Clutch not quite disengaging

[A TR7 16V]

The clutch on my 13/60 seems not to be disengaging properly and perhaps getting slowly worse. I can still get all the gears, including reverse, but that can be a little crunchy. It's most noticeable that with the pedal all the way down and starting with it in gear, like when it stalls at a junction, etc., the starter motor is clearly under more load than when it's out of gear - pretty sure there's no extra load on the starter with the clutch down not in gear, cos I keep forgetting I'm not starting the wife's Chrysler, which needs that.

So what's the likely problem, wear in the actuation mechanism somewhere or hydraulics? I did check it's all topped up in the reservoir on the master. Pumping the clutch seems to have no obvious effect.

Graham

[NonMember]

One very common cause of that problem on the Herald / Spitfire / Toledo / Dolomite setup is the pivot pin for the clutch release arm. It's only held in by two crinkle sleeve things and they are prone to falling out. The release arm then moves around at the pivot end, constrained only by the clutch housing, so that the pedal movement is not transferred to the clutch release bearing properly.

[Pete Lewis]

you can just see the pivot pin in its hole in the clutch hsg.   worth a bit of  a clean a look at the pin movement when someone presses the pedal

if the crinkle sleeve has failed you may notice the pin is a slack fit in the hole  this is a common failing 

its gearbox of to renovate the pivot bushes   

https://www.canleyclassics.com/?catalogue=triumph-herald-13/60&diagram=triumph-herald-13/60-gearbox

, any bleeding must have the nipple above the slave feed pipe  often its reversed and you cant bleed air out

worth a check the pedal pivot has not seized it must return to its back stop to give you a full stroke 

Pete

  

[A TR7 16V]

2 hours ago, Pete Lewis said:

you can just see the pivot pin in its hole in the clutch hsg.   worth a bit of  a clean a look at the pin movement when someone presses the pedal

if the crinkle sleeve has failed you may notice the pin is a slack fit in the hole  this is a common failing 

its gearbox of to renovate the pivot bushes   

https://www.canleyclassics.com/?catalogue=triumph-herald-13/60&diagram=triumph-herald-13/60-gearbox

, any bleeding must have the nipple above the slave feed pipe  often its reversed and you cant bleed air out

worth a check the pedal pivot has not seized it must return to its back stop to give you a full stroke 

Pete

  

I looked at the pedal pivot as the easiest thing to fix. Couldn't see a problem there, but I did find the carpet had slipped down the inside of the bulkhead and folded up along the top of the ridge just under the pedal. I think that was stopping it a bit early - perhaps against that ridge so more than just 2 carpet thicknesses early. So I pushed it up and made sure the pedal goes into the recess above that ridge properly. That seems to have at least improved things. I may have to look at gluing it up against the bulkhead if this really is the cause and repeats again.

While I'm still not ecstatic about how far down the pedal has to go down to properly disengage the clutch, and the need to push it so that it's further than flush with the ridge between the floor and bulkhead; now there's no sign of it dragging and slowing the starter when that's operated in gear. I've only checked it with everything cold, and I did notice the problem when everything was well warmed through. So I'll see if there's a thermal aspect to the issue next time I've chance.

Thanks for the advice.

Graham

[A TR7 16V]

I've had a bit more of a look at the clutch pedal and there seems to be a lot of slack in it when it's up. So much so that the spring is well off being tight at that point. Is that normal?

It looks like this is a combination of slack in the hinge pin on the pedal and in the junction at the end of the master cylinder piston rod. I reckon that if I take out that slack, I'll get the clutch to disengage with the rubber on the pedal at a point something like 1 cm before where it does now. It don't sound a lot, but maybe it will be enough to make it all feel better. However, I don't want to risk taking that apart while I need the car. So I'll want another pedal at least, and maybe the bracket the hinge pin is in, to play with for that. 

Graham

[Pete Lewis]

this might be frowned apon but  i have slotted the master cyl braket to bulkhead fixings and as you move the assy it will raise or lower the pedal  pad height 

do not remove the free play /endfloat of the push rod that must have a bit of a rattle fit to ensure the cyl is not under pressure ,foot off

just needs decent washers over the slots 

Pete

 

 

[A TR7 16V]

Slotting the bracket holes would help. But I'd still want a spare to work on.

I see the pedal pin bushes are available on eBay. What wears most though, that bush, the pin, or the bracket?

