Jump to content
KiwiTR6

J Type overdrive harsh shifting

Recommended Posts

I'm sure I've asked about this before but can't find the thread so here we go again.

The gearbox and overdrive units in my 73 CR were 'rebuilt' for the PO and I have no doubt that this was the case.  The gearbox is sweet to use but the overdrive engagement/disengagement has been so harsh that I have to use the cluch for fear of damaging something.  It was like this when I purchased the car as the PO made me aware of it.

Recently I took the slack out of the diff rubber mounts and that got rid of the horrible banging but did nothing for the harshness.  This weekend just gone I drained the oil (which appeared to be a 90W gear oil), removed the sump, made up a tool and dismantled the oil control valves, high pressure filter and non-return valve.  All appeared to be in good order and correctly assembled, although there was a worrying amount of fine metal particles in the high pressure filter (none in the main suction filter).

After reassembling everything I filled the gearbox with SAE30 oil that I had on hand and took her for a drive.  The harshness had decreased by at least 50%, but still nowhere near as smooth as I remember when a teenager driving my Dad's 2.5 PI sedan.

I sort of understand the basics of the system and how high viscosity oil can cause issues with pressure and flow through the restrictor, so my thinking is that with the 30W oil neither should be an issue.  This leads me to believe that clutch material is biting rather than smoothly engaging.  The reason for my suspicion is that the PO in his list of completedworks notes that the cluch was rebuilt by an 'engineer' rather than an overdrive specialist.  I'm wondering if the clutch friction material is not suitable for this application.

Any thoughts as to what the problem may be and where to from here?

Gavin

Share this post


Link to post
Share on other sites
1 hour ago, KiwiTR6 said:

I'm sure I've asked about this before but can't find the thread so here we go again.

The gearbox and overdrive units in my 73 CR were 'rebuilt' for the PO and I have no doubt that this was the case.  The gearbox is sweet to use but the overdrive engagement/disengagement has been so harsh that I have to use the cluch for fear of damaging something.  It was like this when I purchased the car as the PO made me aware of it.

Recently I took the slack out of the diff rubber mounts and that got rid of the horrible banging but did nothing for the harshness.  This weekend just gone I drained the oil (which appeared to be a 90W gear oil), removed the sump, made up a tool and dismantled the oil control valves, high pressure filter and non-return valve.  All appeared to be in good order and correctly assembled, although there was a worrying amount of fine metal particles in the high pressure filter (none in the main suction filter).

After reassembling everything I filled the gearbox with SAE30 oil that I had on hand and took her for a drive.  The harshness had decreased by at least 50%, but still nowhere near as smooth as I remember when a teenager driving my Dad's 2.5 PI sedan.

I sort of understand the basics of the system and how high viscosity oil can cause issues with pressure and flow through the restrictor, so my thinking is that with the 30W oil neither should be an issue.  This leads me to believe that clutch material is biting rather than smoothly engaging.  The reason for my suspicion is that the PO in his list of completedworks notes that the cluch was rebuilt by an 'engineer' rather than an overdrive specialist.  I'm wondering if the clutch friction material is not suitable for this application.

Any thoughts as to what the problem may be and where to from here?

Gavin

Hi Gavin,

My OD unit was rebuilt by ORS in the UK and I believe that the engagement pressure can be adjusted and I know that ORS have a test rig to do this. I think that you would be well advised to phone them as they are very helpful and are ex Laycock and ask for Peter. I see that you are in NZ but that call could save you a lot of aggro!!! Another point if you use engine oil SAE30, I assume that it is not a gear oil? You run the risk of the engine oil starting to break down and form a sludge type mess which blocks up the oil ways in the OD. I have seen this a number of times where TR owners suffer this fate, which turns out into a very expensive exercise. If you want to use engine oil only use mini oil which was also designed for gearbox use as it has hypoid additives in it, as a TR has hypoid cut gear teeth. Tel. 01142 482632, email: info@overdrive-repair.co.uk

Good Luck,

Bruce.

Share this post


Link to post
Share on other sites

Gavin - how are you actually driving the car when you engage or disengage the OD?  If you are lifting off the accelerator in anticipation of the OD engagement or disengagement, you will get a very obvious and jerky action.

Try keeping your foot hard down and engage OD and see it is any different, and likewise don't lift off when deselecting. Do you know if your J type is a standard 25% ratio or has it been upgraded to a 28%? If the latter, it is even more relevant to NOT lift off - just think about the different turning speeds of the various components trying to accommodate each other in a very short space of time.

