Diff rebuild question (1 Viewer)

[Atomic City]

I am finally just about ready to start the re-gear and addition of Eaton e-lockers process on my 96 FZ and am looking over as many resources I can. This will be my first setup of Toyota gears ever. I have done a couple of Ford 9 inch re-gears and one Dana 44. Anyway, in my research, I came across this page from Zuk talking about how aftermarket rebuild kits suck:

Gear Install Toyota

ZUK shares many close-up good pics of Toyota gear installs

gearinstalls.com

In it, he shows the difference between true OEM Toyota inner and outer pinion bearings for the rear and the ones commonly found in rebuild kits. He gives the following OEM part numbers:

Outer: 90366-30038
Inner: 90366-40059

Then he gives the part numbers for the "not-so-good" bearings. I checked my Sierra rebuild kit that I got from CruiserTeq, and sure enough - the pinion bearings are the "not-so-good" part numbers:

Outer: 30306JR
Inner: 30308JR

I am going to try and source the better part numbers, but I am wondering if there is a similar situation with the front diff pinion bearings? I haven't found any information on whether the aftermarket parts are inferior or not for the front. My front rebuild kit is from Nitro.

Thanks!

 

[LandLocked93]

Those 'not-so-good' p/n's belong to Koyo, so I'd think better of them. Haven't had an issue with them in other applications.

 

[UsedLuxury]

Those 'not-so-good' p/n's belong to Koyo, so I'd think better of them. Haven't had an issue with them in other applications.

Zuk mentions that the angle of the rollers is the issue not build quality of the bearing. Koyo makes good bearings but these do not seem to be proper spec for the application.

 

[NLXTACY]

I literally just installed these from ZUK two weeks ago. I wholeheartedly trust Ken’s suggestions.

 

[cruiseroutfit]

Those 'not so good ' bearings have been installed in tens of thousands of diffs and are found in install kits from Sierra, Nitro, Yukon, Revolution and many more. I've never seen a failure related to the thrust angle of the bearings though acknowledge & agree they are 'better angles' on paper. Should you want the OEM bearings, we have those in stock too! I'm on year 21 with the commercial install kit variants bearings in my FJ40, we run them in our race car and rock crawlers we competed in too. My 2 cents.

 

[-Spike-]

Those 'not so good ' bearings have been installed in tens of thousands of diffs and are found in install kits from Sierra, Nitro, Yukon, Revolution and many more. I've never seen a failure related to the thrust angle of the bearings though acknowledge & agree they are 'better angles' on paper. Should you want the OEM bearings, we have those in stock too! I'm on year 21 with the commercial install kit variants bearings in my FJ40, we run them in our race car and rock crawlers we competed in too. My 2 cents.

Unfortunately, I believe my diff was the first that Zuk discovered the problem with. Possibly because I torture test pretty much anything on my rig, due to going off road twice weekly. The problem was real for me, I don't know if it has cropped up for anyone else. I'm not technically savvy enough to explain it, but Zuk showed me the problem and explained it to my satisfaction. Bearing tapers are specced for a reason.

 

[cruiseroutfit]

Unfortunately, I believe my diff was the first that Zuk discovered the problem with. Possibly because I torture test pretty much anything on my rig, due to going off road twice weekly. The problem was real for me, I don't know if it has cropped up for anyone else. I'm not technically savvy enough to explain it, but Zuk showed me the problem and explained it to my satisfaction. Bearing tapers are specced for a reason.

He discovered the different tapered angle exists or the problem with the varied tapered angle?

There are some old threads on this subject, also relating to the tapered angle difference between different knuckle bearings. Interestingly we definitely do see major wear issues with the incorrect taper (low) angle on knuckle bearings as they need much more axial capacity.

 

[-Spike-]

He discovered the different tapered angle exists or the problem with the varied tapered angle?

There are some old threads on this subject, also relating to the tapered angle difference between different knuckle bearings. Interestingly we definitely do see major wear issues with the incorrect taper (low) angle on knuckle bearings as they need much more axial capacity.

