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my new gearbox? (Mazda MX-5 to TR)


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Good idea,

but I've been told there are 2 different (what is the difference?), and how to make the finish.

My idea is to make a console "extension" for 2 charging socket (want to get them away from my wife's lovely knee)

I have seen this on a TR, maybe cigarette lightners? Mayby a period accessoire?

Roger (?) also showed a modified console some time ago, but I cannot find the post...

Ciao, Marco

Edited by Z320
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Ups, the adaptors are already delivered, I'm really surprised about the laser cut surface! Tomorrow will be first fit, please keep fingers crossed for me.  

Thanks Russell and Andi, thank you very much, all worked well, fit was 100% on first attempt, the 8 mm drills are exaxtly to the point they have to be for the 5/16" bolts! Btw, the bar is on

Talking of gearbox changes, back in the 8o`s when I was involved with Jaguar racing we converted a V12 XJS from a GM 400 auto box to a Cosworth T6 manual 5 speed by a cut and shut of the two bell hous

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HI Marco,

Looks like very good progress is being made!  On the gear lever position, I would be tempted to return to the straight gear lever and modify the console to accommodate it - as it seems you will need to make modifications in that area anyway.

But there may be some reason why this is not a good idea?  I'm not familiar with the TR4/4A.

Cheers

Nick

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Hi Nick,

the straight lever will go direct through the rear vertical end of the console. So I decided to continue the way I started. Perhaps a mistake?

I think better would be to find a way to get the housing 70 mm more forward. But I missed that point...

This is now about 25 mm lower.

JmlwOgGMIMbIkV6RDVCRVtUqXvcf7Ve-JhSZIoKK

With the H frame fitted I realized the lever could be about 10 mm more behind - did I measure anything wrong?

Av_8zf7A7lW2KG8Ys2JzbrYn_wH8XePoM95EghhF

with the plastic parts off/out it is ready to weld - or solder?

8YhZf5oYzkgyNcCBPXnDnuCWGRSoSoAVUnKoBSMG

I like soft soldering steel very much, easy to do with extra flux, clean, no angle grinder, the surface looks much bettern than welded

jI2CCLLR2Ac-7yPtwGmfet2c1PFDQULIH1LyzyWE

8xXTh4Jtn0XXM0Xl9gMLsz-WSoRaab0fnlrdRRrn

This allows me now to cut out 25 mm less from the H frame, means I don't have to cut is through

_NJig8tkby6LGPDgzoQwwmh20ePgKHt2BKKzCxHj

I show tomorrow

Ciao, Marco

Edited by Z320
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This is the way I had to cut the console out to allow the movement of the lever.

x98xuf5GoefJVr5wOiq3KDYF0SfHI1uyfJsXOtWu

And this is the position with the MX-5 lever vertical up,

regarding the space for moving forward and backwwad this would be a full cut through of the console.

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Now the H frame in the final position I had to move the lever 10 mm forward again.

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Also I bleeded the clutch, it works lovely, did some electric modification and tryed to get my temperature gauge working again.....

Hopefully tomorrow the 1 1/8 inch socket is in to torque up the nut of the diff.

Ciao, Marco

 

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For his view from below on the gearbox I hope the TÜV guy wears welder glasses,

and for his view from above on the console I will bend a curtain rail and my wife will knit a curtain :D

I don't know.... 

Edited by Z320
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Yesterday the propshaft was in - and today out again to check.

Because I determained (and ordered) the lenght 20 mm shorter to allow the engine and diff to move and the sliding yoke to move 20 mm in the MX-5 gearbox, 10 mm perhaps is also OK, but I had only 7 mm?

My mistake? Lenght from U-joint to U-joint I found OK and the yoke on the rear end has the same dimension. On top is the new one.

ss1qfQiup6evauwCYhmCUQOSGnfQzGWS5aphPrez

What I did not know, and the propshaft builder did not consider or also not know:

the "fork" of his new sliding yoke on the gearbox side is different from the original Mazda yoke, while the total lenght is about the same!

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@&%4/!!?§@

But my lathe safed my day, as you can see on the photo above was able to win about 5 mm.

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Now I got about 12 mm way to let engine and diff move; I don't know how much is needed.

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An o-ring will be my indicator and "warning system"

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2 liter of oil are in the gearbox now, clutch is bleeded, tomorrow I start the engine and hope for no surprice.

Sorry, no seats, no drive.

Ciao, Marco

Edited by Z320
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This is how the o-ring works, it will show how much it is max. pushed  back

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two layers of heat tabe hopefully give some protection for the speedo drive

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cutting out the tunnel needed some time

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With a first start of the engine in the garage everything worked well (starting, glutch, gear shifting).

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Day finished before work finished

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Because I'm also busy with  fitting a new hood frame and softtop the seats are still out and - sorry - I was not able to drive.

Ciao, Marco

Edited by Z320
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Hi there,

I'm very pleased to tell you the project is finished, the gearbox works well and I'm pleased.

