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Discussion Starter #1
Hey guys. So I thought I had busted my diff, like so many others that I've read. I hear today from the shop that I actually broke a tooth off my pinion??? Anybody experience that one? Since it happened last week I did some homework and decided to do the True Trac. Even though the diff doesn't appear to be broken, I'm still going to put the TT in (no brainer) since it's torn apart anyway. Need a little help on the R & P though. I'm looking at the 3.73 set-up from 4x4parts.com, but am not sure that is the right gearing to avoid making my computer/speedo go nuts. Looking for a 1 for 1 replacement for the current set-up to avoid further costs & pain. Any advice appreciated.
 

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Discussion Starter #2
Seriously.....no one has anything on this? The guy at 4x4parts says the 3.73 & TT will work with our Dana 44 mod set-up. Only negative by-product is a 4-5 mph over on my speedo. Can I believe this advice? I have yet to find a successful plan to replace the R & P thru the forums. I know somebody has to have done this by now.......SO SPEAK!
 

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You probably have the 2.94 gearing (3.36 is the only other oem option) so a jump to the 3.73 is going to be a big one.

The Titan have its speed sensor or etc... in the diff itself and not on the wheels so a gear sway will throw off your cruise but I am not sure it if will affect your speedo or not.

This is all the info I have for you but atleast it is something.

Side Note: Have you checked to see what a set of 3.73s will do to your rpms and thus mpgs? I would run a check thru an online calculator.
 

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There is no speed sensor in the differential. There is one in the transmission and also signals from the wheel sensors.
The switch to the 3.73 gears may cause a problem since the system checks both the transmission sensor and the wheel sensors. If there is a difference in the readings from the two sensors there may be problems, such as incorrect speedometer readings and the failure of the cruise control to function.
This problem can be solved by some reprogramming by UpRev.
 

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get the true track , youll love it
 

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Discussion Starter #6
There is no speed sensor in the differential. There is one in the transmission and also signals from the wheel sensors.
The switch to the 3.73 gears may cause a problem since the system checks both the transmission sensor and the wheel sensors. If there is a difference in the readings from the two sensors there may be problems, such as incorrect speedometer readings and the failure of the cruise control to function.
This problem can be solved by some reprogramming by UpRev.
scr38 - Tell me more about the upRev. I've read some but would like some first hand info. Is using the upRev essentially flashing the computer? Any negative by-products come from using it?

I went ahead and bought the 3.73 gears and the TT today, so they are on the way. I have the Big Tow, so I was running the 3.357 gears. Hoping that the jump to the 3.73's doesn't completely screw up my computer. It's kinda crazy that I'm not able to find much discussion from guys doing this, given all of the rear end problems we've got with these trucks. You see guys talking, but no one ever comes back with how it went in the end. I'll be sure to post my results when I have them.
 

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I believe your truck will consume much more fuel with the 3.73 gears, you may want to to a search on it here. Truetrac is definitely worth the money. Just remember what you need to do to the new LSD prior to installing it, research about it here.
 

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UpRev ="bad butt"
it is just reflashing the ecu but its not a onw time dill when you put more parts on your T you can get it tuned. ...i think...its kinda like a stand alone just only using your stock ecu.

how much where thoes gears you have
 

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I believe it is Hypertech that has a physical device to install under the dash to correct for changes due to tire size, or in your case gearing on a 2 WD. Cost is around $200 or less. It is not a Tuner, but rather specifically for this need. It would not interfere with or be seen by a Tuner.

UpRev is the absolute best Tuner on the market, but only recently began doing anything with the Transmission Control Unit (TCU). I do not know what they are able to do with Speedo correction. A couple years ago, they did not do anything, but may now be able to totally do it for you. That would eliminate the Hypertech device cost. Price of UpRev Osiris has dropped a bit from original.

TrueTrac is excellent. It does handle different on wet roads, do not apply much power in turns, just glide threw them. Read the Manual, it says to change fluid after a 500 mile break in period. Use Synthetic Fluid as final fill.

Keep an eye on the Axle Seals as the axles will be slid out for the install of your Gears.

Consider a Stillen Diff cover for increased capacity and cooling ability. You should have a bullet proof rear after all these upgrades!
 

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Discussion Starter #10
Bought the package deal from 4x4parts.com. Just under a grand for the whole set-up: TT, gears, carrier bearings, crush sleeves, races........ Not too bad considering it's hard to find a TT for under $600 by itself.

Also heard some crazy break-in info from the guys @ 4x4 -1st 500 miles, in-town driving only and not above 50mph. I guess the idea is doing stop-n-go traffic will keep the gears from heating up too much and breaking down the coating/plating on the outside of them (???). That was new. I mean, I can see that going directly to the highway and hauling a$$ for 200 miles would heat them up, but never have heard anything about the plating breaking down. Luckily, it's only 8 miles of in-town driving to work, but damn, it's going to take 2 months to go 500 miles!!!

I'll call upRev on the other thing and see what I can find out. I'll post findings.
 

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Hey Rick!

Quick question:

What was your symptoms when you thought you lost your diff? I've developed an annoying "whump whump whump" going over 20 mph and then progressively worse till engine/road/exhaust drowns it out...

I have an '05 LE X2 w/big tow...so I am curious about the gearing and what you run into...

