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MG TD TF 1500 - 3rd gear problem

Hello from Oz,

My problem is shifting up from 3rd into 4th gear. No matter how I do this, either trying to closely match revs, or double clutching, a nasty grind is evident.

By way of background, I once owned this very same TF some 45 years ago. It went through a major re build soon after I sold it, and has done 30,000 miles with the same gearbox as the one I had re built by our legendary John Needham, back in the 1970's. Apart from this 3rd gear issue, the gears work as smooth as the day they were re-built.

I'm wondering if the problem can be diagnosed through this forum, so I can possibly attempt the repair myself.

Alternatively, can anyone out there suggest a good gearbox expert here in Victoria, Australia.

In anticipation, many thanks.

Tim.
T R Patkin

Tim
Sounds more 4th gear than 3rd
When you say a nasty grind, do you mean like grating gears, or, more of an abrasive rubbing/grinding noise up through the gearlever
Does it actually go into 4th ok (although noisy) or does it balk along with the noise--does it do it every time

willy
William Revit

Tim, Get a service manual..you MOST definitely can overhaul this gearbox your self.

Regards, Tom
tm peterson

Take the cover off the gear box, watching you do not drop the detent springs inside.
Check the selector lock screws are tight and there is minimal wear in the selector forks/synchro hub groove. You can feel if the extension end is OK just by wiggling the gear lever
Also check the flange nut is tight.
If they are OK then it is a box out job.
Gearboxes are now reasonably priced with so many 5 speed conversions.
Ray TF 2884
Ray Lee

Thanks, Willy, for responding.

To answer your questions, the sound is more like grating gears, a little like trying to go into 1st before coming to a stop.
This occurs going from 3rd into 4th, and it happens every time, regardless of doubling the clutch, or trying to carefully drop revs to ease it into 4th gear. Once into 4th gear, everything goes smoothly, even changing back down to 3rd gear, with absolutely no grating, just a smooth transition down.

I'll give a try tomorrow, going from 2nd into 4th, to see if the problem persists, hopefully providing more clues.

And to Tom, thanks for that encouraging note that having the service manual (is that the same as the workshop manual?) would guide me through a repair. It would be good, however to have a few clues as to where to look in order to rectify this issue.

Thanks, guys.

Tim.
T R Patkin

Thanks, Ray (TF 2884),

You have anticipated my next question as to whether I can check anything with the gearbox still in the car.

Your pointers are most helpful.

Cheers,
Tim.
T R Patkin

It sounds like worn synchros, but the advice offered by other posters maybe helpful in sorting out your issue.

The gearbox is pretty straightforward, parts are available and the service manual is pretty clear. Once you get into it there is an abundance of experienced owners on this site to fill in any gaps and answer any questions.

In my opinion it is easier to bite the bullet and spend an afternoon pulling the box and putting it on your bench straightaway.
Good luck.
Regards, Tom
tm peterson

A TF is a little time-consuming as seats, floors and the trans cover has to be pulled to remove the tranny from inside the car, as the crossbar rear mount is in the way to pull it from underneath. Just did this to install a High Gear 5 speed. Not complicated, just a pain. PJ
PJ Jennings

Thanks, guys, for your comments to date.

I just have to make a slight correction. The problem comes from a grinding protest of gear teeth reluctant to engage smoothly when shifting up from 2nd to 3rd, not 3rd to 4th, as I had previously said.

Today I went for a drive, and there's absolutely no problem changing down through the gears, including from 3rd, down to 2nd.

In fact, the gearbox is working perfectly (apart from the present issue!) and feels in every other respect as good as it did some 45 years ago after John Needham re built it.

Today, I removed the carpet and seats, however I ran out of time to start on the gearbox cover for a good inspection, as suggested by Ray (TF2884).

Depending on the outcome of what I might find (or not find!) tomorrow, I'm preparing myself mentally to start on the removal of the gear box.

In the meantime, I would be most grateful for any clues as to what to look for once it's out, and on the bench.