All gears work well, the position is slightly different from the TR gearbox (1-2 less left, 3-4 in the middle like the TR gb, 5th very much right).

Mainly I have to learn not to pull the shifter to go in reverse! Driving with 3.100 revs with 130 km/h on the Autobanhn is lovely quiet.

Also my speedo drive works and the speed is indicated correcly.

 

Different is the sound of the gearbox.

Positiv and so lovely: with the bonnet opened and the engine idling there is no growling anymore to hear from the TR ingoing main bearing.

Driving on speed 1, 2, 3 the sound is some more on higher frequences, I guess because of more straight thoothed gears.

Shure in a MX-5 with the gearbox under the car this is not to hear, but with the gb next you you in the TR it is.

 

The last days I stuggled by some details, all caused the 80 mm wrong position of the shifter housing:

I had to take rubber parts out of the gaiter, because the lever moves up and down and that did not really work.

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Also the horizontal lever extension touched the console slightly (even with the rubber of the gaiter reduced), so the 2nd gear was slighted out while driving.

k8N1Ba-LXXgPNcANmaVCNUA6-oHVgLSai9WQz30d

I was so pleased I soldered the extension on the lever, so it was simple solder it out and to make a modification due to the red line (after H frame out again)

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You see I also had to cut out the rubber fixed between the tunnel cover and the console.

This is a lovely heater now, with some smells from the engine - not funny at all, but I have an idea how to solve that.

37d9TdBIvTIynD5Ly5YLLKDjt130da-VENiwtrh_

If anyone will make a MX-5 gearbox to his DIY project my advice is to do everything to move the shifter housing in the correct position.

 

Another issue is the gearbox bell, which I had to cut out to fit in in the TR.

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Through the "hole" I can hear the friction plate sliding on the flywheel in the moment before the clutch is engaged on 1st gear.

Not awful but special, so I will cover this next winter with a strap of ali.

 

Well, that's it, it was alway a pleasure to report, but to put the gearbox in the car was the most annoying chapter of the project!

If anyone of you has any question please ask. If not I think I will report again if something special happens.

Now my wife has a list of 25 projects without wheels - and I better have fun with them (if you know what I mean)

Ciao, Marco

Edited by Z320
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Brilliant Marco. Well done. 
I have followed this thread marvelling at your engineering solutions that are very much beyond me. 
Thanks for sharing it all with us.

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Great stuff Marco:lol: many like myself have been following this, not only with interest but admiration for your problem solving skills. Very glad it has all worked out. You deserve some kind of award for your efforts but I suppose the fact it works is a great reward in itself. Top marks old chap top marks.

Paul

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Well done Marco, some good engineering skills there and great ways of getting over problems encountered. The first one is always the hardest, just hope the TUV guy doesnt notice next year ;)

Stuart.

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On 5/24/2021 at 8:34 PM, Z320 said:

Hi Nick,

the straight lever will go direct through the rear vertical end of the console. So I decided to continue the way I started. Perhaps a mistake?

I think better would be to find a way to get the housing 70 mm more forward. But I missed that point...

This is now about 25 mm lower.

JmlwOgGMIMbIkV6RDVCRVtUqXvcf7Ve-JhSZIoKK

With the H frame fitted I realized the lever could be about 10 mm more behind - did I measure anything wrong?

Av_8zf7A7lW2KG8Ys2JzbrYn_wH8XePoM95EghhF

with the plasic parts off/out it is ready to weld - or solder?

8YhZf5oYzkgyNcCBPXnDnuCWGRSoSoAVUnKoBSMG

I like soft soldering steel very much, easy to do with extra flux, clean, no angle grinder, the surface looks much bettern than welded

jI2CCLLR2Ac-7yPtwGmfet2c1PFDQULIH1LyzyWE

8xXTh4Jtn0XXM0Xl9gMLsz-WSoRaab0fnlrdRRrn

This allows me now to cut out 25 mm less from the H frame, means I don't have to cut is through

_NJig8tkby6LGPDgzoQwwmh20ePgKHt2BKKzCxHj

I show tomorrow

Ciao, Marco

See PM

Peter W

Edited by BlueTR3A-5EKT
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On 6/5/2021 at 9:34 AM, stuart said:

Well done Marco, some good engineering skills there and great ways of getting over problems encountered. The first one is always the hardest, just hope the TUV guy doesnt notice next year ;)

Stuart.

+1 very well done.

i bet that you will be thinking in the next few months and come back to it with a solution .

Roy

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Congratulations Marco!

Thank you for doing regular and detailed updates of your “voyage”, I admire your persistence and “only good is good” approach.

Regards,

Waldi

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Thank you all fpor your laud,

indeed I have that second MX-5 NA gearbox at my garage,

and indeed it would be a challegne to move the shifter housing in the correct position.

But this makes only sence if I'm willing to put the gearbox out again to change its tail.