There are high grip cone clutches available for the OD, mainly for hard users, and these will give a more aggressive response, but not as you describe so it's possible one was fitted in the earlier rebuild  - like Bruce suggests though, be wary of using the wrong oil - it will come back to bite you

cheers

Rich

Share this post


Link to post
Share on other sites
2 minutes ago, astontr6 said:

Hi Gavin,

My OD unit was rebuilt by ORS in the UK and I believe that the engagement pressure can be adjusted and I know that ORS have a test rig to do this. I think that you would be well advised to phone them as they are very helpful and are ex Laycock and ask for Peter. I see that you are in NZ but that call could save you a lot of aggro!!! Another point if you use engine oil SAE30, I assume that it is not a gear oil? You run the risk of the engine oil starting to break down and form a sludge type mess which blocks up the oil ways in the OD. I have seen this a number of times where TR owners suffer this fate, which turns out into a very expensive exercise. If you want to use engine oil only use mini oil which was also designed for gearbox use as it has hypoid additives in it, as a TR has hypoid cut gear teeth. Tel. 01142 482632, email: info@overdrive-repair.co.uk

Good Luck,

Bruce.

PS. I assume that your car has an A type overdrive which is known for its harshness of engagement and Laycock modified this action at least 3 or 4 times. Are you certain that your OD is as original spec. and has not been changed backwards??? That is why BL went over to the J type.as Volvo did not like the A type, Laycock's biggest customer.

Bruce.

Share this post


Link to post
Share on other sites

At the risk of reigniting the great TR6 gear oil debate, hypoid gear oil is generally GL5 with it's attendant material compatibility and synchromesh problems. I'd do a bit of a check around before I changed the oil specification and maybe damaged the gearbox &OD.

I have an A type overdrive and it will change harshly if I really flog it, do you drive the TR6 differently to the sedan?

Share this post


Link to post
Share on other sites
21 hours ago, astontr6 said:

PS. I assume that your car has an A type overdrive which is known for its harshness of engagement and Laycock modified this action at least 3 or 4 times. Are you certain that your OD is as original spec. and has not been changed backwards??? That is why BL went over to the J type.as Volvo did not like the A type, Laycock's biggest customer.

Bruce.

Hi Bruce.

Thanks for your advice, ever helpful as always!

My unit is definitely a J type with the bottom sump plate and 3 plugged chambers above.  The 30W is mineral engine oil and was added just for trial purposes as it was on-hand and I didn't want to wait around for some good stuff to arrive (and its expensive).  I will eventually use a Morris oil fit for purpose.

Also, I will definitely call ORS as you suggest, it's just a matter of timing with where I'm located.  I have a suitable gauge for testing the pressure (0-600psi from memory) but don't want to take the OD out of the car at this stage so testing could be a bit of a mission.  I could run it on my 2-post hoist but I'm a little wary of doing so considering the rpm and gear I'd need to run it in.

Hopefully ORS will be able to advise on this also.

Kind regards

Gavin

Share this post


Link to post
Share on other sites
21 hours ago, rcreweread said:

Gavin - how are you actually driving the car when you engage or disengage the OD?  If you are lifting off the accelerator in anticipation of the OD engagement or disengagement, you will get a very obvious and jerky action.

Try keeping your foot hard down and engage OD and see it is any different, and likewise don't lift off when deselecting. Do you know if your J type is a standard 25% ratio or has it been upgraded to a 28%? If the latter, it is even more relevant to NOT lift off - just think about the different turning speeds of the various components trying to accommodate each other in a very short space of time.

There are high grip cone clutches available for the OD, mainly for hard users, and these will give a more aggressive response, but not as you describe so it's possible one was fitted in the earlier rebuild  - like Bruce suggests though, be wary of using the wrong oil - it will come back to bite you

cheers

Rich

Hi Rich.

I'm almost certain that it will be the original unit and not upgraded.

I''ve tried changing with no throttle position change (which is how I recall using it in the family PI) and with backing off the throttle a little.  Neither produces a smooth change.  If I recall correctly I used to be able to sit behind a car on the open road in 3rd overdrive then flick the OD out and rocket past when the coast was clear with no noticable shock.  At that tender age I would have been horrified if that had happened.

