Twinpot Brake upgrade on 78 Skunk

[Chuck78]

Help! Does anyone have their old Suzuki dual disc brakes still? I need a front caliper piston from a 78-79 GS750EC/EN dual disc model with the 3mm diameter caliper pistons. Trying to put together a bike for a friend with a big time crunch. I should have just gone twinpot mod after the cost of dual caliper seals and all rubber parts, and a major hassle with the master cylinder disassembly on the original parts...

All new rebuild parts for the stock setup (existing pads) and new reservoir... live and learn...

I think the GS1000E 78-79 may be the same but I'm not certain. May Dremel the rust pits out and JB Weld/sand them smooth until one can arrive NOS from England (obsolete from Suzuki)

Thanks

Chuck

[salty_monk]

One back at you

Hey Salty you have a PM

[limeex2]

Just some info for those struggling to find decent used rotors from almost 20 year old motorcycles. I bought all the parts a number of years ago, then life intervened with a house move followed by a divorce so I didn't do the actual conversion until last year and then didn't get to ride it until this spring. On the first ride the F3 rotors showed their age and one warped fairly massively during the 30km or so bed-in run. Looking at fleabay showed nothing but tired rotors that are now 20 years old so I took a chance and ordered these:

http://www.ebay.ca/itm/141665954758?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

The price wasn't cheap, but they were brand new and had a warranty. They shipped to me in 3 days for $20 (try that in North America...). They are nicely made, quality looks good and everything fit exactly as it should. Mounted on my 82 1100E:



Just for reference, the OEM Suzuki rotors weighed 1653g each, the F3 rotors weighed 1342g and these ones weigh 1230g. That is a savings of 423g per rotor for a reduction in unsprung rotating mass of nearly two pounds. If you can bring yourself to run Chinese brake parts these offer a way to get a much more certain component than the ebay lottery.


Mark

I believe those are Arashi rotors and I am running them on my ZRX. They work well. If you look, most modern wheels are made by Arashi. They were $178 shipped to my door in about a week.

[mmattockx]

Just some info for those struggling to find decent used rotors from almost 20 year old motorcycles. I bought all the parts a number of years ago, then life intervened with a house move followed by a divorce so I didn't do the actual conversion until last year and then didn't get to ride it until this spring. On the first ride the F3 rotors showed their age and one warped fairly massively during the 30km or so bed-in run. Looking at fleabay showed nothing but tired rotors that are now 20 years old so I took a chance and ordered these:

http://www.ebay.ca/itm/141665954758?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

The price wasn't cheap, but they were brand new and had a warranty. They shipped to me in 3 days for $20 (try that in North America...). They are nicely made, quality looks good and everything fit exactly as it should. Mounted on my 82 1100E:



Just for reference, the OEM Suzuki rotors weighed 1653g each, the F3 rotors weighed 1342g and these ones weigh 1230g. That is a savings of 423g per rotor for a reduction in unsprung rotating mass of nearly two pounds. If you can bring yourself to run Chinese brake parts these offer a way to get a much more certain component than the ebay lottery.


Mark

[salty_monk]

Looking really good Rob!

All sorted, once I put a few brain cells into the mix Will take it out today for a test ride, happy with the look though, might just need to get one of those gold chains that Trevor likes so much. Might even put on my EPM rims to boot.





Thanks a ton Dan for making these up!

[Chuck78]

I gotta ask...what's the braking difference between the different sized twin pot calipers that everyone is using and the matched hole calipers?
procuring parts for my twin pot upgrade, my 07 Kawi EX650 MC came with it's matching calipers - which happen to be the same sized hole type. I'm told those aren't the ones of choice.....I get that....but it's my usual curiosity that makes me ask why this is?...

When I saw this GS picture on Carpy's Cafe Racers/CB750 shop's website/blog (GS's he was making early Yoshi style hand bent exhausts for), I instantly recalled this post on here that confused me with it's "matched hole calipers" terminology for twin pistons of equal diameter.

