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his new gearbox? (Rover LT77 to TR)


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Hi there,

yesterday I had a visit from my friend Jochem to have a closer look on his new gearbox.

My MX-5 project has been diskussed at the German TR-Freunde and he has been told the Rover LT77 gearbox with Rover V8 bell fits more easy.

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The gearbox bell is bolted to the gearbox, has a very characteristic shape and is easy to identify.

It is fixed with 6 M12x40 bolts, 2 of them go through dowel bushes.

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The lower part on the right side is for the rover clutch mechanism.

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INDEED! The gearbox bell fits perfect on my TR4A engine! The dowels and all bolts fit perfect.

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But folks - that all that fits.....

The part of the bell for the clutch mechanism could touch the exhaust. This is 0 - 15 mm too low.

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Because the Rover clutch mechanism is different and it would touch the exhaust pipe and the oil pan we have to fit an concentric release unit.

Jochem already wanted to go this way on his TR gearbox.

  CTraQlcFNSi2BE_zLKucVlfs7iLdTMGF2E_WQN_v

It will look like this on my old TR gearbox, it is out of use since I use the MX-5 gearbox.

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But the gearbox cover of the ingoing shaft is completely different from the TR cover we can’t use the unit I already made for Jochem.

I suggested Jochem to sell the hole unit and built it new, to swop it means too many good TR parts remain needless in the workshop.

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A close look on the front of the LT77, please notice the ingoing shaft is not in the correct position because the gearbox is empty!

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Pulled in the correct position the shaft fits the pilot bearing - but the splined part touches it because it is about 5 mm too long.

No fit, we have to turn it shorter on the lathe. Not my part, I don't get it though my lathe...

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With the gearboxes in the same position

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It is obvious the gear shifter is about 160 mm in the wrong position!

Meens: this gearbox would fit a Mazda MX-5 NA/NB perpaps better than a TR :lol:

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The outgoing flange of the gearbox fits the TR probshaft perfectly - but the probshaft is about 90 mm to short for the LT77!

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Also no fit: the rear gearbox mounts, very likely the crossmenber to the frame also does not fit.

After 2 hours comparing, measuring and calculating we had each one 2 pots of coffee and 2 pieces of my lovley wifes plum cake.

To tell you the truth: we both have been a little disappointed, but we get this project working because others also got it working.

But "easy to fit" is story telling.

Ciao, Marco

Edited by Z320
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Thank you Marco for this introduction in our little project. It made most sense to me, looking for help from Marco since he proved lots of time his engineering skills and creativity. Which in this case, are needed once more again. Eventhough the complexity compared to the Mazda Gearbox is manageable, yet some items remain. In this case the Shifter Housing need to be shortened.

A friend in the german TR Forum mentioned Sherpa Van has a reduced housing. Maybe someone here can confirm or has any other ideas of solving this particular problem.

I look forward to the discussions.

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29 minutes ago, BlueTR3A-5EKT said:

Stag prop shaft is about 4” or 100mm longer than a TR item and has the same sized flanges as TR.

Nice! Or using 2 45mm spacers on each side to extend the TR propshaft.

Edited by JochemsTR
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Could you add a 15-20 mm spacer between GB en bell housing? This avoids modification of the GB ingoing shaft. Or will it make other issues worse?

Waldi

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16 minutes ago, Waldi said:

This avoids modification of the GB ingoing shaft.

The shaft only requires 4-5 mm which I need to remove on a lathe. This is a relativ small issue. Bringing the shifter housing forward is the main issue. 

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Hi there,

I have no hope to find a „ready to fit“ shifter housing,

we have to cut a 160 mm piece out and weld it together again,

to find out about the mechanism below is the first step to find out.

Any advice or photos are welcome.

Cheers, Marco

Edited by Z320
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Hi,

indeed Jörg from the German TR-Freun.de forum (thank you) gave us the advice to have a look on the "very short" shifter houing from the Leyland Sherpa van.

Comparing photos the Sherpa housing indeed is very short, I guess the shifter lever is 2 - 3 cm too far forward...

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But very interesting is what the Sherpa has below the housing.

I found another photo (the internet is my friend), it's simply a cranked ball joint.

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As the connections below the shifter housing are also simple ball joints

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Another photo shows how it finally could look like.

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Today I opended the empty gearbox to install the shifter shaft.

And I gave some attention on the rubbers and how the shifter housing should be fixed on the gb.

I suggest Jochem to make this rubbers from aluminium for a fix fit, so he can anyway use PU or rubber ones.

Because we loose the rear mount fixing the housing with rubber mounts will be very „flexible“.

Ciao, Marco

Edited by Z320
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they look like this

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now it was possible to measure exactly with a dummy shifter lever

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before I cut the housing in pieces I have to find out the dimension of this offset

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and make a connector

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Hi,

after determine the offset I decided to cut the housing in pieces first to send it to Jochem and his welder.

hy6eOwX0NNhN9EySqR5nAiRlvrq5iZg9GcG4inw0

I know some of you don't value the result of using a hack saw...

Working with this tool 1st you need is patience, 2nd patience and finally ...patience.

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This way the housing is shipped tomorrow, the parts 2, 3, 4 are for the welder to do some exercise and variation of the welder setting.

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Hi,

this evening I checked the Sachs hydraulic release bearing I made for Jochem for his TR gearbox some time ago.

There is to much to change to fit it on the LT77 gearbox and too many TR specific parts remain not needed.

This is why I make him a new on and ordered a unit via eBay.

Ciao, Marco

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Today I wanted to make the excentric connector on the lathe, but by my fault I crashed the drill rod.

