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Wear on Stub Axle & Stub Axle Conversion Kits


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I've spent ages reading the numerous excellent topics covering replacing wheel bearings, worn stub axles and stub axle conversion kits, but have not found the answer to the two quesions below.

As I understand it, even when both are new the bearings are not a tight fit on the stub axle.  It's certainly the case that mine (TR4A) just slid straight off when I pulled the hub off.   Also when you set them up the procedure surely relies on the ability of the bearings to move slightly on the stub axle.  I gather that the wear on the stub axle arises from the bearing spinning on the stub axle   -   my first question is "What on earth is meant to stop the bearing spinning, given that it's not a tight fit on the stub axle?"

And my second question is "Does using a stub axle conversion kit (with a spacer and shims) prevent the bearings from spinning on the stub axle?"

Thanks for your advice,

Tony

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Many thanks, Ian.    

I'll definitely go with the spacer and shim arrangement, then.   

Still intrigued to understand "What on earth is meant to stop the bearing spinning, given that it's not a tight fit on the stub axle?"    Any ideas?

Thanks again,

Tony

Edited by tonycharente
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Unfortunately as standard the bearings do spin on the shaft (both front and rear) and eventually you have play in the hub even when the bearings are tight.

I went for the spacer option many years ago and it stopped the problem of stub axle wear and significantly reduced problems with brake pad knock off which would see the pedal hit the floor on auto solos.

Eventually bearing failure wrecked a hub as the outer race spun instead of the inner. At this point I went for an upgraded hub, stub axle and bearings

Neil

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The only issue that I have found with the spacer and shim arrangement is that adjusting the front bearings can be a bit of a faff.

In my case the spacer had seized on the stub axle on one occasion, necessitating removal of the calliper so that I could pull the disc and free up the spacer to remove it and get access to the shims.

Rgds Ian

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Thanks again, Ian.

Yes, I can see that setting up the spacer arrangement will be "a bit of a faff"  -  but surely nothing compared to replacing a stub axle?

I've already found four suppliers for the spacer conversion  -   now I'm wondering which is best (???)

Cheers

Tony

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52 minutes ago, tonycharente said:

Still intrigued to understand "What on earth is meant to stop the bearing spinning, given that it's not a tight fit on the stub axle?"    Any ideas?

The weight of the car will be sat on the stub axle to inner race interface and friction between the two is enough to stop the inner race spinning on the shaft........until there’s a problem with the bearing.

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I use spacers on my cars to stiffen up the assembly and minimise pad knock back when in ”hooligan mode”

As Ian has pointed out they can take a bit of effort to set up but the faff factor can be minimised by cleaning the grease off all the parts and setting the shims with the bearings lightly oiled prior to greasing everything for final assembly. 
Check the clearance again after a few miles to bed everything in. 
 

Edited by Drewmotty
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Aren't the bearings graded for size originally?  Isn't there a code for a slide fit?

I've sent back some stub axles to Moss a while ago now, as I couldn't get new bearings on the shaft, and the machining didn't look too good.

I don't believe the ones we get now are centre ground, as there aren't holes in the ends.  perhaps just done on cnc machines.

If you have a used stub axle, usually the underside of the axle will be the  part that will be worn.

John

Edited by John L
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Thanks again Andrew, very helpful.   (Had gone to bed when you replied last night  -   it's an hour later here)

When you say "Check the clearance again..." what precisely do you mean, please?   

Just feel for play and adjust shimming if need be?   

Or re-torquing the hub nut come what may?

And if adjustment needed, does that imply starting over (remove hub and remove all the grease?)

Or what?

Thanks again,

Tony (Spacer conversion virgin...)

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29 minutes ago, John L said:

If you have a used stub axle, usually the underside of the axle will be the  part that will be worn.

John

Thanks John.

I can feel with my finger that the underside of my left-hand stub axle is very slightly worn.   I am keen NOT to have to replace the stub axle as it is so much more work and I don't have a 20 ton press.    Hence my interest in trying the spacer plus shims conversion.

Cheers

Tony

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Remove calliper,brake disc complete with hub.

Stub axles are fairly easy to get out. I jack up the suspension to relieve the tension. Remove both top ball joint bolts which will allow you to swing the vertical link down.

Undo the stub axle nut a few turns, holding the vertical link in your hand give the nut  a clump with a club hammer. It should then come out.

Regards Harry

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8 hours ago, tonycharente said:

Thanks again Andrew, very helpful.   (Had gone to bed when you replied last night  -   it's an hour later here)

When you say "Check the clearance again..." what precisely do you mean, please?   

Just feel for play and adjust shimming if need be?   

Or re-torquing the hub nut come what may?

And if adjustment needed, does that imply starting over (remove hub and remove all the grease?)

Or what?

Thanks again,

Tony (Spacer conversion virgin...)

You can set up a dial indicator and measure clearance if you wish but I usually set them so that I can just discern a slight movement at the wheel rim. 
Once they’ve been set up it’s easy to try one increment smaller on the shims to see if you still have movement. If you don’t have any then put it back like it was.

 
To remove the stub axle Harry is correct in that a ballistic load works better than a press. I remove the vertical link (you can unscrew it from the trunnion once the ball joint is free and the lock stop removed) and get it well supported close to the sides of the axle and on a sturdy bench where you can get a good swing with a lump hammer. 
Heat is your friend; I use a paint stripping gun rather than an open flame so that I Don’t  cause any heat damage and get it evenly hot. Protect the threaded end from hammer damage by putting a nut on it flush with the end and then protect the lot by using a piece of ally/copper/brass (a coin is good) between the hammer and the nut. 

Edited by Drewmotty
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Thanks again Andrew, very helpful again.

I'm currently still thinking of trying new bearings plus a stub axle conversion kit (the spacer + shims)   -    if I get significant play at 12 o'clock / 6 o'clock I can then bite the bullet and change the stub axles.   Does that make sense?

Any significant difference in the various stub axle conversion kits available ?

Thanks again

Tony

Edited by tonycharente
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You should be able to accept or reject the axles on a visual inspection. Any visible wear, corrosion or damage will be grounds for rejection. Quality bearings should be a nice slide fit with no discernible radial play between the inner races and axle. You could crack detect them too but where do you stop?

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I do plenty of hill/mountain runs and brake pad knock back was a problem on any twisty section  of road.

Solved problem completely by fitting uprated stub axles and bearing spacers from TRF in USA.  No issues knocking out old stubs on the car with hammer (as per Harry above). Did fiddle to set up as found spacer was .020 " too long and had to reduce in order to set up correctly with shims.

One of the best mods i have done

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Thanks again Andrew and thank you also Nobbyc.

Inspired by "To remove the stub axle Harry is correct in that a ballistic load works better than a press. I remove the vertical link (you can unscrew it from the trunnion once the ball joint is free and the lock stop removed) and get it well supported close to the sides of the axle and on a sturdy bench where you can get a good swing with a lump hammer" this afternoon I decided to stop being "in denial" (like a certain American president...) and strip things down further in order to remove the stub axle and replace it come what may.

Worked a treat!  Placed the vertical link on top of the just sufficiently open jaws of a sturdy vice and smashed it a few times with a club hammer and out it popped.   In fact I had a harder time removing the track rod end...     One side down...

Just need to decide where to buy all the bits now.

Thanks again to everybody  -  very very helpful!

Tony

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