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MG TD TF 1500 - Pictures of my worn gear box components...

So... I tore into my gear box and got everything out to have a look see. I'd like to know specifically about the sliding hub for 1st/2nd gear. Does that amount of wear seen on the forward edge of the aft set of teeth dictate replacement?

Also, my first gear teeth on my lay gear (cluster gear) are showing HEAVY pitting on one side only of about 3-4 teeth. My hunch is that this was caused by the excessive wear you'll see on both ends of my layshaft. Neither first gear or the reverse gear show any pitting on the teeth faces. Does this wear shown dictate a cluster gear / lay gear replacement?

The other interesting thing I found was that the dowel pin for the lay shaft was heavily damaged. I would assume that this would allow the lay shaft to move. Any idea why that much movement would be seen? Has anyone else seen that sort of damage?

Thanks for watching!

Alex

Alex Waugh

Here is picture number one of two of the 1st/2nd sliding hub...

PS: what causes this type of wear?

Alex Waugh

Here is number two of two on the sliding hub

Alex Waugh

This is the lay shaft forward end wear

Alex Waugh

Here is another shot of the forward end wear indicating that the rollers were going OVER the flat spot on the lay shaft (what is this flat spot for anyway? I don't see an immediate reason for it to be there.)

Alex Waugh

hear is a picture of the aft lay shaft wear. YIKES! Look how deep the needles reached into the shaft.

Alex Waugh

Finally... here is the dowel bolt for the lay shaft. I had initially thought it was damaged at the time of initial installation, however, a closer look seems as though the notch was made by the shaft loading up on the dowel pin. By the wear, I'd say the shaft was allowed to move about 2MM. CRAZY TOWN!

Alex Waugh

If you want your car to drive nicely you have no alternative but to replace things. It will cost you more but you will be glad in the long run!
Barry Bahnisch

Alex,

Your box shows all the common wear points of this design.
If you want it to work correctly your only option is to replace all the worn parts. New parts are available but not cheap, a new layshaft cluster alone costs around $1000.
This is why most people opt for a five speed conversion.
The flats on the layshaft are there to enable oil to reach the layshaft needle rollers.

John

52 TD
J Scragg

I see my question was misunderstood. I will replace everything that needs to be replaced. I believe in doing things only once and have a motor to prove that. I read a lot in the archives of people saying that there was some wear that was allowable in the first gear components due to how little they are engaged over time. However, no one ever posted any photos of their wear so I could not compare it to mine.

So... with 1 thousand dollars alone for a new cluster gear, I want to make sure that the 1st gear wear is enough to condemn it. If you ask me the pitting on the faces of the 1st gear on the cluster will likely lead to damage on the faces of the first speed gear. Thus, if I had no one to ask I'd replace it, but since there is a wealth of knowledge and experience out there, I'd like to know specifically what others have experienced or done.

John, thanks for the info on the flats. I couldn't tell how they came into play.

Alex
Alex Waugh

Hi Alex. If you don't already have it, Horst Schach's book "The Complete M.G. (note the dots) TD Restoration Manual" has a very comprehensive section (11 pages)on the restoration of a TD gearbox, including quite a few photographs, albeit in black & white. I found this very useful when researching my gearbox restoration. I'd never pulled a gearbox apart before but with his book & the Workshop Manual I was prepared to have a go. You may be quite surprised at what he considers acceptable in terms of wear, missing teeth & pitting. Based on his recommendations on page 100, I acquired the suggested parts prior to the teardown. All was not plain sailing however, so much so that I was prompted to rewrite a major part of the gearbox section of the Workshop Manual. You can download this from the current edition of TTT2 on the internet. Sorry I can't give you an answer to your specific questions but you may well find the information you need in Horst's book. Good luck.
Peter TD 5801.
P Hehir

Alex,
From my limited experience I think the cluster gear is shot. There are gearbox reconditioning people that can machine off the first gear section of the cluster gear and shrink fit a new first gear in place. it may be worthwhile to research this option.
Max Irvine

I have seen a couple original inner sliding hubs with the same wear at the edges of the splines. Is that where the outer edge of first gear rides when in engaged in first? If so, the gear sort of torques a bit and causes that wear. The replacement inner hubs have continuous splines without the gap to prevent this. I would be more concerned with wear inside the cluster gear where the needles run. The pitting would likely cause no problem for years. If any doubt, Moss has really nice looking new gearbox components, so change everything. George
George Butz

The layshaft bolt as I found it, versus a new one. Bud

Bud Krueger

Hi Alex, that wear on the layshaft is typical and definitely needs replacement. The wear on the layshaft bolt would not cause any problems with the operation of the gearbox but should also be replaced. As for the laygear itself - the one you have is probably useable even with the pitting, I would be more concerned about the taper (non-parallel) on the teeth which may cause it to jump out of 1st gear.
I have some new laygears for $600 and very good used for $450. I think I have a new sliding hub as well but will need to look, no layshafts tho' .
Cheers, Hugh
H.D. Pite

Alex, the layshafts for the A transmission from Moss have not been manufactured with enough hardness recently. I'm not sure if that has been corrected or if it's even an issue with the T gearbox but I would definatly inquire about it before ordering one. See Barney Gaylords site about how to test a new one and why...even though it's MGA the shafts both function the same. I agree with Hugh about the gear teeth and the taper.
MG LaVerne

Hugh,

I sent you an email last night about the lay gears. Did you receive it? I'd be interested to talk to you more about gear purchases when you find out if you have sliding hubs.

LaVerne,

Thanks... I'd not heard that yet. I'll check it out. Any idea if Abingdon's are better?

Alex
Alex Waugh

I bought a length of hardened ground shaft form my local bearing supplier and got them to drill a hole in it for the screw. It was a lot cheaper than buying from an MG parts supplier.
Max Irvine

I don't know Alex...more often that not they both buy from the same vendors. I have received packages from both that have the others stickers on them. I'd ask for NOS if it's available.
MG LaVerne

Alex...have you seen this from the latest issue of Totally T-Type 2?

http://ttypes.org/ttt2/section-f-gearbox-of-the-tdtf-workshop-manual-how-it-could-should-have-been-written
Gene Gillam

Gene, I trust that you're aware that author of that paper is our associate, Peter Hehir. Bud
Bud Krueger

Duh....didn't notice his name up above. Hello Peter!
Gene Gillam

Hi Gene. No pun intended!
Cheers.
Peter TD 5801
P Hehir

This thread was discussed between 24/01/2014 and 26/01/2014

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