Concentric Clutch Slave

[Sardonicus]

Pupp said:

And now for the bad news - nope, not that the master doesn't drive the slave to sufficient extension; didn't get that far. On filling, had the dreaded trickle of fluid under the car and seems the bleed fitting has got broken when putting the gearbox back in (can feel it and could probably reinstall another in situ if the broken end could be extracted - unfortunately, no chance of that as loctited in). Ho-hum gearbox out again.

Bugger

Ah FFS Gary I feel for ya mate you'll get there I bet the air was blue

[Alexdaredevils]

This sucks

[Pupp]

Well, the box came out double quick (about 20 mins) after undoing the slave through the hole - the silver lining is that there is actually enough room to get to the fasteners with the box fully home. Suspect I broke it when faffing about trying to cinch it up before the box was pushed all in. Won't be doing that next go.

The language was a tad florid; made the cat blush!

[Pupp]

It's back in and the hydraulics intact and leak free. With the assistance of an able assistant operating the (very light) clutch, have ascertained the 0.500 bore master is possibly just a bit marginal - it is making maybe 8mm of extension on the slave, which is certainly safe in terms of the pressure plate and slave limits but perhaps a tad under what would be ideal to ensure plate separation when hot. I can see a clamping gap at full pedal in but it's not a great deal and I'm half expecting it will start to drag when hot so suspect a move to an 0.625 (with maybe a pedal stop) will be on the cards but we'll see. That's easy whatever.

Anyway, will weigh the pile of iron that has been deleted tomorrow and maybe post a link to a vid of the thing operating (contain yourselves).

Although I doggedly clamped the bearing/slave unit in place through the access hole after putting bell and box in separately, it probably would be much quicker to do the bell/box as a complete assembly if the weight/bulk can be handled (difficult on low ramps I would say)..Otherwise do on a warm day when muscle memory is working for the top bolt.

Anyways, I'm claiming it as a victory!

[Richard 858]

Apologies for my earlier, and somewhat premature congratulations Gary, I certainly hope I didn't jinx things Glad you got there in the end

[Sardonicus]

Minor glitch for Gary hes on the mother

[ChimpOnGas]

Good luck with it, the way I see it Gary is forging the way here.

With any new development there will always be a few setbacksuntil the idea is perfected.

Top work, once sorted it'll be another great development.

[Pupp]

Richard 858 said:

Apologies for my earlier, and somewhat premature congratulations Gary, I certainly hope I didn't jinx thing

Not at all - any jinxing was entirely my own as a result of trying to be clever when unnecessary

Hopefully running in the next day or two so we shall see

[Pupp]

So, the deleted steel and iron bits weigh in at circa 3.6 kilos

I didn't weigh the new retainer and slave but well under a kilo together I'd say ...

[Pupp]

Update now it's all back together and running... the 0.500 master cylinder is confirmed as being too small.

Whilst there is enough separation to enable the car to run down hill when in gear with the clutch in, there is nothing like enough to enable clean (or any) gear selection with the engine spinning (not entirely a surprise but not what was hoped for). The bite point is right at the bottom (very bottom) of pedal travel but to all intents undrivable ... an 0.625 will be going in as soon as it can be whistled up; that should sort it...

[Sardonicus]

Pupp said:

Update now it's all back together and running... the 0.500 master cylinder is confirmed as being too small.

Whilst there is enough separation to enable the car to run down hill when in gear with the clutch in, there is nothing like enough to enable clean (or any) gear selection with the engine spinning (not entirely a surprise but not what was hoped for). The bite point is right at the bottom (very bottom) of pedal travel but to all intents undrivable ... an 0.625 will be going in as soon as it can be whistled up; that should sort it...

Well done Gary your there really whats stock TVR here 0.625 or 0.700 MC?

[Pupp]

Thanks Simon - the stock TVR cylinder is a .700; that would definitely over-extend the slave and exceed the limits of the pressure plate. If anyone else is contemplating this route, the .625 bore size is available in the integral reservoir form that will go entirely under the cover (going to keep my remote set up as the work is done now).

[BoostedChim]

Thanks for posting that Gary, that's a shame the 0.5 didn't work. But really useful for everyone else.