A new one is ordered but the lathe is blocked because I can't undo the chuck until the drilling is finished.

kbmZy47l_Zp_7ceu7xAnzscYx3yGQiHwTEWAhzAW

So I hade a closer lock on the gearbox's rear mount on my dummy frame,

the crossmember and rubber mount are in the position they will be on the cars frame.

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aeRyjtCL3Y3osYSPFlVVFEuRt3jvfg_4NxWq1DoZ

Sadly the rear end of the LT77 gearbox is too low for the TR original crossmember and rubber mount (40 mm high).

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With a bar of flat steel 40x5 mm, slightly angled (about 10°) the gearbox could be fixed very easy - but will lift the rear end about 25 mm.

In my opionion the fastest way to get to a result for a first test - and could work.

With the rear end not lifted there is only about 23 mm space for a rubber mount and an angled bar of flat steel.

jt75qZZzVHvvpWIKPzi5vCEgmnwDGFbgM8fZ0ofS

You may notice the wedged gap between the gearbox and the crossmember?

Well, the aluminium surface is parallel to the gearbox shaft, perpaps the engine and gearbox are horizontal in a Rover and on the frame.

But on our TRs the engine and gearbox is wedged about 10° - while the surface of the frame is horizontal.

This is why the rear end of the TR gearbox is angled about 10% (my TR gearbox on the photo is horizontal on a the work bench).

QtDdONdZSf2PBQXoRAAshQerhXehojV-HDUqJEZt

This is a steel sheet "connecting bar", about 10° angled, just to test, not solid enough this way.

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In position, gap to the crossmember to fit anything made of vulcanised rubber between is only 20 mm.

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Any idee what could fit? Or use the original TR mount and lift the end of the gearbox 25 mm?

Andreas (V8) - how did you solve this, please?

Ciao, Marco

Edited by Z320
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On 11/27/2021 at 10:59 PM, Z320 said:

Today I wanted to make the excentric connector on the lathe, but by my fault I crashed the drill rod.

A new one is ordered but the lathe is blocked because I can't undo the chuck until the drilling is finished.

kbmZy47l_Zp_7ceu7xAnzscYx3yGQiHwTEWAhzAW

So I hade a closer lock on the gearbox's rear mount on my dummy frame,

the crossmember and rubber mount are in the position they will be on the cars frame.

800e2cQAKvCXCOxbd45NVry5R2XIu8_BBsTQV1uD

aeRyjtCL3Y3osYSPFlVVFEuRt3jvfg_4NxWq1DoZ

Sadly the rear end of the LT77 gearbox is too low for the TR original crossmember and rubber mount (40 mm high).

sHBvYGlNa_kVhDw7C9eJuMSHK6IU8htrB5SfXN71

With a bar of flat steel 40x5 mm, slightly angled (about 10°) the gearbox could be fixed very easy - but will lift the rear end about 25 mm.

In my opionion the fastest way to get to a result for a first test - and could work.

With the rear end not lifted there is only about 23 mm space for a rubber mount and an angled bar of flat steel.

jt75qZZzVHvvpWIKPzi5vCEgmnwDGFbgM8fZ0ofS

You may notice the wedged gap between the gearbox and the crossmember?

Well, the aluminium surface is parallel to the gearbox shaft, perpaps the engine and gearbox are horizontal in a Rover and on the frame.

But on our TRs the engine and gearbox is wedged about 10° - while the surface of the frame is horizontal.

This is why the rear end of the TR gearbox is angled about 10% (my TR gearbox on the photo is horizontal on a the work bench).

QtDdONdZSf2PBQXoRAAshQerhXehojV-HDUqJEZt

This is a steel sheet "connecting bar", about 10° angled, just to test, not solid enough this way.

Ibr8gzgf1rD9bQNI1aQi3OEjwqejXbKYrK8sV0kX

In position, gap to the crossmember to fit anything made of vulcanised rubber between is only 20 mm.

JdgsF0gOAdot5xvqg7Nx8c2LzrG-XfdJ7YBcgqFS

Any idee what could fit? Or use the original TR mount and lift the end of the gearbox 25 mm?

Andreas (V8) - how did you solve this, please?

Ciao, Marco

Which TR chassis is this to fit in.?

Remember after 1973 TR6 moved the gearbox mounting bracket down 20mm and backwards 50 mm.   This was to fit the J type overdrive.

https://www.moss-europe.co.uk/shop-by-model/triumph/tr5-6/clutch-transmission-drivetrain/gearboxes-components/engine-gearbox-mountings-tr5-6-1967-76.html
 

 

2E38D57E-7AF4-45F6-AACE-DCFE83296CCC.jpeg
 

 

PS.   I have a spare Chuck.   You can swap it and maintain concentricity of mounted work.

Edited by BlueTR3A-5EKT
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1 minute ago, BlueTR3A-5EKT said:

Which TR chassis is this to fit in.?

Remember after 1973 TR6 moved the gearbox mounting bracket down 20mm and backwards 50 mm.   This was to fit the J type overdrive.

https://www.moss-europe.co.uk/shop-by-model/triumph/tr5-6/clutch-transmission-drivetrain/gearboxes-components/engine-gearbox-mountings-tr5-6-1967-76.html
 

 

2E38D57E-7AF4-45F6-AACE-DCFE83296CCC.jpeg

Doesnt help on a 4a though the J Type chassis brackets used to be available. I have converted a CP Chassis to a CR by changing the brackets.

Stuart.

 

CR 526 O 032.jpg

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