And this is not the case at all (at the moment), so the 2nd gb must stay as a sleeping beauty.

Ciao, Marco

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Hi Marco,

congratulations on completing the g/box swap and a huge ‘thank you’ for sharing the steps/bumps/joys involved - great job! 

Like you, I would simply drive the car and enjoy the fruits of your labour, tidying up the location of the gear-lever can wait for another day (or not ;)

Lack of facilities (and skill :D ) means I won’t be trying this anytime soon, but it has been an inspirational read, thank you!

cheers...... Andy 

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Hello Marco,

I am sorry that  I have not seen your post till tonight! I have had a TR6 for 40 years and been in the register for 30+ years but have found very little time to use the forum.

I may have been of some help to you and possibly still yet as I fitted an MX5 gearbox to a 1275 MG Midget in 2018/19 and recognise all the the problems with less room!

Gearshift roll-pins, dowels, clutch. starter motor, etc, etc. I had intended to write an article like yours but have not found the time, though I did post on the MG forum during the build. ( I will try to re-open it and forward)

My first attempt for the gearshift was to try an "easy fix" of welding up an adapter bracket from 3mm steel but was this too flimsy and gave very poor gearshift.

I then went more properly engineered, though only in my garage with a lathe and hand tools and now have a perfect shift with the shortest extension possible.

I cut as deep into the rear of the gearbox casting as I dare and squared it up with a power-file and hand tools. But I also cut the front of the turret off and squared it up.

I then took a piece of tool-grade aluminium I had and drilled it and drilled & tapped back into the turret and down into the gearbox to match.

It now sits perfectly for an MG Midget and works excellently, as good as original. I imagine this position would suit most classics very well also.

I have yet to finally finish my speedo conversion but have a working prototype  method of using a stepper motor mounted directly on  the speedo  via an Arduino

microcontroller (ebay app. 5 euro) being pulsed by a sensor on the prop-shaft and adjusted by a potentiometer on the controller card to calibrate. Unfortunately work and family have stopped

getting it completed and now the MG is off the road for some major body renovations. The stepper motor method is the easiest electronically but it is is a bit too slow so 

does not indicate full speed. I plan to try a larger stepper motor  connected to the speedo cable in the engine bay or otherwise a DC motor with tacho pulse but this is a bit more involved.  This is a very low cost method and would suit any classic conversion. If there was enough interest I could produce a kit I suppose.

If you or or anyone would like more details/photos I would be happy to post.

Again sorry for being too late to help when you wanted it.

 

 

gearbox initial drilling (002).jpg

gearshift 2 (002).jpg

turret drilling (002).jpg

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Hi Marco,

very well done. An excellent lesson in engineering, R&D, and dogged determination.

The problems you are having with the 'H' dash support around the gear stick could be solved by remaking/creating a new (bigger) lump around the gear stick  - similar to that which I knocked up for my electric window switches.

 

Roger

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Hi Marco,

further to my post regarding a gearchange alternative, I do apologise for not first congratulating you on a very well executed modification and a terrific build post.

It was so familiar only reading it last night (most of it) after seeing it referred to in TR-Action. Seeing all the same series of small steps to be taken.

Aren't those dowels a pain! And now I know you must select the correct gear before trying to knock out the roll-pin...aagh!

I cut my own adaptor plate from 8 mm aluminium sheet but the Midget is so much less powerful. I made my own hybrid centre-plate from a Midget plate and an MX-5 plate

because no Mazda centreplate would fit a midget clutch cover. I would do another by flat facing the flywheel and drilling for an MX5 cover.  I did not want to ruin the flywheel

if it did not work.  I had also planned to get one laser/water jet cut but was just impatient when I got to it!

By the way, the aluminium block I used to fit the gearchange it drill to a nice fit on the selector shaft so provides excellent location and action.

Very well done, John

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Hi John,

thank you for your post, that's interesting different people go a similar way.

You answered my question already: did you use a different gearbox bell or an adapter?

So I guess you also cut the original bell down? Waht did you do with the holes and do you also hear the friction plate sliding before engaged?

You mention a refer at TR-Action - I do not know about because I'm member of both German clubs (IG+Register) but not the UK Register :ph34r:

I guess the position which is good for your MG is also better for the TR - but still not enough.

Sadly I did not measure exactly and hoped the console of the H frame will cover it....

Well, I drive it now and see next winter.

Ciao, Marco

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12 hours ago, RogerH said:

Hi Marco,

very well done. An excellent lesson in engineering, R&D, and dogged determination.

The problems you are having with the 'H' dash support around the gear stick could be solved by remaking/creating a new (bigger) lump around the gear stick  - similar to that which I knocked up for my electric window switches.

 

Roger

Hi Roger,

I knew about your console and browsed the Forum - but did not find it.

So thank you for your link, but I wait for an inspiration - or my wife knitting a rag, or what else.

Currently I like this cyborg style.....

Ciao, Marco

 

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