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Leaking clutch slave cylinder?

Meap
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Meap

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Hi guys, recently I suddenly lost almost all pressure in my clutch pedal, only the last few centimeters give any resistance. I'm still able to change gears and drive but the biting point is now at the very bottom whereas it used to be much more up top. I read some posts here and figured I probably have a leak somewhere. Got the car up on the lift and it seems like my slave cylinder might be leaking? The little boot is all sticky and when I pull the boot back quite some fluid spilled out, is this normal or does this indeed indicate that the slave is leaking?

Furthermore I noticed that the clutch booster (not the damper) is completely corroded from the bottom, so I'm assuming it's leaking as well? I've seen some delete kits and was wondering what you guys think of those? I don't mind a heavy clutch and I'm never going triple plate or something crazy like that anyway.

I've attached some pictures of the slave and the booster.

Any help much appreciated!

booster.jpg

slave cylinder.jpg

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https://www.sau.com.au/forums/topic/483709-leaking-clutch-slave-cylinder/
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Murray_Calavera Mentor

Murray_Calavera

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I'd be very grateful that your car gave you notice regarding this issue, rather then leaving you stranded and needing a tow home. 

I would replace the master cylinder, slave cylinder and use a braided line that deletes the damper. The stuff from GKtech work well. 

You can bench bleed the complete system out of the car, then install it all together and do the final bleed once installed. Bench bleeding will get you 95% there and will make your life much easier. 

I've deleted my clutch damper and noticed 0% change in the way the clutch performs or feels. 

  • Like 1
Meap Rookie

Meap

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Thanks for the quick response and the solid tip to bench bleed it!

About the damper, to avoid confusion, I believe you are talking about the clutch damper, the square box underneath the car, whereas I was asking about the clutch booster, which is behind the M/C mounted to the firewall. I will without a doubt get rid of the damper but deleting the booster seems to get mixed reactions on the forums.

Furthermore, a new booster appears to be around 400 AUD whereas a delete kit can be found for 100 AUD. This raises the question if the booster is really that needed.

Duncan Grand Master

Duncan

Posted
Posted

You will be fine without the booster, it is one of those things that nissan over-engineered on the GTR.

Murray did mean that box and the looped clutch line, because again it is not required and does not improve things (in fact, it will make the new setup almost impossible to bleed as it traps air because it is horizontal not vertical).

The damage on your booster is due to the clutch master leaking brake fluid onto it, and it does look like the slave is also leaking. The booster damage is probably just cosmetic because if the booster was leaking you would notice poor/inconsistent clutch pedal feel and/or poor idle in the motor.

So, take the booster off, clean and paint it and reinstall, buy a new master and slave cylinder with a new braided line between the two and you will have another 30 years of trouble free clutching.

  • Like 1
Murray_Calavera Mentor

Murray_Calavera

Posted
Posted
On 6/2/2022 at 2:28 AM, Meap said:

Thanks for the quick response and the solid tip to bench bleed it!

About the damper, to avoid confusion, I believe you are talking about the clutch damper, the square box underneath the car, whereas I was asking about the clutch booster, which is behind the M/C mounted to the firewall. I will without a doubt get rid of the damper but deleting the booster seems to get mixed reactions on the forums.

Furthermore, a new booster appears to be around 400 AUD whereas a delete kit can be found for 100 AUD. This raises the question if the booster is really that needed.

Yes sorry, I was talking about the damper and not the booster. I've got a gtst and it doesn't have a booster so it didn't even come to mind when I was typing up my reply. 

GTSBoy Grand Master

GTSBoy

Posted
Posted
On 6/2/2022 at 5:01 AM, Duncan said:

The booster damage is probably just cosmetic because if the booster was leaking you would notice poor/inconsistent clutch pedal feel and/or poor idle in the motor.

So, take the booster off, clean and paint it and reinstall, buy a new master and slave cylinder with a new braided line between the two and you will have another 30 years of trouble free clutching.

