Voltage regulator and Swingarm bearings

newguy · Jul 31, 2007

Hi guys,
Work colleague got his hands on a box of odd BMW spares, ranging from 1970's upto what looked like R1100 handlebar controls.
So he let me scratch around and take some stuff. In the box I found a voltage regultor. It's black and red and the casing is plastic (will try and post pic later). Anybody familiar with this part? Can I fit it / or is it worth fitting to my airhead?

The other thing is my swingarm bearings. I think the previous owner put different bearings in. It's got FAG 580619 (dont think that is original, is it?) sealed taper roller bearings in. I want to replace it, but that specific bearing does not seem to be available in South Africa according to the FAG suppliers. I'm no genius on bearing sizes, what other bearings will be ok?

This is for a 81 g/s.

Thanks,

avrolancaster · Jul 31, 2007

The voltage regulator is a direct replacement for the one originally fitted to your machine. It is superior.
The FAG bearings are original on bikes after about 1982. FAG will not sell them to you because they are what is called a 'protected part', that is tied up by BMW (many parts are like this now).
You could retro fit the bearing from the first bikes, 30203 (available anywhere and cheap as chips) but you will have to fashion a spacer washer. This washer is thick enough to go flush with swinging arm bearing recess. The hole obviously has to be big enough for the pivot end to pass through.

newguy · Jul 31, 2007

Schweet, will go buy that bearing and see how it matches up, NSK's in that size should be nice n cheap. Great news for the regulator as well, now I have my old one as spare! :aidan

Thanks again

Rob Farmer · Jul 31, 2007

The earlier bearings were narrower and had a seperate seal (I think they were 40 X 17 X 14 bearings) the later bearing has its own internal seal (the bearing is a 40 x 17 x17). If you fit the earlier bearing there is a standard seal that will save you making your own. When I replaced my R100 bearings I fitted the later ones. I may have the originals seals laying about if I have you are welcome to them..I'll have a look to see if I still have them.

avrolancaster · Jul 31, 2007

If you fit the seals from the pre 1981 models you must also fit the thrust sleeves. You should not really do this as the spacings are different so I can not recommend it.

I was referring to the first year of production 1981 models where the early bearing is used without a seal as there is not really enough room for it, hence the large washer.

There 3 variations of swingarm bearing:
Pre 81: early bearing with seperate conventional grease seal & thrust sleeve.
1981 only: early bearing with thick metal washer
1982 on: late bearing with integral grease seal (expensive protected bearing)

newguy · Jul 31, 2007

I think I have the late bearing, but with the thick washer :blast

Basically theres the FAG 580619 bearing with its own rubber seal, then a plastic dust cover type ring and then a thick washer the diameter of the bearing.

Rob Farmer · Jul 31, 2007

You need the late bearing :aidan

Have you tried Motorworks? They are £21 each for how often they need replacing I wouldn't worry about the cost.

http://www.bmwandguzzispares.co.uk/...sub_part=Swing+arm+and+driveshaft&partcode=EA

If they don't ship to SA then drop me a line and I'll order a pair for you and post them on.

newguy · Jul 31, 2007

with the exchange rate as it is right now, 21 is quite a lot for us here in ZA (about 1GBP = 14.20ZAR -Yikes!). That's the right bearing. I just check the shops again locally, otherwise I will order them from motorworks.
Cheers!

avrolancaster · Jul 31, 2007

You do NOT need the later bearing.

You already have the washer, so buy two 30203 bearings usually 5-7 GBP each. No need to import over priced bearings.

Remove the bearings currently fitted.
Fit 30203 in each side, large washer on top, job done.
This is how all the bikes came from the factory in the first year, not just the G/s but all models built 1980/81. R45's and R65's also had this set up in the late in 1979.

Sometimes giving correct, factual and helpful information is made very difficult!

Rob Farmer · Jul 31, 2007

The later bearing has a better seal and is less prone to contamination - cheap isn't always better. Why else would BMW go to the hassle of having a one off bearing made. The original was superseded for a reason :rob

newguy · Jul 31, 2007

I'm not to worried about the sealing of the bearing too much. If you maintain the swingarm bearings the way you are supposed to, you pump it full of grease and the dirt is pushed out and the grease keeps it sealed. I think this is why mine had warn as I never did this. I have to say though that the later type probably does seal slightly better and is more expensive, but looking at how often I will replace them, I will probably spend the extra ching.

