Master clutch cylinder HOW TO:

[dmc3130]

I need to replace my master clutch cylinder because it's staring to leak at the push rod. Is there a HOW TO on this job? I look and could not find one.

Thanks :wrenchin:

[jawn101]

Hey Stephen - it's not bad at all. We could do a tech day soon if you want and work it with you, I'd get wrist deep in brake fluid in exchange for some of those burgers... ;-)

Seriously it's basically just disconnect the clevis at the pedal. Then remove the access panel in the trunk, drain the reservoir, disconnect the hard elbow (to the soft line leading to the slave) and the soft line to the reservoir. Take a giant Philips screwdriver (I think it was a #3) and remove the 2 screws inside the car holding the master to the pedal box. You might need line wrenches to get the hard elbow off the cylinder.

Wipe any dripped brake fluid off your frame/fuel tank immediately (wouldn't want to hurt that stellar frame of yours) and reverse to reinstall. Bleed the clutch.

[Tillsy]

The only pain is maneuvering the old / new master cylinders and the soft line elbow around the brake booster - bit of a PITA tight fit

[uhhair]

The shop manual should have some instructions in it, but honestly this job isn't too bad, only a few things to remove before you can get to it, mostly the access covers, etc. Some of the wrench work can be a tight fit and slightly annoying due to the cramped space down there, but that's about all of the difficulty involved.

[Victor]

It's true, a mostly easy job.
I did it a few months ago _ the only thing I had to be carefull was to bleed it carefully specially at the elbow just where the master cyl. attached. There was a bubble there. I just unscrew a little bit the line at that location and push the pedal, then screw it back. Works wonderfull now.
I also have an adjustable clevis.
It may also be an opportunity to installed a braided stainless steel flexible line between the master and slave.
Good luck

[David T]

When replacing the master cylinder you should also replace the slave. If the master was rotten enough to leak the slave is probably going to leak soon if it is not leaking already. If you still have the red plastic hose it should also be replaced. Ditto for the hose from the reservoir to the master cylinder. If the brake fluid is dark and thick check the brake master and see what that looks like. If it is also dark you are probably going to have to rebuild the brake system too. The brake (and clutch) fluid MUST be flushed AT LEAST every other year. If you do not do that the fluid WILL get corrosive and damage the interior of those systems.
David Teitelbaum

[dmc3130]

It's true, a mostly easy job.
I did it a few months ago _ the only thing I had to be carefull was to bleed it carefully specially at the elbow just where the master cyl. attached. There was a bubble there. I just unscrew a little bit the line at that location and push the pedal, then screw it back. Works wonderfull now.
I also have an adjustable clevis.
It may also be an opportunity to installed a braided stainless steel flexible line between the master and slave.
Good luck


Thanks for all the advise. My slave and master was replaced about 8 yrs ago and a stainless line installed at the same time. I was not replacing the fluid as much as I apparently should have. I bled the clutch about 6 months ago and now it just started to leak about 2 weeks ago. I'll keep an eye on the slave to see what it does. I do have the bleeder line from SpecialT to make the bleed job easier.:biggrin:

[dmc3130]

Hey Stephen - it's not bad at all. We could do a tech day soon if you want and work it with you, I'd get wrist deep in brake fluid in exchange for some of those burgers... ;-)

Seriously it's basically just disconnect the clevis at the pedal. Then remove the access panel in the trunk, drain the reservoir, disconnect the hard elbow (to the soft line leading to the slave) and the soft line to the reservoir. Take a giant Philips screwdriver (I think it was a #3) and remove the 2 screws inside the car holding the master to the pedal box. You might need line wrenches to get the hard elbow off the cylinder.

Wipe any dripped brake fluid off your frame/fuel tank immediately (wouldn't want to hurt that stellar frame of yours) and reverse to reinstall. Bleed the clutch.

What are you doing this Saturday?????? JK.

[jawn101]

What are you doing this Saturday?????? JK.

Lol, Saturday is pretty open but it sure sounds like we are both booked up Sunday. Do you already have the master at the house? Let's set something up in the next month or two, even if you don't wanna wait that long to do the job we should still all get together.

[dmc3130]

Lol, Saturday is pretty open but it sure sounds like we are both booked up Sunday. Do you already have the master at the house? Let's set something up in the next month or two, even if you don't wanna wait that long to do the job we should still all get together.

I was able to get installed in about 2-3 hrs with the help of my 12 yr old to bleed the clutch. I took my time and painted the access cover at the same time. All is good in DMC hood. Thanks for the offer. We do need to get together before this weather lets loose.:rofl:

[jawn101]

Awesome! See, it isn't so hard :) One of the easier jobs actually. David did mine while we were overhauling the whole car earlier this summer but I helped him a little and other than attaching the clevis back to the pedal, it didn't seem so bad.

[Chris 16409]

Take a look at what I found in the bore of my newish (purchased 10/29/2012) DMC-H clutch master cylinder. I appears like the piston has started to scratch the walls of the bore. My previous reproduction unit had started eating through the seals. Upon further inspection, the bore had become scored. Has anybody seen this before?

[BABIS]

Take a look at what I found in the bore of my newish (purchased 10/29/2012) DMC-H clutch master cylinder. I appears like the piston has started to scratch the walls of the bore. My previous reproduction unit had started eating through the seals. Upon further inspection, the bore had become scored. Has anybody seen this before?

wtf!!
I'm afraid of all the reproduction part. for example, I'm afraid of my brand new reproduction brake master cylinder which started to leak from the first day.. I had to use the 30 years old seals from the original one to get it working.

