Using a servo on a hydrailic clutch

[turbominor]

Good news the knee is slowly getting better,

am going to fit the hydraulic clutch kit to make the clutch lighter, but I was wandering if I could use an in line servo to make the pedal lighter. Only issue i can think of is if it has enough moment for the amount of fluid to make the clutch work

[Cam]

Interesting............ well it will have a variable effect. The clutch will be REALLY light when decelerating but hard when you are flooring it.

I don't think the overall effect will be very good or practical to be honest.......

Mind you, it COULD work.......... If you let your foot off the accelerator when you declutch......

[turbominor]

Mind you, it COULD work.......... If you let your foot off the accelerator when you declutch......

that's what most of us do

I am not sure what the effect would be to be honest.. Will see what it is like with the hydraulic kit on... was thinking if modifing the linkage aswell to give more leaverage

[Cam]

Mind you, it COULD work.......... If you let your foot off the accelerator when you declutch......

that's what most of us do

Yeah , but what I was getting at is when you slowly pull off in a traffic jam using the clutch and accelerator in a see-saw motion you might get variable results because of the changing manifold vacuum.

[turbominor]

true.. was looking at a 205 diesel today for a friend with a belt operated vacume pump.. that may get round it

[bigginger]

Probably a useless thought, but some cars (VW, Audi) have electrical vacuum pumps for the central locking. Probably not what you'd need, but it's maybe worth a ponder...

[jonathon]

What your after is increasing the mechanical advantage of the system. A hydraulic kit should be light in operation by nature, if the ratio between master and slave is correct. If you are able to increase the master size, you may be able to achieve the desired result.

[Scott]

I used to work on Nissan Patrols in the late '80s & they have a boosted hydraulic clutch.
As far as I can remember, there were no issues with variable levels of assistance.

Some diesel engines have the vacuum pump inbuilt with the alternator if you wanted to go that way.

[rayofleamington]

I was wandering if I could use an in line servo to make the pedal lighter.

With the ever increasing rise in engine torque, clutch pedal servos are being investigated for modern junk but from what I've heard they make it very difficult to operate the clutch smoothly as it add some disconnect between the pedal and the clutch.
The other alternative is clutch-by-wire but that's pretty leading edge stuff and you're not going to find it 'off the shelf'. With that you would use the clutch pedal against a light spring. A sensor monitors the pedal position and an actuator (either hydraulic or electromechanical) moves the clutch.

[Cam]

A sensor monitors the pedal position and an actuator (either hydraulic or electromechanical) moves the clutch.

Good grief! That's going a bit far! If they carry on, we might as well just have a remote-control car.........

I bet that feels awful and I bet there is a delay too...... like the accelerator on a lot of modern junk.

I can see it now.......... the new Tamiya Focus!

[rayofleamington]

I bet that feels awful and I bet there is a delay too...... like the accelerator on a lot of modern junk.

Delay?? Nah - us transmission boys can work this stuff a lot faster than you would expect (it does depend on having good software boys who know how to program a feed forward control loop properly)
But yes the 'feel' factor would be limited. One of the things that helps a normal clutch pedal feel 'normal' is the high load and a certain amount of frictional hysteresis. Clutch by wire with an extremely light and smooth pedal would be something that would take a while to get used to!

I can see it now.......... the new Tamiya Focus!

Well drive by wire is now the norm (electronic throttle control). Brake by wire is coming on well. Shift by wire has been around for nearly 10 years, so if clutch by wire comes too (well shift AND clutch by wire is already available but not clutch by wire on its own), then you only need steer by wire to have the full set
Then you could drive the car fully by remote control (eg using a remote control CAN unit plugged into those 2 clever wires).

David Hasselhof would feel right at home!! (well - in reality they used drivers squatting behind the dash o: but that silly red lighty array made up for the fake technology ;-))

[Alec]

Hello Iain,
one way to even out the level of vacuum is a reservoir and a check valve. Used on MK 2 Jaguars and P.I. Triumph saloons that I know of.
beware of increasing the mechanical ratio by using a larger bore M.C. as the clutch throw will also be increased and may cause the cover and driven plates to clash. If you limit the clutch throw you reduce the clutch pedal travel, may work but I'm not so sure.

Alec

[Kevin]

Nah - us transmission boys can work this stuff a lot faster than you would expect (it does depend on having good software boys who know how to program a feed forward control loop properly)

Hmmm dont think I will ever use this on my Moggie 1st because the character would be changed and 2nd I dont understand it especially a programmable clutch...............................

[rayofleamington]

I dont understand it especially a programmable clutch...............................

Well this page should give you a taster of what some organisations are up to
http://www.toomonline.com/gearboxlinks.htm

It's only a taster - there's a lot less information from some of the major players than others.

[Matt]

we might as well just have a remote-control car.........

I've got one of them it goes nearly as fast as the minor....