[Pupp]

Okay - not driven it yet as waiting for some sealant on the master cylinder access hatch to cure but 0.625 bore master arrived and installed today. Bled up very easily and now have a completely reasonably weighted clutch that appears to bite right where you'd want it to. I've not bothered getting under it to try and measure the slave extension as it's clearly working just fine - now why didn't I just fit that size to start with?

[carsy]

Superb job Gary, hope it drives as expected.

[Pupp]

Thanks - done a few miles on it now and, although taking it fairly gently in deference to rebuilt gearbox, driving absolutely fine (great to have a non-slipping clutch) - bite point perhaps just a tad lower than expected but that maybe compared with an unusually high point as was for the knackered unit that was removed. Only issue at all so far is there is a discernible release bearing noise in neutral with the clutch out.... goes away as the pedal is pressed and a lot less noticeable when warm. Heard worse on many a car and nothing felt so am assuming nothing more than a characteristic but wasn't expected given the bearing is in constant contact with the fingers under a light loading.

The rebuilt and upgraded box feels really nice and positive.

[Sardonicus]

You may find your noise is due to your release bearing not having a bevelled face Gary If that's your clutch cover/ pressure plate with flat/straight fingers in earlier pics they generally use a bevelled/round bearing where as curly fingered pressure plates use a flat style bearing, on Fords from way back i.e Pinto's motors etc mismatch of the above usually put up a squeal sound until light pressure was applied to the pedal .......... Just an idea

[Pupp]

Although the bearing is flat faced Simon, there is an adaptor ring bonded to it with a half-round profile so I'm not sure it's that exactly - think it could just be normal bearing whirring but amplified somehow by this particular set-up (or perhaps a resonance through the spring that holds the bearing in contact with the fingers). Next time I'm under the car (seems a daily occurrence at the moment), I'll pop the bung out and make sure there's no obvious signs of mechanical distress but not expecting to see any on the strength of how it's going.

[Sardonicus]

Pupp said:

Although the bearing is flat faced Simon, there is an adaptor ring bonded to it with a half-round profile so I'm not sure it's that exactly - think it could just be normal bearing whirring but amplified somehow by this particular set-up (or perhaps a resonance through the spring that holds the bearing in contact with the fingers). Next time I'm under the car (seems a daily occurrence at the moment), I'll pop the bung out and make sure there's no obvious signs of mechanical distress but not expecting to see any on the strength of how it's going.

Couldn't see you missing a detail like that Gary ah well it was just a suggestion you'll sort it minor only annoyance I would imagine

[Brerabit]

I’ve been absolutely riveted by this post. A well thought out project with detailed research and some interesting innovation and engineering. I’ve always believed that a concentric release bearing is a far more elegant solution than the traditional external slave and lever arrangement. I’m particularly interested in any mod that will improve the drivability of my Chimaera - and the clutch action and weight are definitely strong contenders for enhancement.

So while discussing some other work I’m lining up to be done the next time my car is in the workshop, I mentioned the possibility of converting to concentric clutch release. To my surprise they advised me against it, citing problems they had experienced with a tendency to leaks and of course the subsequently much bigger and expensive job it entailed in accessing the problem.

To put this in context, these guys are anything but conservative and are normally up for some pretty adventurous projects. My car is currently with them for a number of jobs including conversion to electric PAS and an S10 tailstock conversion on the T5 - but this is kids stuff compared to some of the projects that go through their workshop - so I respect their knowledge and experience and do have to take their advice seriously.

I’ve yet to have a proper conversation with them as so far, we’ve only discussed it via email but would be very interested in hearing about anyone else’s experiences, good or bad. Are there problematic systems out there that are getting the idea a bad name and are best avoided? Conversely are there some good ones that we need to know about?

I had one (it may have been Tilton) fitted to a Type 9 mated to an Essex V6 via a Flotech bell housing about 15 years ago and was very impressed with the results although I only kept the car for about a year and therefore don’t have any long term experience.

I know CCRs are commonplace on modern vehicles; but do they work better when designed in from the outset with possibly lighter clutch’s? Is a retrofit with the TVR clutch a bigger challenge?

I hate post’s that pour cold water on innovation and that is definitely not my intention here, in fact quite the opposite. I’m really interested in finding a solution that works - and keeps on working. So any encouraging news would be very welcome.