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Lockheed slave

Posted: Tue Jun 12, 2018 2:43 pm
by Corky
Jimscim wrote:
Tue Jun 12, 2018 12:50 pm
I don’t agree ! If Lockheed had have had a cylinder on the shelf ie Land Rover , they would have used it . It is not just the size of the bore . It is the stroke , the configuration of the valves and the weight of the vehicle all have to be taken into consideration. Many months of work went into the specification, many trials were done . They never just created a Part number for the sake of it. I cannot understand when the parts are still available would you want to change the specifications of your pride and joy .
In my experience, if you get the pairing of the slave/master from the LR parts bin right, then the clutch feels just like the original. As I said earlier some configurations give a heavier pedal. You could get a lighter pedal than the original by choosing an annular clutch . Another alternative is to move the pedal pivot point. There are loads of ways of doing it. Some more difficult than others.

We have a classic motoring journalist on here, who has also converted to LR hydraulics. As far as I know he's happy with the results.

As I'm sure you know, these cars use parts from many manufacturer's bins, so there is often a cheaper/available/plentiful/adaptable (delete as appropriate) alternative available. Sometimes we discover a part that's actually better in some ways than the one Reliant fitted, such as rear light clusters (not better made but easier to change the bulbs and the indicators are at the edges), electric cooling fans, radiators, radios, carpets, paint, bushes, shock absorbers, springs, hoses, batteries, fuse boxes etc etc etc....

Lockheed slave

Posted: Tue Jun 12, 2018 2:47 pm
by scimjim
Jimscim wrote:
Tue Jun 12, 2018 12:50 pm
I don’t agree ! If Lockheed had have had a cylinder on the shelf ie Land Rover , they would have used it . It is not just the size of the bore . It is the stroke , the configuration of the valves and the weight of the vehicle all have to be taken into consideration. Many months of work went into the specification, many trials were done . They never just created a Part number for the sake of it. I cannot understand when the parts are still available would you want to change the specifications of your pride and joy .
No valves in the clutch cylinders and weight of vehicle is irrelevant. I would certainly prefer a slightly lighter clutch, so will investigate options when I change the engine later in the year.

Lockheed slave

Posted: Tue Jun 12, 2018 3:00 pm
by philhoward
I do recall changing the Master on my Dad's 6a down one size and whilst it made the pedal nice and light, adjustment was critical to get full disengagement for foot to the floor (and making sure a mat didn't creep under the pedal) and no slip.

An annular/concentric slave cylinder does generally reduce pedal pressure though.

Lockheed slave

Posted: Tue Jun 12, 2018 4:15 pm
by Jimscim
No valves in the clutch cylinders and weight of vehicle is irrelevant. I would certainly prefer a slightly lighter clutch, so will investigate options when I change the engine later in the year.[/quote]
Any oriface the fluid passes through internally in the cylinder is called a valve in Lockheed speak . The weight of the vehicle is certainly relevant as the hydraulic system moves the clutch and depending on the weight ,amoungst other factors , determines what size clutch is fitted so determines what size clutch cylinders are fitted.

Lockheed slave

Posted: Tue Jun 12, 2018 4:49 pm
by Coupe Racing
Surely the weight of the clutch is determined by the effort required to overcome the spring pressure on the pressure plate , and in turn , the relationship of the pedal ratio to the clutch master/slave bore combination ?

Lockheed slave

Posted: Tue Jun 12, 2018 5:24 pm
by Jimscim
Exactly, all the components in the system are in harmony . Add an odd one to the system and you have chaos. :oops: Or to put it another way, the system cannot work as well as one designed by the OE engineers.

Lockheed slave

Posted: Tue Jun 12, 2018 5:36 pm
by scimjim
It’s often quite easy to improve something that was designed 50 years ago, with newer parts.

