Clutch Issue

[Ecosse]

Having messed about with cars for over 60-years now it still seems that every day is a school day. I have made a number of posts regarding issues encountered with my Hillclimb TR7 and received suggestions which have sometimes help resolve issues, so here is the latest.

I am still breaking in the rebuilt engine and all is going well except for a new issue which has started to manifest itself. Changing gear at the start of a run is absolutely fine, but after about 10-miles or so engaging first gear, and even more so, reverse gear, is impossible. the solution is to switch off, select gear and restart with the clutch depressed. Once started there is no clutch drag whilst stationary in gear, and when accelerating there is not any clutch slip. It is a new uprated clutch.

I have never encountered anything like this previously, even on my Hillclimbing TR3 and TR6, has anyone ever experienced a similar issue. Any thoughts would be gratefully received.

Cliff

[TR Rob]

Slightly related , my TR3a when it gets hot, and I mean after a good half day of continental driving or similar and you hit a queue of slow stationery traffic develops a clutch problem where the clutch pedal goes ‘soft’ and it is very hard to engage first gear, (car runs a TR4a gearbox) Pumping the pedal restores pressure enough to engage gear (just)

Have had all clutch fluid replaced but no major improvement, am now thinking is there a flexi pipe, rubber that connects to the slave cylinder and if so could this have deteriorated in such away that if it gets hot it is distorting and causing a momentary loss of pressure.

When back on the open road gear selection returns to normal, as if the pipe has cooled down and become less flexible, could a similar situation be affecting your gear change …..?

[TR Rob]

Forget rubber pipe theory…just checked Rimmers catalogue and the slave cylinder is hard piped in …!

I think I might get the slave cylinder replaced, as like Cliff when on the move clutch is solid, no slip and if everything is relatively cool…gear change is OK

[RogerH]

Hi Cliff & Rob,

 have you got the clutch slave adjusted correctly. It sounds like something is expanding (or not) and causing the crunching.

The plastic piping usually works well.

Roger

Edited May 29 by RogerH

[Ecosse]

Good Morning Rob and Roger,

Thanks for your thoughts.

All hydraulics are new with 5/8" travel on the pushrod which is what I believe is what it should be. As previously mentioned I have had to increase the length of the pushrod to have any clutch operation, standard length is useless, probably as a result of a modified flywheel. The supplier of the uprated clutch has suggested some 'vigorous' bedding in as when everything heats up any free play is negated, so I shall try that in addition with some further increase in the operating rod length.

All of this hassle just to drive up a hill a couple of seconds quicker.

Cliff

[Hamish]

Well worth it for a couple of seconds. 
I piss about trying g to get a tenth or two

[RogerH]

Perfection   

[Ecosse]

23 hours ago, Hamish said:

Well worth it for a couple of seconds. 
I piss about trying g to get a tenth or two

Hi Hamish,

I am around five seconds off from where I would like to think I should be at Doune, perhaps I am a tad more circumspect these days. If I can get a tenth off on every run I should be back to where I was in my prime in the late 80s by 2030, in time to mark the 50th anniversary of my first ever run at Doune, I even hope to compete in the same car, 2999F.

Cliff

[Ecosse]

23 hours ago, RogerH said:

Perfection   

Hi Roger,

Perfection would be great, these days it seems more like frustration and exasperation.

Cliff

[Hamish]

1 hour ago, Ecosse said:

Hi Hamish,

I am around five seconds off from where I would like to think I should be at Doune, perhaps I am a tad more circumspect these days. If I can get a tenth off on every run I should be back to where I was in my prime in the late 80s by 2030, in time to mark the 50th anniversary of my first ever run at Doune, I even hope to compete in the same car, 2999F.

Cliff

Yet to do Doune. Those dry stone walls are a worry. 
 

but I guess not toooooodifferenttoshelsley and how close the sleepers are

[Jules TR6]

On 5/29/2026 at 3:56 PM, Ecosse said:

Having messed about with cars for over 60-years now it still seems that every day is a school day. I have made a number of posts regarding issues encountered with my Hillclimb TR7 and received suggestions which have sometimes help resolve issues, so here is the latest.

I am still breaking in the rebuilt engine and all is going well except for a new issue which has started to manifest itself. Changing gear at the start of a run is absolutely fine, but after about 10-miles or so engaging first gear, and even more so, reverse gear, is impossible. the solution is to switch off, select gear and restart with the clutch depressed. Once started there is no clutch drag whilst stationary in gear, and when accelerating there is not any clutch slip. It is a new uprated clutch.

I have never encountered anything like this previously, even on my Hillclimbing TR3 and TR6, has anyone ever experienced a similar issue. Any thoughts would be gratefully received.

Cliff

Try Dynolite Gear 40, worked for me after trying many high spec oils that ground gears when hot. 

[Hamish]

8 hours ago, Jules TR6 said:

Try Dynolite Gear 40, worked for me after trying many high spec oils that ground gears when hot. 

It’s what I use and suits the box and OD very well

Edited June 6 by Hamish

[Ecosse]

Hello Jules and Hamish,

Thanks for that, Dynolite is worth a try.

I have tried various lengths of actuating rods and have arrived at the optimum length of being able to select gears, particularly reverse, and not have any clutch slip. As was suggested to me, I have been 'Vigorous' in bedding in the clutch and it does seem to be having the desired effect.

I still have two weeks until Doune to try to resolve the issue.

Cliff