k100/1100 Running Gear on a K75?

[imoir]

I've seen some photos of K100/1100 front ends on K75's.

Anyone done this?  Any advice? 

Does the rear wheel fit?

Thanks

[mystic red]

Duck will be along shortly... ;)

[imoir]

Thanks Duck.

Both actually.  I've seen examples so I know the front end thing works.  My question there would be about ABS.  If I have a 92 K75S, would I need a 92 RS front end to make sure the ABS was compatible?

My question about the rear had more to do with the wheel width.  Can it be directly swapped out S to RS?

How much work is it to fit the Paralever?

Thanks again.

[frankenduck]

The 93 and earlier K1100s have a different front ABS modulator and ABS brain from a K75. (94+ K1100s have ABS II so that's a whole different ball of wax and would be more work.) You have to modify the wiring harness and brake lines as well as swap the ABS brain and front modulator to make things work right.  At least that's the conclusion I came to after studying the details of the different ABS systems of both bikes so I made a hybrid ABS system in order to be sure things worked properly.  It might be possible to use all K75 ABS stuff but I can't say with any certainty if that would work out or not.

My bike has a 3x17 K1100LT rear wheel.  I haven't messed with it personally but supposedly the 4.5x18 RS rear tire will clear the swing arm but not the center stand so you need to swap in a 4V center stand for that to work.  The ABS ring on the rear rotor is the same so that shouldn't be an issue.

The paralever requires a 4V transmission so you have a place to mount the front of the paralever strut.  You also need a 4V shock and you need to make the right pegplate step out to clear the bulge in the swing arm.

[Rick G]

I have found that most of the transmissions after 89 had the tags under the case to allow for the paralever but not drilled to accept the bolt.  It is not just a matter of drilling a hole, it has to be in the correct place or you remove the parallel component from the paralever and upset the geometry of the rear end.

[frankenduck]

I have found that most of the transmissions after 89 had the tags under the case to allow for the paralever but not drilled to accept the bolt.  It is not just a matter of drilling a hole, it has to be in the correct place or you remove the parallel component from the paralever and upset the geometry of the rear end.

Yup. I have a buddy in LA who drills the tangs.  Me, I'm lazy and just use a 4V tranny where the sots in Chermany have already done it for me.

[motodude]

I don't have ABS on my '90 K75RT.  What's involved in the K1100 front brake swap?  Obviously (at least) fork lowers, wheel & caliper.  What else?  Any modifications necessary or bolt-on?

Thanks,
Tom

[frankenduck]

I don't have ABS on my '90 K75RT.  What's involved in the K1100 front brake swap?  Obviously (at least) fork lowers, wheel & caliper.  What else?  Any modifications necessary or bolt-on?

Thanks,
Tom

Forks are a different diameter so you need:

Front master cylinder
Upper and lower fork trees
Forks
Rotors
Calipers
Brake lines
Different front ABS sensor
K1100 front wheel

The K1100 also uses a different modulator up front.  Of course it has a different size fitting on one of the metal ABS lines so you need to change that.  I was lucky in that I found a local dude who had the right tool to do it and I had the right fitting from a parts K1100.

You also need a K1100 ABS brain and you have to move the one of the wires in the wiring harness connector for the ABS brain.

At least that's how I did it. You might be able to get away with using the K75 ABS brain/sensor/modulator but I was building my bike from scratch and I felt that building a hybrid system like I did had the best chance of success.  Took some analysis and extra work to make sure it would all be right but it worked as planned right off the bat.




My next project is to put a K1100 front end on a K75S but I've decided that will be non-ABS to simplify things.

I must say that it is quite awesome to have the 4V front brakes on a K75.  Allows you to push the bike quite a bit more.... ;D

[motodude]

Thanks for the quick response.  Can I get away w/o installing ABS?  Would I still need the K1100 front master cylinder?

This is very interesting as I'd love to improve the (front) brakes on my K75.

Thanks again,
Tom

[frankenduck]

Yeah, I think you'll definitely want the 20mm 4V master cylinder to push the four pot calipers. I ride a bit crazy at times and the only time that ABS has kicked in is on the rear.  I think anybody with a few miles under their belt can easily deal with a locked up rear - just don't let it slide out too much (or get it straightened out) before releasing  or you might highside.

[motodude]

BTDT.  Now, I always make sure I'm hard on the front brake before touching the rear brake.  Practice that, so that when it counts you do it w/o thinking.

Thank you for all the information.  Now to source the parts.