[David T]

Hard to tell from the pictures but to me it looks more like scuff marks than scratches. Scratches typically are much narrower. If you can't catch your fingernail or a probe on them they they are just scuff marks. Should polish right out with a cylinder hone. Scuff marks won't affect sealing anyway. It IS an aluminum piston in a cast steel cylinder and from rubbing it can scuff the bore. What usually happens to ruin the seals and make the master leak is the brake fluid gets corrosive and you see pits in the bore, not scratches. Once you get pitting the seal going over the rough surface of the pits gets damaged and then leaks.
David Teitelbaum

[chris williams]

Funney, I have just done a how to on this for our next club magazine, simply because I had to for my own project car. Just for interest this is a picture of the inside of a M/C that has not moved for 12 years. Replaced with a DMCH unit.
16085

[Nuclearbacon]

Hello All! I'm about to do this job tomorrow afternoon. My clutch pedal sank to the floor, and fluid was in my foot well. I called up Cameron down at DMCCA (Those guys ROCK) and he got me up a brand new shiny DMC master cylinder. It looks great. I've been reading up on bleeding procedures, and I see that the FSM says to bleed at the slave cylinder, but then in this thread, I read this:


... the only thing I had to be carefull was to bleed it carefully specially at the elbow just where the master cyl. attached. There was a bubble there. I just unscrew a little bit the line at that location and push the pedal, then screw it back. Works wonderfull now.

Looking at my new DMC unit, there is no bleeder screw, sooooo :hmm: I also saw the picture here (http://www.specialtauto.com/delorean-parts/images/clutch-air-bleeder-1.jpg) leading me to think that the only place to bleed it is at the slave cylinder. If so, anyone have any techniques? I'm only going to have a few hours to tackle it before work, and I'd love to have my car this weekend, it's the only time I carved out. Just trying to get as educated as i can ;) (I already own the stainless line, and I'm going to be ordering the slave cylinder asap., just trying to get on the road this weekend)

[DMC5180]

Luigi,

You will need a helper for this job. The 2 screws that hold the Master cylinder require a #4 phillips bit or screwdriver. Someone will need to hold the screw heads while you loosen the nuts on the front side.

Getting at the slave cylinder is easier from under the car, but can done from the top. There is a lot of stuff in the way on the top side, but it is doable if you carefully move things around. the easiest access is with the Air/fuel meter assembly out of the way.

[Nuclearbacon]

Ok, I'm going to go at it from the bottom, and a helper is planned to be here tomorrow :) Sounds much easier. I'm trying to locate a photo of where the slave cylinder is attached to the transmission, and I also assume I'm using the bleed screw at the top of the slave (http://store.delorean.com/p-8681-slave-cylinder.aspx) not some other fitting from the system like the fitting at #7 (http://store.delorean.com/c-384-4-4-1-clutch-hydraulics.aspx) It just seems like (again from memory) that the slave cylinder was at the top of the transmission, hence the location of this bad boy. (http://www.specialtauto.com/delorean-parts/images/clutch-air-bleeder-1.jpg) could just be a trick of what I'm looking at. ...by not having the car infront of me :)

[Nuclearbacon]

This picture makes me think the bleeder/slave cylinder is on the top of the engine... (http://www.specialtauto.com/delorean-parts/images/clutch-air-bleeder-1.jpg)

[Rich]

This picture makes me think the bleeder/slave cylinder is on the top of the engine... (http://www.specialtauto.com/delorean-parts/images/clutch-air-bleeder-1.jpg)

And it is indeed there. On top of the bell housing to be precise.

[Rich]

This picture makes me think the bleeder/slave cylinder is on the top of the engine... (http://www.specialtauto.com/delorean-parts/images/clutch-air-bleeder-1.jpg)

Another reference point to help you spot the slave:

http://store.delorean.com/c-384-4-4-1-clutch-hydraulics.aspx

The faded gray lines beneath the slave are the tranny/clutch housing for reference.

You won't see it from below, of course. But you can reach it from there.

Have fun.

[Nuclearbacon]

I wish I could let everyone into my head and show this crazy thing i"m picturing :) I will totally have fun :) hehe

[Chris 16409]

I recommend swapping out the philips/posi-drive screws for some allen head bolts. Much easier to deal with in my opinion.

[Nuclearbacon]

IT HAPPENED!!! I finally got the job done, thanks to a helping hand from my dad. I extended the job by ordering a new slave cylinder from DMCCA. (good thing too, mine was shot!!) So! I got the new master cylinder in, a new SS braided line, and a NEW Slave cylinder from DMC. The slave was a pain, but not as bad as I originally thought.

KEY FACTOR! when replacing the slave cylinder, you only need to remove the air cleaner and engine cover. Take off the heater hose in-between the hard line of the slave and the distributor (very back of engine). It'll allow you to pass the slave cylinder with the hard line down and out of the car. Then put the slave in place, and snake the line back up and tighten. I also zip-tied the heater hose flow controller to the spring loaded engine cover flapper thing to move it out of the way, bleeding was easy from the top of the engine with that moved towards the front of the car.

Then! My driver side rear caliper threw up a bunch of brake fluid, as the seal has died on the caliper. Onto the next! :) But WOOHOO for an awesomely stiff and solid clutch pedal! Thank you everyone for your insight :) I love this forum.


I recommend swapping out the philips/posi-drive screws for some allen head bolts. Much easier to deal with in my opinion.

Do we have thread pitches/sizes?? Does someone sell these? Because that's EXACTLY what we were saying yesterday. Why are these not allen head?!!?!?