Bleeding the Clutch

[Qavion]

Guys, I'm trying to understand the process of bleeding the clutch on my '89 SE. I assumed it would be similar to bleeding the brakes. However, with the bleed open on the slave cylinder, when I pushed the pedal, it went to the floor and stayed there, even after I closed the bleed nipple. I assumed a combination of springs and fluid pressure should have restored the pedal to it's original position.

 

I don't know how, but I managed to get the pedal to come back a few inches. It now sits about 1&11/16" below the level of the brake pedal (I can't remember where it was before, but it doesn't seem right). Has air got into the system, or do you think I have damaged something?

 

Unfortunately, the paper manual I have for the SE is missing the chapter on the clutch, and the S4 manual just says bleed the clutch using standard methods.

 

I have a clutch kit on standby if needed, but I'd rather not pull the cylinders to bits.

 

The car is fairly level. I jacked up the rear, but then lowered the car onto a stand.

 

Any ideas?

 

Thanks

Ian

 

 

 

 

[dodge1979]

Un bolt the slave and let it hang down with the bleed nipple upwards. The bleed it either with a vacuum unit or a victim in the seat pressing the pedal. If youve hung the unit upside down and using an assistant then put a clamp or some such on the cylinder to stop the piston popping out..

[jonwat]

Yes, the pedal should normally return to it's resting position when it's released.

What have you done, why are you bleeding it?

I have found that often after replacing the master cylinder the slave cylinder gives up the ghost in sympathy :-)

[Vanya]

Hey,

 

Have you messed around with the pedal itself? If you accidentally put the bolt through the pedal hole marked with "B" for brake, your clutch pedal will get stuck at the bottom of travel, and should you get it working it'll feel like the worlds heaviest clutch.

 

Use the other hole marked "C" for clutch.

 

Otherwise nah I don't think you could damage anything. Bleeding the clutch is a MAX 5 minute job provided you have the car off the ground (for access to slave) and a helper.

 

With the slave hanging freely via the clutch hose:

 

Press pedal down and hold it there - get helper to open bleed screw (carefully) and let air/fluid escape. Close bleed screw. Pedal should return, if it doesn't, pull it back up. Repeat above process 2-3 times until no more air is seen escaping. Done.

 

Ensure during this process that the clutch fluid reservoir doesn't empty otherwise you'll just introduce more air. Also keep in mind not to top it up too much whilst the pedal is still "to the floor" because when it raises, fluid comes back up and might overflow at the reservoir.

 

P.S. Piston shouldn't pop out if you have the circlip fitted in the groove provided at the end of the slave.

[CarBuff]

The clutch pedal SHOULD return to the upper position. You didn't run the master dry, did you?  (I did that once, the reservoir is SMALL)

 

 

If your 89 SE has the SIR (air bag) footbox, it might not have the two-hole clutch pedal, as that was a new design. (Our 88 has the C and B holes, and yes, the wrong hole prevents the pedal from returning to the proper height.)

[Qavion]

Sorry for the slow feedback, guys.

 

I was just trying to renew the fluid in the whole system. I haven't changed or topped up the fluid for a few years. The levels were ok. The fluid just looked a bit black.

 

In answer to your questions: Nothing in the system has been dismantled. The reservoir didn't go dry. In fact, I couldn't understand why the level wasn't going down (initially), despite fluid coming out of the bleed nipple. I started to suspect that the spring washer (in the master cylinder) which allows the fluid to flow from/to the reservoir was broken. I tapped the master cylinder with a rubber mallet to see if I could free any stuck components. Anyway, the pedal did come up eventually, probably because I manually pulled up on the pedal (which I think should have opened the valve allowing fluid to flow from the reservoir). I just don't know how far the pedal should be behind the other pedals.

 

Anyway, if I don't have any luck today, I'll start pulling things apart.

 

Thanks for the heads up on the circlip, I had no idea the cylinder might pop out.

 

Cheers

Ian.

Edited May 25, 2014 by Qavion

[ramjet]

Is the slave cylinder still in position with the clutch fork? If it is, the pedal should definitely return.

 

If it doesn't something else is going on.

[Qavion]

Yes, the slave cylinder is still in position. I was having trouble getting access from underneath the car. In the meantime, I thought I'd look at the master cylinder. I pulled it out of the car and tried to dismantle it. I removed the circlip, retaining washer and pushrod, but the plunger assembly seems stuck inside. I assumed it would pop out because of the spring. Perhaps the seals are holding it in.

 

Should it pop out, or do I need to pressurise the port?

 

I hear that master cylinders are not that expensive, so I don't mind experimenting.

 

Cheers

Ian.

Edited May 25, 2014 by Qavion

[Vanya]

You maybe need to use a bit of compressed air to get it to pop out - this isn't too unusual as the master spring isn't too strong. However, if the piston seal's totally buggered and has swollen, you might need a huge amount of pressure to get the piston out so BE CAREFUL (aim away from face and all that).

[GavinT]

The slave cylinder I put on two years ago has started to weep already. So I'm going to be playing this game soon.  I shan't be buying from the same source, unbranded overpriced junk from JAE.

