Brake bias valve / Proportioning valve

[H7ERO]

Where is the brake bias /proprtioning valve located on the supra? (iv searched the forum and read through two different workshop manuals)

 

It looks to be built into the master cyinder (the second cylinder on the side of the MC) but then how would that work with a diagonal dual circuit set up? (if indeed this is where it is located)

 

are there separate valve towards the rear of the car?

 

in the workshop manual it says to test the valve by using pressure guages on the front and rear calipers however the factory settings show no rear reduction in bias (i.e mastery cylinder pressure is the same as the rear caliper pressure)

 

The reason i want to know is iv decided to fit a manual brake proportionaing valve and remove the ABS, and i cant see the point in this without eliminating the factory valve (if there is indeed one) as ultimatly on maximum rear bias would still only be what the factory valve would allow.

 

Any input apreciated

[Paul Whiffin]

I've never found one, only thing I could think of is its built into the ABS unit perhaps?

[Morpheus]

This might help. Could be the same setup.

 

http://www.toyota-supra.info/forums/non-generation-specific-questions/13417-bad-proportioning-valve.html

 

I was thinking about this myself as I have a pair of 8 pots to fit so keep us updated?

 

This looks nice..... http://www.chasebays.com/product/toyota-supra-9398/brakes/chase-bays-2-way-brake-proportioning-valve

Edited June 22, 2011 by Morpheus (see edit history)

[ManwithSupra]

If you get anywhere with us keep us posted, I am looking to bring a bit more braking from the rear, however when I looked into it, to do it properly entailed having a non assisted dual master cylinder setup which is expensive and difficult to fit as the suspension tower gets on the way.

[ManwithSupra]

This may help.... http://www.mkivsupra.net/vbb/showthread.php?206571-1993-Supra-Features-Brochure

Page 165 - Brake system

[H7ERO]

Paul: i suspect that it is built into the ABS module if there is no other unit on the car (although what is the second parallel cylinder builot into the master cylinder? . . it looks very much like other toyota brake proportioning valves . . . but it must be disabled or it would proprtion the brakes diferently LF RR to RF LR . . Ie very highly unlikely)

 

Morpheus:

 

that first thread is for a mk3 supra it has a differnt brake circuit layout, and ABS system (my last car was a mk3 and i removed the ABS but didnt fit a valve)

 

im using the compr brake one:

http://www.compbrake.co.uk/Brakes-Acc-39-s/Brake-valves/BIAS-VALVE-knob-WITHOUT-UNIONS/prod_969.html

However they all seem to be the same one . . just different brands etc out all the ones iv seen for sale

 

Richard:

Page 164 of the manual:

States there is a brake proportioning valve : delfelction point of hydraulic pressure 427psi (2jgte) and 356psi on the 2jzge . interesting different figures for both engines, and a reduction gradient of 0.37

 

I might consider fabricating a using a dual MC set up . . but not till iv tried this first . .

 

i might get round to it later today . .

[ManwithSupra]

Paul: i suspect that it is built into the ABS module if there is no other unit on the car (although what is the second parallel cylinder builot into the master cylinder? . . it looks very much like other toyota brake proportioning valves . . . but it must be disabled or it would proprtion the brakes diferently LF RR to RF LR . . Ie very highly unlikely)

 

Morpheus:

 

that first thread is for a mk3 supra it has a differnt brake circuit layout, and ABS system (my last car was a mk3 and i removed the ABS but didnt fit a valve)

 

im using the compr brake one:

http://www.compbrake.co.uk/Brakes-Acc-39-s/Brake-valves/BIAS-VALVE-knob-WITHOUT-UNIONS/prod_969.html

However they all seem to be the same one . . just different brands etc out all the ones iv seen for sale

 

Richard:

Page 164 of the manual:

States there is a brake proportioning valve : delfelction point of hydraulic pressure 427psi (2jgte) and 356psi on the 2jzge . interesting different figures for both engines, and a reduction gradient of 0.37

 

I might consider fabricating a using a dual MC set up . . but not till iv tried this first . .

 

i might get round to it later today . .

 

Did you manage to sort out a Dual MC set up?

[H7ERO]

the bias valve requires some non standard unions i havnt been able to source yet . . .

 

Im now looking at these:

http://www.compbrake.co.uk/PEDALBOXES/PEDALBOXES7.html

http://www.compbrake.co.uk/PEDALBOXES/PEDALBOXES4.html

 

il have a measure up in the supe tomorrow to see if its possible without to much hammer and grinder

[Paul Whiffin]

the bias valve requires some non standard unions i havnt been able to source yet . . .

 

Im now looking at these:

http://www.compbrake.co.uk/PEDALBOXES/PEDALBOXES7.html

http://www.compbrake.co.uk/PEDALBOXES/PEDALBOXES4.html

 

il have a measure up in the supe tomorrow to see if its possible without to much hammer and grinder

 

Didn't Ryan try these out and found them to be rubbish?

[H7ERO]

ok my inital problem is brake MC seal failiur some nicks out of the pistons (looks like they were cut on the output holes inside the MC bore) wierd as this only occured after i wound back the pistons in my rear calipers.

 

initial research into dual MC set up:

 

supra brake pedal ratio = 3:1

non servo assisted ideal ratio 5.5-6.5 to 1

there is space to fit a bias box to the existing servo but i dont think it will seal properly with the movement (as you can brak the seal with a tiny deflection by hand)

removing the servo and using the existing pedals -plenty of space but again incorect pedal ratio, i think there is space to redrill the current brake pedal for as 5.7 ratio (move the linkage 5cm up) due to the angle of the curent cylinder (its tilted downwards) making it more level would allow a more aceptable ratio (may not be enough stroke on it ?)

 

or just rebuild or replace my own MC

 

or a reverse floor mounted pedal box? (space for that)

.....................................................

 

So more reading and calculating . . seems moving the MC clevis up 5cm (achieving a 5.7 ratio) and using a dual Mc set up with like a .75 and .625 bores should be not much harder than the current effort required on the brakes (If anyone has real world experience please comment . . )

 

then i found this : pricy but aparently requires no modification to fit ( how can this be so?)

http://www.compbrake.co.uk/Bias-Pedal-Boxes/Floor-Mounted/Toyota-Supra-Hyd-Clutch-cockpit-fit/prod_587.html

 

looks like the one ryan tried? that was an OBP one but like to be the same unit

Edited July 3, 2011 by H7ERO (see edit history)