MARK 1 Clutch force

[Richard_2012]

Hi to everyone.
I was wondering if anyone could advise please on the peculiarities of the 1956 Mark 1 clutch operation which seems to require excessive pressure to operate (compared to modern systems). The question is …is this normal…and if so what can be done to improve things to make it easier to operate?
Many thanks if you can help.
Richard

[J44EAG]

This link makes interesting reading about XK models of the similar period. Clutches between the cars do differ but there are some good pointers raised in this script. Reference to the Mk1 is towards the end of the text written by Guy Broad.

http://www.google.co.uk/url?sa=t&rct=j& ... GU&cad=rja

Mike K

[Martec]

Carrying on from Mikes link, the MkI, MkII, 240 and 340 had hydraulically operated clutches, my 1961 3.8 had an early coil spring clutch. As I have a habit of uprating my old cars It was suggested that I fit the 'E' type coil spring clutch (she of the purple springs) and this is very heavy on the leg and back, I wanted to fit the later diaphragm clutch but was told it would not be up to an uprated 3.8, but that was in 1999.

To fit the later diaphragm clutch I would need to accurately centre the pressure plate and then drill and tap the flywheel to mount it. Precisely what you would need to do to the MkI I don't know (you didn't say if it was a 2.4 or 3.4, I think they use a different size of clutch).

To lighten the operation of the clutch I copied what was done to a friends XK140, as the pedal is a direct mechanical operation on the clutch release spindle. The clutch hydraulics were fitted from a MkII and then a servo was used. I copied the servo and mounted it under the front wing with an old welding gas bottle (very thick steel) reservoir.

So long story short you have the choice of taking the engine out and having a diaphragm clutch fitted, or servoing it, can't think of another alternative other than an auto!!!

Be wary of the early and later clutch slave cylinders, I don't think the early ones are available (long cylinder) and it can be replaced with the later short cylinder, BUT the early cylinder had an external spring and the later cylinder will not release properly if the spring is fitted (I found out the hard way).

I hope that is of some use to you.

Brian

[Richard_2012]

Very many thanks indeed to both Mike and Brian for their very helpful replies.
The "CLUTCH PROBLEMS AGAIN! BY GUY BROAD" is an extremely useful article and makes a very good point about standardisation to the heaviest version of clutch assembly at a certain time in production...!
Sorry for not saying the vehicle is a 2.4 L...so this could be the issue given the above scenario?
(engine out ...to find out!). The idea from Brian to fit a servo system is very appealing...and I'm sure someone is now offering a conversion kit...but not sure where I saw the Ad? Many thanks again guys...it's great to have some useful advice from people who care and carry the passion...
Richard

[J44EAG]

"Carry on" being the operative words for me!

Mike

[Martec]

Hi Richard, if you do go down the route of a servo then be aware there were two sizes of servo on sale last time I looked. It is the mini servo kit you want (fitted as an aftermarket kit to minis without servos), there is a ratio quoted but can't remember what it is.

You break into the vacuum line to the brakes and fit a NRV, I used a new one from a ford. Then you break into the hydraulic line to the clutch slave cylinder and thats it. You will need to make up brackets and pipes, but I made it from scratch in day, and then spent 3 days painting and waxing the bits to stop corrosion, its been in service for about 10 years now.

Brian

[Richard_2012]

Hi Brian,

Many thanks for the advice on fitting a servo....and I can see why you might want one on the 3.8L MK2!. It is tempting for me to consider fitting two Non Return Values (in series) as it connects to a 'safety critical system' i.e. the brakes....(just my feeling). Well done on a successful modification lasting 10 years!!

Interestingly , my other car is also a 2000MY 'S' Type which I love, but it has auto transmission. Your manual box must be quite rare on a modern 'S' Type...and probably more fun than an auto?

Thanks again

Richard

[Martec]

I think the S type is under rated, after 12 years of touring europe in the MkII and our age we sold my wifes old Porsche and replaced it with the S type which now does duty as a long distance cruiser, but the 3 ltr manual almost has the performance of a 4 ltr auto. I'm old fashioned and prefer the delight of a good gear change.

The vacuum side of the servo is obviously connected into the inlet manifold vacuum take off. When I rebuilt this car from scrap I looked at all the systems and considering the MkII had a very early form of disc brakes and times have moved on I repaired the servo and uprated the brakes, mainly to deal with those that overtake and then slam on the brakes. I didn't regard the reservoir as important so dispensed with it which meant I needed a different NRV, so fitted a new ford one in the line.

When I fitted the clutch servo I 'tee'd' into this vacuum line before the brake NRV and then fitted a the servo vacuum line with its own NRV, but bizarrely I fitted a reservoir to the brake servo (one of those small welding gas bottles).

The initial concern was possible weakening of the mixture on the rear cylinder (vacuum take off point) but after 10 odd years its has been fine.

When I realised that I couldn't live with a worn out moss box, I had the 'pleasure' of removing the engine and box from the car and refitting the full synchro box and overdrive, I decided I didn't fancy doing that job again, hence the servo idea was very appealing.

Best of luck

Brian

PS I fitted the servo for a tenth of the cost of a professionally fitted job (labour is so expensive).