Regards

Gavin

 

 

Share this post


Link to post
Share on other sites
10 hours ago, Mike C said:

At the risk of reigniting the great TR6 gear oil debate, hypoid gear oil is generally GL5 with it's attendant material compatibility and synchromesh problems. I'd do a bit of a check around before I changed the oil specification and maybe damaged the gearbox &OD.

I have an A type overdrive and it will change harshly if I really flog it, do you drive the TR6 differently to the sedan?

Hi Mike.

I was just following up on what I had found on various forums where I noted several comments about high viscosity gear oils causing high pump pressure and slow oil flow through galleries.  I think I proved that there is some validity to this argument as the shock reduced by half with the 30W, but it's still not right.

My driving is probably no different now - hard on the motor and gentle on the drivetrain!

To date I haven't found any information on adjusting the pump pressure so I'm hopefull that Bruces suggested contact with ORS will give me some relevant guidance.

Regards

Gavin

Share this post


Link to post
Share on other sites

I have no problems with 30W although I've  personally used SAE 80 GL4 in various guises over the years. But I would do a lot of checking before I used GL5 in any viscosity.

 

Share this post


Link to post
Share on other sites
8 hours ago, Mike C said:

I have no problems with 30W although I've  personally used SAE 80 GL4 in various guises over the years. But I would do a lot of checking before I used GL5 in any viscosity.

 

Agree, any gear oil used will be GL4.

Share this post


Link to post
Share on other sites

Hi Gavin,

I’m afraid I can’t offer any immediate solution – just commiserations …

I thought it might just be worth sharing my own similar experiences from ‘across the ditch’, to see if there is anything to be learned ….

I have, over the past few months, just rebuilt and fitted a J-Type (28%) from a 2500 Saloon, to my previously non-overdrive TR6. The rebuild included replacing all of the o-rings/seals and also a replacement Cone Clutch from the aforementioned Overdrive Repair Services.

I have so far covered only a couple of hundred kms, but I was similarly surprised by the harshness of engagement ( given that the J-Type is reputed to be much ‘softer’ than the old A-Type ). I am still experimenting with different engagement techniques, but still cannot achieve a consistently smooth change without the clutch.

At this stage, I had put it down to the new cone clutch grabbing a bit, and was going to wait and see if it improves once it gets a few more kms on it.

Not having previously driven an overdrive car more than a couple of kms, I wasn’t sure whether there was really an issue or not. However, your post struck a chord ….

I guess one significant point is that the symptom does not appear to be unique to your particular clutch friction material ….

I am currently using Castrol VMX-M which is a 75W-85 GL4 Manual Transmission Oil

To quote Castrol Australia Web site :

FEATURES & BENEFITS

- Provides quieter transmission operation

- Easier low temperature gear shifting – driver comfort

- Improved gear tooth and bearing durability

- Effective lubrication over a wide range of operating temperatures

- High shear stability providing excellent protection during the life of the lubricant

SPECIFICATIONS

- Mitsubishi TGO-2

- SAE 75W (extrapolated) 85W (equivalent to 10W-30)

- API Service Classification GL-4

I am somewhat bemused by the theory that the viscosity of EP80 or EP90 Gear oil results in excessively high pressure in the overdrive. ( I think this may have originated from some testing carried out by a US specialist .. ).

As I understand it, Gear Oils and Engine Oils use a different SAE viscosity scale, such that an SAE85 Gear Oil is similar in viscosity to an SAE30 Engine Oil and SAE90 is about equivalent to SAE40 in an Engine oil.

This seems to be consistent with Castrol’s specification above.

I can’t see much scope for using anything thinner, since I suspect the gearbox is generally more fragile than the overdrive.

Cheers,

RobinC

 

Share this post


Link to post
Share on other sites
2 hours ago, RobinC said:

Hi Gavin,

I’m afraid I can’t offer any immediate solution – just commiserations …

I thought it might just be worth sharing my own similar experiences from ‘across the ditch’, to see if there is anything to be learned ….

I have, over the past few months, just rebuilt and fitted a J-Type (28%) from a 2500 Saloon, to my previously non-overdrive TR6. The rebuild included replacing all of the o-rings/seals and also a replacement Cone Clutch from the aforementioned Overdrive Repair Services.

I have so far covered only a couple of hundred kms, but I was similarly surprised by the harshness of engagement ( given that the J-Type is reputed to be much ‘softer’ than the old A-Type ). I am still experimenting with different engagement techniques, but still cannot achieve a consistently smooth change without the clutch.

