Jump to content

Difficulty engaging gear when gearbox is hot


Recommended Posts

Hi

 

I have a TR2 with an uprated all synchro gearbox with uprated overdrive currently running 20w/50 oil. That was changed last spring since when I've only done about 600 miles

 

The box has been trouble free until this year when it has become increasingly difficult to change gear when the gearbox is hot. There are no problems when the engine and box are cold but once up to temperature it’s becoming a nuisance

 

I’ve changed the clutch fluid (which had been overlooked) which has improved the gear change but the problem has persisted. Because it improved, it might point to clutch issues but the engagement point on the pedal travel doesn’t seem to change with temperature and there are no signs of fluid loss (hard to tell round the slave cylinder because of the ever present oil drips but the fluid level doesn’t drop). The clutch is a TR6 cover and plate on a TR4A aluminium flywheel

 

Next thoughts are to change the oil for say Millers EP 80w90

 

Any ideas?

Link to post
Share on other sites

Yep. (No obvious signs of leaks but haven't checked the level this year)

 

Oil was changed early 2014 and the issue has only developed this year

Link to post
Share on other sites

Hi Philip,

you have tried 20w/50 and are now considering EP 80W/90. Have thought about using a gearbox oil Penrite 40 or similar.

 

However with the heat I would have thought the problem lies in the clutch area.

What are the linkages like - worn clevis pins/holes etc

 

Roger

Link to post
Share on other sites

Simple clutch test:

 

Start engine. depress clutch. wait 30 seconds. slowly engage reverse gear. (no synchro on reverse)

If it goes in without a crunch then clutch has fully released.

 

repeat this when everything is hot (i.e. when you are having problems in other gears).

 

Bob.

Link to post
Share on other sites

What Roger said plus

Check the clutch adjustment to eliminate it - that is if you still have the original TR2-4 system and not the TR4A onwards solid rod, no return spring, hydrostatic system at the clutch slave.

Which hole is the clutch slave fork connected to on the bell housing clutch lever?

Is the steady rod to the engine sump screw from the slave bracket present?

My own car is prone to gear crunch if I fail to readjust the clutch correctly.

 

Peter W

Edited by BlueTR3A-5EKT
Link to post
Share on other sites

Thanks Bob, looks like clutch issue

 

Fine when cold but the clutch isn't releasing when hot

 

Likely causes?

 

Phil

Link to post
Share on other sites

Thanks everyone

 

Problem was clutch actuating rod needed adjusting. Everything else was fine, stay rod in place, clevis pin and (middle) hole in lever were fine.

 

Still puzzled why it released when cold but not when hot but problem solved. Another thing to keep my eye on.

 

Thanks for your guidance

 

Phil

Link to post
Share on other sites
  • 7 years later...

Will the points/checks raised above apply to TR5 overdrive box as well?
Would an oval hole in the clutch pedal also result in difficulties?

Thanks,

Tim

Link to post
Share on other sites

Thanks Roger. I will put it on my list of jobs for the winter.

Cheers,

Tim

Link to post
Share on other sites

Roger,

Do you think that fitting an adjustable pushrod on the clutch slave cylinder would be an option?
Cheers

Tim

18 hours ago, RogerH said:

Hi Tim,

any slack will cause problems. 

You can adjust out the slack caused by oval/worm holes/pin  but they will increase the load on your legs when pressing down on the pedal.

 

Roger

 

Link to post
Share on other sites
21 minutes ago, Tim T said:

Roger,

Do you think that fitting an adjustable pushrod on the clutch slave cylinder would be an option?
Cheers

Tim

 

You shouldnt really need it if you have taken all the slack out of the actuating mechanism, also do you have the right pushrod on the master cylinder as this has come up before with the left hand drive push rod being shorter than the right hand drive one, check your original if you have replaced it.

Stuart.

Link to post
Share on other sites
49 minutes ago, stuart said:

You shouldnt really need it if you have taken all the slack out of the actuating mechanism, also do you have the right pushrod on the master cylinder as this has come up before with the left hand drive push rod being shorter than the right hand drive one, check your original if you have replaced it.

Stuart.

The master cylinder and rod are the original ones reconditioned by Past Parts. Will have good look through the whole linkage and have a fiddle …..

Thanks,

 Tim 

Link to post
Share on other sites

if you have doubts  on the operating  temperature  you  use these https://www.testo.com/en-UK/products/temperature-measuring-strips  i have used  them during engine trials and  they are good for an indicative reading , as long as the surface is clean they stick ok , i normally use brake cleaner on the surface  and we have been able to detect bearing issues without the use of an infrared  spot temperature device .. i'm sure   someone must have used them before but just in case 

Im putting together a gear oil comparison  document  which is a quick comparison of the physical properties of each make, viscosity and type of gear oil and engine oils  so if anyone has product suggestion,  i can see if i can locate the technical data and then share the document i have some data  from my time in  Castrol & BP   but its been a few years since my automotive days  so just let me know the product name and ill see what vi can do  . It will then be possible to compare  viscosity of  multigrade gear oil v  Mono v Engine oils mono and multigrade

cheers

Steve

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
×
×
  • Create New...

Important Information

Please familiarise yourself with our Terms and Conditions. By using this site, you agree to the following: Terms of Use.