I have ridden a couple of bikes with those later brakes fitted. Similar in every way. The bracket does not suit our purposes as well & they don't work with that bracket. Eventually I will look at them as an alternative when it becomes impossible to get good calipers but haven't had a chance as yet other than to have a quick look and see that it will be a 4 bolt bracket & will be more complex than what we currently have. (Read MORE EXPENSIVE )

That is a GS, but I believe it has Morris Magnesium mag wheels with Honda CB bearing retainers. I noticed old Goldwing wire spoke wheels looked very much like GS hubs in that they had a 6 bolt rotor pattern of similar proportions and similar hub design (ribs in between the flanges).

[azr]

All sorted, once I put a few brain cells into the mix Will take it out today for a test ride, happy with the look though, might just need to get one of those gold chains that Trevor likes so much. Might even put on my EPM rims to boot.





Thanks a ton Dan for making these up!

If you really felt the need to go "bleeders down", I'd suggest you leave them unbolted from the forks, throw a block of hard wood in between the pads {or pistons} so they don't blow out....hang them up over the handle bars and bleed them up high / bleeders up. Let air/gravity do it's thing. When all clear of bubbles you can drop them back down and bolt them up......
....my 2 cents, fwiw...

[azr]

Hey Dan, or anyone else for that matter, does it matter if I turn the calipers around? so the bleeders are at the bottom instead of the top? I mounted them both ways and it doesn't seem to matter spacing wise but I'm having the usual pain in the arse issue with bleeding and was wondering if that would be the issue. Keeping the bleeders on top gets in the way of the old school stainless lines I have.

[salty_monk]

Yes all twin discs are 274mm as far as I know.

[bobtail84]

if you have a 295 mm dual front disc setup, I have never heard of such a thing, but that would require 310mm rotors with this brake setup.

the only way you would normally be able to use stock GS rotors would be if you have a 275 mm dual disk then used 295mm (single disc) rotors for left and right front. you lose a lot of the benefits that by using the very large heavy stock rotors, and they won't last very long with modern pads.


basically with this brake conversion, if you are running a Suzuki GS fork that had 275mm rotors, these calipers will then be in the position to run a 296mm rotor.
if you are running a single disc Suzuki GS Fork that originally had a 295 mm rotor, then you will need to run a 310mm rotor with twin piston caliper setup. there is no set up with this type of caliper swap that will allow you to keep the same size of rotor that the original caliper ran on.

Well Chuck78 I do sit corrected.. I went outside and re measured the rotors in the day light and guess what? you were spot on they are 275mm not as I first said 295mm. When I measured the rotors and then contacted a friend he mentioned that there were some 295mm twin discs about so I assumed that was what I had.. what do they say about assumption.

[Chuck78]

at some point this spring or summer, I will have a set of 35mm dual disc fork lowers to part with if anyone has a single disc and is looking to convert to dual disc. the stanchions are rusted, and my spare stanchions have one that is slightly tweaked less than half a millimeter after hitting a deer. (could be straightened)

[Chuck78]

Just measured mine and they are 295mm I do think the GS1000 over here in the UK all pretty much came with 295mm Rotors, mind you I could be wrong

Offering one of the brackets with caliper attached to the fork it looks like will fit with the original rotor. Is there a reason it can't be used? I do have a slight ringing bell in the back of my mind but can't for the life of me remember if there was a good reason for it not to.

Jeff

if you have a 295 mm dual front disc setup, I have never heard of such a thing, but that would require 310mm rotors with this brake setup.

the only way you would normally be able to use stock GS rotors would be if you have a 275 mm dual disk then used 295mm (single disc) rotors for left and right front. you lose a lot of the benefits that by using the very large heavy stock rotors, and they won't last very long with modern pads.


basically with this brake conversion, if you are running a Suzuki GS fork that had 275mm rotors, these calipers will then be in the position to run a 296mm rotor.
if you are running a single disc Suzuki GS Fork that originally had a 295 mm rotor, then you will need to run a 310mm rotor with twin piston caliper setup. there is no set up with this type of caliper swap that will allow you to keep the same size of rotor that the original caliper ran on.

[bobtail84]

Check post #546 for a list of rotors that will work. The GS550 Solid rotor in on the list, as well as some "L" models. The key is 296mm, most GS's are 275

Hmmm.. Just measured mine and they are 295mm I do think the GS1000 over here in the UK all pretty much came with 295mm Rotors, mind you I could be wrong according to my wife....