Silly thing only has 18000 miles on it-bought it new in '05 with .5 on the odo-don't ask, Uncle's Canoe Club has kept me pretty busy these past few years.

Cheers!
 

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Discussion Starter #12
Crash -

My symptoms go like this: Came around the corner, got on it to avoid oncoming traffic and the traction control kicked in as I slipped a bit. When power came back, I had a noticeable vibe coming from the rear. Only a few miles from home so I kept going. Vibe never got worse, but the next day I started developing a shaft rub sound. By the time I got it to the shop, the noise had gotten louder, but the vibe wasn't any worse.

Saw the pinion today - 2 broken off teeth and 3 more cracked. Forgot to take pics, but I will get the parts back tomorrow. Test drive from the shop with the 3.73 & TT installed sounded positive - no bad sounds. They are going to check it one more time in the morning, and also talk to a local guy who may know something about flashing the ECU to clean-up the light show on the panel (Slip, VDC, maybe others). Will post what I find out.

The saga continues........
 

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the reason you haven't found much on gear replacement is because they don't often break. i've heard and saw my own R & P and they are pretty beefy, it's actually pretty strange you broke yours and not the spiders... it's normally the other way around.

and from experience... if most ppl that have broke their rearend are like me, if aint broke you don't fix it. especially if you just dropped $1000-$1200 having a TT installed. that was enough for me and most others so they just slapped the old, unharmed ring gear back in and called it a day.

good luck with getting ur speedo thing worked out, enjoy your new bulletproof rearend :D :cheers:
 

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Discussion Starter #14
the reason you haven't found much on gear replacement is because they don't often break. i've heard and saw my own R & P and they are pretty beefy, it's actually pretty strange you broke yours and not the spiders... it's normally the other way around.

and from experience... if most ppl that have broke their rearend are like me, if aint broke you don't fix it. especially if you just dropped $1000-$1200 having a TT installed. that was enough for me and most others so they just slapped the old, unharmed ring gear back in and called it a day.

good luck with getting ur speedo thing worked out, enjoy your new bulletproof rearend :D :cheers:
I'd have to agree lead_sled, the R & P is not what normally breaks, but take a look at these pics...they pretty much tell the story of what broke. And the pinion didn't just kinda break....it flat busted into fragmented pieces. Oddly, the diff looks fine. Can't help but come to the conclusion that this was just a bad part - no way it should just splinter out like this.

On the subject of the light show, got it back today - NO LIGHT SHOW. None at all. Self correcting ECU? Haven't run it thru the gamut yet (Cruise Control & such), but no SLIP, VDC...nothing. They were on yesterday when they first drove it, but not today. Maybe I get to avoid the additional $200-$500 in ECU flashing.

COST
3.73 gears & True Trac - ~$1000
Labor - $530
TOTAL COST - ~$1530
New stocker rear from Nissan - ~$2800
I WIN!:money-big:
 

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Helo,

Thanks for the gouge on symptoms. Not what I have at all-talking to my neighborhood gearhead he thinks it may be the diff, but might be a tire delaminating-since they have sat for extended periods-and they are SR-As after all...

Those gears look sick! Gessus H. Last time I saw something like that was when a F404 busted in the test cell...

How is you new stuff working for you? Any weirdness with going to the different gear?

Thanks for the pics-things that make you go "Wow..."
 

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Discussion Starter #17
New gears & True Trac working great. Only weird thing going on so far is that the Cruise Control works sometimes and doesn't work other times - turn on cruise and SET flashes sometimes, which keeps cruise from latching. RPM's definitely higher, which was to be expected - running about 2000rpm @ 62mph in 5th. Haven't pushed it to break the tires loose yet to check the traction control - trying to take it real easy with those new gears. Speedo is pretty close - within about 1-2 mph per my phone GPS. Will let you guys know if any other weirdness crops up.
 

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Helo, thanks for getting me to this thread. I haven't opened mine up yet to see but my symptoms are pretty different. I, like you, got on it a little bit pulling into traffic, but what I got was a couple of loud pops. once I was going straight everything was fine. No vibrations etc. Got to work and turned the corner into the parking lot and you could feel the tension building in the rear and then a couple more loud pops. Limped it home that night with real wide radius turns where I could, but no problems when going straight.

Anyway, since this thread is getting some traction "pun intended" I thought I'd ask here. To swap out the diff with a TT (I also have big tow and the E-locker) what is involved. I'm assuming that you drain the oil, pull the back cover. Release the axles and slide them out of the way, remove the original diff, bolt in the new one, slide the axles back in, replace the cover and fill with oil? Is it that easy or is there an art to setting the diff correctly? Thanks for any help.
 

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Nothing?

New question, I dropped the drive shaft to the rear axle last night and am driving in 4WH so that I can get around till I can afford to make this fix. Any recommendations regarding how far etc. and what speed I should limit myself to in this configuration? I need to go around 40 miles (one-way) this weekend. Part of the trip (25 mi) would be 55 mph.
thanks.
 

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Certainly a mfg defect. Likely bad machining ; a sharp corner at the base of the tooth. The crack started at the notch and grew by fatigue. Secondary cracks then started at other locations.
Another possible cause is defective heat-treatment at the tooth root. These gears will be carburized and Q&T, or flame or induction hardened; For the latter, improper control can leave the root too soft-causing fatigue.
 
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