Wheels for K75S

[jonzn]

I recently purchased a 90 K75S and have ben doing some upgrades on it. One of the things that I wanted to do was to go to the 3-spoke wheels. I found someone selling a set of 3-spokes from a later/larger K-bike and bought them assuming that they would be a straight switch. What I found was that the rear was "fine" except that I will need to modify my center stand in order to clear the tire on the left side. The front wheel is the problem in that the mount for the rotors is comtletely different (6 bolts away from the hub vs. 4 bolts close to the hub on my stock wheel). Is there any easy fix for this or am I stuck with wheels that won't work in any way on my bike?:dunno BTW, the new wheels are 3.5X17 front and 4.5X18 rear.
Thanks,
Mel

[deilenberger]

Originally posted by JONZ
I recently purchased a 90 K75S and have ben doing some upgrades on it. One of the things that I wanted to do was to go to the 3-spoke wheels. I found someone selling a set of 3-spokes from a later/larger K-bike and bought them assuming that they would be a straight switch. What I found was that the rear was "fine" except that I will need to modify my center stand in order to clear the tire on the left side. The front wheel is the problem in that the mount for the rotors is comtletely different (6 bolts away from the hub vs. 4 bolts close to the hub on my stock wheel). Is there any easy fix for this or am I stuck with wheels that won't work in any way on my bike?:dunno BTW, the new wheels are 3.5X17 front and 4.5X18 rear.
Thanks,
Mel

Given cubic amounts of money - anything is possible.

You are correct - you WILL have to modify the centerstand to fit the rear wheel/tire on. And it changes a few other things.. to remove and replace the rear tire - you have to drop the muffler. It will not clear the muffler and the brake caliper.. too wide.

It's not a big deal to drop the muffler - actually I find it easier than dropping the license plate flap.

The centerstand mods are a bit more complex - basically 1/2 of the left leg of the centerstand has to be cut away, changing it from a O to a D shape. And to reinforce and close up the open side - some rather precision welding has to be done, with a gusset added to the curved section up into the straight part of the left leg.

The front wheel is more of a problem. There is a wider front wheel that will fit - 3 spoke - but it's rare. It was from a 1991 K100-4V. It is a direct bolt up, including the rotors. You have a later front wheel that isn't going to work since the rotor design is entirely different.

For some more info on this:

http://www.eilenberger.net/K75S/K75S.html

It's quite a nice modification to make, but the rear wheel is now offset towards the left side by about 5/8". I have felt no change in handling due to this - and the bike will go straight down the road with my hands off the grips (so much for the theory the stock offset causes drift to left/right/whatever), and you are restricted in what size tire you can fit...

I'm using MZ4 Metzler 60 series on the rear and 70 series on the front. The rear tire JUST clears the ABS modulator on the right side, and JUST clears the modified centerstand on the left side.

These are a nice grippy tire - way more grip then I'll ever use cornering, and lots of grip for braking. I'm looking forwards to wearing them out so I can try the MZ6 series, which are a lot of the same but better.

Best,

[jonzn]

Thanks Don for your reply. I had seen your site previously and feel that you know if there are any other solutions available. By the way, do you have any leads for the '91 K100RS 4Valve wheel that you mention?
Thanks
Mel

[deilenberger]

Originally posted by JONZ
Thanks Don for your reply. I had seen your site previously and feel that you know if there are any other solutions available. By the way, do you have any leads for the '91 K100RS 4Valve wheel that you mention?
Thanks
Mel

Mel - no real leads except keep an eye out on EBay motors and the MOA Marketplace and the IBMWR Marketplace.

Oh - one thing did occur to me. If you're not looking for the additional tire width - the later model K75's did have a 3 spoke rim option in the same size as the stock rims. There was a package available from BMW (for about $1,200) for them - or you could likely find a good set from the sources above if someone is breaking up a bike. The model designation of /3 - ie.. K75S/A/3 was usually added to indicate the 3 spoke rims. The /A indicated ABS.

Best,

[knary]

Originally posted by deilenberger
Given cubic amounts of money - anything is possible.

You are correct - you WILL have to modify the centerstand to fit the rear wheel/tire on. And it changes a few other things.. to remove and replace the rear tire - you have to drop the muffler. It will not clear the muffler and the brake caliper.. too wide.

It's not a big deal to drop the muffler - actually I find it easier than dropping the license plate flap.

Weird. I remember pulling the rear wheel without dropping the muffler or pulling the rear flap. It took a little wiggling, but the wheel would come out. :dunno

[deilenberger]

Originally posted by knary
Weird. I remember pulling the rear wheel without dropping the muffler or pulling the rear flap. It took a little wiggling, but the wheel would come out. :dunno

Scott..

