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Mk2 golf 02M gearbox: master clutch cylinder question

3K views 4 replies 3 participants last post by  sdezego 
#1 ·
Hi,

My mk2 golf has a 1.8 20vt + 02m 6 speed gearbox for about a decade.
The clutch kit was a stage 2 kit from clutchnet with single mass flywheel.

Ever since installing the 6 speed gearbox my clutch pedal has been very heavy to operate.
So heavy that you can see the firewall and master brake cylinder moving a little bit.

I now swapped the entire clutch kit for a Sachs performance kit, also with single mass flywheel, hoping this kit would give me a better pedal feel.
Unfortunately that had no effect.

Every thing clutch related is now brand new with fresh oil except the master clutch cylinder on the (golf g60) pedal box.
The master clutch cylinder I’m using on the pedal box is from a Golf mk3 vr6.

That master cylinder worked fine before years ago when I was still using the 02J 5 speed gearbox but maybe it’s not adequate anymore to work with the clutch in the 02m gearbox.


Does anyone have done a similar swap? What master clutch cylinder are you using?
And are there other clutch cylinders from newer models that will dit the G60 pedal box?


Thanks,
Richard
 
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#3 · (Edited)
EDIT: (I had them mixed up from memory)

The 02a/02j Clutch Master is larger than the 02m. With some light machine work you can use the 02m Master Cyl with will give you a better feel.

Are you running the 02a Firewall bracket that supports the Master (i.e. from Corrado or Passat). If not as mentioned there are a few companies that make one.

02m Master on 02a Corrado Bracket and mods needed about mid way down on this mage from my build thread:

https://forums.vwvortex.com/showthread.php?2805002-Project-Build-sc2020/page27
 
#4 ·
Hi,

Thanks for your reply.
You say "The 02a/02j Clutch Master is smaller than the 02m". You mean in overall size or the piston size?

A friend on mine looked at his supplier webshop and thought that the 02m clutch master has a smaller piston then the VR6 one I'm currently using.
And then we had the discussion if a smaller piston will give a lighter or heavier pedal feel...


But as everything else is now new, this was my idea as well, swap the master clutch cylinder.
Get a 02M clutch master so it matches the slave cylinder in the gearbox. That should be a better match.
And cut off the ball end and do something like you have done to attach it to a mk2 pedal.
Actually, that is what I've done with my current VR6 clutch master. That also had a ball end so I ended up screwing a ball joint in it.
Just need to be sure it has the correct length for the pedal movement.

From what I found, the clutch master for a 02M is part 1J1 721 388 G (that is the latest model) and if I look at online pictures, I think the two bolts for mounting look the same so that should fit.


I'm using the firewall bracket from a Passat. This was a straight fit for the Audi TT MBC and vacuum pot. And I attached the Audi TT abs unit to it as well.
Actually, there are 2 brackets that mount as one onto the firewall; one from Passat and the other is G60 I think. Anyway, that was a straight fit without any modes need.
 
#5 · (Edited)
Hi,

EDIT -> The 02m MC Piston is smaller than the 02a/02j That is the same base PN that I have except mine was old revision A since I bought it like 8 years ago lol...

Outside of the clevis, you will need to machine some spacers as I did for the mount bolts. But physically they will work w/o needing to modify the firewall bracket. You will also need to trim a bit of the plastic of the MC to get it to fit into the Firewall bracket.

All in my build thread in that link, and all pretty simple modifications.

From a Friend

The O2M master is 0.630" bore and the O2A/O2J is 0.750" bore. Using the O2A master on an O2M slave gives terrible clutch feel as I found. I changed to a Mk4 O2M master as well, and I made a pedal pushrod clevis as well with a bronze bushing, and I cut that top rib as well. Fluid displacement per inch of master cyl pushrod travel tells the story:
Mk4 O2M: 0.630 bore, volume = 0.3117 in2 per inch
Corrado O2A: 0.75 bore, volume = 0.441 in2 per inch: 40% more fluid for the same travel = clutch pedal becomes on/off switch

Clutch feel is vastly improved which I assume was your goal as well?

However, bleeding the slave was not improved so I cannot yet get all the air out.
Sorry, I had the size backward, but the end result is accurate :)
 
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