merchauser

1990 GT: I have searched and can't find any write ups on the specific procedure for replacing the clutch master cylinder.

Recently, my pedal has been intermittently "sticking" half way down, and today it was stuck fully depressed.
Pumped up a few times and the pedal operates properly. I will attempt to bleed the system and see if that helps, but I am getting feedback that the master might need replacing.

Looking for any info from others with this issue and how to replace the clutch master: I hope that this can be done with brake master, and booster in place? Also, I keep hearing about the blue hose, can someone educate me? Thanks

Mrmerlin

Here is what i would suggest you do to fix your car,
order the following parts.

NOTE make sure that the S4 version of slave cylinder is purchased,
its the longest version of the three made.

new clutch MC,
new Slave cylinder,
new Greg Brown flex line ( from the sway bar to slave)
new release arm bushing
check the MC push rod clevis pin for play if its worn replace the pin and clevis.
New Brembo Black feed hose
1 liter of Gold ATE brake fluid
Roger sells all of this .

NOTE fixing one part of this system will almost guarantee a future failure in short order,
thus you will be retracing your attempt at a repair.

AO

I disagree with Stan.

I would try bleeding the system first and see if that fixes the issue. If you can raise the front end quite a bit that may help to get the offending air bubble that is causing this issue.

Another thought is to make sure the line from the master to the slave is not touching or too close to the exhaust as this can cause the fluid to boil and introduce these issues.

If after all that, then I would look at replacing the MC and related items. Be forewarned, replacing the MC is a MAJOR PITA!

merchauser

the slave was replaced with correct part in May 2016.

what is the advantage to the Greg Brown hose? and what is
the Brembo black feed line and its advantage over the blue line??

I hear you Stan, and hope that I don't need to go down that road right now.

Mrmerlin

Well you could try Andrews suggestion first,
its the least expensive and might extend service life.
BUT.

Based on your report and whats happening the hydraulic system for the clutch has failed,
bleeding may restore operation but it will not be a long term repair,
I am giving instructions to restore the system to long term operation with minimum servicing or rework .

NOTE this hydraulic system is kind of like a battery,
it lets you know that its getting time to replace it.


Most hydraulic systems are original .
so if you replace one part then the next weakest link will fail, this is what your seeing now.


For my repair time and from fixing more than a few of these systems,
its best to replace the entire system so your starting fresh with all new parts.

These parts will last a long time if proper maintenance is followed.

That said the GB flex line will remove the air pocket that forms over the starter ,
it loops around the front of the starter and makes bleeding the clutch a painless operation ,
The old flex line and hard line are removed.

The new line is a life time part and its insulated from heat.

With the recent replacement of the slave cylinder then remove that part from my suggested list.

The black hose is just that,
a black hose to replace the blue hose, same hose different color,
made for brake fluid,
no clamps are necessary .
Always fit a new feed line onto the MC before installing it.

hacker-pschorr

How I swap a clutch master:


https://rennlist.com/forums/928-foru...he-fender.html

dr bob

I don't have a clutch master cylinder. But I did speak with a woman at a bar who had a cousin who sat in the waiting area of a repair shop while a lot of cussing was going on in the workbay. Apparently a clutch master was being refitted... That and a Holiday Inn Express pillow leads me to the following:

I'd thread a couple short lengths of 8mm all-thread into the MC ears. Then fit the hydraulic line and the blue hose. Then slide the MC into place with the all-thread poking through into the footwell. Pull the MC back into position using the all-thread from inside. Carefully unscrew one of the all-thread pieces, and replace it with the proper bolt. Snug said bolt. Unscrew the other all-thread piece, replace with the proper bolt. Snug said bolt. Peek in the engine bay to confirm that the hydraulic line and the blue hose were still where they need to be. Back into the footwell for final tightening of the bolts, and fitting of the pushrod linkage and the boot. Were it mine.

My local True-Value and Ace hardware stores carry 8mm-1.25 steel all-thread. I keep a piece handy for such adventures. It's cheap. Plus it keeps the workshop wall paint from turning blue, keeps my blood pressure normal. Lots of fringe benefits.

merchauser

Referring to my original post from this thread, I thought I needed a clutch master (since the slave was recently replaced),
because my pedal was inadvertently sticking half way down.

it was suggested that there might be an air bubble in the clutch line, which is close to the exhaust.

I have since flushed old brake fluid, filled with new ATE 200, bled brakes, and clutch system; and, for the past few weeks, my
pedal has been great.

so perhaps, when a symptom like this appears, the first plan of attach might be fresh fluid and bleeding.

Mrmerlin

Good an easy fix, glad your clutch is working,
if it fails in the future the advice I posted will restore long term operation.

merchauser

thank you, Stan. I agree with you and hope that I have a good while before
need to really "go through" the system