On a bone stock K bike - if you have full height suspension and a perfectly flat area - sometimes you can get the stock size rear wheel out without removing anything.

With the wider wheel - it's a different story entirely - which is what we're discussing. The wheel with the tire on it is so wide that it will NOT clear the brake caliper and the exhaust. It hangs quite solidly on the caliper.

Pulling the exhaust (which is two nuts and loosen one bolt) allows it to come right out. Takes about 5 minutes to get the exhaust off and about the same to put it back on.

[knary]

Originally posted by deilenberger
Scott..

On a bone stock K bike - if you have full height suspension and a perfectly flat area - sometimes you can get the stock size rear wheel out without removing anything.

With the wider wheel - it's a different story entirely - which is what we're discussing. The wheel with the tire on it is so wide that it will NOT clear the brake caliper and the exhaust. It hangs quite solidly on the caliper.

Pulling the exhaust (which is two nuts and loosen one bolt) allows it to come right out. Takes about 5 minutes to get the exhaust off and about the same to put it back on.

ack. brain fart.

[YB in IN]

Originally posted by deilenberger
Mel - no real leads except keep an eye out on EBay motors and the MOA Marketplace and the IBMWR Marketplace.

Oh - one thing did occur to me. If you're not looking for the additional tire width - the later model K75's did have a 3 spoke rim option in the same size as the stock rims. There was a package available from BMW (for about $1,200) for them - or you could likely find a good set from the sources above if someone is breaking up a bike. The model designation of /3 - ie.. K75S/A/3 was usually added to indicate the 3 spoke rims. The /A indicated ABS.

Best,

You can but them here (http://catalog.ascycles.com/browseGroup.cfm?item_group_id=46718) for less along with some other goodies.

[deilenberger]

Originally posted by YB in IN
You can but them here (http://catalog.ascycles.com/browseGroup.cfm?item_group_id=46718) for less along with some other goodies.

They're still a tad expensive: Price: $1,023.68

Funny - my bike appears in the page you linked to..

Can you spot it? :confused:

[CustomSarge]

I had NO idea there are 2 visually identical 3 spoke K rear wheels! My K11LTX has a rear tire good enough for rest of season, but to go Nat'l (2k mi each way); NO. My spare rear 3 spoke has a new tire, so I just swapped 'em. DUH..... After heeding the wisdom of the guru....I went & looked (after 700 mi, MI->MN) it's offset to right by about 3/8"! Offhand I wouldn't have bought into the "static offset=no tracking difference", but I can vouchsafe firsthand. It would be just Too Much if somebody had a year(s)/model(s) fitment table. On rtn to MI, I'm putting a vernier caliper to each; from bare mating surface (no spacer) to outside of rim (straightedge on bead seats). I've simply GOT to stop making logical assumptions about part interchangabilities.
Some Harley traits die hard. TNX Don, I needed it again <<<)))

[knary]

yep.

There are the 3-spokers for radial tires as used on the R1100RS and there are the 3-spokers for bias-ply tires as used on some late K75Ss.

FWIW, both kinds are made of an extremely exotic alloy with the strength of wet clay. :huh

[CustomSarge]

Could the depth offset difference be solid attached vs. Paralever rear ends?

[deilenberger]

Originally posted by knary
yep.

There are the 3-spokers for radial tires as used on the R1100RS and there are the 3-spokers for bias-ply tires as used on some late K75Ss.

FWIW, both kinds are made of an extremely exotic alloy with the strength of wet clay. :huh

And 3 spokers made for radial tires on the 4V K100RS..

I've been lucky so far - I haven't bent the front rim even with NJ potholes.. I do pay a LOT of attention to the tire pressure, especially the front. Run it at 37PSI. Apparently letting the pressure get a bit low is a sure fire way to end up with a bent 3 spoke rim (I remember it was a BIG complaint when they first came out).

Best,

[deilenberger]

Originally posted by CustomSarge
Could the depth offset difference be solid attached vs. Paralever rear ends?

Sarge - I believe it might be, but I'm not certain the 4V K100RS had paralever. I think that showed up with the K11 series (might have shown up around the K1 also - but don't have one in the garage to check..)

If I get ambitious - I'll start up the parts CD and look.. hang on..

OK - the parts CD shows '89-92 K1 and '89-91 K100-4V as having paralever rear ends.. so I think your guess is correct. Using this wheel with a monolever rear end offsets it to the left.

Best,