Cheers,
Tim.
T R Patkin

Before you pull the box, check the rear flange nut for tightness. If really loose, snug it up and try before removal. This has cured a lot if issues over the years. George
George Butz III

Hi Tim,
This is a real long shot as I have never heard of it happening before. However, I have never heard of the symptoms you describe either. Maybe the sound actually is first trying to engage! That would only be possible if there is an issue with the balls and pin between selector shafts which normally prevent two gears being engaged at once. That is ... maybe the 3rd/4th selector shaft is somehow dragging the 1st/2nd selector shaft with it. I guess it could also happen if the locating pins on the 1st/2nd shaft are loose, but I would think you would have other symptoms (jumping out of 1st/2nd) if that were the case.
My brother's Y-tourer once had an issue changing between 2nd and 3rd. It was difficulty in changing rather than noise. That turned out to be demolished needle rollers (1st motion to mainshaft) which were floating through the synchro' region.
Good luck with the diagnosis.
Bob
Bob Schapel

Does it crunch going back from 4th to 3rd or just from 2-3
George and Bob have both got good suggestions, you could lever on the rear flange and see if it has any back/forward movement, it should have virtually nil but you might get a tiny bit of movement in the rear bearing if it's been there for a while--everything else can be checked with the top off
William Revit

Tim,

Attached is a photo of a simple tool which you can make, to hold the three selector shaft balls and springs without the gearbox cover. with this, you can fit it to your gearbox whilst it is in the car and check it out. I used it on my box, on the bench to check alignement and clearances. I haven't tried this, but you may even be able to run the engine at the same time. "beware of oil slosh". The tool took me about one hour to fabricate.

John



J Scragg

Many thanks for those responses.

Just an update, I have separated the rear flange from the drive shaft, and there doesn't seem to be any looseness in the nut there. I have removed the split pin, and with a socket tried to nip it up, with no success, so all looks good there.

I've removed the 4 bolts holding the remote cover, hoping to inspect the selectors. I have carefully separated it from it's gasket, however there seems to be resistance there in it's removal, so I'm wondering what more needs to be done. I understand there's some small parts (detent springs?) that need safeguarding so they don't fall in. Any tricks there?

I'm hoping to spend more time on the project this coming weekend, and will report on progress.

By the way, thankyou Peter Tehir (NSW, Australia) for your 2016 Thread, "Gearbox Tip". It relates to engaging 3rd gear, which is exactly my problem. If my problem can't be traced to the selectors, I will be looking closely at the centre mainshaft bearing washer, which apparently can become worn and make 3rd gear difficult to select.

Cheers,
Tim.
T R Patkin

there is a shaft extension underneath the remote with a support housing bolted to the remote, If you remove this extension you can wiggle out the remote.
I cut a slot in the head of the retaining bolt to ease re-assembly as it is tight for space.
Ray TF 2884
Ray Lee

Thanks for that, Ray.

I've explored the 'search function' for this site, looking for guidance in removing the remote housing.

I found a response from Bud Krueger, back in 2013, pointing out the additional attachment of this shaft extension, and how to detach it.

So thanks, Ray, and others for making it known that gear boxes are not necessarily items of mechanical mystery, only to be delved into by 'experts'.

I hope I'm not speaking too soon!

Cheers,
Tim.
T R Patkin

The detent springs are under the cover, not the remote.

The cover is the panel with the fill plug forward of the remote.

Peter
P G Gilvarry

Tim, could you please give me the link to my 2013 response? Perhaps I can add something more. Bud
Bud Krueger

Tim
Just a suggestion
I wouldn't be removing anything like the remote housing until you've found the cause of your problem
remove the top cover and have a look inside first to see what's going on. It could be a syncro issue or it might be selectors which will be hard to diagnose with half the linkages removed
Measuring the wear of the syncro ring is dead easy with the top off and also you'll be able to watch what is happening in there with the top out of the way

willy
William Revit

Once again, a big "thanks", guys for your responses.

It seems, from Willy's last comment, that I shouldn't be trying to remove the remote, as it will hinder further diagnosis.

Thanks for that, as I was under the mistaken impression it would expose the inside workings. It would seem, however, that it's the top cover I should be removing, being careful of those detent springs.

And to do this, with the gearbox still attached to the engine, and both still in the car, requires the pressed metal cover to be removed, which it seems is to be my next step.

So Bud, can I save your input to a later time if/when needed for the remote removal? That also gives me time to retrieve your 2013 response, as I seem to lose what's written here if I go elsewhere searching in this BBS site.

In summary, my project continues, somewhat hesitantly, with the help of much appreciated input from all who have responded.

With my back giving merry hell, and Christmas approaching, my "better half" has suggested some lay days.

Guys, please be assured this is to be continued, so stay tuned.

And once again, much appreciation for the help offered from this valuable forum.

Cheers,
Tim.

T R Patkin

Bud, just to let you know, I've found your old thread, entitled: Remote control removal-late TD. I'm not too sure how to send it as a link, however you posted it 30th November,2013.

Hope you can retrieve it.

Can I "save" you for later, when I will undoubtedly have more specific questions?

