BC

I bled it dan - but I bled it dirty with a vice grip.

BC

I should correct that. The letter in the car said Leeroy, so I am using that now. My wife likes "humphry" but we won't discuss that here.

BC

I don't have that info Jim. I can check that next time I can get the car down for maintenance. I think I actually have a slave cylinder that is new in a box. Are there part numbers to differentiate?

BC

I can check this when I get it off again. I was actually afraid of taking the rod out and breaking some rubber on it - it looked like it had been replaced and I had alot of other work going on at the same time, and was down to my wife's car. I may buy a cheap truck just to have a third working car this month. We'll see how sales go.

Landseer

I love that quote.

Git 'er done!

BC

Just an update for those following along at home:

I put the car next to the xilver 78 today in the garage to work on it while staying out of the beautiful San Diego sun today. 73 degrees and as perfect as it could be.

Anyway - the threads regarding the improper clutch master cylinder plunging piston shape had me thinking this would be the best second plan on getting the clutch on Leeroy to act as though its a clutch - instead of a rusty steel trap that doesn't want to let go.

I took out the plunger piston on the clutch master and voila - the piece has been replaced - and it was replaced with that funky kind that has the longer nose to it - keeping the travel of the master to a minimum that is NOT what the finicky DD clutch requires.

So I cut off over 15mm of it, and put it back in while putting pressure on the system with a motive bleeder. I put it in, let it come out a bit to burp the system, and operated it with my left hand on it, while with my right hand I (don't tell anyone) slowly approached reverse with the gear lever. when you do this GENTLY, you can audibly hear the reverse gears grinding slightly (very slightly) I do this, as it is an audible test of the amount of time it takes the gears to slow down to mesh when you depress the clutch. This time has been improved (reduced) and I did feel that I had made a difference.

I buttoned it all back up and man its so much more pleasant going through the gears. The transmission is finally allowed to do its job!

I found that the pedal stop is a rubber puck sort of thing hiding behind the rubber stuff in the footwell - and I may machine that down a bit to get another mm or so for the pedal to travel - but I can already tell that the machinations of the master and slave have changed where the clutch take-up is, and what happens during the entire travel.

I have no changed my opinion of the DD clutch. I think its a bastard of a system which required all individual parts operating at 99.5% at all times - which would be okay if the car were properly supported by the manufacturer - but it is not - and we are getting occasional out-of-spec parts or pieces which would be fine if the system was not so finicky.

Anyway - thanks for the help her and elsewhere to those who know. I may get porken's pedal stop if it can be adjusted to below where the stock pedal is stopped on a stock early car.

Mrmerlin

Ahh Brendan, you said you cut off 15MM of the MC piston??
Did you infact do any measuring to make sure that the outer piston seal wont go past the feed port when fully depressed in the MC??
If the outer seal does go past the feed port on full stroke then the MC will leak into the car when the pedal is pushed all the way down.
IIRC the correct amount to remove is 4 to 5MM and then reslot the tip.

BC

It's still not going all the way in because of the limitAtion provided by the firewall rubber puck. The measurements made by others have been to remove 14mm or so on one thread. I don't even see how it would have worked in this car with less removed.

I see your point- but because the travel was so off, I don't think this is a danger here. I'm just ecstatic about being able to drive the car normally now and enjoy it.

Mrmerlin

one other thing to add if you cut off too much piston then the return spring inside the MC will get crushed and eventually shatter this will in short time damage the rubber seal as metal shards will be floating around the Hydro system. BTDT

dprantl

Can you link that? I'm with Stan on this one, I recall threads talking about cutting off ~15mm from the *slave* rod, but only about 5mm from the *master* rod.

Dan
'91 928GT S/C 475hp/460lb.ft

Mrmerlin

I think its important to know what you actually cut Brendan.
as for cutting, the part I am referring to is the tip of the piston inside the master cylinder for the clutch.
The piston holds the sealing rubbers that slide against the MC bore.
If a new MC is used then the tip should be trimmed back about 4 to 5 mm and then the tip reslotted.
Prior to this the piston should be checked so that the outer rubber seal wont go past the feed port otherwise the feed port will leak fluid into the backside of the MC and begin leaking into the car once the pedal is pushed to its limit, also pay attention to how far the inner spring gets compressed as i have seen other MC with shattered springs this leads to the metal shards cutting the rubber seal on the piston

If your talking about trimming the slave push rod thats a different story

BC

I said master. I am not at the experience level where I will mistake a master and a slave cylinder.

The travel is not compressing the spring too much. The travel is not uncovering the feed port as I explained.

https://rennlist.com/forums/928-foru...e-old-one.html

As I mentioned, the pedal stop is restricting full compression.

It all works great. If you ever get the car Merlin, you would obviously be welcome to spend as many hours as you wish compressed into the footwell. Its torture for me, and the work I did is complete.

On to the suspension!

Mrmerlin

Ahh so you did say master my bad , Dan mentioned the slave pushrod, thats what threw me off.
BTW I was not questioning your skill level , I think that you possess quite a competent skill set when it comes to machines.
But just sharing experiences and information usually results in a better outcome for everyone

BC

Nice Dig on my skill level "when it comes to machines" LOL - specifically trying to divert a between the lines assumption of my skill level with people. I deal with people every day - I can be very charming when I need to - just not here. I sell life insurance for a living - my skin is thicker than you could imagine - so feel free to come out with it and call me an egotistical ******* if you want. It would be more straight forward.

My point technically is that it does not matter, in the end, where you cut that nose off - because as long as you control the pedal movement through the use of a stop of some sort - you will not have the feed hole issue, or the shattered spring issue -

For this system in THIS car,I need every millimeter I can get. I mad sure that the stop for the pedal is not letting the piston bind the inside spring.

The secondary issue of Porsche suppliers starting to run amok of the original OEM specs is a growing one, however, and I assume we will need to "customize" parts to make them work more and more with these cars.