At this stage, I had put it down to the new cone clutch grabbing a bit, and was going to wait and see if it improves once it gets a few more kms on it.

Not having previously driven an overdrive car more than a couple of kms, I wasn’t sure whether there was really an issue or not. However, your post struck a chord ….

I guess one significant point is that the symptom does not appear to be unique to your particular clutch friction material ….

I am currently using Castrol VMX-M which is a 75W-85 GL4 Manual Transmission Oil

To quote Castrol Australia Web site :

FEATURES & BENEFITS

- Provides quieter transmission operation

- Easier low temperature gear shifting – driver comfort

- Improved gear tooth and bearing durability

- Effective lubrication over a wide range of operating temperatures

- High shear stability providing excellent protection during the life of the lubricant

SPECIFICATIONS

- Mitsubishi TGO-2

- SAE 75W (extrapolated) 85W (equivalent to 10W-30)

- API Service Classification GL-4

I am somewhat bemused by the theory that the viscosity of EP80 or EP90 Gear oil results in excessively high pressure in the overdrive. ( I think this may have originated from some testing carried out by a US specialist .. ).

As I understand it, Gear Oils and Engine Oils use a different SAE viscosity scale, such that an SAE85 Gear Oil is similar in viscosity to an SAE30 Engine Oil and SAE90 is about equivalent to SAE40 in an Engine oil.

This seems to be consistent with Castrol’s specification above.

I can’t see much scope for using anything thinner, since I suspect the gearbox is generally more fragile than the overdrive.

Cheers,

RobinC

 

I use Castrol VMX80 in 3 TRs, two TR2s with A type and a TR6 with a J type. All of the overdrives work very well and have for many years on two of the cars.

The TR2 I have just rebuilt does have a more solid od engagement than its well used brother which is probably as it should be.

The TR6 od works fine in and out.

Share this post


Link to post
Share on other sites
22 hours ago, harrytr5 said:

Is it a competition one I wonder as they can come in with a bang.

Regards Harry TR5 Nutter

Hi Harry.

As far as I know it's the standard setup, just overhauled and done around 7,500 kms since.

Cheers

Share this post


Link to post
Share on other sites
On 11/18/2019 at 4:31 PM, RobinC said:

Hi Gavin,

I’m afraid I can’t offer any immediate solution – just commiserations …

I thought it might just be worth sharing my own similar experiences from ‘across the ditch’, to see if there is anything to be learned ….

I have, over the past few months, just rebuilt and fitted a J-Type (28%) from a 2500 Saloon, to my previously non-overdrive TR6. The rebuild included replacing all of the o-rings/seals and also a replacement Cone Clutch from the aforementioned Overdrive Repair Services.

I have so far covered only a couple of hundred kms, but I was similarly surprised by the harshness of engagement ( given that the J-Type is reputed to be much ‘softer’ than the old A-Type ). I am still experimenting with different engagement techniques, but still cannot achieve a consistently smooth change without the clutch.

At this stage, I had put it down to the new cone clutch grabbing a bit, and was going to wait and see if it improves once it gets a few more kms on it.

Not having previously driven an overdrive car more than a couple of kms, I wasn’t sure whether there was really an issue or not. However, your post struck a chord ….

I guess one significant point is that the symptom does not appear to be unique to your particular clutch friction material ….

I am currently using Castrol VMX-M which is a 75W-85 GL4 Manual Transmission Oil

To quote Castrol Australia Web site :

FEATURES & BENEFITS

- Provides quieter transmission operation

- Easier low temperature gear shifting – driver comfort

- Improved gear tooth and bearing durability

- Effective lubrication over a wide range of operating temperatures

- High shear stability providing excellent protection during the life of the lubricant

SPECIFICATIONS

- Mitsubishi TGO-2

- SAE 75W (extrapolated) 85W (equivalent to 10W-30)

- API Service Classification GL-4

I am somewhat bemused by the theory that the viscosity of EP80 or EP90 Gear oil results in excessively high pressure in the overdrive. ( I think this may have originated from some testing carried out by a US specialist .. ).

As I understand it, Gear Oils and Engine Oils use a different SAE viscosity scale, such that an SAE85 Gear Oil is similar in viscosity to an SAE30 Engine Oil and SAE90 is about equivalent to SAE40 in an Engine oil.

