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


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Hi Bob,

I'm back from the garage where I checked one more the spin of the speedo drive: on both, the TR and the MX-5 gearbox it spins clockwise.

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The belt drive does not change this on the second shaft with the cable to the right side,

but you are right, it spins anti clockwise from the left side where I want to connect the speedo cable.

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I want so solve this with 2 POM cogs, this inverses the spin, I want to connect the speedo cable on the 3rd shaft from the left side.

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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 Stef,

for several reasons this is not my way.

The old prob shafts from my german prop shaft builter is back, I'm waiting for the one I ordered at the UK.

I will tell you the whole story when I have all 3 in. While waiting for this I'm working on some small parts....

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Today my wife caught me at my workshop and asked me with serious voice:

ARE YOU SHURE EVERYTHING WHAT DO DO HERE IS CORRECT?

Ups, seroius situation.....

WHAT YOU ARE DOING....HAS ONLY TWO WHEELS!

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She's my darling, my huggy bear, but she is wrong.

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What I'm doing has tree wheels!

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  • 2 weeks later...

Hi,

today I got the new propshaft from Dave Mac / Coventry and this is the time to tell you the hole story.

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As I'm simple minded my hope was my probshaft builter cuts the TR 2" propshaft and the MX-5 2.5" propshaft in pieces,

slides an adapter ring between and welds all together - like a blacksmith would do - but he told me he is not allowed to work this way.

So he offerd me to built a new one, but the Mazda propshaft is not made to repair, so he was not able to buy any one of the needed pieces.

I found "Powertrain" (USA) calls the sliding yoke "1503-22", 0.959" x 22 splines, the welding yoke "1526-25" the u joint "1551-20",

but all this parts are not (no more) possible to buy. And the u joint is pressed in and not secured with a clip. No change to repair that.

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So I asked Nick Jones, who posted earlier this thread - and he told me he had the same problems with 3 propshaft builters.

Until he got in contact with "Dave Mac propshafts", John McMahon is your man.

On their webside they offer "one off manufacturing" and for kitcars propshafts for.....MX-5 gearboxes!

I told hin the length and what diff I need it for, and he made it within 10 days for a very reasonalbe price incl. shipping.

Thats the needle in the haystack you have to find, I'm very pleased.

Thanks a lot to Nick for his advice and John for his work.

Ciao, Marco

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2 hours ago, Z320 said:

Hi,

today I got the new propshaft from Dave Mac / Coventry and this is the time to tell you the hole story.

6mIVyFYomCFIotX4O5F6T61jWExf1B11AY40M-7C

As I'm simple minded my hope was my probshaft builter cuts the TR 2" propshaft and the MX-5 2.5" propshaft in pieces,

slides an adapter ring between and welds all together - like a blacksmith would do - but he told me he is not allowed to work this way.

So he offerd me to built a new one, but the Mazda propshaft is not made to repair, so he was not able to buy any one of the needed pieces.

I found "Powertrain" (USA) calls the sliding yoke "1503-22", 0.959" x 22 splines, the welding yoke "1526-25" the u joint "1551-20",

but all this parts are not (no more) possible to buy. And the u joint is pressed in and not secured with a clip. No change to repair that.

AiWF1cNi0pphP3nPGbJ7oNMLt2Q5W_Uj9g_qFHpW

So I asked Nick Jones, who posted earlier this thread - and he told me he had the same problems with 3 propshaft builters.

Until he got in contact with "Dave Mac propshafts", John McMahon is your man.

On their webside they offer "one off manufacturing" and for kitcars propshafts for.....MX-5 gearboxes!

I told hin the length and what diff I need it for, and he made it within 10 days for a very reasonalbe price incl. shipping.

Thats the needle in the haystack you have to find, I'm very pleased.

Thanks a lot to Nick for his advice and John for his work.

Ciao, Marco

Did you consider carbon fibre composite?

https://www.lentuscomposites.co.uk/composite-prop-shafts-and-transmission-shafts/

 

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Ah ha..... I have a box like that too.  Propshaft looks good........  Even shorter than mine!

Really pleased it worked out for you.  I hope to be testing John's work on mine within days.  The speedo won't be reading right though as I have to get it recalibrated.  I'm waiting to prove the rest first though.

Nick

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9 hours ago, BlueTR3A-5EKT said:

Hi Peter,

I'm here at Germany, my TR is historic registered and "steet legal" AND has to be TÃœV-ed every 2 years.

So the propshaft and the hole gearbox issue has to be as inconspicuous as possible......

Two years ago I had serious problems because of my "obvious" to see adjustable trailing arm brackets.

Yes, that's ok but annoying.

Ciao. Marco

Edited by Z320
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On 3/8/2021 at 11:30 PM, Nick Jones said:

Ah ha..... I have a box like that too.  Propshaft looks good........  Even shorter than mine!

