Rear wheel finally swapped.

MACHV · October 11, 2019, 08:59:01 AM

With my Avon finally getting down to the wear marks, it was time to put that pile of parts together and accommodate the new PR4GT.

Charlie-brm · October 11, 2019, 11:30:33 AM

I am 'amping up' to do the conversion, possibly over winter or at least by next season. Once you had the parts all gathered, how long of a job was that, please?

Paul.1478 · October 11, 2019, 11:45:07 AM

Great looking bike.
I also want to do the conversion over winter.

MACHV · October 11, 2019, 01:48:20 PM

Quote from: Charlie-brm on October 11, 2019, 11:30:33 AM
I am 'amping up' to do the conversion, possibly over winter or at least by next season. Once you had the parts all gathered, how long of a job was that, please?

If you are talking pure assembly of all the wheel parts, ready to go, maybe 20 min.
In my case, this was all done kinda piecemeal. The wheel assembly was acquired 5-6 years ago. The Caliper and wheel needed rebuild and refurbish. Needed a custom brake line (obcessed about the length). Painted the wheel twice because I didn't like graphite. Obcessed about tire clearance (180/55 17 is a non issue). Had the tire mounted at the local bike shop. Obsessed about how long a bolt I needed to replace the lower foot peg bolt for the torque arm mount. Completely pulled out the swingarm and shock to lube everything (never done it before... to anything). Then a bunch of little OCD stuff to boot. Had fun though.

Tuned forks · October 11, 2019, 11:09:17 PM

GSXR wheel?
Have you read Ron Oort's post about shearing off the torque arm bolt?
I like the color of your wheel. Something similar to what will eventually happen to mine.

Joe

MACHV · October 12, 2019, 11:23:44 AM

Quote from: Tuned forks on October 11, 2019, 11:09:17 PM
GSXR wheel?
Have you read Ron Oort's post about shearing off the torque arm bolt?
I like the color of your wheel. Something similar to what will eventually happen to mine.

Yes, a 91 1100. Will have to look that up. Not too worried. I used the stock zuk bolt for the caliper and a hardened one for the forward mount. Can't imagine the failure is the norm, rather than an exception.
Joe

Tuned forks · October 12, 2019, 11:36:01 AM

A post from roortcloud in the West Coast Rally thread. I think he may have started his own thread with pics too. Don't remember.

WARNING!!
To anyone who replaced the right foot peg mount bolt with a longer one and attached the rear brake torque arm to it.
Mine just failed going home from the WCR. Sheared off at
the frame and spun the caliper around the axle.
Luckily it happened at very slow speed at a freeway exit stop sign.
The bolt I used was a grade 8 socket head cap screw that I obviously thought would hold up.
Anyone with this modification beware!!!
Ron Oort

Joe

MACHV · October 12, 2019, 11:52:25 AM

Quote from: Tuned forks on October 12, 2019, 11:36:01 AM
A post from roortcloud in the West Coast Rally thread. I think he may have started his own thread with pics too. Don't remember.

WARNING!!
To anyone who replaced the right foot peg mount bolt with a longer one and attached the rear brake torque arm to it.
Mine just failed going home from the WCR. Sheared off at
the frame and spun the caliper around the axle.
Luckily it happened at very slow speed at a freeway exit stop sign.
The bolt I used was a grade 8 socket head cap screw that I obviously thought would hold up.
Anyone with this modification beware!!!
Ron Oort

Joe

Well of course this would come to light right as I finish the mod. I mean, I just paid off a cc so my Jeep transmission could need a rebuild 3 weeks later. Life. Live it.

MACHV · October 12, 2019, 12:02:33 PM

It's gotta be a fluke. Otherwise, why wouldn't either the original aluminum swingarm mount bracket or a new welded one not crack before shearing a steel bolt? Seems a little counter-intuitive, at least, when looking at the meat of the old mount point.

woodcreekpete · October 12, 2019, 02:54:58 PM

Every time you hit a bump with your setup, the torque arm is trying to move the caliper to compensate for the changed geometry of what is now a triangle with one fixed point (the footpeg mount). Caliper's not going to move without a fight so there's loading on the bolt and sooner or later the bolt's going to lose the battle.

fj-f3a · October 12, 2019, 03:09:39 PM

Quote from: woodcreekpete on October 12, 2019, 02:54:58 PM
Every time you hit a bump with your setup, the torque arm is trying to move the caliper to compensate for the changed geometry of what is now a triangle with one fixed point (the footpeg mount). Caliper's not going to move without a fight so there's loading on the bolt and sooner or later the bolt's going to lose the battle.

This is 100% correct.

Please, for safety sake, do not mount the Torque arm to the footpeg mount.

It must be mounted to the Swingarm.

Bones · October 12, 2019, 04:12:51 PM

I'm pretty sure the torque arm isn't mounted on the swing arm on the early gsxr's, like on the FJ it looks too long to mount there, the torque arm I have is about two foot long. The whole setup is designed to move when riding, the caliper is free to move on the axle when the wheel is tight, there's a bush on the end of the caliper where the torque arm mounts to it so it's free to move up and down, plus there's a rose mounted bush on the other end of the arm where it mounts to the foot peg bolt that allows up, down and sideways movement there. I think the problem is the foot peg bolt is only supported one side and the stresses on the bolt can bend or sheer it off. If the arm was mounted between two tabs on the frame then the bolt would be supported both sides of the torque arm and be a lot stronger.

An FJ owner in England came up with the idea of fitting a caliper off a Gsx600f, this caliper sits upright like the FJ and the torque arm mount is to the front so gets mounted to the original tab on the swingarm, just have to make a torque arm to suit, or possibly modify the standard arm to fit.

MACHV · October 12, 2019, 04:19:11 PM

Is this happening on all the gsxr mods that linked to footpeg and have put on thousands of miles since? Because the only aluminum welder I knew just died three months ago.

MACHV · October 12, 2019, 04:40:50 PM

Got an idea. I am nowhere near the bike right now, but I wonder if I could install a long bolt on the top peg mount too and bracket the two bolts together. It should increase overall strength if there are no clearance issues. Will update later in the week.

fj-f3a · October 12, 2019, 07:32:02 PM

It should not be too hard to find a machine shop which can manufacture a new torque arm in the shape of a "Z".
That way, the original mount on the swingarm can be used.
The torque arm can be strengthened with some gussets if required.

If you desire to place a mount on the bottom of the swingarm, I would prefer a clamp type mount as opposed to welding a tab on.

I am in the fortunate position of being able to manufacture my own mounts.

Gavin

News:

Rear wheel finally swapped.