Ok guys updated situation, measured the runout on the wheels, brake disks and then hubs, all show 0.02 - 0.25" which in my book is way to much. JTIS calls for 0.002 maximum installed. So I guess I know the vibration and noise is coming from the runout on the rear.

So I disassemble the rear knuckle again and removed the half shaft. Once out the rear of the bearing was exposed and it appeared all the grease from the sealed bearing was pushed out and on the rear of the bearing. So to cut a long story short, I am sure that by applying torque to the rear hub nut I am preloading the bearings. That said I used JTIS for the original torque specification, JTIS said 302lb/ft. After reading this thread again and looking at the SKF website on their guideline for hub nit torque the torque is specified as 221lb/ft. So is it possible that I applied too much torque and blew out the bearing, hence the runout, loose of grease and now squeaking rear wheels when rotating?

 

Ok so update on the rear end vibration, took the rear knuckles in had the bearings pressed out and new one pressed in didn’t see any big change in position or fitment.

Installed and torqued to 221ft/lb on the rear half shafts, measured the runout on the rear brake disks and surprise surprise, 0.002 which is right on the money according to the JTIS spec. So I ran the car in gear on the jacks to get a quick visual before doing a road test. No wheel wobble that I could see on to the road test, and the result perfect all the way up to 80mph. So the second set of bearings to the manufacturers torque spec works perfectly.

Lesson learnt, don’t always trust the service manual torque specifications. The302ft/lb torque shown in JTIS will overload the bearings with too much preload and cause premature wear in as little as 50 miles and once worn cause excessive rear end vibration. Hope this helps everyone that has or may have this problem in the future.

 

Thanks for posting.

 

Ncjagguy,
While I'm glad that you got the problem sorted, I still can not understand why high tightening torque would cause runout. If 320 ft-lb distorted the bearing you should have been able to move the wheel with your hand. If the bearing was installed crooked, it would not cause runout, only wrong orientation of the wheel after reassembly. Maybe our definition of runout is different?

 

Tony runout is the relative movement of the hub, brake disc or wheel while rotating on its axis. I used a dial gauge with a magnetic base to measure the runout while turning the hub.

My only logic is the the over torque caused excessive preload which gauled the bearings overheating them and forcing out the grease, this led to a dry bearing and hence the squealing noise after a few miles. I only measured the runout of the failed bearings after they had failed unfortunately. So the runout could have been correct prior to my over torque.

Hope that makes sense?

 

I decided to change out the rear diff myself. I found fluid on Amazon.com for 14.00 a quart (buying 2 of them) and a used rear diff with 100k on it for $275.00

I'm reading that the hubs are a PITA to get off and the axels out. I'm looking for some advice on this aspect of the work I'm getting myself into. I've done plenty in the past on my cars I've owned including timing belts and technical stuff like fuel floats in a carb. As far as tools needed, I'm assuming I should rent an axel puller? Your help and time is appreciated.

 

Also, are there any seals or anything else I should change whilst I'm in there?

(e.g. cars that need a timing belt, should also have the water pump done...)

 

Someones addiction, soak the spindles with PB Blaster for a few days before the work. Use a few well placed stiff blows with a hammer and the axles should pop out of the hubs.

 

Ok so on the story goes wellI almost made it to 2 weeks without any problems. I noticed a very fainted rear grinding noise start up over the weekend it was very intermittent and not very noticeable. Today it is very constant around 45 mph and always there it sounds like the bearings are shot again, grinding with increased noise as speed increases.

It is not possible to have 2 completely new sets of bearings go bad on the same install within 2 weeks after installation there must be some other explanation at this point. The vibration has not come back yet, but I an sure once the bearing wears a little more the vibration will start to creep in. At this point I am open to any suggestions, this issue is now out of control. If you have been following my posts I am at a loss to explain how the bearings canget destroyed so fast.

 

I had a similar situation on a kit car (self build) that had a problem with the bearing surface on the rear half shaft. Every time it was torqued up with a new bearing in the housing it pushed the bearing apart and the bearing failed.
Is it only one side thats causing problems at the moment?

It may be that the over torque not only damaged the bearing but also the half shaft?

 

I am starting to suspect the half-shaft as this is the only part I have not replaced to date, all other suspension parts, bushings, upper / lower arms, bearings, brake parts are brand new. It appears that it always start on the right rear but ends up being both sides if I let it wear enough.

I have considered driving it till it failed and then I would probably have a good understanding of why by looking at the failed parts, but I dont really want to take a chance with suspension parts failure while driving.

 

hmm... Theyre not under torqued are they? Can be as damaging as over doing them....

I blew my diff last-last weekend, went from being a little bit noisy on deceleration, to a POP on the highway and now permanently noisy... Limped it home, was gonna drop the diff and take it apart last week but got lazy... Need to get to work on it this week though, see what failed, still trying to decide if i should overhaul my current broken diff, or go the quick in and out replacement route with a used diff for about $300...

 

GT the rear half-shaft wheel end nuts have to be torqued to 300Nm, i have torqued them to the manufacturers specification. The rest of the drive train appeared to be free and the run-out on the wheels once assembled was great. Now just a a week later and about 200 miles the wheel bearings are noisey again. Go Figure, this does not appear to be a diff or driveshaft problem.

 

My comment isn't really insightful, but if you had the original bearings, I would carefully compare and look for any size difference. Small ID or inner/outer flushness difference can make big pre-load variations.

 

So update, ended up taking the car in to a friends shop. They stripped down the rear knuckles again and sure enough the rear wheel bearings had failed again. The in board side races showed heat again and the bearings were pitted on the inside once we got them out. So this would be the second set of bearings in the car in 400 miles. (Bearings from Timken and National)

We have removed the rear knuckles and measured the bearing bores both diameter and bore straightness, they check out great. We have measured the hubs for diameter and straightness and they are great. I am not sure what is causing the bearing failure at this point.

We are going to assemble the car and try again, however I dont expect a different unfortunately. We have not found any smoking gun in the setup and I am starting to get concerned.