Very heavy clutch

[JonB]

Hi

As I mentioned a while back, by Plus2 has a very heavy clutch. I have amanged to adjust it so the bite point is off the floor, but I want to try and make it a bit lighter.

I reviewed some old threads and I have some questions.

• Master cylinder bore is 5/8", slave 7/8" on a standard car, but one poster mentioned that his car had a slave cylinder with incorrect bore. Are there any markings on the master / slave that indicate their bore so I can verify mine are correct?
• Much has been said about the plastic clutch pipe. I think mine is copper (or alloy), obviously aftermarket. Might it be interfering with the flow? I note the pedal is a little slow to return fully after being depressed. If this is the case should I try a braided hose like this one: https://www.tonythompsonracing.co.uk/pa ... lutch-hose ?
• On the subject of the braided hose, what other alternatives are there and what do they cost?

Thanks
JonB

[RogerFrench]

Don't know about Plus2, but in my experience sometimes cylinders are marked and sometimes not.
Unlikely that a metal pipe is causing a problem unless it has a kink. Is there just one pipe from mc to slave? There should be some flex somewhere.
I'd suggest a rebuild kit on your MC. If it's slow to return it may be has partial blockage. Clean and rebuild should fix that.

[Chancer]

A restriction will manifest itself as being very heavy to move the pedal rapidly but as light as normal when operated very slowly.

[MarkDa]

As Chancer says there's a difference between heavy and low bite point - or do you have both?
Surely load on pedal can only really be affected by clutch plate?
Bite is down to adjustment at slave or worn master.

[Chrispy]

I've been through similar recently... I checked my slave cylinder size, rebuilt my pedal box, adjusted the pushrod and all I could put it down to was that's just how heavy it is! I did find that the clutch pedal was over-extending and the last section of travel was especially heavy. I installed a stop on the pedal and it feels better now.

[derek uk]

How old is this clutch? When the diaphragm on this type of clutch gets old and/or tired it loses it's ability to work as it should. When working well it will seem heavy at first and then lighten up so it takes less pressure to hold it down. Bite point will still be in the light part of the movement and then the spring pressure will increase to hold the drive plate firm. When the diaphragm loses its spring the clutch feels heavy throughout its movement up and down. So, maybe you need a new clutch?

Non owner, first post.

Derek UK

[vincereynard]

They do tend to be heavy as normal. Apparently some are worse than others.

Mine had a knacked driven, 4 speed pressure, 5 speed release bearing, loose (as in rattling about) release support tube, and a wrong size slave. It still worked, but it was ****** heavy!

As Chancer states a kink / resistance will be apparent if the pedal is pumped. A slow depression will be lighter. To check the slave simply measure the bore. Often marked .875.

If they are OK then it might be engine / box out job which will give you the opportunity to mod. the box for a better change quality!

Do you remember what spare time was?

[StressCraxx]

Sometimes the symptom of a heavy clutch pedal is due to a worn clutch disc. The pressure plate travels further towards the flywheel and the leverage upon the diaphragm spring is less efficient.

[JonB]

Per my other thread about the steering column, I put the car on axle stands and bled the clutch to refresh the fluid. Took a picture of the casting and it's the correct bore. During the bleed, I thought the fluid wasn't being impeded as it felt the same as any other car I've done. Have to drive it now to see if bleeding made any difference, but not until the other jobs are done (trunnions, top ball joints, track rod ends).

[Orsom Weels]

Jon, wow, I have a few days 'off the grid' & I need a day to read through all your progress You're really getting into this, aren't you, of course you now once inflicted with this disease, there's no cure, don't you
Anyway, back to matters in hand. The +2 clutch is naturally quite heavy, much more so than the Elan. I can only put this down to the different pedal box/pedal combination giving a more favourable fulcrum point in the Elan, everything else being the same, but have never really looked into it to be sure. Something for another time, perhaps.
I know of a couple of +2's that have been modified by adding an in line servo to the clutch hydraulic system to help, & having driven one of them, I can confirm it does make a big difference.
However, it should be manageable in it's original form, just a bit of a pain in traffic & you need to develop a knack for avoiding rotoflex wind up. I have a 3/4 inch slave on mine, which makes it a little heavier still, but it's still not as bad as some other vehicles I have driven from the era. It may be worth changing the flexible section of your pipe, they can become restrictive over time, & could account for your slow pedal return.
When I put my car back together in the late eighties, one of the few parts I didn't have & couldn't source was the correct gearbox bell housing, so with everything else done, I put it together with a std 1500 Cortina bell housing, flywheel & small clutch, (hence the small slave). I was always worried the clutch wouldn't stand up to the twincam's power, so after twenty years & about 30,000 miles, I eventually found the correct bell housing & as part of a mini refresh, decided to change it & fit the correct spec clutch etc.
However, in all that time & mileage, I had only had to adjust the push rod about twice, & the clutch still looked almost as good as when I had put it together, it would have gone on for many many more miles, I'm sure. With this arrangement, the clutch was as light as the proverbial feather & worked without issue, by far the nicest clutch I have ever experienced in a +2, & I have wondered on several occasions why I bothered to go to all the trouble & expense of finding & fitting the original components !
I suspect racing/track work etc would find it's limits, but for normal road use with a reasonably std spec engine, I have seriously considered changing back to the Cortina clutch should I have to have the engine &/or gearbox out again in the future.
Good luck with your progress,
Regards, Tim

[JonB]

Hmm, just wondering if a modification to the pedal box would help. Something like moving the clevis pin on the clutch master cylinder actuation rod closer to the pedal pivot point (for more leverage, but less travel). Not sure how do-able this is, mind.

If there is restriction in the clutch pipe, it will surely be in the flexible section. Does this stuff swell up over time? I didn't notice any particular difficulty pumping fluid through it when I was bleeding the system.

It's true that I've been doing lots of stuff lately. I'm keen to get this car sorted, at least the safety critical bits, and I am able to get into the garage most nights without too much wifely opprobrium. My next job is related to the steering column work; I'm fitting new joints to the front suspension - track rod ends, top ball joints, trunnions - because I don't like the look of any of it. Torn / perished rubbers, rust, caked on grease, utterly dry - the whole nine yards. I used to fret about the doughnuts giving way, until I saw the state of the trunnions.

Sorry about all the extra reading. I like to chat...

[William2]

Is it possible that it has been fitted with a completion clutch? That might also explain why it feels excessively heavy.