Really pleased it worked out for you.  I hope to be testing John's work on mine within days.  The speedo won't be reading right though as I have to get it recalibrated.  I'm waiting to prove the rest first though.

Nick

Hi Nick,

I want to solve the speedo drive first because I can only bolt it on the gb while the gearbox is not in the car.

I know you use a modified TR angle drive and do the calibration somewhere else.

Ciao, Marco

Edited by Z320
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Marco,

you mentioned you were very tight for space alongside the speedo drive, is there any reason not to use an angle drive there and then fit your reduction gearbox up behind the dash whee there is more space?

Really impressed by your engineering skills sorting out the issues.

Colin

 

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Hi Colin,

yes, to use a standard TR angle drive and a speed up gearbox behind the dash would work, but I do not for 3 reasons:

1st: the standard angel drive is not only plug and play, Nick shows what he had to do

2nd: the money: angle drive + speed up gearbox + short speedo cable + 2-3 x shipping is at least 200 GBP, what I do is about 10% of this

         I want to keep the project below 1.000 Euro, and because of the high torque starter and propshaft I'm at this limit

3rd: the challange to DIY

Ciao, Marco

-2RmWNdtyhswwoFRrLMYRnlHwddmgb_RH9TeaECx

 

Edited by Z320
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Look at all that lovely shiny metal........ very interested to see how this works out.

Happy to report that after a disappointing hiccup on Friday (not enough measuring of the right bits), overcome by a "field solution", there is definitely now at least one GT6 in the world running and driving with a Mazda MX5 gearbox mated to the original Triumph 6 cylinder.  And it drives very nicely, though rather noisily so far as I've yet to refit the tunnel cover. 

My speedo works too - insofar as the needle moves around the dial, going further with increasing speed and the odo clicks round - but at this point the numbers indicated are pretty meaningless.... Calibration is needed, so I'll be packing it off to Speedograph Richfield shortly.  This was expected.

I think it's likely fair to say that this is a fairly exclusive conversion as it's not an easy one.  Fair to say that if Vitesse Transmissions can (as is rumoured) come up with a plug 'n play conversion solution for the GT6/Vitesse then much respect will be due to them!

Nick

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Hi Nick,

GREAT to hear your GT6 is back on the road with the MX-5 gearbox!

Yes, it is a challenge to do that and looking at the thread I work since 11 months on it (shure, not all the time)!

Perhaps others will follow? I still got 2 adapter plates in my workshop and I will sell them if it works.

It would be great we and our MX-5 cloned Triumphs would meet one day...

Ciao, Marco

 

Edited by Z320
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Thanks Marco - not quite finished yet as I still have to put the interior back in and get the speedo calibrated, but it drives well.  I am happy - and relieved.  Been working on this for months!  Of course, with just 12 miles covered I am not ready to call is proven yet!

On 3/14/2021 at 6:37 PM, Z320 said:

It would be great we and our MX-5 cloned Triumphs would meet one day...

It would, and maybe we will.  My Vitesse has been to Germany many times, so why not the GT6 also....

Looking forward to seeing your gearbox going into your car.

Cheers

Nick

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Hi Nick,

I've got my speedo drive ready - but I'm not 100% pleased, perhaps I make a different one

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A first test on the lathe with 1,000 revs for some minutes was OK - but it is "wobbling" a bit

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Maybe the pitch of the belt is not constant and it is a mini-minimum too tight, maybe the cogs are not 100% concentric...?

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The "wobbling" will be less or hopefully away with the unit bolted on the gearbox...well, it works or not, I will see....

"Ich lass' das jetzt so" ("it is like it is now")

Next are some little works: sand blast and black oxide for the crossmember and adapter plate,

make the bolts shorter (adapter to engine), modify my gearbox crane, move the gearshifter about 6 more cm foreward.

I still have 6 more weeks until I got freshly made TÃœV

Ciao, Marco

Edited by Z320
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With the gearbox out last year to fit the hydraulic release mechanism I took the dimensions from the TR gearbox.

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I knew I can move the shifter box of the MX-5 gearbox only about 160 mm forward (I got 157 mm)- and this will not be enought.

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665 - 585 = 80 mm are missing and this was my plan:

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The connection is - glued again, later I will fit a roll pin cross or M6 bolt from behind,

this offset will be covered by the "box" of the H-frame on my TR4A (and also on TR250/5/6).

That was a fast job....

Ciao, Marco

 

 

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Hi Marco.

Trust you and your family are safe in Germany.

With regard to your last post, the gear lever position. This detail was always going to be a problem. I was hoping that the gear lever could be moved even further forward by breaking into the gearbox itself, and thus bring the gear lever into the original Triumph location. As you know I have a gearbox, and I did look into the possibility of a direct connection, and to do away with the extended linkage. So far I have not managed to solve the problem.

