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Discussion Starter · #1 ·
I spoke with Brent, EXT 6762 at Eaton and he gave the following recommendations for our installs and TrueTrac maintenance:

1. Use 80W-90 petroleum based gear oil rather than synthetic.

Synthetic oil tends to shed heat better than petroleum based oil but unless that heat has somewhere to go other than back to the gears and such it's a bad idea. I explained that we had finned diff covers to shed heat so that helps but I will be putting petroleum based oil in mine from now on due to some of the other reasons listed below. Brent also stated that 9 out of 10 noisy rear end problems he is called about have Synthetic gear oil.

2. Torque spec on the TrueTrac housing bolts is supposed to be between 50 and 55 Ft Lbs and should be checked regularly.

Generally speaking, if my bolt backed out after 20000 miles, I believe they should be checked at half that if you tow or race and if any bolts are loose, Locktite should be reapplied and the bolts should be torqued back to spec.

Someone who knows more than I do may want to chime in here with the best way to rotate the TT without pulling the unit out of the differential housing so that all the exterior bolts on the TrueTrac housing may be inspected for proper torque. Most people don't have a digital caliper to reset the gear backlash so pulling the unit completely out is not a good option for them.

3. Pre load on the bearings should be set to factory spec upon initial install and checked regularly thereafter.

We have nuts with holes in them rather than shims to set preload on the bearings and we need the factory spec on them if someone knows what that is.

Apparently the factory differential housing stretches over time and the preload needs to be reset to maintain tension on the TT unit so that the housing bolts don't back out like mine did. Brent suspects that is why my bolt backed out so it is advisable to check the bearing preload on a regular basis.

4. Backlash of the existing rear end should be checked and the same backlash should be set on the TruTrac upon installation.

A digital caliper should be employed to measure the existing backlash and that should be matched when the TT is installed.

The bottom line is that although the TT is a very robust unit and can take quite a bit of abuse, it still needs to be maintained due to stretching in the factory differential housing causing the bearing preload to vary and in turn, stress on the TT housing that may loosen the housing bolts over time.

If anyone has any of the above information that is lacking such as the proper bearing preload spec, please chime in and I will update the thread.

If any of this information is known to be incorrect, please feel free to tell us also because there are a lot of these units in service and we would like to keep it that way.


some of the correct settings are as follows

-The ring gear bolts get torqued to 135 ft/lbs.
-Side bearing caps get torqued to 80 ft/lbs
-Adjuster lock plate bolts get torqued to 89 INCH/lbs
-Diff cover gets 31 ft/lbs..
 

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Good info Brian! Below are the torque specs and backlash tolerances I got from Shailey.

-The ring gear bolts get torqued to 135 ft/lbs.
-Side bearing caps get torqued to 80 ft/lbs
-Adjuster lock plate bolts get torqued to 89 INCH/lbs
-Diff cover gets 31 ft/lbs..

Backlash tolerances are between .08 and .13 mm. Adjusted by using the side bearing adjusters.

So when are we doing a "I Love My Truetrac Maintenance Party" at Randy's? LOL
 

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Discussion Starter · #4 ·
So, this diff does better with conv oil rather than syn oil when
most diffs do better with syn......and the bolts have to be
checked regularly so they don't fall out.
Sounds like an "interesting" product.:)
http://www.tundrasolutions.com/foru...suvs/55096-beware-eaton-true-trac-bolts-fall/
It beats the stock rear end, lol.

Seriously though, I wonder what issues have been due to improper installation like bearing preload or too much heat wicking back to the parts due to the Synthetics we have been running. If the differential housing stretches over time like Brent said, the bearing preload should be checked regularly anyway. Brent was saying that in some shimmed units that were checked, the Differential would just fall out once the axels were taken out and that bearing preload was non-existant in them due to differential housing stretching.

One thing's for sure, we don't really have a better choice in the aftermarket and here's a good quote from another site.

