Wheel Bearing Replacement - Guru's guide w/pics

[DECALFX]

amazing, thanks

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[okiedude]

Has anyone tried the heavy duty bearings that Vlad ordered? I have a 03 wagon/track car and need to replace the bearings and would like to try the HD bearings.

[BIGSKYWRX]

I've been keepng a pretty close eye and not to my knowledge- ofcourse someone could have and not posted, but that wouldn't be nice

[okiedude]

Wonder if Vlad would sell me the ones he bought?

[Vlad]

Yes, I would. I can always buy another set and this will help everyone, because all (including me) want to know what happens if you install these. Let me go look for them. We'll just have to agree on a price, PM me.

[Vlad]

here is a pic

[Vlad]

more info..

[Vlad]

The whole kit

[forced4]

Vlad: Can you post a close up of the bearing box (with part numbers/etc) please?

[Vlad]

last one..

[okiedude]

PM sent.

[kainam00]

Just out of curiousity, what's the difference between those HD bearings and the OEM? I'm assuming someone took both of them apart and compared

[STI4ME]

4T-CRI-08A01 (OEM) Dynamic Load Rating of 75000 lb
4T-CRI-0823 ("HD") Dynamic Load Rating of 82500 lb

See my post #46 on this thread.

[Drew888]

Why is it neccessary to tighten the axle nut when not on the ground? Did I read that right a few posts back?

[LyveWRX]

Ok, Ive just been reading about comparitive life and the equations used to estimate the life of any particular bearing. There seems to be a way to substitute the different dynamic load and static load ratings into the maths to solve for f(lr)=life. The main thing is to understand that this would be an estimate based on several empirically (I'm guessing thats how NTN developed their life equations.) determined equations.

(No-one who works at NTN technical center (in A^2) drives a Subie? Thats rediculous, engineers generally like them.)

Otherwise I'll try to use the brother hood of engineers to get some sort of answer.


Here is my guess:

1 ) IFF (if only if) the two bearings are dimensionally exactly the same.
2 ) The increased dynamic and static load ratings will result in a longer life.

Ha Ha! Eureka! See link: http://www.ntnamerica.com/Tech_Supplements/news10.htm

By that little bit there I believe that the higer rated bearing will replace the OEM one.

NTN# -0881 is Nissan Prt#: 4021-001-E00
NTN# -0823 is Nissan Prt#: 4021-016-E00

The guy at NTN Tech support said that the B/p he looked at were pretty much the same. I'm going to try -0823 and find out.

So if no one has tried these bearings I'll be your Huckleberry.

[BIGSKYWRX]

longer+ sronger = better Please let us know if they work.

[Vlad]

Okiedude has mines, hopefully he'll have some info for us too, when he's ready to do the work.

[LyveWRX]

NEWEST Update!!!!!~


From NTN engineers:

"The general opinion of the WRX "conehead" racers here is "don't fix what ain't broke". Load ratings for your application are not as important as the proper endplay clearance and the Nissan bearings have a slightly larger clearance."

So on that note I am NOT going to be installing the -0823, I'm going to order the OEM from my local dealer.

[BIGSKYWRX]

Well- that certainly changes the outlook on things- I assuming theya re very close- a couple of thousandths different?

[LyveWRX]

bigsky- yea thats my estimation also.

The trouble is that I am not a bearing designer, I cannot even conceptualize how I would measure endplay clearance. And I dont have both infront of me. I do know that thousandths can be really big when talking bearings.

[Vlad]

I just found an article describing endplay and the clearance associated.
If i ws to venture a guess, it could be that when applying the proper tightening force, after everything is installed, instead of a normal axial play of x, you'll have an x + 0.0 etc
So if you were to take a dial gauge and look for the Subaru proper play you won't find it. however, since that bearing was DESIGNED to run that clearance, it will run that clearance. Possibly, a good thing to know would be the proper tightening torque for the bearings. That could be found easily, if we knew which Nissan it was.
Just my afternoon theory..

link

[LyveWRX]

vlad- reading that article IMHO the endplay on the two row bearings that our cars use is set by the ground width of the inner races (cones) since the axle nut seems to tighten on those and tightens them into a flange on the spindle. (of course this is going by the diagrams and pictures. In that case it would not be possible to adjust the endplay by too much just with torque alone.

[Vlad]

I was thinking that proper torque has to be the one pertaining to the bearing, I realize it would not really be an adjustment.
If it's a Nissan-specified bearing, it would probably have to be torqued properly per Nissan, even if installed on a Subaru.
I would like to have more info about how the endplay clearance would affect the bearing life, or maybe the warning refers to how the bearing would affect other components.

I was just thinking that maybe the endplay clearance is a function of the dynamic load rating (due to heat generation by example)?

But if our cars are lighter and therefore develop less heat in the bearing and therefore need less endplay clearance and also less dynamic load specified, unless if you drive them hard enough, then the situation changes..

[LyveWRX]

"I was just thinking that maybe the endplay clearance is a function of the dynamic load rating (due to heat generation by example)?"

Yep I think you're right, and quite possibly higher endplay clearance dose allow a higher load rating. One point is that the -0881/-0823 both weigh 1.32lbs while the -08A01 weighs 1.28lbs... There must be a construction difference that provides that.

I noticed when I took one bearing apart last night that the cage is a plastic in the OEM, if there is a brass or steel cage in the nissan that might account for both changes, endplay and weight.

(Dang where is the mechanical engineer when you need them, I can tell you what to make things out of, and how to heat treat them, and analyze them when they break. But no chance in bearing design.)

[Gary U]

Originally Posted by LyveWRX

NEWEST Update!!!!!~


From NTN engineers:



So on that note I am NOT going to be installing the -0823, I'm going to order the OEM from my local dealer.

Well, interesting to read this! The NTN technical support person you quoted asked me (NTN Design Engineer) about your question. I guess that makes me the "Conehead Racer". OK, so I do own an STi and have been to more than a couple autocrosses.

I read through some of the long list of posts here. I'll look into the real differences in the various T/U hubs we make of this same physical size. Chances are I will need to do this myself someday.