Lockheed slave

Posted: Tue Jun 12, 2018 6:18 pm
by Jimscim
On the subject we are talking about no improvement is being gained . It goes to show what a brilliant job Lockheed did 50 years ago :D :lol:

Lockheed slave

Posted: Tue Jun 12, 2018 6:27 pm
by scimjim
Your car, your call.

Lockheed slave

Posted: Wed Jun 13, 2018 5:32 pm
by Oldconn
Does your friend's car have the same make of clutch as yours. Many clutches have been changed over the years. In my experience a Lux feels slightly heavier than a Valeo, and an AP racing clutch is even heavier. Nothing to do with the weight of the car, it's all down to the pressure plate.

Lockheed slave

Posted: Wed Jun 13, 2018 5:56 pm
by Jimscim
If the clutch has nothing to do with the weight of the vehicle why do heavier vehicles have bigger clutches ,you would not expect to see an 8 inch clutch in a Volvo truck . AP racing clutches are normally paddle clutches and are designed to be heavier . You would not fit a paddle clutch in a road going scimitar .

Lockheed slave

Posted: Wed Jun 13, 2018 6:16 pm
by philhoward
Torque output of the engine might be the contributing factor..

Lockheed slave

Posted: Wed Jun 13, 2018 6:34 pm
by Jimscim
Torque is a factor along with many other considerations. Williams put a formula one engine in a Transit and try as they did AP racing could not get a clutch to do more than 5 or so starts . It was quite funny , on the one hand to stand and admire all this fantastic engineering and then seeing men pushing the Transit just to get it moving to help the clutch last longer.

Lockheed slave

Posted: Wed Jun 13, 2018 7:26 pm
by gtcse8
I have a few 2.9 Cosworth clutch plates that are an Organic compound, they are Very slightly thinner than a standard plate, AND they are known as "Low Lift".

Probably because the clutch cover is much stronger and thicker than a "Normal" road going car.

Mark

Lockheed slave

Posted: Thu Jun 14, 2018 10:58 am
by philhoward
Jimscim wrote:
Wed Jun 13, 2018 6:34 pm
Torque is a factor along with many other considerations. Williams put a formula one engine in a Transit and try as they did AP racing could not get a clutch to do more than 5 or so starts . It was quite funny , on the one hand to stand and admire all this fantastic engineering and then seeing men pushing the Transit just to get it moving to help the clutch last longer.
The torque output of the engine is the greatest contributory factor on the rating (generally relating to the pressure of the cover plate).

Whilst the weight (specifically GVW) of the vehicle will have an affect, this defines the output of the engine (along with gearing) and the engine output defines the clutch capacity, not the other way round although I do agree that the usage pattern of the vehicle may need to upgrade the clutch needed for that application.

For example:
1.6 Mk2 Escort, 1.6 Sierra, 1.6 Granada and a 1.6 Transit all have exactly the same 215mm clutch. Same engine, but wildly differing GVWs. The 1.3 versions of the Sierra and Escort use a 190mm clutch, for comparison, even though the vehicle weighs virtually the same.
The V6-powered Sierra, Granada and Transit (anywhere between a 2.3 and a 3.0) all use the same 242mm clutch. Same vehicles (mostly) as their 1.6 counterpart in terms of GVW, but different engine outputs, hence bigger (heavier) clutch.

If you (try and) fit a smaller (lighter) clutch in a Scimitar 3.0 because it only weighs the same(ish) as an Escort, not as much as a Granada, it won't last very long at all..

F1 clutches are designed to be the smallest and lightest component that will cope with the estimated number of standing starts it will do (2 or 3 for practice, 1 for the race start and 3 pit stops, so it has a "life" of 7 or 8 starts) and cope with the torque of the engine for a defined distance of about 200 miles. At a guess, the Transit weighed 2 or 3 times the Williams F1 car (a google suggests the F1 car is probably 600kg or so with driver, and a Transit around 1600kg), so we are back to a usage pattern adjustment upwards over a "normal" F1 clutch pack but I don't see your example proving your theory..