Can you bore the master cylinder 5/8 to 3/4?

[4000GT]

Got a JZA80 5/8 and need a 3/4, can it be bored that far? or are there 3/4 options that bolt on? Thanks!

[manny]

Interested in replies also as I'm in the same position.

[styler]

if theres enough metal there you can bore it out as that is how resleeving
old master and slave cylinders is done, with a bigger stainless steel tube
insert put in the oversized bore and finished as the original inside diameter.

finding internals to work inside is the problem at hand though...

its common to swap master cylinders in from other cars with the
bore size required and bolting pattern if lucky or drill firewall to suit.
pedal throw, single / dual circuit, pipe mounting and pedal linkage
should be considered, boosted should be okay generally but im not sure
on how abs works or how abs would be affected by it though.

[4000GT]

^ Ok so you dont know either...

I will take mine out today and see if anyone local wants to have a go at boring it. Will keep you posted manny.

[JustenGT8]

We have a local brake shop that does this regularly....i can't say the exact size is doable but if not it would be near enough. The stainless sleeve means you never have to worry about corrosion and leaks again

[4000GT]

Hmmm I just went to a mates house, had a look at some old Toyota master cylinders, there didnt seem to the much meat on the bone to bore. I think Ill space the release bearing slightly closer to the fingers as its a 1mm too far at the moment. I hate dealing with this tight tolerance stuff.

[Crambo]

I got a new 3/4" master from 4WD shop (Hilux, I think) bolt in for A61, about $50.
I will do the same for brake master when I figure the bore I need, (about $110)

This is old series stuff tho.
Later stuff need the reservoir more accessible, could be worth a look at Holden/Ford, they use remote reservoir connected by hose.

[wilbo666]

Just to clear this up, we are talking about clutch master cyls, not brake right?

Cheers
Wilbo

[4000GT]

yeah mate clutch master.

[allencr]

A smaller slave also has the same effect you may be looking for

[4000GT]

Only I have a hydraulic QM floating release... so not possible.

Im getting a seat machined up at the moment to trying moving the bearing closer to the springs. Will see if that works, guessing it will.