Ser IIA Clutch woes

[LndRvr64]

Hi everyone,

I have a 64 Ser IIA 88" with clutch issues. I replaced the master cylinder about a year ago and all was good until I started losing pressure a few months ago. The clutch still will work, but I have free pedal movement until about 3/4 of the way to the floor and then I will get pressure and the clutch engages and disengages. If I am driving for more than a few miles, It will become difficult to put into first gear without grinding. I bled the system through the slave cylinder, but it did not improve. I have never had a clutch go out, but is this how it acts when they start to go? It almost feels as if the linkage has somehow backed off and is not engaging when the pedal is first pushed.

Any advice would be appreciated.
Thanks.
Jack

[superstator]

First instinct would be to rebuild both cylinders. It could be leaking around the piston at one end or the other without actually leaking out of the system, and it would act just like you describe. Not 100% sure about Series clutches, but my MGB did the same thing to me once upon a time...

[leafsprung]

It almost feels as if the linkage has somehow backed off

Have you checked the linkage?

[Jeff Aronson]

Have you adjusted the slave cylinder rod correctly? The Haynes Manual -and the RN Series Parts Guide - show the correct measurement between the "locknuts" on the slave cylinder shaft. You'll need calipers or a compass to get the right measurement from underneath the car, but it's worth doing. If those dimensions are not correct, your clutch will have the symptoms you mention - I know this from experience.

I'm not quite understanding your description of the pedal travel. Usually when a clutch is wearing out the clutch "bites" with the pedal high in its travel. You have a lot of free pedal before you get engagement, and then you say that the clutch feels as though it is ineffective, that it is not disengaging effectively to allow you to go into first gear.

What's the engine rpm when you try this? My clutch has been in my car for a LONG time and by now I can't really shift into first gear unless the rpms are low; for example, I must push in the choke before shifting into first.

All this said, the possibility of an internal leak in either cylinder, as mentioned by other posters here, makes sense. You say that you replaced the clutch master - did you replace the slave cylinder at the same time? The slave cylinder is more likely to the problem, particularly if it's never been replaced.

You'll have to take this step by step. I would suggest looking at the slave adjustment, then the slave cylinder itself, then the master and then the clutch itself.

And someone suggested the linkage - have someone pump the clutch and observe the linkage underneath the car. Does it appear to move correctly?

Good luck!

Jeff

[LndRvr64]

Thanks all. I will check out the linkage from below and also the locknut spacing. When I put the new master cylinder on I just matched the spacing to my old one. Did not know there was a specific measurement. I did not swap out the slave cylinder at the same time - everything seemed to be working fine, so I let it alone. Will check that out if the others don't get me anywhere.

[Griffinwerks]

The symptoms seem to point to a bad master. The system may not bleed properly if the master is bad you will continually get air out of the bleeder, did the fluid run clear with no spits and sputters when it was bled. The air is due to the seal cup not sealing in the bore and pulling in air due to damage to the bore or the cup. The piston may also not be moving properly in the bore due to an obstruction or corrosion, if it does not fully return to it's stop it will not uncover the "compensator port" the hole into the bore from the resivoir allowing fluid in or out to allow for expansion due to heat or loss of some kind. My advice is to check the adjustment if it is correct rebleed the system watching for air in the stream, if air is present next step is takedown the master. An easy way to check for air in the fluid while bleeding if you can't see it is to use firm pressure on the pedal and just crack open the bleeder, you will be able to feel the air coming out as pops that you may be able to feel through the wrench. Good luck. Jim

[Rineheitzgabot]

If you replaced the master one year ago, I would not mess with the master right away. I think that this is the most time consuming of all the problems that can occur with the clutch accuation system, so be glad that this one is probably not on the table now.

Jeff Aronson above has some useful input. I too, have went through the "clutch saga". My symptoms were exactly as you describe.

If I understand your description of the problem, I would recommend your next step is to: Get under the hood and look for hydraulic oil on or near the circuit. This will tell you if it is leaking. If you can't tell, clean everything really good with a product like "Brakleen" then operate the system vigorously for a while and check later. If there is oil, find the source and fix it; this will solve the bleeding off problem, If that doesn't fix it, go on to step 1) read the spec on the measurement from nut to nut and check it, and adjust it if needed. If that doesn't fix it, go to 2) re-bleed the circuit. If that doesn't fix it, go to 3) Change the flexi-hydraulic line. If that doesn't fix it, go to 4) Replace the slave cylinder. After 4, you will have replaced the whole circuit and after making certain that all the fittings are tight, this will have fixed your problem. I would be very surprised if your clutch is going bad, as the way you describe your problem, it sounds as if there is a variance in the symptoms from when the car is cold to when the car has been driven for a while (this is exactly what mine was doing). The only explanation that I could think of, is that the hydraulic fluid, when warmed, would decrease in viscosity and therefore decrease in it's ability to properly pressurize the circuit that accuates the clutch, thingy.

Nonetheless, if the symptoms vary, it would not be the clutch itself, as the symptoms would be consistent.

Hope this helps.

[I Leak Oil]

Clamp off the flex hose then apply pedal pressure. That will point you in the right direction. Tough to fix something without doing any evaluation first.
Jason T.

[Griffinwerks]

The change in system performance when hot is due to the air in the system expanding. As the air expands if requires more fluid to compress it and provide the pressure to activate the clutch. Thus the pedal must move farther or the clutch may not be released completely = grinding when hot. Clamping the flex line is a good idea to diagnose. In a properly functioning system by clamping the line you will remove virtually all the pedal travel as the compressed fluid has no where to go. If the pedal still travels 3/4 of the way before you get resistance the problem lies on that side of the clamp. As far as the clamp goes use only a rounded clamp not one with square edges as it may damage/break the hose internally. Looking for leaks is good as well but remember that a hydraulic component may fail and leak very little, if it is slightly wet inside the boot it may be bad. The clutch as it wears will compress the slave cylinder. In the extreme the release bearing is constantly in contact with the pressure plate as the slave cannot compress any further. Thus relieving some of the clamping pressure so a worn out clutch will require very little movement to disengage hence little pedal travel, right at the top not on the floor as yours is. I would be quite supprised if it is a mechanical prob with the clutch itself.

[LndRvr64]

Finally got my wing off and the lock nut on the master cylinder had backed off. Anyone know how to keep it from backing off again other than tightening it well? Thanks to all for your help. It has taken me awhile due to lack of time and rusty bolts, but I am glad it finally came off and doesn't seem to be anything major.

Jack