Vitesse ltd had the same issue, and solved it as you have suggested. As you can see from the picture below, in the case of the TR2, 3, 3a, and 4, the gear box tunnel has to "butchered" to make room for the amended gear lever position. I believe the TR4a, 5, and 6 have a gear lever console box on top of the tunnel. It may be that this detail would help to hide the required alteration to the tunnel?

The picture below shows my modified gear lever. Vitesse Ltd use a standard unmodified lever, which is angles and has a black ball mounted on the top. I have say "it stand out a mile", when you look into the car

The Vitesse Ltd gear box drives well in my TR3a with all the attributes of a modern box, and a light touch. When the carpet is fitted over the tunnel you need to look very hard to see increase in the carpet height. BUT, it is a shame that there would seem to be no alternative to the placing the gear lever, or is there?

Regards to all.  Russell

 

 

 

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Hi Russell,

thank you, yes, we are all OK here and I hope you and your family also stay well.

On your photo (and previous photos) it is good to see Vitesse bothered more to keep this offset about 20 mm more flat than I did.

I just tust the TR4A console box of the H-frame will cover it all.

Glue and a solid 18 mm aluminium bar was my choice because I did not want to weld, what I had to do to keep it als flat as possible,

because I know what problem this can be with different steel quality.

To get the shifter more forward Nick went a differnet way for his GT6, perhaps he shows a photo of a sidewards view on his construction....?

In the meantime I started to modify my bearbox crane, it was come [mm] too high to fit without problems down under the exhaust.

Ciao, Marco

 

Edited by Z320
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On 3/20/2021 at 9:52 PM, YOW500 said:

 

Hi Marco.

Trust you and your family are safe in Germany.

With regard to your last post, the gear lever position. This detail was always going to be a problem. I was hoping that the gear lever could be moved even further forward by breaking into the gearbox itself, and thus bring the gear lever into the original Triumph location. As you know I have a gearbox, and I did look into the possibility of a direct connection, and to do away with the extended linkage. So far I have not managed to solve the problem.

Vitesse ltd had the same issue, and solved it as you have suggested. As you can see from the picture below, in the case of the TR2, 3, 3a, and 4, the gear box tunnel has to "butchered" to make room for the amended gear lever position. I believe the TR4a, 5, and 6 have a gear lever console box on top of the tunnel. It may be that this detail would help to hide the required alteration to the tunnel?

The picture below shows my modified gear lever. Vitesse Ltd use a standard unmodified lever, which is angles and has a black ball mounted on the top. I have say "it stand out a mile", when you look into the car

The Vitesse Ltd gear box drives well in my TR3a with all the attributes of a modern box, and a light touch. When the carpet is fitted over the tunnel you need to look very hard to see increase in the carpet height. BUT, it is a shame that there would seem to be no alternative to the placing the gear lever, or is there?

Regards to all.  Russell

 

 

 

IMG_0270.thumb.JPG.f811eedb14911042bdd5fad6ff8a196a.JPG

Russel, blue crimp connectors! Not nice.

Stuart.

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1 hour ago, YOW500 said:

OK Stuart, more embarrassment, for me and those who don't know why, why not blue crimp connectors.

Russell

They often arent crimped correctly and make very poor connections, Ive had more electrical problems than enough on cars fitted with them.

Stuart.

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On 3/21/2021 at 11:04 AM, Z320 said:

To get the shifter more forward Nick went a differnet way for his GT6, perhaps he shows a photo of a sidewards view on his construction....?

I did..... there is no room for the step-forward rod.  The GT6/Vitesse gearbox also has a factory dimension of 585mm from gear lever centreline to bell housing face.  I chose to make this dimension a key requirement of my design brief - and I did achieve it.  It was alot of effort though and the change feel will be slightly altered from the original Mazda - I suppose - I have never actually driven a car with the Mazda gearbox as Mazda produced it.  Only my version.  Which has a quite a nice change, though for sure with a wider gate than the Mazda original. I could change this but in fact it is probably about the same as the original Triumph.

IMG_5622s.jpg.bbcfde9ebd74def6ac37d42a0a1fbc3a.jpg

Mazda original near the camera, Triumph far end, special in the middle.

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Inside the car nothing looks different except there is a no longer a switch on the gear knob for the overdrive.  Mission accomplished.

Nick

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Hi Nick.

Thank you, and a lot to take in. Your forward location of the gear lever itself looks like a good, and proper answer to the problem, although not an easy fix. Your tunnel has a raised box around the gear lever location and this would help with regard to the height of the gear lever platform. As you can see from my previous picture the gear lever platform level looks as if it may just work with the TR3 tunnel. The gear lever mechanism may just be able to be accommodated by the existing opening and its rubber boot above, providing it is no higher than the existing Mazda box platform.

Thank you for sharing. Regards Russell

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