He tore down my diff after it grenaded, about a year after he installed new gears in it with an install kit I purchased from you. I watched the teardown, and he showed me the damage and figured out what went wrong. He documents all the steps and measurements he takes on every diff, and was able to determine what allowed the preload to get loose, which was that particular bearing failing.

I believe he has had several failures attributable to that bearing since then.

 

[cruiseroutfit]

Wild, I'll have to dig thru his site. Those are not recent bearing additions to aftermarket kits. For example Sierra has been using that variant for at least 20 years now.

 

[-Spike-]

Wild, I'll have to dig thru his site. Those are not recent bearing additions to aftermarket kits. For example Sierra has been using that variant for at least 20 years now.

Here's my original install- 529 Sierra Gear install - http://gearinstalls.com/benrearfront.htm

 

[Atomic City]

Thanks for the responses. I figured that this was a not-so-common thing, but I think I would still like to source bearings with the steeper angle. And it doesn't sound like this is an issue for the front - I'll just compare the new bearings with the current bearings when I am in there.

 

[cruiseroutfit]

Circling back on this.

90366-30038 isn't the only bearing of this application, in fact Toyota themselves bounced around a fair bit for the exact dimension bearing i.e. 90366-30011, 90366-30038 and 90366-30071 will all have the same OD/ID and relative thickness. What may change is the taper angle or manufacture, each of which make get a new number from Toyota. 3 Japanese variants I have seem to have a VERY similar steep taper angle, one has same taper angle as the Timken offering. Difference is a tiny bit of height and manufacture for the others.

Obviously that taper angle is important in bearing design/selection and I'm going to do continue to do more research into the bearings used by Toyota and aftermarket kits, fortunately we have each here to measure/inspect. What I do know is we've not had an issue with the bearings found in kits. Those same bearings are used in the Canguro 200, Rusty Nail racing uses them in his shop builds and King of the Hammers Toyota (2 time champ), etc and Sierra, Nitro and others use them in their kits for 58-90 9.5" diffs, 90-97 9.5" rear diffs, 8" kits use the same outer bearing and the 100 Series uses the same bearings on the rear. We've sold thousands and setup thousands of the kits, combine those gear vendors, hundreds of other dealers just in the US. If these were a prevalent issue, I'm shocked we haven't heard about it.

This is also true for the 90366-40059 which should see the bulk of pinion load, hence why it is larger. It has/is the 90366-40004 and 90366-40088 also. Zuk (whom I have much respect for) shows the NSK 30308DJ variant as the OEM for 90366-40059. However I've got a handful of NOS (dealer tag as old as 2005 on one) and brand new 90366-40059's here in Toyota boxes and they are all Koyo STA4090 sets. I have a 90366-40004 and it is in fact an NSK 30308DJ/HR 30308DJ. So perhaps a few of us are confused

I'll keep playing with this as I have time.

 

[cruiseroutfit]

I'm baaaaaaack.

The bearing tangle is deep but I'm confident all of our Japanese (usually part# -KOYO kits) will have the steeper angle bearings. All of the ones I've sampled do.

What do those differences look like?

Inner Pinion Bearing: 90366-40059 (our part# PN40059OEM on left) & 90366-40004 from our IKTOYLC-KOYO/IKTOYLCB-KOYO kits on right - SAME TAPER ANGLE

Outer Pinion Bearing: 90366-30038 (our part# PN30038OEM on left) & 90366-30011 from our IKTOYLC-KOYO/IKTOYLCB-KOYO kits on right - SAME TAPER ANGLE

But the Koyo bearing in a Sierra, Nitro, etc kit will have a different taper than a OEM or -Koyo kit taper

So long story short, we have adequate solutions for both options for 9.5" differentials. If you want the steep angel bearigns, order our OEM or IKTOYLCB-KOYO kit, if you're OK with the long-standing bearings that 'most' in the US use. Go with the IKTOYLC variant.

 

[Atomic City]

Thanks for the follow-up.