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-   -   Totally worn out rear hub (http://www.advrider.com/forums/showthread.php?t=856176)

Andy_unaventurous 01-17-2013 01:24 AM

Totally worn out rear hub
 
Greetings knowers of more than me!
My R80G/S has a totally worn out rear hub, brakes dragging or being ridden on I suspect. Anyway , gotta do something about it for rego. The great guys at BM Ringwood talk of machining out the hub and pressing in a sleeve internal diameter ( when surfaced down) same as a stocky. They are pretty straight guys , but I'm just checking what else is out there? Must have happened to other 31 year old bikes I guess

Anyone hear about this or have any knowledge of any other way, or indeed (ha ha ha ) have a second hand 3 bolt hub for sale?

Andy

8jest 01-17-2013 01:34 AM

Man. How many miles you have on it?

There is some bidding going on here on eBay:

http://bit.ly/10B4Ir9

TEXASYETI 01-17-2013 01:54 AM

Went through this myself recently. Ended up getting a wheel from Germany and it was not cheap. Someone did a modification where they put a 4-lug monolever reardrive on a G/S. They took a GS paralever rear wheel (4 lug and spoked) and machined some metal off on the inside and popped it on.

Problem is, paralever rear wheels seem to be just as rare as g/s monolever wheels. I hope that BMW is hearing the increasingly numberous and loud cries for these rear hubs and does something about it.

Rob Farmer 01-17-2013 01:57 AM

I didn't think you could sleeve out the GS wheel. the steel drum is cast in below the level of the aluminium around it. Be nice if you could but I don't see how they could fit a new one without chopping out a lot of aluminium.

Andy_unaventurous 01-17-2013 02:44 AM

Hi Mate, Impossible to say how many miles, there are some areas where its really tight and you think , wow, low miles, but then I took off the rear wheel and the drum is so worn you have to adjust the brakes up before you can remove the wheel, such is the lip on the drum itself? That there auction is for a diff/final drive, that seems ok on mine
maybe we'll be able to 3d print one soon :-)
Andy

Quote:

Originally Posted by 8jest (Post 20505848)
Man. How many miles you have on it?

There is some bidding going on here on eBay:

http://bit.ly/10B4Ir9


Andy_unaventurous 01-17-2013 02:46 AM

Hi Rob, please clarify mate, are you saying the 'level' of the brake hub is below the outer cast alloy of the hub? If so is it normal to have to adjust the shoes in to be able to remove the wheel?
thanks for your thoughts

Andy

Quote:

Originally Posted by Rob Farmer (Post 20505876)
I didn't think you could sleeve out the GS wheel. the steel drum is cast in below the level of the aluminium around it. Be nice if you could but I don't see how they could fit a new one without chopping out a lot of aluminium.


bikerfish 01-17-2013 04:19 AM

I always have to adjust the brakes to remove the rear wheel on my airheads, G/S included. before jumping to conclusions, take measurements to see if it is truly worn out, I'm sure someone here has the specs.

Rob Farmer 01-17-2013 04:28 AM

Andy,

I didn't word that too well.

When the wheels are new there isn't a lip. What I was trying to say is the steel liner is cast into the wheel. I cannot see how you could remove it or fit a replacement in there as the outer diameter of the replacement liner would need to be smaller than the worn original drum to fit it through the gap in the aluminium casting...hope that makes sense...I have a g/s wheel in my spares I'll dig it out and take a picture if needed.

mendoje 01-17-2013 05:09 AM

Quote:

Originally Posted by Andy_unaventurous (Post 20505972)
...I took off the rear wheel and the drum is so worn you have to adjust the brakes up before you can remove the wheel,

Rather than mileage, what is the measured diameter of the drum? I cant recall the number from memory, but the max acceptable diameter is cast on the hub somewhere. As others have said, it's normal to readjust the brakes when R&R'ing the wheel.

One Less Harley 01-17-2013 06:16 AM

I'd be interested in what you find out. I purchased an extra rear wheel from Germany, used and at a pretty good price and was glad to get it. At the time he had one other wheel for sale. I checked and he no longer has it.