[Qavion]

I managed to get the plunger out and this is what I found:

 

http://www.iinet.net.au/~b744er@ozemail.com.au/Lotus/LotusClutchMasterCylinder.jpg

 

I'm assuming the spring is not supposed to be a double helix?

 

Just wondering if I broke it, or if it was broken before.

[Simon350S]

Nope, that's definitely broken!

It happens, it did with me the day I picked my Esprit up many many years ago. I couldn't find a replacement spring so ended up fitting a new cylinder instead.

7ish years and 200 miles later, I've never had an issue since.

[ramjet]

That will definitely be part of your return problem there.

[Qavion]

Whilst waiting for a new master cylinder, I thought I'd check the adjustment of the fork at the slave cylinder end. Unfortunately, I'm missing the chapter in my manual which specifies the length of exposed thread on the abutment for my '89 SE.

 

Lotus Esprit World says the dimension should be 9~12mm for the Renault box, however, the S4 manual says 12.5mm. Does anyone have Chapter QC of the paper manual for the early series Stevens cars? If so, what should the dimension be for the SE?

 

Thanks

Cheers

Ian.

[Sparky]

Same - 12.5mm 

[Qavion]

Perfect, thanks!

I disassembled the slave cylinder to change the seal. The slave seems rather primitive compared to the master. Just a short-ish plunger, tapered spring, rubber seal and a primitive looking circlip. Nothing really to keep the spring from scoring the bore. Feels like there us something missing.

Cheers

Ian

[Qavion]

Update:

 

I bled the clutch with the slave cylinder hanging down and there seemed to be no air bubbles. The clutch pedal also returned to full height after each push.

 

However, whilst I was under the car, I noticed that there seemed to be very little range of movement of the fork when I moved it by hand. The fork went all the way aft, against a very light spring, but only seemed to go half way forward.

 

Anyway, I refitted the slave, and pushed the clutch pedal, but I saw no movement of the fork. 

 

Should I have started this job with the car out of gear? Should I try to start the car with the wheels off the ground in case I run through my garage wall?

 

[Sparky]

Gear selection won't affect hydraulic bleeding.  You're feeling slack at the fork, quite normal.  The required movement is only around 15mm, but that's against the clutch cover and you won't be able to do that by hand!

 

Do you have an assistant?  If not, how are you seeing the clutch fork movement whilst pressing the pedal?

 

You should know if you're not in gear by feeling crossgate travel.

[Qavion]

Do you have an assistant?  If not, how are you seeing the clutch fork movement whilst pressing the pedal?

 

 

No assistant. Would you believe my head in the wheel arch and my right hand manipulating a long broom handle pushed against the pedal?

 

The gear lever is moving freely (cross-plane). I thought there might need to be some rotation to disengage the gears  (I'm probably thinking of a generator drive disconnect on a 747 )

 

With the slave hanging down, when I push the pedal, the plunger goes to its full travel and appears to stay there even when I take my foot off the pedal. Is it only the gearbox fork pushing on plunger (via the rod) which moves the plunger back?

 

Anyway, I'll try bleeding some more and see what happens.

 

Thanks

Cheers

Ian.

[Qavion]

I've noticed that the nut which holds the abutment in its mounting bracket on my car looks somewhat fatter than the one depicted in the manuals. If the fore/aft position of the fork is so critical, I wonder if this is an issue. The nut looks original, however.

 

 

In hindsight, I probably should have noted its position prior to setting it up to specs. The gear change was working (reasonably well) before.

[Simon350S]

No assistant. Would you believe my head in the wheel arch and my right hand manipulating a long broom handle pushed against the pedal?

Exactly how I did both of mine

How much force are you having to put on the pedal? If it is really really light then you still have air.

It should be quite firm to push.

[Qavion]

It was quite soft yesterday. Anyway, I re-bled the line and let it sit overnight. In the morning the pedal was really firm and there was lots of movement of the fork, so I put everything back together again.

 

On the test drive, there was a bit of graunching (noticeable in 1st and 2nd), so something is still not quite right. Either there is still some bleeding to do (ugh), or the fork abutment might need tweaking.

 

If I move the abutment 2mm (closer to the early series Stevens), I'm wondering if this would be enough to make a difference.

 

Or should I just let things settle down first?

 

Thanks

Cheers

Ian.

[Vanya]

When you have no air in the system the pedal will be ROCK HARD and you'll need to be pushing down with the force of Hercules on that final bleed to get any remaining bubbles out.

 

Unless something is off with the clutch, fork adjustment per the manual should be just dandy.

 

Seriously best to get someone to help you - you'll be done in 10 minutes, no problems.

[CarBuff]

Another tactic to remove unwanted air is to prop the pedal down overnight. (Use a stick against the seat frame)

 

This allows the bubbles to exit out the reservoir.

 

 

Doesn't always work, but it's cheap and easy!

[Qavion]

Strange, I went for another drive and there was no graunching. I think this time I was deliberately pushing the pedal further to the floor though.  But if I see any Hercules types, I'll invite him into my garage

 

Another tactic to remove unwanted air is to prop the pedal down overnight. (Use a stick against the seat frame)