Clutch biting point

Clutch biting point was created by billcoleman

Posted 1 year 4 months ago #203247
I'm sure this has been discussed before, so point me in the right direction if necessary.
The clutch on my LE500 definitely bites too close to the floor. Although I'm getting used to it, it's not right, makes the gearshifts heavy and is uncomfortable to drive.
The clutch plate, cover, release bearing, release arm, steel pipe, flex hose and master cylinder are all new and I replaced the seal in the slave (all carried out when I refurbished both subframes).
It is all fully flushed through with pressure and vacuum bleeders (took a lot of effort to eliminate all the air).
I recall this happening on other cars, but I cannot remember how I fixed it.
Maybe someone has encountered the same issue and has a quick fix suggestion.
I'll talk about the accelerator in another thread.

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Replied by Airportable on topic Clutch biting point

Posted 1 year 4 months ago #203249
I like my clutch & brake pedals to be at the same height within degrees, with the throttle depressed in relation to the other two. This goes back to double declutching & heel & toe, both of which I still practice, even though the need is lost, a bit like intellectual rigger amongst Tik Tok viewers. It does however mean that I can get into the cab of an old Foden tractor unit & make a fair stab at driving it (two stroke diesel, look it up on YouTube).
I digress, to reach a point where I could use the pedal box without any conscious effort & using the brake as reference I tweaked the throttle**& made a packer to lift the clutch pedal hight until it was comfortable. And so it has remained.
** Whilst I had my head in the footwell & following a thread posted by Sundance (iirc) in this august organ, I found the pedal solid in the nylon bearings, which were turning in the bracket. Once through the workshop & with a new set of bearings made & fitted the improvement was instantly noticeable.
M
Last Edit:1 year 3 months ago by Airportable
Last edit: 1 year 3 months ago by Airportable.

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Replied by billcoleman on topic Clutch biting point

Posted 1 year 4 months ago #203252
It sounds like you like the clutch to be about the same as I like it then.
I don't feel comfortable when I have to almost push the clutch pedal through the floor to ensure it is disengaged, plus it makes every pull-away seem like a racing start (and the non-progressive action of the accelerator doesn't help things).
I have changed the clutch assembly and/or master cylinder on my ZT about three or four times (because the concentric slave normally gives up on those cars). The last time I changed it, I discovered that the master cylinder was at fault because of some debris letting fluid leak back across the little non-return valve from the reservoir. When fixing the master cylinder, I discovered that the hydraulics would randomly set the disengage point to a different position depending on how you bled them. I think that this is caused by the amount the slave cylinder is pulled back by suction from the master cylinder, which is probably controlled by the non-return valve from the reservoir.
What I may try doing is to use my pressure bleed system to make sure that the slave cylinder is pushed as far forward as possible while the clutch pedal is released, this will make sure the initial pedal movement is not just taking up any clearances between the release bearing and spring fingers.
I'm probably completely wrong, but its got to be worth a try.

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Replied by Airportable on topic Clutch biting point

Posted 1 year 4 months ago #203256
It doesn’t help much when one side of the conversation is muttering into a void at the front of the car & the reply is buried in the darkness at the back occasionally with one leg in the air. Whether you engage an assistant to operate the pedal (usually the better half, or daughter, sons tend to argue) or push the fluid or pull it, the reservoir has to be kept topped up which means wandering back & forth & loosing track in the process.
Last time I changed the slave cylinder the pedal came up first time & it took me ages to convince myself I had indeed managed it without incident.
Having the pedal too far down makes a quick dab to float out of one gear & into the next more difficult even with the revs synced.
Keep at it chum it could take you many months (or years) to massage it all to your taste. And then you start changing things when some inconsiderate bugger starts talking Bilsteins.
M

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Replied by billcoleman on topic Clutch biting point

Posted 1 year 3 months ago #203427
Over the weekend I decided to re-bleed the clutch.
Absolutely no air at all and the overall operation is very good.
However I did see that the slave cylinder mounting does deflect slightly as the clutch is actuated.

