Original, genuine slave cylinder?

James-
This may be the all time dumb question, but why use an over-travel on the clutch lever? It isn't obvious to me how, if the master and slave contain the same volume, you need to worry about it. I know throttle cables usually have have a stop, sometimes at the petal and linkage both to protect the carb, and an extra return spring to prevent an overspeed (I am assuming), but how would an over-travel of the clutch be a serious event?
 
James-
This may be the all time dumb question, but why use an over-travel on the clutch lever? It isn't obvious to me how, if the master and slave contain the same volume, you need to worry about it. I know throttle cables usually have have a stop, sometimes at the petal and linkage both to protect the carb, and an extra return spring to prevent an overspeed (I am assuming), but how would an over-travel of the clutch be a serious event?

Presuming that the GT40 system works like the Pantera system, this piece isn't an over-travel piece. It's an adjustable stop to allow you to maintain free play in the clutch system. The stop hangs down and when the clutch is released, the spring pulls the clutch arm up until it hits the stop. The stop is adjusted so that there is a tiny bit of free play, so that when you first step on the clutch pedal, the initial movement of the clutch fork (inside the front of the gearbox) is through free space, before the fingers touch the throwout bearing, and continued movement operates the clutch.

If it wasn't for this system, the fingers could touch the throwout bearing all the time, leading to premature wear. And the stop prevents the return spring from compressing the slave cylinder fully, so that there is always some volume of fluid in the top of the slave.

(I honestly don't know why having the slave cylinder piston fully compressed would be a bad thing, but the engineers seem to believe that it is, for they have come up with various systems to prevent it from happening).

Here's a drawing of the Pantera system:

ill09b.gif


The bolt #34 is an adjustable stop bolt; it threads through the clutch arm lever #35, and rests against the stop which is part of the slave cylinder mounting bracket #45. #42 is the spring which pulls the stop bolt/clutch lever arm towards the stop.
 
This may have been resolved by now, but I'll add confirmation.
I worked for GIrling in the 60's and 70's and have the original installation info.
The correct slave cylinder is 3010201.
The system used forged banjo 352241 and banjo bolt 376102 on both master cylinder and slave cylinder, to bring female threads up to 7/16 UNF for the use of 1/4" bundy tubing.
These parts and a lot of other GT40 Girling brake and clutch bits are available out here.
 
This may have been resolved by now, but I'll add confirmation.
I worked for GIrling in the 60's and 70's and have the original installation info.
The correct slave cylinder is 3010201.
The system used forged banjo 352241 and banjo bolt 376102 on both master cylinder and slave cylinder, to bring female threads up to 7/16 UNF for the use of 1/4" bundy tubing.
These parts and a lot of other GT40 Girling brake and clutch bits are available out here.

"Out here" is rather vague; Australia is a pretty big place, you know. :laugh:

Could you be a bit more specific with respect to sources?

THANKS!
 
Hi Mike

I guess I was being a bit coy, to avoid appearance of a commercial post!
Since the great days at Girling, I have been operating a Motor Racing supply business, mostly brakes and clutches.

The clutch connection came from a joint venture between Girling (UK) and Automotive Products (UK) - Lockheed, Borg & Beck, Purolator etc.
This was for Australia, New Zealand and South Africa. The new name was Girlock, (get it?).

By then I was the Racing Manager for the group in Australia, with all the engineering from Girling, Lockheed, Borg & Beck, Lucas and other great names.
All that and a salary too! My Company car was an E49 Charger (Chrysler), which may not be well-known outside Aus, but it sure as Hell was out here!

The Borg & Beck 8 1/2" twin-plate clutch that was in the GT40 (and Ferrari Boxer) came to Australia in large numbers. It was a beautiful clutch, although needing understanding in initial set-up. I supplied them for countless blown road cars, where the 7 1/4" racing clutches would not have been durable in Saturday night traffic! Nothing else could handle the torque. We even uprated them with the grey diaphragm for the more insane road cars! Grey was the mother of all diaphragm springs!

This seems to have gone on a bit, although there was a GT40 thread through it.

We have stock of the 3010201 slave. Can also supply the correct size master cylinders, the clutch line banjos, bolts and other bits. We also have a few pairs of original Girling BR calipers, as used on the rear of the cars.

