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Rear Wheel Bearing Quandry


c7trp

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Noticed some play in the rear hubs of the car. On closer examination I could detect a noticeable movement of the hub both vertically and horizontally. Car has done 45k miles so assumed bearings are worn.

 

Fitted new bearing and seals tonight. Tightened the hub nut up v.v.tight and still got a bit of movement. 😔

 

The amount of play is very small - you can't see the wheel rim move, but you can feel a definite amount of movement. I would guess its less than 0.5 mm at the rim.

 

Is this normal?

 

The drivers side hub nut looks like its been loose in the past as the washer looks like its been rotating, and there is a little wear in the inboard side of the hub but nothing else looks too worn.

 

The near side looks fine.....

 

Anyone any experience of this?

 

Car is an '03 road sport with de-dion.

 

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Yep - I think this is wear on the hub - making the internally splined bit shorter so you can't load the bearings up before the hub nut hits the end of the thread on the half shaft.

 

If you know what I mean *confused*

 

Will place a temporary shim behind the hub nut and torque it back up to see

 

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Rob,

 

I know that they are not adjustable.

The process above is to ensure you have used the correct torque, and have overcome the run on torque when fitting the bearing. If the wheel is torqued up correctly, there will be no play....

 

(It's a standard process we use all the time in wheekl changes etc.

And with 22 wheels and tyres to change, it works quite well).

 

Only dead fish go with the flow....!

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yeah - I torqued the nut up once to 'seat' the bearings. An then slackened off and re torqued again *cool*

 

Haven't had chance to look again today, but suspect the wear on the back of the drive flange is causing the problem.

 

Can easily test this theory with a big washer when SWMBO lets me out.....

 

If it is, then time for new drive flange *cry*

 

Can't really think of any thing else it could be

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Cagey & Tim,

 

You are both failing to understand how the rear hub bearings are loaded . The 200lbs torque as applied to the hub nut on the end of the driveshaft is only applied to the drive flange which is used to clamp the the bearing inner races together against the step machined on the drive shaft. It is not applied to the taper roller bearings which are contained within the hub carrier. There should be little or no static side thrust applied by the torque applied by the hub nut or they will fail in minutes. The taper roller bearings rely on the 5mm machined step within the hub carrier for location of the outer races. The overall width of the two complete bearings and step is 35mm which and this is accomadated within the space that is machined on the driveshaft. I am not a fan of this bit of engineering as there is no provision for correctly adjusting the amount of static side thrust that each wheel bearing sees. I had a total failure on track at Le Mans 2 weeks ago when the NS bearings broke up completely and also cracked my disc.

 

Rob

 

 

 

Edited by - Rob Walker on 18 Jul 2008 18:55:44

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Tim,

 

The only sure way of finding out what static side loading you have is to withdraw the drivshaft and remove the hubcarrier and assemble the whole lot on the bench or held in the vice.

 

It is possible that you have some bearings that have been machine out of tolerance or damage to either your hub carrier or drive flange.

 

Rob

 

 

Rob

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OK

 

Here are some pics of the RH side drive flange.

 

I reckon there around 0.1mm run out (14.8 to 14.7mm measured from the step) on the mangled inner face (that locates the inner race of the taper bearing?)

 

If I'm understanding Rob correctly this face locates the inner race of the bearing, but the design of the shaft/hub carrier prevent this putting an significant axial load onto the taper rollers.

 

However if its a bit worm (as it seems) this will prevent the inner race of the bearing fully locating giving me a bit of movement?

 

Thanks for your help

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Funny you should have this as a post as I have just come across the same problem. I have a previously enjoyed ( Secondhand. ) CV joint on one side and have the same anoying amount of movement at the wheel. The problem does not exist on the side that I have put a new joint on. Both the drive flanges are the same age and milage. Both sides have a brand new wheel bearing.

 

I can guarantee the joints are torqued up correctly. I am beginning to think that the slpined section on older cv joint has stretched a tiny amount.

 

 

 

What are the chances?

 

 

 

Edited by - guilleracing on 12 Jul 2008 16:44:14

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I'm just in the throws of building a new 7 and I have five new zero miles rear hubs at home. Two good ones on the car and three which have too much play in them and will be on their way back to CC shortly.

 

I have been told by CC that the bearing is not the problem and its that the depth the hubs are machined to or something like that. We were talking about new ones though.

 

Jason

 

 

Currently, I am qualified to plead ignorance.

 

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Now I've had time to strip the half shaft out and assemble the whole lot on the bench.

 

Everything is fitting OK - the inner bearing races are against the shoulder on the drive shaft and the nut nips up OK.

 

Checking with a dial guage I'm getting 0.25mm movement @ 115mm radius. (so movement is going to be about 0.75 at the rim). I'm certain this is movement from the bearings. As I've got the DTI clamped to the de-dion ear measuring off the brake disk.

 

I had a similar amount of movement from the old bearings on both sides...

 

Anyone any thoughts on what to check next?

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Found it!

 

The play is between the inner race of the bearing and the shaft.

 

The fit of the bearing doesn't feel too sloppy but there is a bit of play. Surface of the driveshaft in good condition with no scoring or obvious wear.

 

TADTS or crap bearings?

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