Wilwood Master Cylinder Replacement

I own P/2171. I am experiencing braking problems. There is absolutely no pedal resistance when pressing for the first 2-3 inches. I get limited braking when the pedal gets pushed all the way.
I went through a brake bleeding process. The front brakes bleed properly. However, no fluid comes out of the bleed nut on either rear brake.
It appears as though I am only getting the use of front brakes when driving the vehicle.
I have a lock nut on the brake bias bar. I don’t believe it has changed over time, and it looks OK.
I think I must have a defective rear Wilwood master cylinder.
Installing a new master cylinder looks very complicated.
Could someone please direct me to thread(s) describing the procedure; provide some general guidance; or suggest some other possible reason for the problem.

Thanks, Don in Maine (had the car for 5 years but still a rookie)
 
Don,

Your parts are on the way.

The replacement process is not that complicated, it is just difficult due to the space you are working in. Once the front lid is off, the A/C evaporator has been moved you open the crescent shaped hatch on the front of the tub. Six bolts hold the pedal assembly to the tub, once these are removed you can "duck walk" the assembly towards the cockpit to gain room. The reservoir hoses to the masters must be removed; have a container to put the open hose end into or you will strip the paint off the tub. Same for the flex hoses that go to the brake lines. Once this is done you can remove the masters. Bench bleed the new units and install. Make sure you replace the units with the correct parts, one is .625" bore and the other is .700 bore...they are marked on the housings. Replace the assembly and bleed the system.

It is not difficult work, just time consuming.
 
Try bleeding the master first if you can get to it. If you have calipers with bleeders on the outside and inside units, bleed the outer completely first, then inner.
 
Don, I hope that you got your master cylinders replaced last year. I'm just starting out on the same job (on 2140, early UK supplied car) and wondered how you got on with moving the ac evaporator to get access to the top of the pedal box/master cyls? Mine's well and truly glued in with masses of rtv and I'm a bit wary about what's under the plastic cover of the evaporator. I managed to trim out the rtv around the dummy alloy oil tank and remove that but now I'm staring at the plastic cover wondering if/how it's connected to the back of the dash. If it's just the wiring and ac gas hoses that exit the cover into the under front clip/radiator bay that connect to the evap unit then I'm happy to start cutting away at the sealant but I'd just like some idea what I'll find.

Cheers,

Mark
 
Mark- DO NOT open the plastic case for the evaporator if you only want access to the pedals. You should be able to pull the entire case forward and then unscrew the air hoses at the back. Disconnect the plastic hose on the drain outlet. There is a wire running under the case that I disconnect before rotating the case and A/C pressure hoses forward out of the way. That gives access to the ovoid chassis closing plate under the evaporator case.
 
Has your braking feel changed over time? If not, your bias bar might not be adjusted properly - when mine was incorrectly set I could sit there for 3hrs bleeding the brakes and they wouldn't bleed other than with just little squirts.
 
Just to put the final info on this, I bought 2171 from Don did the master replacement today. The rear master was stuck halfway down and seized with nasty brown fluid. We are in the process of flushing and bleeding the system.
 
Thought that I'd follow up after finishing my master cylinder replacements. Dave and Rick - your advice was invaluable and saved me a lot of time. Also gave me the confidence to just get stuck in. The original m/cylinders were in a real state with the rear circuit cylinder seized and the adjustable balance bar pivoting around it - no rear brakes. At the same time I installed a Tilton 3 way reservoir mounted on the stainless aircon cover/oil tank and had some new reservoir to m/cylinder hoses made up. The net result is brakes that work (the discs cleaned straight up with use) and a clutch that is still heavy but is now consistent in its action.

The proof will be LMC laps on Friday night (4th June) fingers crossed but, you know, bit by bit the niggles are getting sorted and confidence in (and enjoyment of) the car is growing. It's chassis 2140 which I understand was the first RHD UK demo car.
 
Thought that I'd follow up after finishing my master cylinder replacements. Dave and Rick - your advice was invaluable and saved me a lot of time. Also gave me the confidence to just get stuck in. The original m/cylinders were in a real state with the rear circuit cylinder seized and the adjustable balance bar pivoting around it - no rear brakes. At the same time I installed a Tilton 3 way reservoir mounted on the stainless aircon cover/oil tank and had some new reservoir to m/cylinder hoses made up. The net result is brakes that work (the discs cleaned straight up with use) and a clutch that is still heavy but is now consistent in its action.

The proof will be LMC laps on Friday night (4th June) fingers crossed but, you know, bit by bit the niggles are getting sorted and confidence in (and enjoyment of) the car is growing. It's chassis 2140 which I understand was the first RHD UK demo car.
My brakes on 2171 are now in the "hand of God" category! Took some time to bleed but worth it......and I have the hand scars to prove I did it!
 

Mike

Lifetime Supporter
Each winter when I have my car put away and torn apart for maintenance, I flush both the brake and clutch circuits. The brake circuits stay relatively clean. The cloth circuit is incredibly dirty after just a couple thousand miles the car is driven each summer. My fingers are crossed that by keeping the clutch circuit fluid flushed and clean that I will prolong the life of the slave cylinder inside the bell housing and not need to pull the drivetrain to replace that.
 
Top