I know that there is a stiffening kit available.
Has anybody fitted one?
Does it make any improvements?

The ratio of the pedal to actuator arm movements would probably be about 5:1, so if the deflection at the slave is about 2mm, then eliminating that would give full disengagement maybe 10mm sooner at the pedal.

Apart from a longer push rod between the master cylinder and pedal (which would make the clutch pedal higher than standard), there are no other adjustments that can be made.

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Replied by Airportable on topic Clutch biting point

Posted 1 year 3 months ago #203433
Reading that last paragraph kick a bit of the cortex, I recalling an adjustable rod available quite some time ago.
It was as I recall a cut down original rod with a tapped hole down its length & a new rod of the same diameter, again drilled & tapped with a screwed rod to join the two.
I wasn’t happy with the original design as the threaded rod could have been thicker & it relied on Loctite to lock the two halves together once the distance was finalised.
I guess that the setting of the system must have been a pain & not as an attractive proposition as the purchaser would have wished. I don’t recall them creating a buzz on these pages.
I might make one & see. It will however drop to the bottom of a long list of designs I’ve been asked to look at. One of which is sorting out the oval grommets on the chassis; whilst driving down the A1M (I’m off on holiday again) I sorted that out in my head, prototypes to come.
M
Last Edit:1 year 3 months ago by Airportable
Last edit: 1 year 3 months ago by Airportable.

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Replied by Airportable on topic Clutch biting point

Posted 1 year 3 months ago #203438
On the additional bracket for the slave cylinder, I’ve looked at it & like you wondered. There might be a marginal gain, but would a cost benefit analysis show up an advantage when you’ve got to fit it. Hood up, carpet & dead dog out, access plate off & there’s not many of us in our twenties. What was once a twenty minute job is now a seventy plus minute job with brews.
I know that the success of British Cycling was made due to marginal gains in all areas, is a bit of bent metal going to transform you car?
I can’t answer that for you.
Does your car have the brake servo brace fitted because there’s an advantage to that.
M

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Replied by billcoleman on topic Clutch biting point

Posted 1 year 3 months ago #203439
Interesting comment about the age group of people driving these cars. When I was in my twenties, I was driving a Triumph Stag (That was probably the most fun car I have ever owned, and nowhere near as problematic as people claimed them to be). Now that I should be drawing my pension, I'm driving the smallest car I have ever owned (that also has the least maintenance access of any other car I can think of).
Maybe we all trying to stay young?
I would have thought that these cars would be a great attraction to the younger generation, but I have a feeling that generally, people no longer have the skills (or desire) to "fix things" (I know that there are many exceptions to this statement). Hence we are just a "throw-away society".
I totally agree about the added time it takes to do jobs on these cars (as you become less flexible), especially when you have to take so much stuff off just to see what you want to fix.
I probably will add the stiffening bracket, but I'll save that for the winter. I was quite surprised at the amount of flex (I should have made a video).

Regarding the brake servo, I bought the kit a few weeks ago and its on my to-do list.

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Replied by Cobber on topic Clutch biting point

Posted 1 year 3 months ago #203440
Our cars don’t have enough screens to get attention from the younger folk!

"Keep calm, relax, focus on the problem & PULL THE BLOODY TRIGGER"

by Cobber

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Replied by Airportable on topic Clutch biting point

Posted 1 year 3 months ago #203451
The brake servo brace doesn’t reduce the stopping distance, it gives you more pedal feel which helps overcome doubts about the stopping distance.
I twisted up a couple of pieces of mild steel angle initially & bolted them to the servo mount & bulkhead this curtailed a lot of wag to a degree that I invested time in to a proper job. There was a popular design on here which I based mine on & welded it up. It’s a much neater job than the bent angle, but no better.
M
Last Edit:1 year 3 months ago by Airportable
Last edit: 1 year 3 months ago by Airportable.

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