This seems to be consistent with Castrol’s specification above.

I can’t see much scope for using anything thinner, since I suspect the gearbox is generally more fragile than the overdrive.

Cheers,

RobinC

 

Hi Robin.

Yes I understandard that the viscosity figures for engine and transmission oils are different as you say, but the oil I drained out was quite thick and tacky, a bit like chainsaw bar oil. The 30W engine oil certainly made a diffence but isn't the answer, there is something else going on.  For someone who has mechanical sympathy, this is not going to end well if I continue to use it this way . 

Once I get this sorted I'll certainly take your advice re the oil to use.

Regards

Gavin

Share this post


Link to post
Share on other sites
On 11/18/2019 at 6:42 PM, John McCormack said:

I use Castrol VMX80 in 3 TRs, two TR2s with A type and a TR6 with a J type. All of the overdrives work very well and have for many years on two of the cars.

The TR2 I have just rebuilt does have a more solid od engagement than its well used brother which is probably as it should be.

The TR6 od works fine in and out.

Thanks for your confirmation of  Robin's recommendation John, much appreciated.

Regards

Gavin

Share this post


Link to post
Share on other sites

I have and A type overdrive and if I had this problem I'd be looking at the accumulator operating pressure and relief valve setting. Someone may have set yours  up for hard fast changes as mentioned above. 

Share this post


Link to post
Share on other sites

The only J type upgrade I was aware of was STR0222  the solid overdrive piston assembly, that was specified by BL Special Tuning at Abingdon for Dolomite Sprint.  They existed and we had them built into a wide ratio Dolomite Sprint o/d gearbox we have attached to a family TR2.  I cannot say I noticed any serious difference with the o/d engagement though.

 

Following is extract from BL ST Dolomite Sprint tuning leaflet.

image.thumb.png.a75232aecac2fdc715630e8966ee908f.png

Share this post


Link to post
Share on other sites

Hi All.

I made up an adaptor yesterday for the gauge I'd purchased a while back to test the O/D oil pressure.  With the help of my brother-in-law this morning we videoed the gauge as I ran the car on my hoist with the rear wheels removed.  The clip shows the O/D being engaged in 3rd gear at an indicated 40 km/hr and then disengaged.

The low pressure appears to be OK (high range gauge so the needle sitting off the stop may well represent 20 psi), but what I didn''t expect is the massive fluctuation in the high pressure ranging from 350-450 psi.

Any thoughts as to whether this is normal  or not?  I suspect that the non-return valve on the pump is leaking so that will have to come out and be reseated, but would this account in any way for the harsh shifting?

Video can be viewed at https://youtu.be/ZjPU-duJpkg

Gavin

 

Share this post


Link to post
Share on other sites

For an A type, I'd be looking at the operating valve ball and spring if I was concerned about those fluctuations. Might try  a snubber in the pressure gauge line to get a better idea of the average pressures during operation.

Maybe wait until some J type experts come on line overnight to see if the fluctuations are a concern.

Share this post


Link to post
Share on other sites

Hi Mike. 

I don't think this is the cause of the harsh shifting problem.  I was expecting to see 500 + psi and planned to change the shims in the relief valve to bring this down to where it should be.  Instead I'll carry out the check valve reseat procedure and check the pressure again.

I've just sent the video link and backfground info to Peter at ORS as Bruce has suggested and will await his comments before proceeding any further.  I don't want to pull the O/D out and strip it, but it would also give me the opportunity to address the various oil leaks at the paper gaskets and elsewhere which annoy the hell out of me!

Whoever rebuilt it had never heard of Hylomar :(

Edited by KiwiTR6
Added comment

Share this post


Link to post
Share on other sites
3 hours ago, Nobbyc said:

maybe assembled without the thrust washer.

 

 

 

 

Can you please elaborate Nobby?  Is there any way I can check without removing and stripping the unit?

Edited by KiwiTR6
Added question

Share this post


Link to post
Share on other sites

My J type is ex saloon car and has a very smooth action in/out with no need to use clutch. The overdrive has minimal sliding  movement between the engagement of the internal and external surfaces of the cone clutch.  If the thrust washer on the shaft was missing or much too thin then the sliding movement would be excessive and cause harsh action. Not sure if the thrust washer is sintered bronze or solid bronze but know that sintered bronze bushes in A Type overdrives are known to break up and disintigrate.

 

 

Share this post


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.