Slave cylinder push rod 'shim'

[BaulyCars]

Hi everyone, 

Found a nut inside the slave cylinder (!), which presumably was put there by the PO to shim out the push rod as a band-aid of sorts - anyone done/seen anything similar? 

I am finding gear engagement is crunchy (particularly 3rd and 4th) once up to temp, so suspect an underlying issue. 

I need to have the car running for the weekend so have a couple of choices for now - put the nut back in (it worked afterall...), or remove the nut and maybe try the upper bolt hole on the lever arm for now (it was on the usual middle hole).

Any ideas would be great, and what can I expect as a permanent fix?

 

Kind Regards

Toby 

 

     

Edited December 4, 2023 by BaulyCars

[Mike C]

I've not seen anything like it. It could be limiting the movement of the slave cylinder piston to the top end of the cylinder. Have you tried the clutch operation with the nut removed?

 

[Z320]

Hi Toby,

with the upper hole in the lever arm the push rod and force are out of center to the piston.

This gives sidewards force (down) on the piston, making the piston scratch on the surface of the slave cylinder.

You better don’t do that, in my opinion the middle hole is the correct one while the both others make no sense.

Put the nut back (the rod on the center, not like it was on the side), there will be a reason for it?

You could make an adjustable / your individual push rod with a M8 „Gabelkopf (forkhead)“

 

Ciao, Marco 

Edited December 4, 2023 by Z320

[Waldi]

 

I do not understand the purpose of the additional nut, without it the piston will be a bit more “out”, but still work as long as it is in the bore. 

Do you have the correct diameters of MC and SC installed?
Example: a smaller diameter MC will make the pedal work easier but also reduce the stroke. Travel of the rod should be 16 mm or so, less is not good.

The clutch shaft lever should be vertical, more or less, see picture; is it?

 

Waldi

[elclem1]

I have seen this before, and all that has happened is that the stroke of the piston starts in a different place so less to travel when the clutch is operated. the problem may be in the master cylinder and the amount of fluid being passed to the slave cylinder perhaps fluid is  passing over the seals inside the master . I would check that too. Or as suggested make an adjustable rod and ditch the nut.  As it was working already with the nut you could always revert to that set up or move the whole slave cylinder forward to compensate  for the lack of travel of the rod? i still think the problem lays with the master cylinder.

[Z320]

The problem is always the TR6 with its "self adjusting" clutch and not adjustable pushrod.

There are slaves out there with the flanges in different positions, they can be installed in different ways.

And at least 2 different lenght of not adjustable push rods (I've been told).

The best way to cure the problem is to install an adjustable rod.

Ciao. Marco

[mkmick]

I discovered that a nut had been used as a spacer ( wrong slave cyl fitted) . Something like that might work for you rather than a loose nut in the slave cylinder.

[BaulyCars]

Thanks for all the replies, really appreciated. 

Here’s a quick vid of the arm, which sits vertically and has only a little free movement fore and aft. 

The SC appears newish, with no markings. 

I like the spacer idea, probably means I can ‘tune’ it with washers. 

Overall issue though, I’m guessing wrong SC fitted? 

Cheers

Toby

[BlueTR3A-5EKT]

1 hour ago, mkmick said:

I discovered that a nut had been used as a spacer ( wrong slave cyl fitted) . Something like that might work for you rather than a loose nut in the slave cylinder.

Looks like the bleed nipple is at the bottom on that photo.   If so you may never get all the air out the system 

 

Master cylinders.   Started life as 3/4” (0.75”) and went to 0.7” during TR6   Gives lighter pedal but also less movement at the slave cylinder for an equal pedal stroke length.

….on push rod lengths.   TR 5/250/6 the master cylinder pushrod is  longer if the car is RHD.  Originally It is not adjustable.

Slave cylinders  these were common through TR5/250/6   There are also some on other cars that look identical but have a different bore.

For the slave cyl there was only ever one push rod length.   It is not adjustable.

The obsession with adjustable push rods is to try and cure other mechanical or hydraulic failings.  
Hydraulics not bled properly because the bleed nipple is lower than the inlet pipe at the slave cylinder. Etc…

Mechanically….First thing to look at is wear on all the clevis pins and the holes they fit through.  Repair or replace to eliminate all slop or lost movement.  Weld up holes and re drill renew clevis pins.

The common brake/clutch pedal support bushes and shaft wear too.  In fact at one time Triumph fitted plastic bushes in the pedals which failed quite quickly.  Again eliminate wear and lost movement  fit new bushes and support shaft/axle.

The bushes in the gearbox bell housing that support the cross shaft wear too.    As above.

Then we get to the nutty favourite the failed pin that holds the clutch release bearing fork to the cross shaft.   There is tons in this forum on this subject.
You are usually able to check that failure from under the car without having to take the gearbox out.   Disconnect the push rod from the lever.   Push by hand the lever fully rearwards, then pull forwards.  Keep trying just to get a feel of it.   Is there a change of feel and slightly more movement as you press or pull at the lever at the first mechanical stop ?   If so the pin has started to fail.  

[BlueTR3A-5EKT]

An example if washer fine tuning

 

https://www.triumphexp.com/forum/tr6-tech-forum.2/tr6-od-and-clutch.915069.916445/

 

 

 

[jerrytr5]

With so many moving parts in the system, no matter how precise you are making sure there is no wear in any of them, there will always be a bit of free play. Make up an adjustable push rod and you will ensure that the clutch starts operating at the point that suits you, not some random variable area.

