I picked up a car this weekend that hadn't been on the track in a year. It was stored in a nice garage with no obvious moisture issues. However, neither the brake or clutch pedal would move.
I disconnected the linkage from the clutch and it became clear the issue was the master cylinder. It had seized up from rust somehow. All 3 had the same issue. I soaked in penetrant for a couple hours and no luck blowing the piston out with compressed air.
For reference, both brake master cylinders are Girling 3/4". The clutch is Girling 5/8". Pegasus sells them new for $133 and Jegs sells the RPC branded Girling clones for $59 each, so a cheap fix.
Thanks to Charlie for guiding me through removal. This is a pretty easy job.
Hi Mark, I am glad I was able to help. This is such a strange failure. I’m glad it is turning out to be fairly easy and cheap to fix.
Charley
Yes it's very strange, especially that all 3 master cylinders were frozen and looked identical with the rust you see in the picture. Knowing I wasn't putting them back in the car I put one in a vice and took a wooden dowel and hammer to tap in the piston. It took a pretty hard hit to move it.
Wilwood also makes a master cylinder identical to the Girling part and another more modern design with a slightly shorter stroke (only .125" shorter), both around $65 each. I went with the original part.
Correction to what I posted above. The clutch (driver left) is 5/8, rear brake (center) is 3/4 and front brake (driver right) is .70. All three are different sizes.
Note, there is a post in one of the UK forums that says the front master is .75 and rear is .70. According to Spring Mountain and what I took out of my car this is incorrect. I was told the front cylinder is .70 for higher pressure vs. the rear at .75.
I've seen this happen too on my Girling master cylinders... I'm guessing this is one of the reasons later cars have moved to Tilton...
Also my earlier car SR300376 did not come with a clutch pedal "stop".. As a result when the clutch pedal was pressed to full travel it would operate the rod at such an angle that it would wear the inside of the cylinder and cause premature seizing / leaking. I went through a couple cylinders before realising what the issue was... If you don't have a clutch pedal "stop" on your SR3 then I'd recommend you fit one. 🙂
Mine does have the clutch pedal stop. It doesn't seem to allow a whole lot of clutch pedal travel, but apparently it is enough to operate the clutch.
FWIW I just took apart my master cylinders due to leaking on front and clutch. Here were my sizes:
- front: 0.70”
- rear: 0.75”
- clutch: 0.625”
There was pretty bad scoring on the front and clutch, so I’ll replace. Has anyone tried repairing if scoring is minimal? Bob from Pegasus recommended a brake hone. Curious to know if attempts to repair scoring actually works or not. Here are some pics of the scoring on the cylinders.
I recently purchased all new master cylinders from Team Stradale and they provided Tilton brand master cylinders. They can be bought for around $100. Rebuild kits are $35 so IMO it doesn't make sense to rebuild.
