Clutch Slave Pushrod

[SprintMWU773V]

Thought I'd fit the clutch slave assembly to the gearbox last night. Took me a while to find the pushrod and then when I did I can see it's well worn which won't help clutch operation at all. I don't have the facility to weld any washers onto the existing rod so really looking for another one.

Is there a reliable source for these? I've had a look at work and we have nothing suitable. I would prefer an original type one rather than an adjustable. I have a thought that they might be unique to the Sprint models so obtaining one could be tricky.

[Flyfisherman]

Mark

Mine was the same so I purchased on of theses and cut the shaft down to the same lenght of my old one

http://www.jamespaddock.co.uk/clutch-sl ... push-rod-2

Paul

[cleverusername]

Would it be possible to put in a bush of some kind to restore the original hole size?

[SprintMWU773V]

The problem with a bush is that the hole in which to mount it is not round. The way to solve the problem is to weld on some washers of the correct size but I don't have the facility currently. I think I'll keep hold of this one with a view to fixing it but in the shorter term another one would still be preferable.

Paul's suggestion of cutting a longer one down is good. it would be easy enough to grind a suitable shape on the end of the remaining shaft, though I'm not sure of the purpose of the groove slightly above the end as if I recall there's no circlip or anything like that holding the rod in position. That groove would be slightly more difficult to make but if it's not necessary then I probably won't.

I see that Fitchetts list the correct part, though I don't know if it's adjustable or as original. Had a feeling I'd read somewhere it was adjustable.

[sprint95m]

Would it be possible to put in a bush of some kind to restore the original hole size?

Indeed it is. You plug the hole by welding then cool rapidly (in water) and finally
drill a new hole. The resulting push rod will cause the cotter pin to wear .
This method of repair is very good for the clutch pedal.


Thinking about it, I don't believe that the push rod holes being oval will make any difference.
The slave is self adjusting.



Ian.

[Galileo]

It is self adjusting but when ovalled it translated to about 10mm of lost motion at the end of the 'lever' on my pedal, which means that you don't get the full range of movement of the m/c. Admittedly that's only a couple of millimeters in reality at the m/c end, not sure how much that translates to at the business end and as Triumph always seemed to have designed their clutches to be flat to the floor to disengage types that might be important. Always catches me out in a modern car with the bite point being miles off the floor.

[sprint95m]

It is self adjusting but when ovalled it translated to about 10mm of lost motion at the end of the 'lever' on my pedal, which means that you don't get the full range of movement of the m/c.

That doesn't make any sense to me.

The master drives the slave. If the hole in the clutch pedal is worn then you will lose movement.


The only way I can see what you suggest is if the slave's pushrod was so very worn that it could foul on the bellhousing?



Ian.

[James467]

Mark do you want to post it to me and I'll weld some washers on it for you and send it back?

[Galileo]

It is self adjusting but when ovalled it translated to about 10mm of lost motion at the end of the 'lever' on my pedal, which means that you don't get the full range of movement of the m/c.

That doesn't make any sense to me.

The master drives the slave. If the hole in the clutch pedal is worn then you will lose movement.


The only way I can see what you suggest is if the slave's pushrod was so very worn that it could foul on the bellhousing?



Ian.

Displacement at both ends is dependent on the travel of the master cylinder and slave cylinder pistons, ending up at movement at the end of the slave pushrod. The starting position of the pistons are both in a fully homed position at the extent of their respective barrels, if there is lost motion due to an elongated pivot pin, at either the m/c or the slave end then the clutch arm does not move as fully forward as without that lost motion. This is because if it is at the m/c end then a smaller amount of fluid has been displaced that is equal to the lost motion in the pivot point, and with the slave then it needs to move the distance of the elongation before it starts to move the arm.

There is a misconception that hydraulic clutches automatically take up wear in the driven plate, they do not, it is the alternative cable not stretching that they remove. Think about brakes, there is an cam adjuster on the rears to to take up the wear, and front calipers 'float' off the disc so do not fully return home, the hydraulics are not taking up the slack in the case of the rears and only do so at the front because there is no spring to return the caliper piston to it's fully home position.

Sorry if I'm putting this over poorly, which I strongly suspect I am, I need to whiteboard it really.

[soe8m]

Not quit right I think. The slave does push and is pushed back on one side of the oval hole. It does not pull back.

Jeroen

[sprint95m]

Displacement at both ends is dependent on the travel of the master cylinder and slave cylinder pistons, ending up at movement at the end of the slave pushrod. The starting position of the pistons are both in a fully homed position at the extent of their respective barrels, if there is lost motion due to an elongated pivot pin, at either the m/c or the slave end then the clutch arm does not move as fully forward as without that lost motion. This is because if it is at the m/c end then a smaller amount of fluid has been displaced that is equal to the lost motion in the pivot point, and with the slave then it needs to move the distance of the elongation before it starts to move the arm.

There is a misconception that hydraulic clutches automatically take up wear in the driven plate, they do not, it is the alternative cable not stretching that they remove. Think about brakes, there is an cam adjuster on the rears to to take up the wear, and front calipers 'float' off the disc so do not fully return home, the hydraulics are not taking up the slack in the case of the rears and only do so at the front because there is no spring to return the caliper piston to it's fully home position.

Sorry if I'm putting this over poorly, which I strongly suspect I am, I need to whiteboard it really.

This is getting rather too theoretical for me. I don't think a whiteboard can help that

My understanding of how they hydraulics work is a consequence of having to sort non-functioning,
or at least not properly working hydraulics. I have owned Triumph 2000s after all.


I for one am not under any misconception about clutch wear, I am aware that the "bite" point changes over time.

With regards to the brakes, putting in a mechanical wear compensator means that the pedal won't (or at least shouldn't)
develop long travel.



To go back to an earlier point you made, I disagree about all Triumphs having a "bite" point very close to the floor.
The only one where this is unavoidable is an early 1850 (6 bolt flywheel) using an 1850HL, Sprint or indeed a Saab clutch cover.
This is because of design of the actuating arm being for a specific flywheel/clutch cover height, but said arm could be modified I guess?
(Early 1850s have a thin flywheel allied to a deep cover
whereas 1850HLs have a thicker flywheel allied to a shallower cover.)


On a Sprint or a 2000/2500 it is possible to have correctly functioning clutch hydraulics but have clutch clearance problems nevertheless,
said problems being a result of wear or failure amongst the cross shaft and fork components (tapered bolt, slipper pads, bearings, etc)
but that is a separate discussion in its own right




Thanks

Ian.

[Galileo]

It's a very fair point Ian, the only Triumph's I've owned are a 2000 and Sprint, so my knowledge of clutch biting points with Triumph cars has a common connection!