T56 clutch bleeding

[Zedn]

Hi All,

Tonight i put fluid in my brakes and clutch for the first time.

I did the brakes and bled them and they worked ok except for a small leak in one of the connections. I bench bled the master for the brakes prior to hooking up the lines.

When i came to the do the clutch i had a bit of a disaster. It is the internal t56 slave cylinder. I stupidly thought the clutch bleed screw was supposed to unscrew up the top of the extension piece. I couldn't get it to turn with out the whole thing turning so decided to take the whole lot out (IDIOT!). It was at this point that i realised it is supposed be one piece. by this stage fluid was running out in the bell housing. Hopefully this fluid hasn't got on the clutch!

After bleeding the clutch the pedal is still light as a feather and not pushing the clutch out. I didn't bleed it for long as there was no air coming out after about 5 goes. Because i had fluid leak into the bell housing when i took the bleed screw out, i now don't know if there is a leak inside or if there is just fluid still running down. Its not spirting out when the pedal is pumped so fingers crossed.

Should the master for the clutch be bench bled? Im wondering if there is still a large amount of air trapped in the master cylinder and thats why it isn't working.

I ran out of time to keep bleeding but I'm thinking tomorrow i will just bleed it heaps and see if i can get anymore air out.

Any opinions? I really hope the slave isn't shot as taking the motor and box out now would be a nightmare considering i put the body on after the engine was in and the whole motor, gearbox and engine bay is painted and polished!

[Mrs flatchat]

Was the motor, flywheel, clutch and gear box sourced as complete donor unit ?
Has the clutch been set up for correct spacing to the slave CSC ? (concentric slave cylinder)
Ie:- if the space is to big then you run the risk of popping the slave piston

[sambo]

Zedn, I fitted a clutch bleed extension line and braided line from slave to master, otherwise all factory Commodore gear. We bled the clutch just like the brakes, no issues.

I assume you have taken the lid off the fluid reservoir to avoid vaccum problems when bleeding?

[Gaz64]

You'll only ever do that once, seen it a few times.

I have used a cooling system adaptor to pressurise the clutch master, say 3psi, which helps the master "prime" better.

For some reason, until the master is completely primed it pulls air as well as fluid, but it doesn't push all the air down to the slave, so it appears to bled correctly, but still has a spongy pedal.

I hate the Commodore setup, (master cylinder design, reservoir too small, pressure fluid line too small etc). Hopefully you have improved on that.

I hope this helps.

[Zedn]

Thanks guys.

I did some googling and seems it's a common problem. I am going to have a go at sucking the air out through the reservoir.

[DaveW]

Zedn,
I have bled tremecs a few times. its a crock. especially when you are alone.
This is what I do now.
Go to Kmart.
Buy $12 fish tank pump with the inlet and outlet tube, cheep nasty one, it even comes with a meter of clear plastic flex tube.
Make Coffee or obtain other beverage.
Connect the flex tube to the inlet port, no barb on this end.
Connect the other end to the bleeder nipple on the slave cylinder.
Top up Master cylinder Res.
Put the pump in an ice cream tub, remove ice cream first.
Crack the bleed nipple.
Pug in the pump, 240v and turn it on.
Drink coffee, or other beverage.
Top up Res periodically before it sucks air.
Watch tube till bubbles no longer appear.
Tighten bleeder tube nipple.
Check for clutch actuation.
Repeat if necessary.
Dispose of pump.

Dave

[gjkrv8]

Originally Posted by DaveW

Zedn,
I have bled tremecs a few times. its a crock. especially when you are alone.
This is what I do now.
Go to Kmart.
Buy $12 fish tank pump with the inlet and outlet tube, cheep nasty one, it even comes with a meter of clear plastic flex tube.
Make Coffee or obtain other beverage.
Connect the flex tube to the inlet port, no barb on this end.
Connect the other end to the bleeder nipple on the slave cylinder.
Top up Master cylinder Res.
Put the pump in an ice cream tub, remove ice cream first.
Crack the bleed nipple.
Pug in the pump, 240v and turn it on.
Drink coffee, or other beverage.
Top up Res periodically before it sucks air.
Watch tube till bubbles no longer appear.
Tighten bleeder tube nipple.
Check for clutch actuation.
Repeat if necessary.
Dispose of pump.

Dave

Dave, my simple mind needs a diagram - you've lost me.

FWIW - I used an aftermarket Tilton 7/8" MC for my LS1/T56 stock clutch setup with a bigger -4 line and the pedal feel and operation is great.

My only regret is I didnt fit an external bleed screw/line etc. I have only bled it once but it was a pain in the neck to do.

cheers

Gregg

[Modena]

Originally Posted by gjkrv8

Dave, my simple mind needs a diagram - you've lost me.

you gut stuck on the ice cream line hey Gregg

[Gaz64]

Originally Posted by gjkrv8

Dave, my simple mind needs a diagram - you've lost me.

Gregg

Gregg, Dave is using the pump to pull the fluid through the system, same as a brake fluid flushing tool, uses compressed air to create a venturi vacuum to pull fluid and air out from the bleeder nipples.

[Aussie Mike]

The factory bleed nipple setup is rubbish in my opinion. Difficult to use as you cant easily clip a bleeder hose onto it to stop air going back into the system.

A remote bleeder setup makes life easier.

If the system is brand new you may also need to bench bleed the MC to get any air out of it.

I used 7/8" Wilwood MC. Wilwood High-Performance Disc Brakes - MasterCylinder No: 260-3376

One of the things I like about them is there is a bleed nipple on the MC that makes it easier to get air out of the system since the bleed nipple is at the highest point in the whole setup.

A #4 line is also a must since the #3 line will not flow enough to let the clutch engage quickly enough and clutch slip will result.

My system proved to be dead easy to bleed once setup

[PeterAllen]

Originally Posted by DaveW

Zedn,

...Make Coffee or obtain other beverage.
Connect the flex tube to the inlet port, no barb on this end.
Connect the other end to the bleeder nipple on the slave cylinder...

That's the bit I don't quite follow?

[Modena]

He means connect the tubing to the inlet port on the pump.

[gjkrv8]

Originally Posted by Modena

He means connect the tubing to the inlet port on the pump.

aha - thats where I got stuck too :-)

[DaveW]

Sorry guys, bit sloppy on the description, try this

[deano59]

Originally Posted by DaveW

Sorry guys, bit sloppy on the description, try this

that is gold that's better than some workshop manuals ive had too decipher over the yrs

[Gaz64]

Originally Posted by DaveW

Sorry guys, bit sloppy on the description, try this

Agree with Dean, a lot of techs I work with would actually understand your drawing, versus some factory drawings.

Absolute GOLD.

[guye]

That, Dave, is going straight to the pool room. Best, easiest to read diagram I've seen in years!

[Zedn]

Thanks Dave.

I literally have no weight on the pedal after what I have done so far. It feels like it's not even connected. Also when I crack the bleed screw and push the pedal, the tube is only filled by a couple of centermeters and then the fluid starts to run back in. I would have thought gravity would take over and fluid would keep running.

Will try the pump option and see how I go. I really hope air is all it is as I need to get the car out of where I have it as the house is being sold.

[Zedn]

Thinking more about it. From memory i used the LT1 T56 clutch master cylinder. Im wondering if this could be the problem considering the LT1 T56 uses an external slave. They looked similar and i just saw T56 and thought they must be the same.

Will try the pump idea first and then buy a holden part if it doesn't work.

[Aussie Mike]

Check the piston bore of the MC. The hydraulic throw out needs quite a bit of fluid to operate. You will need a 7/8" or 1" bore MC for it to work.

Cheers