AntonLargiader 01-17-2013 06:34 AM

The rear hub from my R100R is similarly shot, probably from maladjustment. It is worn with a curve dug into the center of the drum face. I'd love to find a solution for that, also. We have a local machine shop that does some very trick stuff, so maybe I'll ask them one day.

At least for that bike I can still buy a new hub, but it's not cheap.

_cy_ 01-17-2013 07:06 AM

Quote:

Originally Posted by AntonLargiader (Post 20507092)
The rear hub from my R100R is similarly shot, probably from maladjustment. It is worn with a curve dug into the center of the drum face. I'd love to find a solution for that, also. We have a local machine shop that does some very trick stuff, so maybe I'll ask them one day.

At least for that bike I can still buy a new hub, but it's not cheap.

not cheap is an understatement on top of extremely hard to find!

it's worth noting that original BMW brake shoe material can get extremely hard. either from age and/or very hard to begin with. while it's normal for brake drums to wear a little. most of the wear needs to come from brake shoe materials.

assuming your drum is still within tolerances... to save what left of your G/S drum. take your drum and old shoes to a local brake/clutch repair shop. find one that will custom fit shoe to drum. if there's wear on drum, thickness for shoes needs to be slightly thicker. reason is max braking occurs at beginning of brake rod travel. when brake cam is in optimal position.

new shoe material will be much softer than OEM. much rather brake shoe wear vs drum. had no clue just how hard shoe material had become. until I tore into my G/S drum to track down why my rear brakes were so underpowered. getting brake shoes relined with slightly thicker/softer brake shoe lining fixed problems of excessive drum wear and lack of braking power.

jackd 01-17-2013 07:59 AM

Quote:

Originally Posted by _cy_ (Post 20507345)
not cheap is an understatement on top of extremely hard to find!

it's worth noting that original BMW brake shoe material can get extremely hard. either from age and/or very hard to begin with. while it's normal for brake drums to wear a little. most of the wear needs to come from brake shoe materials.

assuming your drum is still within tolerances... to save what left of your G/S drum. take your drum and old shoes to a local brake/clutch repair shop. find one that will custom fit shoe to drum. if there's wear on drum, thickness for shoes needs to be slightly thicker. reason is max braking occurs at beginning of brake rod travel. when brake cam is in optimal position.

new shoe material will be much softer than OEM. much rather brake shoe wear vs drum. had no clue just how hard shoe material had become. until I tore into my G/S drum to track down why my rear brakes were so underpowered. getting brake shoes relined with slightly thicker/softer brake shoe lining fixed problems of excessive drum wear and lack of braking power.


That is a very good suggestion - I'll be following that route when the time comes for my rear wheel to be dealt with.

Airhead Wrangler 01-17-2013 10:57 AM

For building up spent brake drums I've been curious about trying a thermal spraying process aka "flamespray" or "plasma coating". I've seen various mention of people using this to build up spent wear surfaces before.

http://en.wikipedia.org/wiki/Thermal_spraying


These guys even mention using it on clutch plates and brake drums. Some of the coatings can be finish ground after application as well. Looks very promising to me:

http://www.plasma-group.co.uk/therma...-coatings.html

Hmmmmmm. My only concern would be that the heat might separate the cast-in drum from the outer aluminum casting due to the difference in coefficient of thermal expansion of the two materials. The flame spray process is much lower temp than welding though, so maybe it wouldn't be a problem. Who wants to be the guinea pig?

supershaft 01-17-2013 11:20 AM

Brake drums are a problem for us. Too bad every airhead ever sold didn't have the brake shoe lining replaced with a lining that actually wears versus the drum! Those linings don't get old and hard. They come brand new like that. The drum wear isn't necessarily from high miles or maladjusted brakes. It's from the linings. A curve dug into the center of the drum? I call that a glaciated drum. The same basic U shape as a glaciated valley. It's from those rock hard stock brake shoes. I see it ALL the time on all the beemers I have been around.


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