Lotus Elan

Front hub bearing failure

PostPost by: paddy » Tue Sep 29, 2009 7:53 am

One of my front wheel bearings has failed and I'm in two minds about what to do.

The history is that the bearing was new, about 3000 miles ago, in a new allow hub. The bearing has been well greased throughout. The end-float adjustment has always been a bit problematic - with the adjustment possible you're always in the position of having no end-float at all, or too much - but I've always had some end-float. Perhaps I was being too conservative here and it should have been tigher than it was.

Anyway, the bearing itself (mainly the inboard bearing, the outer shell) is clearly worn with the wear occurring on the outer edges of the surface (ie the bearing has been too loose and the rollers are rolling on their corners, not flat). Also, the bearing shell itself has been rotating within the hub, so there is slight wear now in the bearing seat in the hub. There isn't much wear - the seat looks more like it is just polished instead of worn - but now a fresh bearing shell is a fairly easy push fit into the hub, with no detectable play once it's in.

So my problem now is whether to fit new bearings with Loctite retainer, or to replace the hubs. The problem I have with the Loctite option is that the various retaining compounds are only good up to 200C and with the heat generated by the disc I imagine the hub would get up to that temperature quite easily.

So I think I'm going to have to go for a new hub.

Any thoughts?

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PostPost by: types26/36 » Tue Sep 29, 2009 8:42 am

paddy wrote:the bearing shell itself has been rotating within the hub, so there is slight wear now in the bearing seat in the hub. Any thoughts?Paddy


I've seen the inner surface (where the outer bearing shell fits) peened with a centre punch to prevent rotation, not an ideal situation but used with a locktite might work.
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PostPost by: 69S4 » Tue Sep 29, 2009 10:36 am

I would have thought it was worth a try to go down the loctite route. If you've already got a new bearing the cost will be next to nothing and you can easily keep an eye on the clearance. if it doesn't work, well, you were going to have to buy a new hub anyway.

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PostPost by: neilsjuke » Tue Sep 29, 2009 12:44 pm

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PostPost by: rgh0 » Tue Sep 29, 2009 1:03 pm

I have peened the outside of the hub once the bearing race is in place with a centre punch to help close up the tolerances. I did this as a temporary repair while waiting for a new hub on my competition Elan to get me through a race meeting. For a road car the inner hub bearing does not probably get above 200C so loctite should last a reasonable time.

An alternative to a new hub would be to bore out the exiting hub and press fit a sleeve or weld up and remachine the bearing mount but the cost would probably be close to the same as a new hub unless you can do the work yourself

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PostPost by: paddy » Tue Sep 29, 2009 1:05 pm

Thanks for the replies.

I think I'm going to go for the Loctite solution because, as you say, I don't have much to lose. (The main worry I had with it was that if it did get up to that sort of temperature, that's the last time you'd want it to fail...)

Anyway, since aluminium and steel expand at different rates, the natural clearance of the bearing in the hub will increase with temperature; by a rate of about 0.05mm (0.002") for each 100C. So any clearance I have now will be small compared with the clearance at temperature. (It also means I do need to have a larger end-float than with steel hub.) I would have thought that the bearing fit in an alloy hub would have to be an interference fit by at least 0.05mm at room temperature, but the bearing taps into the (good) hub really quite easily. So perhaps Loctite was a requirement all along.

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PostPost by: neilsjuke » Tue Sep 29, 2009 2:13 pm

I have took a knats of a nut in the past to get the end float right in the lathe.
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PostPost by: paddy » Tue Sep 29, 2009 2:16 pm

neilsjuke wrote:I have took a knats of a nut in the past to get the end float right in the lathe.


Yes - it would be nice if someone sold shims of various thicknesses to allow it to be adjusted properly.

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PostPost by: Frank Howard » Tue Sep 29, 2009 4:02 pm

neilsjuke wrote:I have took a knats of a nut in the past to get the end float right in the lathe.
Neil
Could someone translate this into American English please?
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PostPost by: paddy » Tue Sep 29, 2009 4:05 pm

Frank Howard wrote:[Could someone translate this into American English please?


I think this is the reference you're looking for:

http://www.urbandictionary.com/define.p ... id=3086722

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PostPost by: stuartgb100 » Tue Sep 29, 2009 5:15 pm

Paddy,

When I bought my Sprint 5 years ago, I decided on a full service
with upgrades to suspension and brakes.

In the course of this I discovered worn rear hubs.

I researched possible solutions with Rohan's sleeve being optimum,
and I would have gone for a steel sleeve. But cost killed that one.

After talking to Loctite's technical department I opted for their
660. This is a liquid metal, but also a retaining compound.

It has been a total solution for the past four years. You might
care to consider it. Not cheap, but you don't use much.

Regards,
Stuart.
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PostPost by: paddy » Tue Sep 29, 2009 7:00 pm

sgbooth wrote:After talking to Loctite's technical department I opted for their
660. This is a liquid metal, but also a retaining compound.


Thanks. I've been looking at the datasheets for the multiple different retaining compounds they have, all varying according to the setting time, strength, temperature resistance and ability to fill voids.

It looked like the most suitable was 640, based on it being the most temperature-resistant, but so far I only found it in 250ml bottles which are more expensive than a new hub :(

I've already got a bottle of 638 (previously used on my rears) which is nearly as good but its effectiveness tails off after 150C but I think I might just go for that.

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PostPost by: andyelan » Tue Sep 29, 2009 7:07 pm

Hi Paddy

Are we talking front or rear hubs here. If it's front, where's the aluminium come in, have you got non standard aluminium racing hubs fitted ?

I had a problem with a rear wheel bearing on my Europa Special and ended up loctiting that in place in the housing. Its been like that now for over 15 years with no problems at all, and the Europa has rear drum brakes but heat hasn't been a issue.

The Loctite you want is 641 "Bearing Fit" or possibly either of the 638 or 648 "High Strength Retainers". Google "Loctite 641 Specification" for more information. Don't use any thing like "metal set" though, that definatly won't work as it's not a proper adhesive

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PostPost by: paddy » Tue Sep 29, 2009 7:14 pm

andyelan wrote:Are we talking front or rear hubs here. If it's front, where's the aluminium come in, have you got non standard aluminium racing hubs fitted ?


Yes, it's the front, hence the concerns with temperature. The disc run-out with my old original hubs was so bad I went for new ones.

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PostPost by: JimWol » Tue Sep 29, 2009 8:44 pm

paddy wrote:It looked like the most suitable was 640, based on it being the most temperature-resistant, but so far I only found it in 250ml bottles which are more expensive than a new hub :(
Paddy


Just found this Loctite 640 http://www.scparts.co.uk/index/lang-2/l ... 343250.htm (!0ml bottle @ ?21.08) It may be worth trying.
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