Kawasaki Twinpot Brake Modification - who wants parts?

[salty_monk]

Hi Jeff,

Thought they would be... Those calipers only fit one way! They look good on there!

Cheers,

Dan

[Suzuki_Don]

Don,

Be careful with welding onto the caliper bracket, I don't know what grade steel it is but I would bet it's not simple mild steel. If it's a high carbon content steel such as quarter hard or EN8 or something welding to it would either "let it down" meaning it could bend easily or make it even harder (especially if you quench it with water or oil) & that could lead to cracking as it would be too brittle.

The Honda CBR900 RR disk from the 97-98 period is a 310mm disk with the right offset & hole PCD, you'd just have to enlarge the holes. I have a left one on Ebay at the moment. (I bought it to see if it would work with the dual disk... it doesn't - too big at 310mm).

Cheers,

Dan

Hey Dan what is the EBAY Item number please?

Cheers
Don

[8trackmind]

Hi Jeff,

Thought they would be... Those calipers only fit one way!
Dan

Ahh, but the spacing on that lower bracket is critical. Too far out and the pad hangs off, too far in and the pad hardware will rub. You have less than 2mm either way to play with. Yours are dead on!

[salty_monk]

Hey Dan what is the EBAY Iem number please?

Cheers
Don

Here Don http://cgi.ebay.com/ebaymotors/ws/eB...MESE:IT&ih=003

Dan

Jeff - thanks, I spent quite a lot of time mocking it up in cardboard & then drawing in CAD, printing it out 1:1 & trial fitting etc to get it right.

[salty_monk]

I now have a limited number of the 45mm bolts available. 8.8 grade. Bright zinc finish.

6 x 45mm x 1.25 fine thread bolts
6 Lock washers (spilt type)
2 Fine thread nuts

$6 + $2.50 shipping

If you want just the 4 x 45mm bolts & the lock washers then $4.50. +$1.50 Shipping.

You can use standard thread bolts & nuts for the other 2 if you want to.

Cheers,

Dan

[willycrash]

uhm...any of these brackets left?

uhm...any of these brackets left? and if so, are they available to complete strangers such as myself?

[salty_monk]

Yes & yes if you don't rip me off like the other almost complete stranger that had some....

[salty_monk]

Well here is phase 3 fitted....

Saves about 1.5lb over stock slotted rotors, 2.5lb over stock non slotted & about 6lb over the mod using GS550 Rotors.

unfortunately fitting these Honda CBR rotors really tightens up the tolerances. The spacer I have fitted I dropped in with a set of pads nearly on the wear limit as I wanted to check tolerances & I knew this would show me the extreme (about 2.5-3mm left a side of friction material) & the nearside pad is at risk of being able to drop out of the caliper...! :no:

The spacer I am using puts the inside of rotor the same distance from the wheel as the 550 rotor but being 3mm thinner the inside (of the caliper) pad has to move over an extra 3mm to compensate. This is just too much.

Fortunately the answer is simple... run an extra 2mm of spacer (which then brings the rotor rivets around 1.5mm away from the bolt (you have to be really careful what bolts, washers etc you use here!)

The other answer is to run pads down to a wear limit of around 5mm a side but I think this means you would be using only about 1/3rd of the pad from new!

I will be keeping the CBR rotors, need to get a friend to knock a few thou off a 2nd set I have so I can double them up & then I'll be running new pads & setting my wear limit to approx 3mm.

Here's some pics....






Dan

P.s. I still have brackets & bolts for sale plus I now have one full set which may go on Ebay.... Rotors, calipers & brackets / bolts. Everything except a caliper rebuild kit & pads.

P.p.s I don't have any sets of these spacers necessary to do the CBR rotor swap available yet (I *may* have one set) but I will probably get a few sets made up later this year.

[Suzuki_Don]

Well here it is. The variation on Dan's (AKA Salty_Monk) CBR front dual disc conversion. It has been done with:

The bike used is a '77 GS550B with wire wheels.
The narrow head stock used for the single disc Suzukis.
GS650G front forks with Progressive's springs and an overhaul (seals, etc.)
Salty_Monk's mass produced custom brackets (still available from him).
'89 Kawasaki Ninja ZX 600 twin piston calipers.
The disc/rotors are off an early 90s model CBR900RR Honda.
Stainless steel brake lines up to master cylinder (no junction below headlight).
Salty's brackets have been installed inside the fork mounting lugs instead of outside as is standard practise.

When Jeff (8TRACKMIND) did his 550 twin disc conversion a few years ago he had to cut the spacer down on the right hand side with a drill and cutting wheel. I was fotunate enough to have the front axle from a GS650 which had a shorter axle spacer by about 3mm and this was perfect for the job and there was no grinding or cutting required.

In fact this turned out to be a straight forward swap. Salty mentioned on his conversion that there may be a risk of the pads dropping out if not monitored as far as wear goes. This conversion was the opposite. I could only just get the new pads in place.

I think I have covered everything.

My only problem is my motor is still in pieces on the work bench so I cant try these brakes out for a while.

[salty_monk]

Well I "got er dun" & the CBR disks are fitted with new pads, all looks great. Works well too. No huge braking performance difference over the GS550 disks that I can feel (possibly a little) but I imagine they would come into their own in the wet.
Losing 7lb in Unsuspended weight shouldn't hurt things either in the handling stakes.

I finished up with the double spacer fitted but here's the strange thing... the distance from disk surface to inside surface of the caliper mount bracket (both of which are fixed as Don described earlier) are different. There's approx 2mm between them. This is not a big deal as I used a shorter bolt on one side & ended up with clearance of around 2.5mm - 3mm on one side & about 3.5mm - 4mm on the other.
In the end I will likely fit a 5mm disk spacer one side & a 3mm the other to even things out.

Now it gets even more interesting... when I measure my skunk (twinpots with GS550 disks) they are different in the same way but only by 1mm! Strange! This also seems to tally up with what Don saw on his setup, they are slightly different.

My guess is this is all due to Suzuki's tolerances & is also perhaps partially intended.

Some more good news... I should have spacers for those that want to do the CBR disk / Twinpot upgrade the middle of next month!

One last thought - if anyone has time to put a vernier caliper between their caliper mounting bracket & nearest disk surface (Jeff I'm particularly interested in yours) & report back I'd be interested to know the results, see if the differences are consistent or different or ??

More pics to follow later.

Cheers,

Dan

[first timer]

see if you can get some ebc HH padss for those calipers you should really notice a bite then.

[salty_monk]

Maybe next time I'll go a different pad compound but even with what I have & not bedded in they are a huge improvement over stock!

[salty_monk]

[steve murdoch]

Dan, are the CBR rotors from an F3?
What thickness of the rotors would be optimum or do you think getting yours turned down was a one-off?
I am hoping to put these on my spoked '78 GS1000.

[salty_monk]

They are F3 rotors. I didn't get any rotors turned down, I just used different thickness of spacer behind the rotor. The rotor is stock 4.5mm thick at braking surface. That matches the Kawa rotor that came with these calipers originally.

I am going to have some rotor spacers available next month for anyone who wants to do this mod incl CBR rotors.

Dan