Clutch issue

[wildoliver]

Right here's a tricky one for you all.

My elan sprint has a dodgy clutch.

when you press the pedal sometimes it goes all the way to the floor with no resistance, but if you press it quickly and hard its perfect, the clutch operation is perfect, it isnt losing fluid, and it doesnt need bleeding.

The problem is mechanical on the pedal / master cylinder, its almost as if the clutch rod that goes in to the master cylinder sometimes misses a slot.

Has anyone had this problem before?

If not I'l have to take the master off, and that looks a git of a job.

Just to reiterate, it is not a hydraulic problem, and it is not on the slave side / clutch mechanism side, when the pedal goes right down to the floor it doesnt seem to move the piston in the master cylinder.

[Dag-Henning]

Hi, - have you checket the pedal mechanism ; the "transvers link" betw, the clutch pedal and the master-rod ? Why Lotus decided not to put the clutch master behind the clutch pedal has always been a mystery to me....
I know it is pain to put your body up-side-down in an Elan footwell, but sometimes you have to...Take a look at yr pedal-box while operating the pedal with yr arm.
Dag

[Dag-Henning]

oops, - maybe this only goes for LHD cars....??
Dag

[wildoliver]

I thought they were inline, if they have that arrangement that will be where the problem is it feels exactly like a mechanical link not connecting.

Shall check tonight!!!

[types26/36]

Not sure how it works in LHD but in RHD the clutch pedal is directly behind the clutch m/cyl and pushes stright into it, the brake pedal has a crossover system transfering the movement.
Brian

[wildoliver]

Ah well thats killed that idea!

[type26owner]

There is a check valve on the deep end of the piston to allow the fluid to flow back into reservoir when the pedal is released. Best guess is yours has a piece of debris stuck under it. I would take it apart to investigate the cause but replace the unit with a new one since they are inexpensive. Before ordering a new unit check the clevis for wear. There should be a clearance hole for the pin, not a slot.

[wildoliver]

No its nothing as simple as the clevis, its really quite bizzare, looks like i'm taking the cylinder off! :

[type26owner]

Okay, I'll only do this one more time. There is a flat disc check valve on the reservoir end of the piston. If that hangs open for any reason then when you depress the pedal no fluid will get forced down to operate the slave cylinder. Got it?

The clevis is another wear problem entirely.

[wildoliver]

yes got that............hence why im going to have to take the cylinder off as mentioned in post!

[type26owner]

Cool! Just making sure we're on the same page.

[wildoliver]

Certainly are!

Even us brits can keep up!

[phil1800]

Folks,
I have the same issue as wildoliver, however 13 years later The clutch is smooth and light, but the longer I drive, the more often I have no clutch. The pedal has zero resistance, but comes back if pumped. I thought it is air in the system first, but bleeding it didn?t change things. The slave is new and I will rebuild the master next. Could it be anything else but the check valve in the master?
Thank you for your input.......

[rgh0]

Apart from the master cylinder check valve the other possible cause would be to much clearance between the slave cylinder rod and the clutch actuation lever. This needs to be set with the slave cylinder piston pushed fully home in the bore and the slave cylinder pushed fully forward in its mounting and hard up against its locating circlip.

Bleeding of the slave cylinder is also challenging and can take many times to get it right as the bleed nipple is not at the top of the cylinder and its hard to get all the air out, a pressure or vacuum bleeder kit helps.

Not a guaranteed fix but worth trying if your struggling to bleed the system fully is the following. Pump the pedal until you have the clutch working and then wedging the pedal down without releasing it with a length of wood against the seat to hold the pressure in the system. Leaving it overnight results in the air in the slave cylinder that's under pressure leaking out through the top of the seal. IN the morning if your lucky your clutch is bled. You need to have got enough of the air out of the system to get a decent pressure when you wedge the peddle down for this to work

cheers
Rohan

[1owner69Elan]

I was experiencing a variable clutch engagement point as well. Acted like air in the system as pumping the pedal would bring the resistance back and restore the clutch engagement point away from the floor. It was an ongoing struggle as described below but it is just now resolved.

I bled the system probably several dozen times, using 2 man system, power bleeder, speed bleeder screws, using a broom stick to emulate 2 man system, etc... Rotated the slave cylinder so the bleed screw was on the top. Made sure the bleed hose and receptacle were above the bleed screw so air could not reenter the slave. After expelling any air, made sure the pedal was depressed and held while closing the bleed screw.

I bought a new slave cylinder. Bought another one to make sure I had a genuine Girling. Rebuilt the slave cylinders replacing the seal even though they were new. Bought and replaced the hose with another braided hose with different fittings. Bought a new clutch master cylinder and installed. Figured if everything was new I would have no problem. Wrong.

Each time that I would bleed the system, the clutch would be firm. But it wouldn't last. It would be OK for a little while, maybe a few hours when sitting but then would revert back to the limp behavior. I could only drive the car by periodically pumping the clutch. But, I was never sure when it would again randomly lose pressure.

I finally solved the problem. Only yesterday, after many, many months of the above ongoing saga.

I decided last night to try again. I removed the Girling slave cylinder. Inspected the bleed screw for scoring on the seat. It was OK. Put my original hose and fittings back on - as these had the U-shape fitting at the master and an easier to fit elbow at the slave. Note-this hose had initially been suspect because of the evidenced bad clutch - changing it out had made no difference so I was confident enough to reinstall it. It provides a better routing of the hose and easier connection at the slave.

So what was different this time that worked? I found that the seal in the repair kit, this time from a different supplier, was distinctly different than the seal in the new (Girling) slave. It was of a different material (looked more like natural rubber as opposed to neoprene). Perhaps more importantly the size of the taper that forms the seal when compressed in the bore was distinctly longer, providing a much more substantial seal. In fact when inserting the piston with the seal into the bore it was much more of an effort to compress the seal and get it to slip in. Not that the overall seal OD or height was different but the leading edge had a shallower angle and longer taper (I should have taken a picture in hindsight) that creates a much more substantial seal. Very evident in a side by side comparison. (Note that I used brake fluid to lubricate the seal prior to insertion in all cases.)

In any event, I have determined that all seals are not equal (both in geometry and material) and don't assume that a new slave cylinder is automatically going to be leak free. Evidently, various (even new) seals do indeed leak enough to allow air to enter, albeit at a slow rate. Moreover, there appear to be a lot of these, what I may call "sub-standard", seals out there as I obtained them from various vendors. These are our usual, reputable suppliers in the US and UK. The different seal that finally worked happened to come from a US supplier with different packaging and identification. Perhaps I was randomly unlucky in what was sent to me from various sources or perhaps the overall quality of the seals currently being provided to our vendors has declined. I don't know.

In any event, I now have proper clutch behavior, after many, many hours of frustration over the last 8 months since I I first fired up my Elan after restoration.