Heavy clutch pedal

[Britr6]

My TR4a has a very heavy clutch pedal. Are there any modifications that can reduce pressure needed to operate it. Would appreciate any ideas, thanks Brian 

[Lebro]

How many miles has the clutch done ? as the friction plate wears the diaphram spring moves frowards, & becomes harder to compress. resulting in a heavyer pedal.

Bob

[Britr6]

Car was restored in early 2000 . I acquired the car late last year 

[harrytr5]

Servo assisted.Or Cambridge motorsports annular clutch kit (gearbox out for that one)

Regards Harry

[Z320]

Fit a 0.625“ master cylinder, your wife will love it.

Other improvements are possible, depending on your clutch cover (gearbox out),

but the 0.625 master brings most benefits for small money,

installed at a afternoon.

Ciao, Marco 

edit: see here

 

Edited March 6 by Z320

[Andy Moltu]

Is the slave cylinder push rod in the middle hole on the operating lever? Sometimes they get fitted to the top hole which increases the throw at the expense of reduced mechanical advantage.

Do you have any information on which clutch is fitted?

If a previous owner has fitted an "uprated" cover you are likely to need to start with a new standard one before considering any of the modifications to master cylinder bore or annular release bearing. 

[jerrytr5]

See pinned topic in TR6 section, probably answer most of your questions.

Jerry

[Britr6]

1 hour ago, jerrytr5 said:

See pinned topic in TR6 section, probably answer most of your questions.

Jerry

 

[Britr6]

3 hours ago, Andy Moltu said:

Is the slave cylinder push rod in the middle hole on the operating lever? Sometimes they get fitted to the top hole which increases the throw at the expense of reduced mechanical advantage.

Do you have any information on which clutch is fitted?

If a previous owner has fitted an "uprated" cover you are likely to need to start with a new standard one before considering any of the modifications to master cylinder bore or annular release bearing. 

Slave cylinder is in the bottom hole, don’t know what clutch fitted 

[Andy Moltu]

I guess the bottom has been used to try and make the clutch lighter.

Have you compared it to any other 4As? That will tell you if something is wrong or whether you might wish to seek one of the modifications to make it lighter than standard.

[Z320]

4 hours ago, Andy Moltu said:

I guess the bottom has been used to try and make the clutch lighter.

Have you compared it to any other 4As? That will tell you if something is wrong or whether you might wish to seek one of the modifications to make it lighter than standard.

The only hole that makes sense is the one that holds the pushrod as well as possible in the center line of the slave cylinder.

All other positions of the hole push the piston sidewards, make it powerfull scratch on the bore of the hydraulic cylinder and reduce the torque.

Don’t use the lower hole it it doesn’t line up with the master cylinder.

Edited March 6 by Z320

[Tr4aJim]

Just as Marco says: on my 4A I have the push rod on the lowest hole, as that lines up with the bore of the slave cylinder.

Jim

 

 

[ianc]

Words of wisdom from Moss's catalogue:

"There ar 3 holes in the clutch cross shaft lever end.  All 4 cylinder TRs should be connected from the slave cylinder to the CENTRE  hole.   The othe two holes are for use on different Trtiumph models".

The photo in the TR4 Workshop Manual correctly shows the connection to the centre hole.

The odd thing is that the lever actually looks to be slightly misaligned when the centre hole is used, but I have been using the centre hole for over 60 years, and Peter Wigglesworth and Pete Cox, who wrote the useful advice in the Moss manual, know their stuff.

The Workshop Supplements for the TR5 and for the TR6 do not have photos of this connection, but I would assume that the same advice pertains sine the gearbox casing is basically the same.

Ian Cornish

[Tr4aJim]

Ian, could it be the difference in the clutch bearing used between the 4 and the 4A? For example the 4A doesn’t use a clutch lever return spring, and the 4 does.

BTW - the Moss US web site lists a clutch lever return spring for the 4 and the 4A. However the Moss UK site only lists the spring for the 4 (correctly so per the 4A Stanpart catalog).

Jim

[Z320]

As long I used the TR gearbox it was the middle hole on my TR4A

[ianc]

When Neil rebuilt 4VC for me in the early 1990s, I decided to change to diaphragm clutch, but I have never noticed that this made any difference to the effort reguired.

In common with many who have a diaphragm clutch, I have that external spring in place - why ?  because Neil fitted it. 

That spring really doesn't affect the load for one's left leg and it holds the thrust mechanism back so that it is not going to be dragged by the spinning of the clutch .

However, it is the owner's choice.

Ian Cornish

[BlueTR3A-5EKT]

If you fit the return spring you must have an adjustable push rod, and be prepared to adjust the push rod length as the clutch wears in service.    Otherwise with a solid push rod, as the clutch wears that wear cannot be adjusted out.   The slave cyl push rod and piston will always be compressed back into the cylinder if there is a return spring ( hint of function is in its title)   No spring and the push rod and piston will extend to take up the wear.   The issue you will now notice is the fluid level in the master cylinder drops as the push rod and slave piston extend outward to take up wear.

Using a solid push rod of the correct length, and no return spring provides effectively a self adjusting clutch.  This was incorporated from TR4A onwards when the smaller diaphragm clutch was introduced.  

All very basic principles really.   I spent years explaining this to TR6 owners with a dud clutch operation who insisted an adjustable push rod would fix their worn out linkage pins and broken cross shaft pin.

…and let us not go down the ratchet clutch problem again.  Fit the dowel bolts first.

Edited March 8 by BlueTR3A-5EKT

[Andy Moltu]

Quite.

The the clutches on 5s & 6s are self adjusting (as were 4as the later clutch) No return spring and adjustment required.

Some of the modifications May have required a pull of spring and  by necessity an adjustable push rod. (In the 90s there were a lot of poor quality release bearings and some of the alternatives needed to be pulled away from contact with the clutch cover other than when the clutch was being actively depressed.)

If you have an unmodified clutch you don’t need any adjustment. If you do, fix the problem not compound it with a bodge.