Graham

[Pete Lewis]

the clevis hole in the M cyl pushrod fork (under the gaitor )  can wear , solution is drill out to take next sized clevis pin 

the pedal pivot if seized can wear the bracket under the dash the shaft has a flat on it and the hole is D shaped so the shaft cant rotate

there is no greaser on the pedals .   ive seen the bracket wear the D hole to a full round O hole

any failure of the bush /tolerance ring on the withdrawl arm pin  needs the box off  the pin can actually fall out and be lost 

new pins are about with a head on ..better 

pete

 

 

[A TR7 16V]

32 minutes ago, Pete Lewis said:

the clevis hole in the M cyl pushrod fork (under the gaitor )  can wear , solution is drill out to take next sized clevis pin 

the pedal pivot if seized can wear the bracket under the dash the shaft has a flat on it and the hole is D shaped so the shaft cant rotate

there is no greaser on the pedals .   ive seen the bracket wear the D hole to a full round O hole

any failure of the bush /tolerance ring on the withdrawl arm pin  needs the box off  the pin can actually fall out and be lost 

new pins are about with a head on ..better 

pete

 

 

Is that the holes in the fork or the hole in the top end of the pedal arm that wears, or both? I've ordered a set of used arms, springs, brackets, and bolts, that were listed as being in very good condition. No clevis pins though. I'll have a look at the pins and holes I've got when I'm ready to replace the clutch set.

[Pete Lewis]

both the pushrod fork and the hole in the pedal can suffer wear 

its an area that rarely gets oiled and gets a lot of use 

the brake is same , travels less but both pedals wear over time 

Pete

[NonMember]

4 hours ago, A TR7 16V said:

see the pedal pin bushes are available on eBay.

Just to clarify, since you've said a lot about the pedal... I wasn't referring to the pedal pivot, nor was Pete when he first responded.

At the gearbox end of things, the slave cylinder operates a lever with a pivot at the RH end. This is the pin that falls out (onto the road, usually, never to be found again). The hole the pin should sit in, in the bell housing, may be just visible from the engine bay on a Herald.

[A TR7 16V]

2 hours ago, NonMember said:

Just to clarify, since you've said a lot about the pedal... I wasn't referring to the pedal pivot, nor was Pete when he first responded.

At the gearbox end of things, the slave cylinder operates a lever with a pivot at the RH end. This is the pin that falls out (onto the road, usually, never to be found again). The hole the pin should sit in, in the bell housing, may be just visible from the engine bay on a Herald.

Well I realized you meant the fulcrum pivot pin for the clutch fork and its tolerance ring. But I can't do much about them easily and right away. Whereas I can easily look at the pedal and its bits n bobs to see if I can at least postpone the car going off the road to have the box off, etc. 

I'm sure somebody (Colin I think) recently pointed out the axiom that you should always look at the things that are easy to fix first, without too much consideration of the probability they are the problem - but put it a bit more pithily.

Graham

[Pete Lewis]

no clevis .....you can use a nyloc nut and bolt with a shank(unthreaded)  of length to keep the threads out of the wear zone 

Pete

 

[NonMember]

9 hours ago, A TR7 16V said:

But I can't do much about them easily and right away.

OK. When it happened to my Toledo I was able to drop a long 5/16" shanked bolt in there from the engine bay. No need to remove anything. Access may not be quite so easy on a Herald, though.

[Pete Lewis]

on the 4cyl  cars you can see the hole in the hsg given covered in crud  but its accessible if you have a poke around 

Pete

[A TR7 16V]

I will look for this hole for the fulcrum pivot pin if it stops raining long enough. Any body got a picture of where it is in a Herald?

On the issue of the pedals, I got the other set, and the hole for the pin in this clutch pedal bracket is a little bit worn - the pin is rotating in that hole, not the pedal rotating on the pin. That's even though the pin's not ceased or even stiff in the pedal bearing. Whereas, the brake pedal is turning on its pin, and the hole in the bracket don't seem to be worn. 

So, I was thinking of putting the replacement in and looking at fixing the one that comes out. I guess I can see if there's much difference while I'm doing that. But supposing there's not, is there any problem in putting this brake pedal and bracket in, instead of the clutch one - other than I would need to take the switch off and maybe bend it's bracket out the way a bit to let the pedal come up fully?

Also why are the holes in the bracket for the spring in different positions on each side? I'm pretty sure the problem with the one in the car being slack with the pedal full up is that it's in the RH hole and should be in the LH one. I doubt that makes any difference to how well the clutch disengages though. But maybe another rattle got rid of.

Graham

[A TR7 16V]

On 14/08/2021 at 19:09, Pete Lewis said:

the pedal pivot if seized can wear the bracket under the dash the shaft has a flat on it and the hole is D shaped so the shaft cant rotate

there is no greaser on the pedals .   ive seen the bracket wear the D hole to a full round O hole

 

No flats on either pedal pin and all holes in brackets are round. Is it different with diff models?

It might be sledging hammering an egg, but I suppose I could drill a small hole in the bracket, replace the pin with a bolt of the right length shank and a nylock, and  use a lock washer with two tabs, one in the hole and one on a flat of the bolt head. Depends if there's a standard bolt size the same as the pin or if I would need to get a bush made special. 

Graham

[NonMember]

58 minutes ago, A TR7 16V said:

is there any problem in putting this brake pedal and bracket in, instead of the clutch one

I'm not sure. They're certainly not identical across the range. I made the mistake of fitting a Herald brake pedal bracket in the clutch position of a Spitfire (I'd sent the wrong set off for powder coating) and it really doesn't work. The brake one is also different between Heralds and Vitesses due to the master cylinder size. Also, on at least some of them (but I can't remember which) the pedals themselves are angled differently between clutch and brake... and neither of them match the other cars (where they may or may not be the same).

