View Full Version : Wilwood clutch master cylinder leak
I finally hit my breaking point with my build and thought the best thing to do is ask for help.
The Mk4 has 200 miles on it and runs great. Took the car out today for one the many Californian inspections. While at a stop light I saw fluid in my pedal box. Once home I was able to inspect and it looks like it's coming from the boot of the master cylinder for the clutch (Wilwood master cylinder). Hard to inspect as there aren't any good angles ... from the top or the bottom. I don't see any other option than take off the body and some of the driver footbox aluminum panels.
Before I commit to taking the body off, does anyone here have any suggestions?
edwardb
08-27-2021, 10:51 PM
Agree it's awkward. But those MC's can be removed/replaced by reaching from the bottom (in the cockpit) and through the footbox access cover in the engine compartment. Body and footbox aluminum removal isn't necessary. FWIW, I had a Wilwood MC also fail in a similar way during a Roadster build. Started dripping fluid from the pushrod boot. But it was early before full aluminum or the body on so easier to fix for sure. A rebuild kit from Wilwood solved the problem. Best I could tell it was a defective seal on the piston.
lewma
08-28-2021, 08:35 AM
I too had a bad m/c on my MK4 but I was able to replace it without removing the body. The hatch on the top of the driver footbox and crawling under the driver pedals gives just enough room to do it
Mark
Thanks guys.
I plan to order the rebuild kit for the mc and attempt a fix once it arrives. I do have another inspection for CA registration at the end of this coming week and would like to drive the car to the appointment. Curious if you think the mc is pulling in air or just leaking. Obviously, it’s a guess given you aren’t able to see it. I’m trying to determine how much of a risk is it to drive with a mc clutch issue.
Also, I have the clutch pedal at full travel while I break in the transmission. Could that cause the push rod to leak? I doubt it but though I’d ask.
edwardb
08-29-2021, 05:26 AM
Thanks guys.
I plan to order the rebuild kit for the mc and attempt a fix once it arrives. I do have another inspection for CA registration at the end of this coming week and would like to drive the car to the appointment. Curious if you think the mc is pulling in air or just leaking. Obviously, it’s a guess given you aren’t able to see it. I’m trying to determine how much of a risk is it to drive with a mc clutch issue.
As you said, just a guess... technically maybe it is drawing in a bit of air if it's seals as I suspect it is. But should continue to operate the clutch with limited use. I wouldn't drive it if it were one of the brake MC's. If it's like mine, the leak wasn't massive. Just drips that eventually filled the boot and then dripped onto the cockpit floor. Not enough to affect operation but something you certainly wouldn't leave that way.
Also, I have the clutch pedal at full travel while I break in the transmission. Could that cause the push rod to leak? I doubt it but though I’d ask.
I doubt there's anything you did to cause it to leak. There are limit stops built into the MC.
SJDave
08-29-2021, 06:30 PM
Mine started leaking after 3000 miles, of course the drip always landed on my new Piloti Driving Shoes!!
If you've got a decent size access panel above the cylinders it's a pain but you can remove and replace in a about 4 hours with a buddy helping.
-
- Remove Driver Seat and put two layers of Harbor Freight moving blankets on the floor. Depending on how much you like your buddy, that's his spot lying on his back with his feet up on the rollbar.
- Remove Access Panel and cable tie electrical wires or hoses out of your way.
- You may need to buy some Harbor freight wrenches so you can grind them down as needed to fit; or cut and weld them to a tube so you van get leverage.
- Buddy on bottom should wear safety glassed or a Covid plastic face shield....because you will drop a wrench from above at least 8 times.
- Celebrate with a beer!
My Wilwood cylinder has porosity in the bore of the cylinder which had chewed up the seal. No rebuild kit was going to fix that. Another guy on the forum switched to a Tilton cylinder with good luck, so I went that way. OMG....the bore is polished and hard Anodized in the Tilton....WORLD OF DIFFERENCE IN QUALITY. About $30 more.
9 years since the Tilton went in and NO leaks.
76-Series Master Cylinders - Tilton Engineering (tiltonracing.com) (https://tiltonracing.com/product/76-series-master-cylinders/)
Blankets for the back is going to help!
Ziptie cables also a plus
Harbor freight wrenches and sand them down to fit … great idea
Face shield also a plus!
All good tips!
JohnK
08-30-2021, 10:52 AM
- Buddy on bottom should wear safety glasses or a Covid plastic face shield....because you will drop a wrench from above at least 8 times.
This made me laugh out loud. Dave, now I know who to call if I ever need to replace an MC since you've done this. :D
Avalanche325
09-01-2021, 03:15 PM
I changed out the entire Wilwood pedal box, put an new one in and converted to a hydraulic clutch in a completed car. You can certainly change a master cylinder.
I would start from the top and see how much you can do. I think you may be able to get it all from there.
If / when you go to the bottom:
Take the drivers seat out.
Put a towel on the body at your roll bar.............that is where your feet are going to be.
Wear safety glasses for all the stuff that is going to be dropping in your face.
Make sure that there are no children in the garage.
Prep your best swear words.