how that plays in the next few hundred miles.
 

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Good info, and good luck!
 
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