I love mine for the street and works very well in most drag applications. I have approx. 50k miles on it now. I did have one problem with mine though.

The bolts on each end cap that hold the unit together backed out. When I was driving, I began to have a huge jerk like I hit a hellacious pot hole but there wasn't any of course. After 3 or 4 times of this happening, I took the rear cover off to find all the bolts to have begun to back out or have been sheered by hitting the housing when they backed out. The unit was being held together by the bearings and the housing its self.
I attribute the problem due to several 5000+ clutch dumps on slicks with a few of them being on a 150 shot. It takes 2-3x's the torque from an automatic to put the same kinds of loads on a rear end as a manual does dead hooking. Heck, I snapped an axle and Parish8 never even did that with stock axles.

Basically, the worm gear design pushes outwards on the end caps during heavy loads and probably stretched the bolts. I replaced the bolts with new grade 8's and red loctite. I have had no issues in 20k miles but I haven't put slicks on it again either.

So my opinon, if you are running an automatic, beat the hell out of it. If you have a manual, be careful with the hard launches at the track on stickies.
__________________
 

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Discussion Starter · #5 ·
Good info Brian! Below are the torque specs and backlash tolerances I got from Shailey.

-The ring gear bolts get torqued to 135 ft/lbs.
-Side bearing caps get torqued to 80 ft/lbs
-Adjuster lock plate bolts get torqued to 89 INCH/lbs
-Diff cover gets 31 ft/lbs..

Backlash tolerances are between .08 and .13 mm. Adjusted by using the side bearing adjusters.

So when are we doing a "I Love My Truetrac Maintenance Party" at Randy's? LOL
Good information Gary, thanks for that and the only thing we are missing is the bearing preload setting and how many holes or revolutions on the preload nut equate to that particular bearing preload setting.
 

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is that what i hear a faint whine while cruising at 60 mph???? i thought it was the worm gears normal sound. i guess i have to change out my synthetic fluid and go conventional :(
 

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I had nissan synthetic in for about 27K changed it out after I thought I was getting glazing on clutchs. At that time I posted Scott from Eaton PM'd me and stated I should use dino. So I've had dino in mine now more as long as the Nissan 75/140. No problems. But I will check my bolts as I've never removed the cover to check them. THanks Papa D:thumbsup-big:
 

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When I got mine installed two years ago the shop use regular oil and staited synthetic was not needed.Nissan just replaced my pinoin seal so I hope they put every thing back correctly.
 

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Pinion bearing preload,with seal installed, 15-33 in. lbs. This is without the carrier installed. A new crush sleeve is required if the pinion is removed. The proper preload with a new crush sleeve will require from 220 to 500 ft. lbs on the pinion nut.

Total preload, with pinion, seal and carrier installed is 22-46 in.lbs. for the 2.93 ratio and 21-45 in. lbs. for the 3.36 ratio.

The pinion to ring gear backlash is .003 to .005 inches.
 

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this should definetly be a sticky, very informative post, thank you sir. I love this site!
 

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i still hear a whine while doing 60 mph on my XE wth 2:93 ratio.. what is it???
Since you didn't disturb the pinion when the TT was installed, the whine is caused by incorrect preload and/or backlash on the carrier.
 

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Pinion bearing preload,with seal installed, 15-33 in. lbs. This is without the carrier installed. A new crush sleeve is required if the pinion is removed. The proper preload with a new crush sleeve will require from 220 to 500 ft. lbs on the pinion nut.

Total preload, with pinion, seal and carrier installed is 22-46 in.lbs. for the 2.93 ratio and 21-45 in. lbs. for the 3.36 ratio.

The pinion to ring gear backlash is .003 to .005 inches.
I don't recall the crush sleeve in my parts list when we changed the pinion bearings and seal?

My installer set the pinion to ring gear backlash to .004"....no whine for 1,000 miles now and I have 75-140W synthetic in. I plan to dump it at 1,500 miles and decide on more synthetic or the dreaded dino.

