Larger Master Cylinder options?

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Larger Master Cylinder options?

Postby Numbchux on Sat Jan 02, 2016 12:50 pm

Having some braking issues with the XT6. I had a small leak at the caliper (turned out I forgot a crush washer when I put it together :shock: ), which was introducing air into the system. Then blew up a steel line going into the proportioning valve. But I've gotten all that solved, and in the process, bled the whole system several times.

I'm confidant that I have all fresh fluid, no air, and all moving parts in the calipers moving freely. I drove up and down the alley yesterday slamming on the brakes, moderate pedal pressure and only the fronts lock, firm pressure, all 4 lock. But the pedal still feels soft. I currently have '88 Nissan 200SX rear calipers (will allow rear ebrake), and Ver 1 WRX fronts (same as first-gen Turbo Legacy, 2-piston, 276mm rotor). Now this is a fairly significant increase in caliper volume over stock, but I ran this same setup on my Loyale with the stock master and I didn't think the pedal felt this soft. I know I've been spoiled by my Celica, as it has phenomenal pedal feel....


So, next course of action is a larger bore master cylinder. I know Caboobaroo used an SVX master on his GL coupe several years ago. Anyone here done anything similar?
'89 XT6, 4EAT AWD
'84 Brat, 4" Lift
'87 Toyota 4Runner...wheeling project
'91 Toyota Celica GT...Poly Bushings, brake upgrades, DD
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Re: Larger Master Cylinder options?

Postby Fury WRXT on Thu Mar 10, 2016 5:19 pm

I used a WRX master cylinder when I did my brake / hub upgrade, but I also upgraded the vacuum boost unit as well. Not sure if I needed to, but couldn't find much detail on capacity between the 2 units at the time, so just used a complete working unit. Cant remember much about it, as I did it years ago and have never done another. It would have been an early series
Chris
WRXT EJ20T XT- with a mind of it's own

Gen 3 Outback Limited 2.5 wagon, sadly as a daily driver

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Re: Larger Master Cylinder options?

Postby Numbchux on Thu Mar 10, 2016 9:16 pm

Shoot, I should have updated this...

Here's from my post on USMB on the subject:
Looks like the pattern for all XTs, EA82s, and EJs (certainly into the early 2000s) is this: Without hillholder cars had 4-ports on the master, the hillholder also functions as a splitter, so cars equipped with one only have 3 ports on the master. Similarly the ABS pump also functions as a splitter for both channels, as such, those masters have 2 ports.

Looks like XT6s had 15/16" bore masters, EA82s had 7/8" (I didn't look into this too closely, as it doesn't apply to me at all, there may be more to it), non-ABS EJs had 1", ABS EJ cars and all SVXs had 1 1/16"

You may notice in my list above, there's a crossover. Non-ABS (AFAIK, FWD only) SVXs had a 1 1/16" bore master with 4 ports. FYI, the official Subaru electronic catalog doesn't show FWD SVXs as being an option for '92-'93, but it does for a '94-'97, and many aftermarket catalogs followed suit.


Having an auto trans, my '89 XT6 does not have a hill holder, and therefore has a 4-port 15/16" master.

I suspect over the 5ish years of basically serving as nothing more than a parts car, I got air in the master, and it needed bench bleeding. I decided if I was going to the trouble, it was going to get an upgrade while I was at it.

As far as I can find, only Cardone makes a remanufactured masters for a FWD SVX. Part # 11-3849. It's either that or used (OE rebuild kits are discontinued...). Luckily those Cardone units are not terribly expensive.


As I mentioned, my old system was not working as intended, but still, after the swap, this is the most positive feeling EA82/XT brake pedal I've ever owned....despite the fact that this car has significantly more caliper volume than a stock EA82 (T-leg front 2-pot calipers, 200SX rears which have larger pistons than stock Subaru). I used the XT6 reservoir in the SVX master, the tab for the lock down screw didn't line up quite right, but it's still a tight fit in the grommets, so I'm not worried.


I then discovered that Centric makes a brand-new part, with SVX reservoir (low fluid switch connector will have to be spliced). Part number 13047019
'89 XT6, 4EAT AWD
'84 Brat, 4" Lift
'87 Toyota 4Runner...wheeling project
'91 Toyota Celica GT...Poly Bushings, brake upgrades, DD
Numbchux
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