Technical 100hp Clutch Issue

[buttonsandzips]

Hi,

When my 100hp gets warm the clutch stops returning up after being depressed. It also occasionally throws an error about insufficient brake fluid but the levels show no problem. When cool there are no problems and everything functions as expected.

Any ideas?

Thanks

 

[A3jeroen]

I'd start with fresh fluid (don't forget the clutchsystem) and bleed it properly.

Hot might mean boiling water in the system (airbubbles).

gr J

 

[DaveMcT]

The clutch wont get "that" hot to be honest.

Check the (so called) quick release connector under the LHS front wheel arch for leaks. They corrode badly and will seize solid. Enough corrosion could possibly lead to fluid leaks.

However, the master cylinder is not particularly well built so the seals could be pulling in air. Bleed the system. I found the best way is to pump the pedal three times and wedge it down with a suitable stick then open and close the slave bleed nipple. Repeat, top up fluid, etc as necessary.

If the aluminium coupling has failed, you can cut the plastic hydraulic pipes and join with 8mm bore 25bar pressure hose. Three jubillee clips in each side will do the job.


Don't worry about cutting the existing pipes because sooner or later you will be replacing the master and slave cylinders which come complete with new pipes.

 

[buttonsandzips]

I'd start with fresh fluid (don't forget the clutchsystem) and bleed it properly.

Hot might mean boiling water in the system (airbubbles).

gr J

Are the clutch and brake fluid shared? Are there separate bleed valves for both? It seems like there must be a connection as whenever it happens the dash complains about brake fluid.

I'd definitely put this down to the temperature around the engine bay. When it happened last night I turned up the heating to max, opened the windows and watches the oil temperature fall slightly. The clutch then came back to normal.

 

[DaveMcT]

Open the car bonnet and you will see for yourself that clutch and brakes are separate. The clutch has no fluid level indicator.

The problem seemingly dependent on engine temperature suggests your clutch is failing but the cheap and simple test is to bleed the clutch hydraulics and take it from there. It's highly likely your clutch fluid reservoir is low but simply topping up will solve nothing as there will be air in the system.

The temperature gauge on the dash panel shows water temperature. Oil temperature is not measured, though you might have a special gauge.

 

[buttonsandzips]

Thanks, as you can tell I don't know too much but having already spent a fair few quid on the car recently I'd like to do what I can myself!

 

[buttonsandzips]

Is this the clutch fluid filler?

 

[DaveMcT]

Is this the clutch fluid filler?

That's the one.

Bleeding the clutch hydraulics is a bit of a pain because the battery and it's carrier are in the way.

Disconnect and remove battery.
Remove plastic under tray.

Remove battery carrier bolts you may need a magnet stick to catch one of them but grease on the socket might hold on to it.
Unclip wiring loom cable clips and lift the carrier away (use a flat screwdriver to open the cable clips).
You can now see the slave cylinder with its push-rod to the clutch lever.
You need some clear silicone or neoprene tube that fits over the bleed nipple and an allen (hex) key to open the bleeder. Put the loose end of the tube into a suitable container.

Now find a suitable length of timber batten to wedge between the car seat and clutch pedal so the pedal is held down.

Pump the pedal three times and hold it down with the wood batten. If you have a helper to pump and press the pedal, you wont need the wood batten.
Check the fluid reservoir is full & leave the lid off.
Put some absorbent rag around the base of the slave cylinder to catch leaking fluid.

Go back to the bleed nipple open and close it. Fluid and air will be blown down the tube.
At the pedal, lift it slowly, pump three times and wedge it down again.
Repeat the bleed nipple open & close.
Repeat the process until fluid only flows out. Don't forget to keep the reservoir topped up.


When fluid is running with no bubbles, make sure reservoir level is correct (bleed some excess away or add more and put the cap back on. Also remove the (now messy) rag. Use a rag under the reservoir when fitting the lid to catch any spills.

Put the battery box and battery back onto the car and reconnect main cables.

Job done.


If you have a helper, the bleeding process is easier. Get them to press the pedal down while you open and close the bleeder. When lifting the clutch pedal, do it slowly so the seals are less likely to suck air.

If you get ANY brake fluid on any paint you MUST clean it off immediately. Use a non solvent grease remover like Jizer or cheap paint brush cleaner and wash with water.

 

[buttonsandzips]

Thanks for the detailed reply, shall try and get someone over to help and have a go at it!

 

[buttonsandzips]

I've not had a chance to bleed it yet but here are a couple of photos. One is of the state of the clutch fluid. Does it look like it needs replacing? The other is the cables from the bottom of the brake fluid reservoir. Reading some other threads it looks like it is the state of those which is throwing the insufficient brake fluid message now and again.

Both the problems seemed to start at once but looks like pure coincidence!

 

[A3jeroen]

I wouldn't drink it
But then again I wouldn't drink fresh fluid either.
Fresh looks much clearer IMHO. Think there's some rust in the system. Water does that.
Cables don't look too bad (except for the outer skin). A bit of contactspray and a dab vaseline might work wonders.

gr J

 

[DaveMcT]

Brake fluid should be flushed through every 2 years regardless of mileage. It rarely ever gets done to the book but old fluid can cause brake failure or at best reduced life of the brake system.

Suck the old c**p away with a syringe and fill with new before bleeding it through. Keep topping up the master cylinder reservoir and keep going until the fluid runs clean.

The clutch is less fussy as it's all plastic and runs at (relatively) low pressure but new fluid always makes sense.

 

[buttonsandzips]

So, managed to do the bleed and a top up. Have it a few runs and problem returned. As per other threads on this issue I took it in and got the slave cylinder replaced. Unfortunately the seals were rusted to the master so both have been replaced. So far, so good....

 

[DaveMcT]

If the slave is looking poor then the master will be even worse. Changing just the slave usually means you have to get the battery out a second time so the master can then be replaced as well. Doing both at the same time is the best option as the master is weak and when worn will suck in air through it's seals.