clutch problem

[johnc]

The slave cylinder piston on my Rootes car does not travel far enough to operate the push rod and hence the fork lever to operate the clutch.This is the result of previous owners fitting earlier/later gearbox/clutch combinations and me now having fitted the correct spring type clutch and operating lever,the push rod appears to be too short.
My question is this; if I extend the push rod by welding in a section is the length critical or would the correct travel be accomodated by the travel of the slave cylinder piston.What amount of travel of the push rod should I expect once the release bearing touches the clutch 'prongs'
Any help would be appreciated.
Johnc

[Wicksy]

Obtain the lever operating rage of movement from the clutch spec - iether online or direct from the maker. Measure the range of movement on the slave.
You will then know if they are compatable and be able to position the slave rod end accordingly.
Rather than welding an extension on to the rod which would entail stripping the cylinder can you not fabricate a drilled extension plate for the slave cyl with slotted mounts or make up a P clip type of mount so you can adjust the position relative to the bellhousing .

[johnc]

Thanks for the reply.
I have a parts book which shows different part numbers but no detailed spec.I have also placed an enquiry on a Rootes forum and shall see what comments I get.I'll try and find spec.for clutch travel but as it's a 50 year old system I'm not overly hopeful.
The push rod is not attached to the slave cylinder it is retained by a pin at the lever end and sits into a cupped end on the piston and is easily removed,so I could weld in a section so my question as to what travel ,clearance etc is still relevant.
Any further input would be much appreciated.
regards
Johnc

[Luxobarge]

A left-field off-the-wall suggestion:

As you plan to make/modify one, why not make it adjustable? I'd think of incorporating one of these into it:

http://www.pinbax.com/index.asp?selecti ... t=7&sc=545

You don't necessarily need to use the forked ends, just the central bottle adjuster, cut some M5 threads into the rod (one of them a left-hand thread) and hey presto, and adjustable push rod! That way you only need to get the dimensions roughly approximate.

Any good?

Cheers!

[Wicksy]

Yup luxo that's a neater solution than welding and I like it. I like making the actual mounting position adjustable and preserving the integrity of the slave too, so two brill solutions.
Having the slave position or rod length adjustable allows mating up to the lever and then testing the clutch action - chances are the travel will be sufficient, specially if it's a new clutch, without having to bury the pedal into the carpet.
The adjustable option will also ensure the correct pedal free play can be obtained - important for preserving thrust bearing life

[JPB]

.....The adjustable option will also ensure the correct pedal free play can be obtained - important for preserving thrust bearing life.

Er no it won't. Only bore ratio changes can achieve that effect. Unless the bore ratio is changed by changing either or both cylinder/s, then the length of the stroke will remain exactly the same, but you would move the entire stroke that's available either toward or away from the floor so could set the point at which the clutch has cleared. It's essential, especially with a coil spring cover, that the pedal fully pressed downwards doesn't move the clutch levers to the end of their travel as that would at best bind their return springs (the tiny, radial ones on the lever pivots, not the cover pressure springs) and at worst, allow the steel edge of the thrust pad carrier to carve a slot through the thrust pad receiver carriers at the end of each pivot finger.
If all parts are original, then don't change their mounting positions. If, as I'm assuming may not be the case here, the clutch is a bit of a Heinz job, then set it all so that, with the pedal fully depressed to the floor, the cover fingers have some very slight travel remaining with the clutch warm otherwise, 'bye-bye clutch cover.

Same - nearly - for a diaphragm cover, but in that case the thrust pad receiver that connects the ends of all the fingers will grind its way into [the fingers] of the spring and you'll then notice broken finger bits appearing in the bellhousing every so often until one day, no clutch clearance.

[Wicksy]

John, I think you misinterpreted me - what I meant was, that by having an adjustable rod, it's length can be adjusted to connect up to the lever under a no load condition. A welded addition would probably need trimming with a grinder to achieve the same "sloppy" fit

[JPB]

Ah right, understood.