I have another problem pending. Measured my front brake disk thickness and it is already down to 4.3mm (minimum recommended is 4.5mm I think). So advise that I really need now is for a new disk. I still have the original tiny disk in front. I was thinking of doing one of the following:
1. Replace disk with same, but new one.
2. Replace with bigger disk and mount caliper on offset bracket.
3. Try and find good condition R80 twin disk and caliper set. (should fit right?)
Your thoughts on the above?

avrolancaster · Jul 31, 2007

Rob Farmer said:
The later bearing has a better seal and is less prone to contamination - cheap isn't always better. Why else would BMW go to the hassle of having a one off bearing made. The original was superseded for a reason

Now you are being very silly.
BMW frequently change things for the worse, there are SO many examples over the years.
Many changes are for reasons of cost, ease/speed of assembly or down right bloodymindedness. Never mind...

(RIP) Proff · Jul 31, 2007

avrolancaster said:
Now you are being very silly.
BMW frequently change things for the worse, there are SO many examples over the years.
Many changes are for reasons of cost, ease/speed of assembly or down right bloodymindedness. Never mind...

Exactly

Why for instance replace the vastly superior Airhead GS, g/s's with an overweight oilhead :blast

Rob Farmer · Jul 31, 2007

Proff said:
Exactly
Why for instance replace the vastly superior Airhead GS, g/s's with an overweight oilhead

Because people like to go over 80 miles an hour without being blown all over the place and without fear of their engines self destructing. Bloody airheads :spitfire

I've just taken the gearbox out of my 78 R100 because the clutch started squealing only to find the pushrod in several parts and the clutch release bearing in a million bits - Still I suppose they were better in the old days :mmmm

Voyager · Jul 31, 2007

newguy said:
I have another problem pending. Measured my front brake disk thickness and it is already down to 4.3mm (minimum recommended is 4.5mm I think). So advise that I really need now is for a new disk. I still have the original tiny disk in front. I was thinking of doing one of the following:
1. Replace disk with same, but new one.
2. Replace with bigger disk and mount caliper on offset bracket.
3. Try and find good condition R80 twin disk and caliper set. (should fit right?)
Your thoughts on the above?

I have seen people fit two right-hand fork legs in order to mount two calipers, but before you rush into that, consider fitting a later four-pot caliper to a standard disk - single-side only.

I'll measure up the disks and calipers on my 1988 R80RT and 1989 R100GS and return tomorrow. From memory the calipers appear to have the same mount spacing but I have a feeling that the disk offset is different between the two bikes.

No doubt the experts will be along shortly !

Bob.

newguy · Aug 1, 2007

Actually the mounting won't be a problem, there is an empty caliper mount on the left already!? Don't know why, maybe the forks were replace at some point in the bike's life already.

Voyager · Aug 1, 2007

R100GS Brake Swap:

Right . . . Here we go.

I have measured my 1988 R80 RT and 1989 R100 GS front brakes and have taken some pics - see below (its raining again this morning !).

1. The disks are the same diameter (roughly 283mm).

2. The disks have the same offset (roughly 24mm from outer surface to base of disk mounting nuts).

3. The R100 disk is 5mm thick, those on the R80 are 4mm (disks replaced this year).

4. The caliper mounting bolt spacing is the same.

5. The R100 Caliper has larger diameter slave cylinder pistons than those in the R80 - but that shouldn't matter if two R80 calipers are to be fitted.

A point to watch. My R80 appears to have been converted to twin disk at some point in its life as the calipers are not quite the same. I found that I had excessive movement in the brake lever (I could almost get it back to the bar) so changed from a 13mm diameter master cylinder to a 14mm. It is fine now.

I'm not sure what the master cylinder piston diameter is on the R100 (yours may be different anyway) but bear in mind that you may need a larger cylinder with twin calipers.

Again, I don't know whether a R100RT would have larger calipers than an R80RT - An R100 may be a better twin-disk donor.

And yes, I know that the R80 fork legs are a mess - I am about to service it and tidy it up a bit (it doesn't need much doing).

Good luck, let us know what you decide and how you get on. Pictures would be nice.

Bob.

newguy · Aug 1, 2007

Well, here is my current setup

Note on the other side the mounting points

Rob Farmer · Aug 1, 2007

newguy said:
Well, here is my current setup

Note on the other side the mounting points

Your forks and sliders are identical to the 81 - 84 R100/80 if you want to fit 2 disks on the front you will need a narrow (2 spline) front hub instead of the three spline one fitted at the minute.

HH front pads are a good/ cheap way of upgrading the front brake. You could fit a bigger front disk from an RT and change the caliper if you just want to upgrade the existing single disk setup. The forks have a tendancy to twist if the brakes effective so you will probably need a fork brace as well.

Voyager · Aug 1, 2007

newguy said:
Well, here is my current setup

Ah well . . After I posted my pics I had a look at the Monolever Register and spotted your bike. I realised then that it had the earlier brake set-up so my comparisons weren't really relevant.

Hope you get it sorted to your satisfaction.

Bob.

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