Stiff Gearbox TR6

[Matt1969]

Hi All

Around 2 years ago, I took out the gearbox and had it reconditioned by Overdrive Repair Services in Sheffield.  I didnt replace the clutch as there was about 20% life left in it.  Immediately the car came back and it was hard to get into 1st and quite hard to get into 2nd.  It was much worse once the car had been driving for around 30 mins and had properly warmed up. In the worst instances it would not go into any of the forward gears, but usually would go into reverese.  This is despite trying double de-clutching etc..  It would go in if you carefull adjusted car speed to gear box speed as you slowed down.

So, I thought, it sounds like a clutch problem.  This year, I replaced the clutch, with the usual trials.  Absolutely no change.  

I have rung ORS and they are willing to look at the box again, but suggest it is more likely a clutch problem. 

Before I take the gearbox out again, does anyone have any bright ideas?

Thanks.

Matt

[Waldi]

Hi Matt,

I would check the clutch lever movement first. 

The rod of the slave cylinder should be in the middle hole of the lever, and have at least 16 mm horizontal travel. It needs a 2nd person to measure this. A failed tapered pin in the fork could contribute to the issue as well.

My gear box was stiff after reconditioning too, but once warm (20 miles or so) it got better. Now, after a couple of thousand miles, it’s ok cold and warm.

Waldi

[Matt1969]

Thanks Waldi

[John L]

Did your refit the dowel bolts in the right places in the gearbox to engine flange, lots of info on here for the positions.

Can you tell us a bit more please.  without the engine running and without dipping the clutch, how easy is it to select gears?  Is it still tight or is it easy now?

You might have the 2 bolts that hold the gear lever from rotating may be just too tight, also it may be the rubber that goes around the tunnel to seal the gear lever housing there are 2 ways it can be fitted, try and remove it completely and try the gear selection. 

John

[Andy Moltu]

Too thick oil?

If it is ok when warmed up then a clutch issue is unlikely. Try 80/90 multi grade gear oil.

[Hamish]

Try slackening the adjusters in the top cover. 
1/4 to 1/2 turn should let you know if it’s the issue. 

[Matt1969]

2 hours ago, John L said:

Did your refit the dowel bolts in the right places in the gearbox to engine flange, lots of info on here for the positions.

Can you tell us a bit more please.  without the engine running and without dipping the clutch, how easy is it to select gears?  Is it still tight or is it easy now?

You might have the 2 bolts that hold the gear lever from rotating may be just too tight, also it may be the rubber that goes around the tunnel to seal the gear lever housing there are 2 ways it can be fitted, try and remove it completely and try the gear selection. 

John

I will try this and let you know.

[Matt1969]

1 hour ago, Andy Moltu said:

Too thick oil?

If it is ok when warmed up then a clutch issue is unlikely. Try 80/90 multi grade gear oil.

It is more of a problem when its warmed up.

[Matt1969]

46 minutes ago, Hamish said:

Try slackening the adjusters in the top cover. 
1/4 to 1/2 turn should let you know if it’s the issue. 

Will add it to the list!  Thanks.

[Peter Cobbold]

You have tried bleeding the clutch hydraulics?

[HSM]

If change is stiff when engine running but o.k. when turned off usually indicates clutch not clearing.

 

                                           Harvey

[elclem1]

I have found that certain release bearing carriers are not the correct size, thus limiting the amount of clearance from the friction plate to the pressure plate. If the clutch friction plate has  been changed then there is more material and even less clearance. This manifests itself if the system need bleeding but actually its a dimension problem. or the master cylinder is leaking internally and not holding pressure enough to move the slave to the full extent of travel. 

[Andy Moltu]

The Tr6 clutch is essentially self adjusting. If the bearing carrier was too long it potentially a cause of slippage rather than failing to clear.

likewise getting stuck on the output flange would generally give jerky release as it is only pushed off by the pressure of the clutch cover. However pressing the pedal exerts rather more force.

Check the mechanism is connected to the second hole in the lever.

Bleed it and check the lever is moving adequately.

if it continues to drag the likelihood is a broken pin. in which case it’s box out which will let you inspect/replace the clutch as well.

Whilst the cover/driven plate is unlikely to be the cause I would, given the sheer hassle of changing the clutch, advocate replacing the clutch almost every time you have the box out unless the clutch is virtually new. 

[Matt1969]

20 hours ago, Waldi said:

Hi Matt,

I would check the clutch lever movement first. 

The rod of the slave cylinder should be in the middle hole of the lever, and have at least 16 mm horizontal travel. It needs a 2nd person to measure this. A failed tapered pin in the fork could contribute to the issue as well.

My gear box was stiff after reconditioning too, but once warm (20 miles or so) it got better. Now, after a couple of thousand miles, it’s ok cold and warm.

Waldi

HI waldi

Well the pin was in the bottom hole not the middle hole, so that is one problem solved.

The second issue is the movement.  Its only moving 13mm.  How do you increase this?

Thanks!  Matt

[BlueTR3A-5EKT]

21 hours ago, Matt1969 said:

Hi All

Around 2 years ago, I took out the gearbox and had it reconditioned by Overdrive Repair Services in Sheffield.  I didnt replace the clutch as there was about 20% life left in it.  Immediately the car came back and it was hard to get into 1st and quite hard to get into 2nd.  It was much worse once the car had been driving for around 30 mins and had properly warmed up. In the worst instances it would not go into any of the forward gears, but usually would go into reverese.  This is despite trying double de-clutching etc..  It would go in if you carefull adjusted car speed to gear box speed as you slowed down.

So, I thought, it sounds like a clutch problem.  This year, I replaced the clutch, with the usual trials.  Absolutely no change.  

I have rung ORS and they are willing to look at the box again, but suggest it is more likely a clutch problem. 

Before I take the gearbox out again, does anyone have any bright ideas?

Thanks.

Matt

Have you fitted a replacement clutch master cylinder?   Could be the push rod to the pedal is too short and you are not getting full pedal throw.   This comes about with the LHD master cyl push rod being shorter than the RHD item.  

[stuart]

6 minutes ago, BlueTR3A-5EKT said:

Have you fitted a replacement clutch master cylinder?   Could be the push rod to the pedal is too short and you are not getting full pedal throw.   This comes about with the LHD master cyl push rod being shorter than the RHD item.  

+1

Stuart.

[Z320]

An adjustable pushrod, like on the 4 cylinders, can keep the clutch „self adjusting“ and could solve the problem.

Ciao, Marco 

Edited July 8, 2022 by Z320

[Matt1969]

Hi All, thanks for all your input, which has been invaluable.  I moved the pin into the middle hole, replaced the clutch fuild (which looked like black gloop) and bled it through.  Hey presto!  It looks like its working.  Please send invoices to the usual address!  Thanks, again.  matt

[Waldi]

Hi Matt,

good to see you solved it.

If you still have only 13 mm stroke, there may be a bit more home work for you. 

Check all the pivot points including the clevis pins (remove them) for wear and replace where required.

Some have installed different diameter  cylinders to have a lighter pedal, off course the down side is less stroke.

Cheers,

Waldi