The model tag# on my TrueTrac is 913A582 When I look at the TrueTrac owners manual listed model #'s that number isn't on the list? Anyone else see this?
 

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I don't recall the crush sleeve in my parts list when we changed the pinion bearings and seal?
The crush sleeve is part #11 in the attached drawing. It can't be reused, and must be replaced whenever the pinion nut is removed.
 

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The crush sleeve is part #11 in the attached drawing. It can't be reused, and must be replaced whenever the pinion nut is removed.
Do you have the NISSAN part#? What's it do exactly? If the tec. forgot it can I install it easily now? Thanks.
 

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I am away from home, and don't have any parts data on this laptop, so I don't know the part number.
The crush sleeve acts as sort of a spring to keep the preload on the pinion bearings. As the pinion nut is tighten, this sleeve is designed to "crush", exerting the proper load on the bearings. The sleeve is longer than the space it occupies, so as the pinion nut is tightened the sleeve bells out in the center. The pinion nut is tightened a little at a time and the preload is measured using an inch pound torque wrench attached to the pinion. The nut is tightened in small increments until the torque is in the proper range.
 

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My installer set the pinion to ring gear backlash to .004"....no whine for 1,000 miles now and I have 75-140W synthetic in. I plan to dump it at 1,500 miles and decide on more synthetic or the dreaded dino.
Eaton states not to use syn in the TT
 

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thanks Papad....kman now i have more things to check and worry about...who woulda thought using aftermarket parts and racing would mean you'd have to watch your maintenance more closely? jeez...lol....regardles of having to check this item every 10-20k miles, i would still much rather have it then the dreaded stock rear-end that shoulda been put in the Sentra lol
 

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Hey Papa_D,
Ever since your buddy installed my "TT" i haven't had any problem's. Until, now!
When i back out of the driveway, i hear a clunking sound coming from the rear end. Usually 2-3 time's every time when i back up. In forward motion , no problem, but i'm becoming concerned w/ what's going on inside there. I have minimal knowledge about the inner working's of the thing. I just got back from a road trip, drove 2000m+ w/ no problem's on the interstate. I just changed my gear oil before i left using the RP syn. I'll change it again, back to dino oil, but i need some help w/ my "TT".

I don't beat on my truck like some of you do, mostly normal driving w/ a few WOT run's in between.

Also, I'm locked out of my map changing control's for my Osiris. I do have a new laptop on the way, just won't get here till Jan.20th. I got a new Dell Vostro 2510. (ALMOST $800) Hope it was something to do w/ the old laptop i was using to datalog?

I could use some help guy's!!!

I have no way of checking these thing's:
-The ring gear bolts get torqued to 135 ft/lbs.
-Side bearing caps get torqued to 80 ft/lbs
-Adjuster lock plate bolts get torqued to 89 INCH/lbs
-Diff cover gets 31 ft/lbs..

Backlash tolerances are between .08 and .13 mm. Adjusted by using the side bearing adjusters.

So when are we doing a "I Love My Truetrac Maintenance Party" at Randy's? LOL
Somewhere...
 

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Hold on everybody, i need to go back and read all the posts but this info needs to be double checked. Papa D we need a second answer from Eaton. This may be one guys opinion. First off 90w rear diff oil burns up waay to fast. I had to use some to get by when my truck was down and it didnt hold up well at all in a short period of time. Second i dont see any benifit from conventional oil. Also Nissan requires a 140w full syn in the rearend or warrenty void. Im sure that is a heat and seal issue.

Third, i gotta re look up the tq specs Eaton gave me before. They are different than what this guy told you.
You can rotate the TT by spinning the rear wheels in opposite directions if i recall. You will NOT be able to get a socket on the actuall TT bolts that me and you had problems with. The bearing that is pressed on is in the way.
Ill check check when i get more info

edit..
Added a pic to show what i mean about not being able to get to those bolts...

 
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