[A TR7 16V]

37 minutes ago, A TR7 16V said:

the hole for the pin in this clutch pedal bracket is a little bit worn

I just looked more closely at the hole for the clevis pin to the clutch piston rod fork on this set I just got, and that's got quite a lot of wear. It's ovalled by about 1mm orthogonal to the length of the pedal, which would be about 5mm play at the centre of the pedal pad. So that would need the set drilling out and a bigger pin/bolt fitting. Whereas the same hole on the brake pedal looks fine.

[A TR7 16V]

26 minutes ago, NonMember said:

I'm not sure. They're certainly not identical across the range. I made the mistake of fitting a Herald brake pedal bracket in the clutch position of a Spitfire (I'd sent the wrong set off for powder coating) and it really doesn't work. The brake one is also different between Heralds and Vitesses due to the master cylinder size. Also, on at least some of them (but I can't remember which) the pedals themselves are angled differently between clutch and brake... and neither of them match the other cars (where they may or may not be the same).

These 13/60 ones seem exactly the same, except for the bracketry for the brake light switch. That may stop the pedal coming up fully when used for the clutch. But thinking about it, the clutch pedal in the car is very near the same height as the brake when it's on the switch. And with no switch, the pedal would, if free from the master cylinder, come up well over an inch higher than the normal position, i.e. above where the clutch pedal stops now. So I assume there's some stop on the master cylinder or that end of the linkage.

I can see how to fix the wear in hole in the clutch pedal for the master cylinder clevis pin - just use a bigger one. But fixing the wear in the holes in the bracket for the pivot pin has me a bit flummoxed. And that set would want a new bush and pin to make it tight as well.

Graham

[NonMember]

2 hours ago, A TR7 16V said:

So I assume there's some stop on the master cylinder or that end of the linkage.

In effect, yes. The pedal is intentionally free to swing well beyond the point that the piston bottoms, because it's VERY important to allow the piston its full travel in the cylinder (otherwise the fluid can't return and the clutch or brakes stop working).

[A TR7 16V]

I went to see if I can swap the clutch pedal and bracket, cos it looks a fairly easy job. I checked that all the screws will undo, and they will. However, the split pin was so solid in the clevis pin on the end of the master cylinder piston rod, the head came off first. There's enough of it left it won't fall out, but I've got to buy something to at least replace it.

Does anyone have an opinion on the differences between these master cylinder rubber boots:

https://www.ebay.co.uk/itm/371709323800?fits=Model%3AHerald&hash=item568b9a2a18:g:-6gAAOSwzYtglAuh

and these:

https://www.ebay.co.uk/itm/254854572363?epid=1816907236&hash=item3b5684294b:g:ut0AAOSwR5BbBUWJ

?

Graham

[Colin Lindsay]

On 17/08/2021 at 14:18, A TR7 16V said:

These 13/60 ones seem exactly the same, except for the bracketry for the brake light switch. That may stop the pedal coming up fully when used for the clutch. But thinking about it, the clutch pedal in the car is very near the same height as the brake when it's on the switch. And with no switch, the pedal would, if free from the master cylinder, come up well over an inch higher than the normal position, i.e. above where the clutch pedal stops now. So I assume there's some stop on the master cylinder or that end of the linkage.

I can see how to fix the wear in hole in the clutch pedal for the master cylinder clevis pin - just use a bigger one. But fixing the wear in the holes in the bracket for the pivot pin has me a bit flummoxed. And that set would want a new bush and pin to make it tight as well.

Graham

The later Spitfire pedals have a larger foot area, so are easily spotted. Some late pedals however have a strange return spring assembly; I don't know how this affects pedal feel but it's stronger than the simple spring found in the earlier versions.

  

The bellhousing has two bronze bushes for the clutch release pivot pin, and the hole through the end of the release lever is larger than the pivot pin; it's the crinkle washer that holds the two together by taking up the gap. You can buy uprated pins that won't drop straight through but the shank is the same diameter as the originals; just buy a new crinkle washer and slip that down into the release lever - you'll find the hole through that is tapered, so larger at the top than the bottom, and the crinkle washer pushes down from the top.

 

[DanMi]

I bought a number of these fulcrum pins from various suppliers and found them to be too large a diameter (probably metric equivalent), which didn't let the clutch arm wobble enough and so was very stiff, eventually found one that was ok and had a head to stop it falling out. So if you do replace with gearbox out make sure that the arm with release bearing moves freely

[Pete Lewis]

that spring idea is to even up the feel of the diaphragm so pressure down and back has a similar feel 

a diaphragm clutch  has a very different  input and output loads the hysteresis  is not a straight line graph

many cars  can  have this sort of  set up  

Pete