Twinpot Brake upgrade on 78 Skunk

[steve murdoch]

The steel lines are a nice touch in completing the good looks of the new setup.
Are you using the stock master cylinder?

[80GS850GBob]

I think he was referring to your 220v (240v?) electrical wall receptacles above your workbench in the top left

Yes...yes he was.
...and I don't think we should be comparing nipples - this is a family site.{lol}

Beautiful, my Wezmoto s/s brake line kit came in today...1 day to get to Chicago from the UK....8 added days to get from Chicago to me {Chicago is a 60min drive from me}...nice to see the USPS is improving.

[bobtail84]

The steel lines are a nice touch in completing the good looks of the new setup.
Are you using the stock master cylinder?

Yep still using the stock M/C.

[niepoort]

does anyone know if GSXF600 / 750 88-97 Suzuki

disks would fit a gs850 1979 instead of cbr disks(really hard to find ,and if to expensive)
thanks

[mmattockx]

does anyone know if GSXF600 / 750 88-97 Suzuki

disks would fit a gs850 1979 instead of cbr disks(really hard to find ,and if to expensive)
thanks

Nope.

89-97 GSX750F rotor dimensions: http://www.metalgear.com.au/mgear-br...e-p-11690.html
CBR600F3 rotor dimensions: http://www.metalgear.com.au/mgear-br...e-p-11663.html
1979 GS850 rotor dimensions: http://www.metalgear.com.au/mgear-br...t-p-11585.html

The Katana rotor has a 5 bolt pattern and 19.5mm offset while the F3 rotor has a 6 bolt pattern and 17.0mm offset. The 6 bolt pattern is key, as the GS hub uses a 6 bolt pattern and you need the same number of holes to allow you to drill the GS bolt pattern into the F3 rotor carrier.

FWIW, that Metal Gear site also lets you search by rotor dimensions to see what can cross reference with what: http://www.metalgear.com.au/search_b...asurements.php


Mark

[pottsy09]

So i have been reading this thread for the last two days reading everything I can, and I have a couple of questions. my buddy had a 90s kawa these came off of, i do have access to machine tools and can make a bracket as need be. also as you can see that is the stock disc from my 850. is there any issue in what im doing? I planned to use the slotteds off my other 850 instead but they are the same dimensions. as long as the clearance is ok as stated before i should be fine?

[salty_monk]

I have provisionally looked at those calipers & I don't think you'll be able to get them in the right spot using the top fork leg mount like that. The pad is not sitting right on the rotor (which is dangerous as it will where a ridge that can then brake & jam the wheel) and if it were then you wouldn't have enough space to fit in the extra bolt you'd need.
You'll need a multi level 4 bolt plate I believe. It should be possible to make it work but I think you'll still need a bigger rotor or to space the caliper away from the fork leg in a clockwise direction top provide bolt clearance (so you may need custom length brake lines).
Check the clearance between the back of the caliper & the wheel spoke carefully.

[Cassius086]

OK...

I am going to read thru the thread, but thought I'll throw out a question anyway...

I have a Bandit front end mounted up on my '82 EZ. I am seriously considering going back to stock forks and upgrading the internals. However, I'd LOVE to be able to keep the huge 6 pot Tokico calipers and 300mm rotors. Will your adapter work with this combo, Salty?

[Chuck78]

I have a Bandit front end mounted up on my '82 EZ. I am seriously considering going back to stock forks and upgrading the internals. However, I'd LOVE to be able to keep the huge 6 pot Tokico calipers and 300mm rotors. Will your adapter work with this combo, Salty?