I hope we can help some time.

Cheers

Keith
 
Hello Mike and John,
Now I'm completely bamboozled and you most probably will be too when you read this....

The original clutch slave cylinder is shown in the attached photos and it's quite different from the catalogue drawing which Mike posted.
I am fairly sure that I purchased the slave in question, to the Girling number and it came in the correctly numbered box so something is amiss here.
To help there is a pattern? number on the casting - 313290 which could be a Lucas number.

You will see from the photo of the original set-up that the inlet and outlet nozzle orientation is at 90* to the boss face on the bell-housing. There are a lot of similar slave cylinders out there with the pairs of nozzles at 45* and 135* and I have loads of them but the correct one is the one shown and thanks to a German friend of mine for putting me straight years back.

The adjustable push rod and return rod are also quite different from the standard Girling parts and need to be machined (see the middle shot) These are clearly shown in the JW Automotive catalogue.
The best way to get the length of the rods is to fit the slave and the clutch lever and measure the stroke and return from the slave to the lever tang as it will depend on your bell-housing casting geometry.

Obtaining the splined lever will be another problem as these are pretty rare these days.
____________________

Hello James

A note on the slave cylinder installation pic in yours of January this year.

It has a 3/8" banjo and small-bore hose, leading to 3/16" bundy tubing to the front.
We originally installed a 7/16" banjo (352241) and large-bore hose on both master and slave cylinders, with 1/4" bundy in between.

The reason for this was that the diaphragm spring has to pump the fluid back to the reservoir so it can clamp the driven plates. The small-bore hoses and tubing cause too much restriction to flow. On a hard change this restriction can cause a bit of clutch slip, because the d/spring can't get the juice back quickly enough.

The hose was 12 1/2" flat-to-flat - 3703925. A really useful bit of trivia is that the early Girling convention with hose part numbers was to use the last two digits as the number of half inches in the flat-to-flat length! Other digits referred to end series and bore. We could see a part number and know all about the hose!

Cars No 6 and No 7 went to America, I think. They used the same hose in the feed line to the master cylinder, because the pedal box was adjustable fore and aft. I don't know whether current cars being restored or built are using the adjustable pedal-boxes, so this para may not be relevant.

For crisp clutch operation, you really need large-bore plumbing.

As a point of interest, it's not needed on brake systems, because brake systems are hydrastatic. Once clearance is taken up, there is not much fluid travel. In fact, large-bore tubing is undesirable in brake systems. With the very high line pressures, small-bore tubing gives much less expansion loss and therefore a better pedal.

I hope you don't mind the comments on your picture!

Cheers

Keith
 

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Sunny Melbourne, Trevor.
Cheers
Keith

Okay, we've managed to narrow it down from 'Australia' to 'Melbourne'.

Let's put it this way. If I was to mail you a letter, just exactly what would I have to put on the front of the envelope to ensure that it would be delivered to you? And if I was to wish to ring you, just what numbers would I have to punch into my phone to ensure that you picked up at the other end? :laugh:
 
Okay, we've managed to narrow it down from 'Australia' to 'Melbourne'.

Let's put it this way. If I was to mail you a letter, just exactly what would I have to put on the front of the envelope to ensure that it would be delivered to you? And if I was to wish to ring you, just what numbers would I have to punch into my phone to ensure that you picked up at the other end? :laugh:

I'm very conscious of forum rules, particularly 4c.
My aim was to add a bit of history and sound engineering for these fabulous cars.
I'll check with the administrator as to whether it's in order to post contact details.
 
I'm very conscious of forum rules, particularly 4c.
My aim was to add a bit of history and sound engineering for these fabulous cars.
I'll check with the administrator as to whether it's in order to post contact details.

Ah, an excellent point. Kudos to you for being so respectful. If nothing else, can you please e-mail me at my address below?

Thanks!
 
Keith
are you very far from sandown ?? I just might happen to be there next week
____________________

Historic Sandown?

I'll be there of course, Trevor.
It will be good to catch up!

Give me a call when you hit town.
0412 400 055

... or drop me a note with your itinerary.
PO Box 24,
Mulgrave,
Vic, 3170

Cheers

Keith
 
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