GS1100E Front calipers fit a GS1100GK?

[Guest]

Hi
Been slowly working through all the issues on my GK sidecar setup and have arrived at the front brakes. Currently they are really terrible with so much slop, the lever is on the hand grip before the brakes start to bite. Having a look at the calipers and there is stacks of slop in the piston/pads part of the caliper and it seems the holes for the slide pins are worn out. Is this a know problem or is again just a lack of maintenance/grease in the right place?

Having a look around, I can get lots of GS1100E calipers at a good price but they are not the same as the GK. Are they compatible? And remember, as for performance, we are starting at a very low bar.

Thanks

Scott

[Grimly]

Hi
Been slowly working through all the issues on my GK sidecar setup and have arrived at the front brakes. Currently they are really terrible with so much slop, the lever is on the hand grip before the brakes start to bite. Having a look at the calipers and there is stacks of slop in the piston/pads part of the caliper and it seems the holes for the slide pins are worn out. Is this a know problem or is again just a lack of maintenance/grease in the right place?

Having a look around, I can get lots of GS1100E calipers at a good price but they are not the same as the GK. Are they compatible? And remember, as for performance, we are starting at a very low bar.

Thanks

Scott

Yep; wear in the sliding pins - more especially, wear in the holes they go into - is a common problem with mileage on all the GSs that use those calipers, causing much lost motion and brown trousers.

Generally applicable point...
Luckily, there are thousands of low-mileage good calipers still available, on bikes that have been broken or about to be. Grab a couple while you can.
There's not much meat left to sleeve the worn holes, but perhaps enough for a v.thin bronze or brass sleeve. It's something I'd have a go at if nothing else was available, but once it gets to that stage, just as well to upgrade to later brakes and adapter plates as necessary.

More to the GK point...
The GK has the non-leading axle, iirc; check the disc size, caliper mounting bracket hole spacing and x-ref on the spares lists to see if any other model used that bracket.
I can only tell you from my own limited knowledge of the 850 - for the early 80s it shared calipers and brackets with a zillion other GSs (the L brackets are different, but the caliper itself was the same), but it suffered from the same wear pattern as every other model using that design. From 83-on there was a change, but I'm fairly sure the whole thing would swap complete. Again, not sure about the GK - it's probably got larger discs than the 1100E you mention, or different mounting hole spacing - thicker fork legs, of course. A lot of the 37mm fork brakes will swap over, but yours is the odd one out.
Otoh, Suzuki were pretty good at re-deploying existing parts, so you might find some combo of bracket and caliper will fit and work fine, but the 41mm forks will skew things - afaik, the GK was the oddball of the day with that size.
Unless you get lucky and find a decent low-mileage set of brackets, you'd probably be as well to look seriously at Salty Monk's upgrade and see if he does a bracket suitable for the GK legs.

[salty_monk]

I think you could also fit the Kawasaki Twinpots to that model. You'd have a lot more brake for your rig then!

[kingofvenus]

I think you could also fit the Kawasaki Twinpots to that model. You'd have a lot more brake for your rig then!

The Twinpot mod is the best bang for your buck for these bikes! I have them on my 850, that has a '84 GK fork assy on it.

[oracwa]

Thanks everyone. That has saved me endless mucking about resulting in a marginal improvement.

Scanned the threads and have a shopping list;
1. Rotors - F3 honda Honda CBR900RR Fireblade '94-97. They are 310mm & the bolt pattern is correct the holes just need enlarging.
2. Kawasaki Twinpot calipers. Sliding type. Not opposed piston. Ninja 600R, Ninja EX250 F 92-, 87-96 ZX750F (TOKICO stamped on the casting is good)
3. Master cylinder to suit above calipers
4. Adapter plate
Please let me know if I have missed anythng.
Thanks
Scott

[oracwa]

Hi Guys
Thought I would give the original calipers one more try and pulled them to pieces to check the piston and seals were OK. While I had it apart I noticed that although the bleeder valve was on top of the caliper (mine have been reversed and are mounted on the front of the shock, don't ask, it is a sidecar thing) the hole bored into the chamber actually penetrates about half way down the chamber as it is positioned now. This of course means that the top half of the chamber is still full of air when the bleeder is just venting fluid!

After the implications set in, I just unbolted the calipers and held them in their original orientation, and bled them like normal. Lots of air came out and after re-attaching the calipers, I had a full brake lever. Now if I grab a fist full of brake, I can easily make the front wheel lose traction.

Modifications are a fine thing but sometimes the unintended consequences take a while to sort out.

Cheers
Scott