what master cylinder brake kit ?

[firsty]

Hi
I have just picked up 77 GS550b that has had twin disc front brakes fitted

the person who did the swap did change the master cylinder to a 5/8" one (Suzuki round screw top reservoir type with 5/8 cast on the underside) for the twin discs

I'm rebuilding the brakes now and I need to know what bike model I should use to order a brake master cylinder repair kit as it won't do me any good getting a 550 single disc one

the brakes are the original round pad style but again I'm not sure what they are off, Is there a difference between the calipers (thus the kits) for the twin disc Suzukis that used the round pads and if so how do I work out what I have

here are a few photos that might help


the caliper has 3/2 on it and the piston has 3.2 if that helps
-

bit of crud in there but lucky it was just dirty in the calipers with no pitting or damage (the pistons just pumped out with the master cylinder)


thanks firsty

[Guest]

Not sure that they are different from the other GS sizes of '77-'79, but they look to be similar to the ones on the 1000's. Sounds like you will need someone who is overhauling their brakes currently to confirm what they are by measuring the pistons, etc. Part numbers for the 550 are different from the 750 which are different than the 850 and 1000. Or compare what you have to other models manuals. From the repair manual, the 1000 front pistons are 42.82mm. The MC piston is 13.96mm. You should be able to find the 750 and 550 manuals on Basscliffs site for those measurements. Ray

[firsty]

thanks Ghostgs1

I downloaded the 750 & 1000 manuals to go with the 550 one I already had
and checked out the caliper piston sizes for bikes using the round pad style front brakes
550 = 42.79 > 42.81mm
550E = 38.025 > 38.05mm (European and Australia models only)
550L = 42.82mm
750 = 42.82mm
750E = 38.116 > 38.148mm
1000 = 42.82mm
1000E = 38.025 > 38.05mm
1000L = 42.82mm
1000S = 42.82mm

the pistons measured approx. 38.03mm, So it looks like one of the previous owners put the twin disc setup from the Australian 550E model on the B models wire wheels and this looks to be the same setup as the 1000E

I'll be looking for the 1000E seal kits because it will be near impossible to find part numbers for a short run 550E from 36 years ago

will be picking up some new circlip pliers this weekend so I can pull the master cylinder apart and make sure it is also from a 550E / 1000E

`

[daturat100r]

get genuine suzuki parts they have all part numbers on fische and generally no problem