What's wrong with my diff??

Engine, Transmission and related drivetrain.
User avatar
JordanTr
Posts: 745
Joined: 20 Feb 2013 22:27
Location: Langley, BC, Canada

What's wrong with my diff??

Postby JordanTr » 10 Oct 2016 14:41

Looking for some help diagnosing my problem diff-- 4.11 stock 2 way from a BNR32 Skyline.

Cliff notes of the diff history:
- ~ 87K km in an R32GTR
- Pulled from GTR and swapped into my S14.
- Removed CV companion flange to swap on 4 bolt flange; retorqued pinion nut with red Loctite (there is no crush sleeve)
- Refilled diff with proper amount of oil. GL5 Redline 75W90 NS with additional LSD additive.
- Drove the car a bunch this summer (nearly 5000km) and never really beat the crap out of it.
- Noticed a noise on the last part of my drive home on Friday.
- Diff still has oil in it and it doesn't look super dirty or anything.
- Took video #1 (200km/h = 100km/h in reality)
- Removed and retorqued pinion nut before taking video 2.

See 2 video links to YouTube below.
Diff video 1
Diff video 2

Needless to say, I'm choked. Would really appreciate some help troubleshooting this. Thanks guys.
Jordan | '72 2 door KA project | '94 240sx RB26DETT | '97 Silvia RB25DET | '90 Audi 90 Quattro 20V (DD)

Three B's Racing
Supporter
Posts: 1028
Joined: 03 Mar 2009 11:58
Location: New Hampshire

Re: What's wrong with my diff??

Postby Three B's Racing » 11 Oct 2016 06:26

You sure it doesn't have a crush sleeve? because as you said Removed and retorques pinion nut before taking video #2 which tells me retorquing it, has changed tolerance where you now have to much play between ring & pinion, or incorrect torquing and not enough play,,eitherway it sounds like incorrect ring & pinion meshing.
"Lastnight the wife said oh boy when your dead you can't take nothing with you but your soul oh "Think"
- John Lennon

User avatar
JordanTr
Posts: 745
Joined: 20 Feb 2013 22:27
Location: Langley, BC, Canada

Re: What's wrong with my diff??

Postby JordanTr » 11 Oct 2016 07:07

I'd have to agree with you on the noise, B.

There is no crush sleeve and changing a pinion seal follows the same sequence I did and is straight out of the FSM. The Z32TT R230 rear end DOES have a crush sleeve.

If I did get my torque wrong (it's only a tq wrench after all), why would it have taken 5000km to manifest itself?

Video 1 and 2 shouldn't sound any different. I just wanted to verify that the pinion nut hadn't backed off before taking video 2.
Jordan | '72 2 door KA project | '94 240sx RB26DETT | '97 Silvia RB25DET | '90 Audi 90 Quattro 20V (DD)

Chickenman
Posts: 477
Joined: 06 Sep 2010 15:10
Location: Coquitlam

Re: What's wrong with my diff??

Postby Chickenman » 15 Oct 2016 23:54

Sounds like a bearing has gone bad. It happens. Time to pull the diff apart and do a full forensic. Oil may not look dirty...YET. That's probably because the RL oil is saving things so far. But I wouldn't drive it any more till you find out what's wrong. The last thing you want is any fine metallic chips going through the gears.

Bearing's are cheap and easy to replace. Gears aren't.

The nice thing about a bearing replacement is that you don't have to change any R+P settings. Just use the old shim packs and spacers ( non Crush only of course )

datzenmike
Supporter
Posts: 5218
Joined: 24 May 2006 12:40
Location: Van. Isle.

Re: What's wrong with my diff??

Postby datzenmike » 16 Oct 2016 09:33

It's an R-something diff. Take the cover off!!!!!!! and look! No sense guessing what it is unless there's a prize for the winner.



For the record. The whirring sounds like gear teeth meshing, bearings tend to whine or growl. (in case I win)
"Nissan 'shit the bed' when they made these, plain and simple." McShagger510 on flattop SUs

Chickenman
Posts: 477
Joined: 06 Sep 2010 15:10
Location: Coquitlam

Re: What's wrong with my diff??

Postby Chickenman » 17 Oct 2016 01:00

BTW, if the diff doesn't have a Magnetic drain plug, install one. Can give you a heads up if something is starting to wear. Or Epoxy a small magnet to the inside of the diff cover, but I prefer the Magnetic drain plug.

User avatar
JordanTr
Posts: 745
Joined: 20 Feb 2013 22:27
Location: Langley, BC, Canada

Re: What's wrong with my diff??

Postby JordanTr » 17 Oct 2016 07:12

For sure. I'm quite sure the drain plug is magnetic. I may just install a mag drain plug on the fill port as well!
Jordan | '72 2 door KA project | '94 240sx RB26DETT | '97 Silvia RB25DET | '90 Audi 90 Quattro 20V (DD)

User avatar
JordanTr
Posts: 745
Joined: 20 Feb 2013 22:27
Location: Langley, BC, Canada

Found the problem!

