View Full Version : ST4 Master cylinders, size

04-14-2016, 08:10 AM
Hi Guys,

I'm wondering if the Master cylinder specified in the plans will be correctly sized for the specified brake and clutch setup.
I've read a few posts reg. other buggy models, f.ex. SS1000 and the R16, that the guys use a 0,75" master cylinder for the front wheels, but a smaller for the single rear caliper, and even smaller for the clutch (to give enough travel on the clutch-pedal.

However, for the ST4, the plans specify 0,75" masters for both front, rear and clutch.

Do anyone have any inpuit on this, and some pointers as to the sizes they are using?



04-14-2016, 10:50 AM
Due to some glitch (or me pressing "submit" more than once), the thread has been posted twice.

04-14-2016, 02:55 PM
I run one 3/4 to two front brakes
one 3/4 to a single rear brake
3/4 can be used on the clutch too, but I run a 7/8 for a shorter stroke

5/8 I run when using a single MC to a single brake on the rear with no front brakes
in that application the softer feel and longer stroke work better

so the bigger the MC the shorter the stroke and the harder the pedal

04-15-2016, 10:57 AM
Great info, Protodie!
Seems the MC's might be correctly sized after all - I guess It boild Down to personal preferences; if one likes a short-stroke clutch, or prefer some travel on the arm for softer shifting.

I'll have to try for myself when testdriving the buggy.

Thanks for input (and parts BTW - they cleared customs yesterday, and was delivered this morning to my address in Denmark)

04-15-2016, 11:15 AM
I run 3/4" masters front and rear , into 4 spot M/C calipers , 2 discs up front and 2 at the rear , with 300mm dia discs all round , The pedal ratio is 6.25:1 This combo makes for a light pedal and run a brake bias bar to adjust braking forces from front to rear

As for the clutch I run a 5/8" master cyl and I restrict the pedal travel to around 2/3's too much travel here can mess up the clutch , clutch plates can drop , damage clutch springs, crack clutch housings ...... etc etc

Every buggy is different though