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Recently Replaced My Clutch Master Cylinder

Dons

By Dons,
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Dons Contributor

Dons

Posted
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Hey guys,

Recently replaced my clutch master cylinder with the assistance of this post here:

http://www.skylinesaustralia.com/forums/To...Ma-t126049.html

Fantastic tutorial helped out heaps. I have completely bled the system out and everything is connected back up. Used the following tutorial for that.

http://www.skylinesaustralia.com/forums/Bl...amp;mode=linear

So my issue is I can't tell if there is air in the system or if there is something wrong. Im only getting pressure in about half the pedal. i Cant see/hear/feel any air coming out of the system and I have bled it from the 3 valves that i can find.

The one on the master cylinder, the one on the dampner box and the one on the slave. I have an 89 GTST and from what I can tell in the tutorial there are 4 valves but I can onlu find 3? Wondering if this could be the source of my problem?

Any ideas would be awesome! Cheers :blush:

Dons Contributor

Dons

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where is the fourth valve? I have found the one on the master cylinder, the one on the dampener box and the one on the slave... i have followed the line from the master to the dampener and cant find one in between but think this is where im missing one???

Dons Contributor

Dons

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I followed the instructions exactly except for the fact that I couldnt find the second bleeder he was talkin about. The one from the master leading to the box. I found the one ON the master, ON the box and ON the slave but none in between. Is it possible that my master cylinder wasn't the problem? I was driving along, I clutched in and I heard a loud pop noise and gear changing was no longer possible. When I clutch in and out at the moment I can see the slave moving but it's not quite enough to fully engage the clutch as I still can't get it into gear.

BH_SLO32 Proficient

BH_SLO32

Posted
Posted

A good indication if air is still in the line is the pedal sometimes won't return completely from the floor. There are 3 bleed points as you have already found. I use a one man bleeding system which comprises a small bottle and clear tube (can be purchased from SuperCheap, Repco etc). With some fluid in the bottle during the bleed process you can attach the clear tube to a bleed point and open it and pump the pedal as many times as required without the need to open and close the bleed during pedal movements as on the return stroke liquid from the bottle is sucked backwards rather than air being sucked back into the system. The clear tube allows you to see the air bubbles and once they stop you can close an move to the next point. I typically do all 3 points twice to ensure all air is removed.

If the air is out of the system and you still can't engage the clutch you may need to adjust the pedal takeup point. The clutch master cylinder rod is attached to the pedal via a fork. The fork is threaded and its position on the rod can be adjusted by simply screwing it inwards or outwards and thereby adjusting the pedal position when the clutch engages. I have only just had to repair my fork as it stripped the thread and moved inwards (moved closer to the master cylinder) making the clutch engage when the pedal was just off the floor. I subsequently drilled the threaded portion out and welded a nut the back of it and screwed it outwards so now it wont be affected by my very heavy clutch and the clutch now engages when the pedal is halfway off the floor.

Hope this helps.

Dons Contributor

Dons

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Ok so for those interested, I have found the source of all my problems. There is a metal bracket that holds the clutch pedal rigid to the firewall. One of the spot welds has popped off meaning there is not enough pressure being put on the master cylinder to enghe te clutch. Effectively the pedal goes a but sideways when pressed in. So, I may have replaced the master cylinder for no reason haha!

ANYWAY, I'm trying to find someone who has a welder I can borrow. The spot that needs welding is tough to access though! Will see how we go.

siksII Grand Master

siksII

Posted
Posted
Ok so for those interested, I have found the source of all my problems. There is a metal bracket that holds the clutch pedal rigid to the firewall. One of the spot welds has popped off meaning there is not enough pressure being put on the master cylinder to enghe te clutch. Effectively the pedal goes a but sideways when pressed in. So, I may have replaced the master cylinder for no reason haha!

ANYWAY, I'm trying to find someone who has a welder I can borrow. The spot that needs welding is tough to access though! Will see how we go.

I had the same issue. Ended up buying a stock second hand one and had it beefed up with extra welding - this way its stronger than a repaired one or a Nismo replacement.

Just remove it to have it welded, there is no space down there. I replaced my master and slave at the same time for peace of mind. Fitting the master was a nightmare and so was bleeding.

Dons Contributor

Dons

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I have been looking around and there is a product that panel beaters use by 3M called automix panel bond. I'm thinking of giving this a crack before replacing it completely. It is still in position where it's sitting and from what I understand this stuff is very strong and equivalent to factory welding in most cases. my next problem is going to be getting some as i dont need a massive amount...

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