Postby JordanTr » 31 Aug 2017 21:57

I was able to tear the diff out of the car this past weekend. I documented the teardown and figured I'd share the results.

Here's what I found from the oil drain plug.

Image

Left cap off. Nothing spun.

Image

Right cap off. Nothing spun.
Image

Gear tooth loaded face. No crazy pitting or anything so that's good. I haven't fully inspected the gear (shame on me) but I was in a bit of a rush.

Image

Left side (thrust) bearing on the carrier. Some damage on the race.

Image

Left side of the carrier (thrust) bearing spun on the carrier. I just pulled it off by hand. It takes thrust from the carrier. Interestingly enough, this is the 3rd GTR diff I have apart that has failed the same bearing!

Image

Both carriers spun on 2 failed GTR diffs. Thrust side.
Image

Found the source of the noise on the outer/front pinion bearing!! Three of the rollers were damaged like this.

Image

Pinion setup. Inner pinion doesn't appear to be too bad.

Image

Pulling the spacer sleeve off the pinion showed a ton of muddy oil trapped inside from the failing pinion bearing.

Image

Cover collection!
Image

Conclusion
This seems like a chicken and egg problem to me. What failed first is the big question. Having disassembled 3 of these diffs with identical failures on the carrier makes me think that the thrust bearing may have a weak fit. Additionally, the other 2 diffs had much more acceptably looking pinions. The diff noise occurred suddenly after a canyon run.

My suspicion is that the bearing spun on the carrier at some point. During my drive home last year I braked hard at some point which flushed the shards from the spun bearing into the front bearing on the pinion causing catastrophic damage.

I'm going to be evaluating the fits on the non spun sides of the 3 failed carriers I have and compared that to Timken recommended fits. During the carrier repairs, I may up the class of fit by 1 to be sure this problem will be put to rest.

From a lubrication standpoint, I don't really know what could be done further. I've run 75W90 NS Redline with an appropriate clutch pack friction modifier additive.
Jordan | '72 2 door KA project | '94 240sx RB26DETT | '97 Silvia RB25DET | '90 Audi 90 Quattro 20V (DD)

510rob
Moderator
Posts: 4538
Joined: 09 Oct 2003 23:37
Location: Vancouver, BC
Contact:

Re: What's wrong with my diff??

Postby 510rob » 31 Aug 2017 22:30

Have you ever measured the diff temp with an infrared temp gun after some canyon carving?

User avatar
JordanTr
Posts: 745
Joined: 20 Feb 2013 22:27
Location: Langley, BC, Canada

Re: What's wrong with my diff??

Postby JordanTr » 31 Aug 2017 23:11

I'm sure it wouldn't be too cool... I will gather some data on that though. Maybe I should go for something in between something standard 75W90 and something crazy. 75W110 has improved properties that are probably pretty reasonable. I just did some reading on Redline Shockproof Heavy and people in multiple places say that it shouldn't be used in a clutch type LSD because of its advanced slippery properties. It would be a good candidate for my Torsen build though maybe.

Here's a quick snapshot of a hot viscosity comparison between some Redline products.
Image
Jordan | '72 2 door KA project | '94 240sx RB26DETT | '97 Silvia RB25DET | '90 Audi 90 Quattro 20V (DD)

User avatar
510wizard
Supporter
Posts: 1009
Joined: 12 Sep 2005 09:50
Location: Reno, Nevada

Re: What's wrong with my diff??

Postby 510wizard » 01 Sep 2017 07:52

I wonder if the STI temp sensor would fit those diffs? That way you could monitor while driving. Do you think that loctite bearing retainer would work?

User avatar
JordanTr
Posts: 745
Joined: 20 Feb 2013 22:27
Location: Langley, BC, Canada

Re: What's wrong with my diff??

Postby JordanTr » 01 Sep 2017 08:06

Loctite 638 is in the back of my mind. It has the same strength as an FN4 press fit so it's pretty sweet stuff. 4500psi shear strength.

That's a good idea. I'll look into an sti temp sensor.
Jordan | '72 2 door KA project | '94 240sx RB26DETT | '97 Silvia RB25DET | '90 Audi 90 Quattro 20V (DD)

User avatar
Byron510
Moderator
Posts: 11651
Joined: 01 Jul 2003 23:06
Location: Maple Ridge, BC

Re: What's wrong with my diff??

Postby Byron510 » 01 Sep 2017 20:41

I'll have spray welding set up in my workshop by this fall.... just in case you were thinking of that method.

Byron
Love people and use things,
because the opposite never works.

User avatar
JordanTr
Posts: 745
Joined: 20 Feb 2013 22:27
Location: Langley, BC, Canada

Re: What's wrong with my diff??

Postby JordanTr » 01 Sep 2017 20:46

Oh very good to know. Maybe we can arrange a batch rate for all 3! :D

I have a few good diffs I can pick from to toss in the car for the meantime.
Jordan | '72 2 door KA project | '94 240sx RB26DETT | '97 Silvia RB25DET | '90 Audi 90 Quattro 20V (DD)


Return to “Powertrain”



Who is online

Users browsing this forum: No registered users and 1 guest