Cheers,
Tim.
T R Patkin

I found it, Tim. I'd be happy to help, if I can. Bud
Bud Krueger

Just an update on my 3rd gear problem.

Well, Christmas, and a bad back have intervened, so the project has come to a temporary halt.

With the new year, things will start once again, so for those who have responded, please stay tuned.

Most importantly, I'd like to wish those contributors, along with others who might be following, an enjoyable and safe Christmas, and a new year to look forward to.

Many thanks to all of you for your input.

Best wishes,
Tim.

T R Patkin

Hello to those who responded earlier to my gearbox problem, particularly to Bud Kruger and others who generously offered help, should I be in need of it.

Yes, indeed, help is needed!

I now have the gearbox (& engine!) out of the car, with the gearbox now on my workbench (see pictures).

To my dismay, all the selectors seem to be doing their job, and while turning the input (splined) end of the gearbox, all gears can be selected smoothly, with no crunching or difficulty in meshing when changing either up or down. This is in sharp contrast when driving the car, as there was an unavoidable crunching/grinding when changing from 2nd up to 3rd.

In every respect the gears are working smoothly, so I'm at a loss as to what to do next.

I'm tempted to take it to the well known repairer of these gear boxes (Old Car Gearboxes) who rebuilt it some 45 years ago.

Am I abandoning this prematurely?

Looking for advice,
Tim.





T R Patkin

Check how much the 3rd gear selector moves before the 3rd/4th synchro hub moves. It should be the same in both directions, if not the selector fork or the annular groove/channel in the hub is badly worn.
I recently fitted a new hub (second hand) into a friends box and it transformed it.
Worst case, there are plenty of boxes about after 5 speed conversion, probably cheaper than a rebuild.
Some new gearbox part seem to need a lot of fettling to fit.
Ray TF 2884
Ray Lee

Tim
You can measure the 3rd gear syncro ring for wear
If you get your fingers in there or a couple of screwdrivers and push the ring towards the gear then measure the gap between the ring and the gear--
New they measure just over .090" as in .092"-.093"
If it measures .060" or less it needs replacing

willy
William Revit

A "thank you" to Willy in Tasmania, and to Ray TF2884 for their suggestions.
I have managed to speak with John Needham (Old Car Gearboxes) who 45 years ago re built this box. He has suggested I bring the box into his workshop, which is only 3/4 hour away. He can test it to see exactly what the issue is.
In this day and age, it's good to see these specialized skills still exist, and that individuals like John have maintained their dedication to their work.
I shall let people know the result of his findings.
Cheers,
Tim.

T R Patkin

There better be warranty left on the work if it has been less than 50 years ago! Hahaha…
Amazing. Very good.
Regards, Tom
tm peterson

Tim
Yes please, if you would be so kind as to letting us know the result from JN, It'll be interesting to know the cause of your issue- for the memory bank, just in case it's some obscure development

willy
William Revit

To Willy, and others following this thread, JN examined the gearbox yesterday.
To his surprise he found excessive longitudinal movement along the output shaft (Lay shaft?), with the rear bearing moving back and forth a good 3mm in and out of it's housing.
His only comment was that he "must have been pretty stupid, back then, to leave a spacer out".
Amazing that the gearbox has worked so well for most of those 45 years!
My hope is that he won't find anything else amiss, and that in a few weeks I can have it back.
I'll let people know more exactly the details of his findings then.
Cheers,
Tim.
T R Patkin

Hi Tim
As we know, John is no fool, if he left something out it would be a 'very' rare mistake and he would be very embarrassed when he saw what was happening--I feel for him, and credit to him for putting his hand up for the cause
my view is--
loses one point --for missing the spacer
gets 5 points --for owning it after 40+ years
He'll always be a star in my view

willy
William Revit

This speaks volumes about JN’s integrity. Amazing fellow obviously.

Regards, Tom
tm peterson

For those who helped previously with advice etc, here's the final update.
Upon picking up the gearbox from John Needham (Old Car Gearboxes P/L) who rebuilt it some 40 years ago, it seems the longitudinal play in the Lay shaft was the main problem.
John repaired some damage to the Lay gear, made a rear seal conversion, and replaced the front seal and 3rd synchro ring.
He said it should be good for another 40 years!
It will be a while before the test drive, as the associated work involved in the gearbox issue has prompted a second 're build' of TF2406 so it can maintain its good grace for the next 40 years.
Cheers, and thanks to all those who helped with advice.
Tim
T R Patkin

Thanks for the update Tim----
William Revit

This thread was discussed between 11/12/2022 and 18/02/2023

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