The bandit fork slider brake mounts both sit against the slider leg, whereas Salty's Tokico twinpot bracket is made to adapt to the type of caliper that has the upper mount against the slider tube, and the lower mount jutting out a considerable amount more. That is just the beginning of the list of why it won't work. The vertical location distance of the caliper mounts from the axle will be off as well. Not to mentionn you would have to have custom triples CNC machined in a width to accomodate those very thick 6 pot calipers, as they will be maybe 1" or less from each other (no room to fit a wheel between them) on GS triple width spacing.
Also you would need very substantial spacers between the rotors and the hubs
Why is it you want to swap back to stock modified parts? If you want GS wheels back, it's a lot easier to get adapters machined to fit a GS axle (GS1100GK front axle if you need something wider for the bandit forks) than it is to make those 6 piston calipers work on GS forks.

Either way, your triples are going to be the biggest roadblock. If you are running bandit triples and GS wheel, your steering geometry is going to be really out of whack. The bandit triples have minimal offset, generating A LOT of trail on a bike with a lazier-than-bandit steering angle (rake/caster) & much larger diameter front wheel than bandits. You would be best off getting custom triples made up CNC billet aluminium for $325 or so to get somewhere around 50mm of triple offset, give or take. That will make your sport bike front end steering sporty on your older bike. 1" longer rear shocks figured into the equation (the geometry really needs calculated accurately to determine rake and then figure proper triple offset) would assist a lot in making it steer sportier than stock.

Far too often, people swap modern front ends onto bikes with no regard for triple offset/front tire diameter/rake&trail geometry/ground clearance... you either end up with a bike that has fancy brakes and front damping but steers like a dump truck, or you get a bike with better brakes and damping but steers slightly slower than stock and has no ground glearance and ruins that nice 4 into 1 exhaust from hitting speedbumps and steep approaches...

[Chuck78]

In a nutshell, swapping modern front ends to vintage bikes is SUBSTANTIALLY more complicated than most amateurs give it credit for, as generally most seem to only consider steering stem bearing sizes and stem lengths, & if they are a step beyond that, they will consider the overall fork height. It is far more complicated than that in regards to chassis geometry, spring rates, & damping carachteristics.. which is why cartridge emulators, sonic springs, the twinpot brake mod, & adding 1/2" to 1" longer quality $200-300+ rear shocks is the best easiest way to go to make the most impact on how to improve the ride of your GS.

CBR600F3 (& Last year of the F2) forks in Honda PC800 triples & axle with the steering stops modified is one of the more straightforward front end swaps to get a cartridge front end, but it is more straightforward because it uses sliding 2 piston calipers... plenty of clearance for wider vintage wheel spokes.
CBR600F4 forks and brakes in 2nd Gen late 90's VMAX 1200 triples is the way to run the 6 piston calipers, but yours won't fit it. This still is close to rubbing the spokes snd nay require clearance milling the calipers slightly.

Both options will require custom wheel bearing and axle spacers, larger bearings, and probably custom rotor soacers.
These combinations (the triples in particular) will allow you to retain an 18" or 19" front wheel and keep your geometry in the right range to make the bike ride as it should with or operating ground clearance

[Cassius086]

Sorry for the confusion, Chuck. Allow me to clarify


I was wondering if the Bandit's rotors and caliper combo would work w/ Salty's bracket if I reverted back to an otherwise stock GS front end.

FWI, I was using 89 GSXR750 triples (Spiegler upper clamp so I can run handlebars) with the Bandit front end...stance is a bit lower and handling is a bit sharper, but I don't ride hard enough to really test limits of it any how. I mainly did the mod so for radial tires and much improved braking. Rear Bandit wheel in stock swinger, too.

[Chuck78]

There was no confusion on my end, as I said above, no, absolutely not. The Honda rotors and Kawasaki calipers will work, however. You can sell your current setup and recover plenty of your investment enough to buy the twinpot parts to fit the stock setup. The bandit rotors and calipers would require different brackets and rotor spacers, and custom wider triples and custom axle spacersto fit the stock forks. Basically the same would be required to fit the bandit forks properly - custom offset triples & axle spacers/bearings and speedometer drive.

[salty_monk]

- Yep what he said

[niepoort]

14355554_548195212044783_8691872777480229233_n.jpg thanks works great

[salty_monk]

Looking good! Thanks for posting a pic!