Jerry

[BaulyCars]

9 hours ago, Z320 said:

These look good Marco.

I think I'll try Peter's washer tuning as a temporary fix.  

And then get a new SC and MC, both mine looks suspiciously generic.  

Need to run through Peter's other checks too (on first feel, the clutch lever arm feels solid at both its stops). 

 

 

[Waldi]

To get all air out of the SC it is best to unbolt it (but leave hydraulic hose connected), bottom end pointing upwards and fully press the piston in and purge. Then re-install.

How much travel do you have?

Peter’s (BlueTR3A) list is comprehensive, if you checked all those points, you could expect a vast improvement.

Waldi

[Tim D.]

Just fyi

In the process of lightening my clutch (saab 900 uprated clutch cover to handle the supercharger torque and sister driving used to  modern audi clutch wieght) I went down Marcos route of a 0.625 inch master. Was very surprised that it worked. Some slight mods to the pedal. But works great. 

But then all the various pivots have been renewed to spec. 

Tim

[PodOne]

When I had difficulty getting the required travel as advised from other Formites I pressure bled the system (Easy Bleed) problem solved. The usual two man technique failed to get all the air out.

To remove any residual play I fitted an adjustable push rod and so far the clutch has been perfect in use.

Andy 

[Z320]

11 hours ago, Tim D. said:

Just fyi

In the process of lightening my clutch (saab 900 uprated clutch cover to handle the supercharger torque and sister driving used to  modern audi clutch wieght) I went down Marcos route of a 0.625 inch master. Was very surprised that it worked. Some slight mods to the pedal. But works great. 

But then all the various pivots have been renewed to spec. 

Tim

Yes, I fitted a 0.625" master and would also swap to a 0.5" master, if Girling would have ever produced them...

0.700² / 0.750² = 87% force

0.625² / 0.750² = 69% force

0.500² / 0.750² = only 44%!! force

But we are drifting.....

Edited December 5, 2023 by Z320

[BaulyCars]

Spaced the SC with washers, then wanted to re-fill and bleed, but… 

 

[Tom B]

On 12/4/2023 at 10:22 AM, Z320 said:

The problem is always the TR6 with its "self adjusting" clutch and not adjustable pushrod.

There are slaves out there with the flanges in different positions, they can be installed in different ways.

And at least 2 different lenght of not adjustable push rods (I've been told).

The best way to cure the problem is to install an adjustable rod.

Ciao. Marco

Sorry to be late into this - I posted this a while ago - you need the longer one. The main issue with mine was wear in the two clevis pins - get those sorted and you shouldn't have any problems or need for an adjustable push rod.

[Z320]

Hi Tom,

thank you for posting this photo.

Please, do you allow me to use it for an article at our TR IG club magazine?

Ciao, Marco 

 

[BaulyCars]

Thanks, Tom, mine looks even longer than both of those. 

5 hours ago, Tom B said:

Sorry to be late into this - I posted this a while ago - you need the longer one. The main issue with mine was wear in the two clevis pins - get those sorted and you shouldn't have any problems or need for an adjustable push rod.

 

 

[BlueTR3A-5EKT]

34 minutes ago, BaulyCars said:

Thanks, Tom, mine looks even longer than both of those. 

 

 

This is a picture of the master cylinder push rods.  it demonstrates visually the wear in the hole that the clevis fits through.  The rh one being egg shaped not round.
 

The shorter length version of the push rod is used on LHD cars.  The longer item will be for RHD cars.   This length change is to do with where the master cylinder is mounted and connects to the clutch pedal.

[Tom B]

2 hours ago, Z320 said:

Hi Tom,

thank you for posting this photo.

Please, do you allow me to use it for an article at our TR IG club magazine?

Ciao, Marco 

 

Of course, No problem. The shorter push rod was supplied as being correct for a TR6 by a well known supplier.

Good luck

Tom

[JohnC]

Interesting info that there is more than one design of s/c out there. It explains a mystery I've had with my car. When I got the car nearly 40yrs ago the s/c was inserted into the mounting plate from the rear of the car, and the s/c had a machined face against the plate (i.e., the face of the mounting flange closest to the bleed nipple was machined).

When I got a replacement s/c many years ago the front-facing side was not machined but the rear-facing was. So without thinking I mounted it from the front so that the machined face was against the mounting plate. The result was that the clutch periodically dumped its fluid as the piston popped out of the s/c. Not every time (that would have been too obvious). It took me months of head-scratching and wear elimination before I realised what I'd done. Fortunately I have plenty of photos so I eventually spotted the change.

I now have the s/c mounted from the rear again, although with a non-machined flange face against the mounting plate. Looks inelegant but does the job. I like the idea of the adjustable pushrod though. That allows one to choose where the piston ends up in the s/c bore. It seems pretty clear from the measurements Marco has posted that we don't need anywhere near the full length of the bore to accommodate full travel (even with a .75" m/c), so no problem there.

BTW I'm a fan of the self-adjusting clutch. If we didn't have it then the pushrod would have to be adjusted to compensate for clutch wear, rather than a simple fluid top-up. I suspect that excessive linkage wear and incorrect s/c being supplied/fitted may be behind the need many of us have had for an adjustable pushrod.

Cheers,
JC

[John L]

Does anybody have the part number for the 0.625" SC, is it available in any of the Moss parts under a different model car or other catalogues please?

John

[BlueTR3A-5EKT]

10 minutes ago, John L said:

Does anybody have the part number for the 0.625" SC, is it available in any of the Moss parts under a different model car or other catalogues please?

John