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Dual brake circuit

Posted: 23 Jul 2019, 12:04
by Stan3
Hi
Can someone tell me (before I get home tonight) whether the dual circuit independently serves i) one for front brakes & one for back, or ii) one for n/s rear & o/s front, and one for o/s rear and n/s front?

The JK diesel manual handbook says the latter, but when I phoned them just now they said the former!

I've changed shoes drums & wheel cylinders and n/s is getting really hot whilst o/s stays cool...have readjusted to the textbook a few times now - nothing binding, flexible hoses not breaking down, and still gets hot.....when I read the manual last night I thought bingo -they're on different circuits so probably the mastercylinder piston seals for that circuit breaking down....so phoned JK and they said rears brakes both on one circuit....aaarrgghh

Does anyone know?....or maybe both systems exist?
Thanks for reading!
phil

Re: Dual brake circuit

Posted: 23 Jul 2019, 12:35
by 937carrera
Generally dual circuits are normally diagonally split...... there's one vehicle exception I know of that isn't.

Re: Dual brake circuit

Posted: 23 Jul 2019, 12:38
by Stan3
Thanks 937....that gives renewed optimism for solving this mystery...next job replace master cylinder!
thanks
p

Re: Dual brake circuit

Posted: 23 Jul 2019, 12:43
by 937carrera
Hah, and now I know of two :wink:

According to Mr Haynes it is split front / rear, page 10.2 of the blue manual, 179 of the green Aircooled version

Re: Dual brake circuit

Posted: 23 Jul 2019, 12:59
by Stan3
ah...so the Blue manual and the Jk Diesel manual (page 107) are in direct contradiction! None the wiser!

Re: Dual brake circuit

Posted: 23 Jul 2019, 13:03
by davidoft1
my rear solid line went recently, it came straight from the brake bias valve in a single line to the rear brakes, presumably the bias means it has to be split front to rear

Re: Dual brake circuit

Posted: 23 Jul 2019, 13:05
by Stan3
that makes sense...going to have look when I get home!

Re: Dual brake circuit

Posted: 28 Jul 2019, 08:01
by bigherb
davidoft1 wrote: presumably the bias means it has to be split front to rear
They are front-rear split.