MR2 Brake master and proportioning upgrade

[Negative Boost]

And a price too if you can remember!

Thanks
Sam

[Joshstix]

Pretty sure it's for an FJ80 and was about $180.

[TooF]

josh, just wanted to ask a couple of things about your hydraulic setup

am i right in saying this is the line setup



so rears get full force and you just limit the fronts using the p-valve? the line locker am i interpreting this as the line locker is locking the fronts then ? how is the locker working? build line pressure locking all 4 then lock it holding pressure to the front release pedal so backs are free but fronts are still under pressure ?

im running st185 twins on the front and aw11 stock on the back and want to put an adjustable bias valve in there to control front end lockup.

also at the same time fitting a bigger MC would be positive given the increase in piston area with the twins.

having the rear pvalve gutted doesnt this rick delivering too much to the rear ? or does the MC have some form of bias already built into it ?

[merc-blue]

Toof your setup is quite tricky,
Having no valve to the rear could deliver to much pressure to the rear
I would go the larger MC see what locks up then put your valve in depending on what is happening with the setup.
There is a good chance you will need the valve in the rear not the front becasue they are proportionally quite small to the twins you have on the front

[TooF]

well i havent setup anythign im just trying to interpret what josh has setup and consequently what will be most approprate for my own setup

[Joshstix]

That diagram is how I have mine setup.

I took it back off the road before doing enough testing with the proportioning valve to figure out if it was going to balance out right but with a couple of turns on the proportioning valve it was still too front biased even with the 324x24mm rear rotors with SW20 calipers.

The line lock is designed to hold presure on the fronts after releasing the pedal for burnouts at the drags.

[TooF]

yup ok, my question with the line lock should have been worded a little clearer (it holds pressure at the front as opposed to preventing pressure to the rear)

i have no need/interest in a line locker as im not a dragger or burn out king

my understanding would be that a "normal" setup for including an adjustable pvalve would be something along the lines of



when using a 1" master cyl would you still think there would be insufficent line pressure to the rear to justify putting the valve in the line to the rear?

i pretty much want it to lock the fronts first and then the rears not far behind them. as it stands i cant lock the rears at all. admittedly my rears need a bit of work on them atm. hence why im going down this path. may as well get it all sorted not just half done.

you dont happen to know which hilux MC's run the lines of the LHS?

my thought is that if i can get a MC with fittings on the left i can then plumb it straight up and simply replace the existing rear pvalve (factory) with the adjustable one. (correct?) just running from memory the front line simply has a single line from the MC to a tpiece then direct to the calipers no extra valving etc in there ?

[Joshstix]

The size of the master cylinder is changed for both the front and rear calipers so I would expect that if it is locking too early in the rear with the 7/8th stock master it would still do it with the 1 inch master. If you aren't sure about where to put the proportioning valve simply gut your current proportioning valves rear section and then test if you can get it to lock up as early as you want in a safe environment.

I'll be surprised if you get a good result with the prop valve in the rear line.

[TooF]

well at current i have st185 twins on the front and stock at the back including the stock p-valve. and the problem is the front locks way too early (feels like the back almost does nothing) and the pedal feel is a little too squishy for my liking.

so i was thinking of going for a 15/16 or 1" MC for increased fluid movment to reduce the squishyness and then the adjustable pvalve for the rear (with gutted or removed faactory valve) to allow a bit more fluid to the rears to remove some of the front bias.

perhaps id be best overhauling all the calipers (happening anyway) then installing the larger MC and go from there with that as my base to go looking into proportioning valves.

[Joshstix]

Definately. The proportioning valve should be a fine adjustment tool prefferably, so get it working as well as possible first. That's why I haven't played around with trying to get my proportioning valve right as yet, I'll be going to FD RX7 front calipers with the same rotors as I'm using on the rear and then I'll get the setup right for those components.

Before putting in a proportioning valve be sure to simply gut the rear section of the stock valve and see if with no proportioning the rears are doing enough work for your tastes. I'd hate to see you do the work to setup the adjustable valve and find that with it adjusted fully out you still aren't getting enough pressure to the rears.

[TooF]

well i priced up the rebuild kits for my calipers today (ironically the twin piston kit is half the price of the singles ?) but ill get them freshened up and then go for the bigger MC and take it from there.

the factory system doesnt have any valving in the front ? just the tpiece correct ?

you mentioned there were come hilux MC's that were more of a straight fitment to the existing aw11 plumbing, you wouldnt happen to know which ones ?

[Joshstix]

Sorry mate I don't remember which of the hiluxs it was, I just saw some when I was at pick and payless. I saw a nice alloy body one in a Surf but again NFI what model it was.

I am not too sure what is in the front half of the proportioning valve but I am sure it's not just a T piece. I did gut the rear section but I can't remember the front section. I simply replaced the valve with a T piece for the fronts and a straight through connector for the rears once I knew having no proportioning valve wasn't a problem.

[TooF]

ok fwiw.. i just went to the shed and had a look at some spares ive got kicking around (everyone has spare aw11 brake valves right ahahha)

the front looks like its just a t piece with an inlet of about 2.5mm and straight though outlets in the same ID. so it looks like the most straight forward solution for the setup im looking at would be to simply remove the stock PV and replace it in the original position with the adjustable unit.

whats even more polite about that setup is that given the inlet/outlet locations on the stock unit it may well even line straight up to the in/out on the wilwood DS488

[allencr]

[QUOTE=TooF]... pedal feel is a little too squishy for my liking. ...so i was thinking of going for a 15/16 or 1" MC for increased fluid movment to reduce the squishyness ...[QUOTE]


"squishy & squishyness" has to do with either air or compliance - something/s expanding and/or bending, and it will not be changed much at all the MC bore size.

[BigWorm]

Hey Josh, do you have the FD calipers already?
If not I have a pair sitting around here you can have.

And for those people looking at bigger bore MCs, MX73 & 83 MCs are 1" & 1 1/16" respectively & have the outlets facing the strut tower (iirc). MX83s are alloy & 73s are steel, but resleeving themm is usually easier than finding new replacements.