With the caveat that brake fluid leaking into the booster can damage the diaphragm. So when taking it off and cleaning it on the outside, do your best to work out what the situation is inside, and deal with any fluid in there appropriately.

  • 4 weeks later...
TurboTapin Experienced

TurboTapin

Posted
Posted (edited)
On 6/1/2022 at 11:09 AM, Murray_Calavera said:

I'd be very grateful that your car gave you notice regarding this issue, rather then leaving you stranded and needing a tow home. 

I would replace the master cylinder, slave cylinder and use a braided line that deletes the damper. The stuff from GKtech work well. 

You can bench bleed the complete system out of the car, then install it all together and do the final bleed once installed. Bench bleeding will get you 95% there and will make your life much easier. 

I've deleted my clutch damper and noticed 0% change in the way the clutch performs or feels. 

No clutch leave you stranded? It's definitely a pity to drive but any manual car can be started and shifted through all gears without a clutch.

In my youth, I had a buddy run an 88 civic without a clutch pedal for 6 months before he could afford a new clutch cable lol. Why buy a clutch cable when you could buy smokes and beer... priorities when young and stupid lol. 

Edited by TurboTapin
Murray_Calavera Mentor

Murray_Calavera

Posted
Posted
On 6/28/2022 at 10:01 AM, TurboTapin said:

No clutch leave you stranded? It's definitely a pity to drive but any manual car can be started and shifted through all gears without a clutch.

In my youth, I had a buddy run an 88 civic without a clutch pedal for 6 months before he could afford a new clutch cable lol. Why buy a clutch cable when you could buy smokes and beer... priorities when young and stupid lol. 

Yep, master cylinder failed about 10km from home. So it was a cheap and quick tow home. 

I'm becoming an old man, I'd rather just get it towed then stuff about trying to drive it without a clutch lol. 

  • 2 weeks later...
BK Grand Master

BK

Posted
Posted
On 04/06/2022 at 8:23 PM, Meap said:

Thanks for all the replies guys! I bought a new master and slave, braided line and the booster delete by PRP. I'll keep you guys posted!

Instead of a new master you know a genuine RB26 clutch master cylinder rebuild kit is like $50 right ? 99% fixes an issue unless the inner bore is scored to shit. Generally just the plunger seal lets go.

GTSBoy Grand Master

GTSBoy

Posted
Posted
On 7/9/2022 at 8:17 PM, BK said:

Instead of a new master you know a genuine RB26 clutch master cylinder rebuild kit is like $50 right ? 99% fixes an issue unless the inner bore is scored to shit. Generally just the plunger seal lets go.

NOBODY ever seems to listen when i talk about rebuilding hydraulic components.....so good luck with this advice Ben.

  • Haha 1
Murray_Calavera Mentor

Murray_Calavera

Posted
Posted (edited)
On 7/10/2022 at 3:33 PM, GTSBoy said:

NOBODY ever seems to listen when i talk about rebuilding hydraulic components.....so good luck with this advice Ben.

To be fair, I went looking for a rebuild kit for the RB25 clutch master cylinder... Couldn't find anyone that had one. 

So I just grabbed a new one from GKtech for $86 and figured no one sells rebuild kits for them when you can buy an entire new one for such a low price. 

https://au.gktech.com/products/gearbox-clutch-components/clutch-masters/hfm-clutch-master-cylinder-s14-s15-r33

Edited by Murray_Calavera
  • 9 months later...
Meap Rookie

Meap

Posted
  • Author
Posted

Just to close this topic off and help people that might have the same issue I did, after replacing the aforementioned parts, all problems were resolved (as expected).

Some notes I want to add;
1) I don't notice any significant change in pedal feel after removing both the clutch damper (square box) and the clutch booster
2) I didn't bench bleed the system before installing it and despite my strong simplification of the system it was still a PITA to get all the air out, so for anyone looking to do the same as me, please bench bleed it first

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