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This was two weeks ago

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299 Euro inkl. shipping seems to be OK for me for the set

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Some modification is needed

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I never did somethink like this but I think it looks more difficult than it is

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For any questions - please ask. And for any suggestion - please tell me.

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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Looks like an MX5 box. I've been involved in similar gearbox/engine mismatch shenanigans myself. Not quite such a mismatch as yours though. 

First time was mating a Toyota T50 to a 3SGE engine it was never intended for then latterly putting an IS200 AZ6 6 speed box on the same 3SGE engine.

The first was achieved by full measurement of both parts on a very, very expensive CMM machine and CNC machining to suit. One advantage of being a CNC machinist working nightshift.

Fitted like a glove. Modifying the AZ6 was a more "hands on" approach as I am now retired. Air-hacksaw, grinder etc. That fitted like a glove too! 

The trickiest part was design and fab of a "reverse remote" to move the gear lever forward five inches. 

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On the gearstick moving, back in the '70's I am sure I saw a Reg Woodcock race/development car with the TR engine and gearbox moved all the way back to the bulkhead, the battery and heater having been removed or dispensed with.  The gearstick was a Triumph saloon one fitted back to front so it pointed forward.  The knob ended up where you'd expect it to be.  Can not recall what happened to the handbrake nor how the exhaust got out.

 

How do the TUV view the transplant of such a major component of the car?

Peter W

Edited by BlueTR3A-5EKT
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Hi Marcel, Spyder and Peter,

it's a Mazda MX-5 NA 5-speed gearbox,

NA because it is possible to move the gear stick foreward, its 5 speed ratio is "exactly" the same as on our TRs + overdrive.

It also has some other benefits.

Some of you might think a 6 speed could be better, but if you compare them you realize it is not the case at all.

What material and tickness did you Spider made your adaptor plates of? I think of tall 8 mm steel S235.

BTW: I don`t own a TR6, but I know it already works with steel adaptor plate, thanks to Jochem, its about 7 mm steel.

Ready to drill different? Someone else could check this, mine is a TR4A

I don`t worry about the TÜV, Peter,

if it ever works to get the gearbox in the car - I don't tell them and they will not realize it.

Ciao, Marco

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Hi Marco. I didn't need an adaptor plate. I was lucky in that two of the boltholes lined up so I had a head start. I had to remove 8mm from the front face to allow the input shaft to engage the crank. New dowel holes and the remaining bolt holes were drilled using the thin engine back plate as a template. I also had to make an adaptor to re-position the starter motor. 

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The projekt with the Mazda Gearbox has been occupying our minds for a longer time. I see the main challenge in fitting the housing to the TR6 or TR4 engine.

In my opinion the Mazda Housing needs to be cut, and an adapterplate need to be attached. This adapterplate should be smaller as the cut part since the Mazda gearbox has a larger overall length than the TR4/6.

Vitesse recognized this too ofcourse. They made a fitting housing and  a matching centerpiece. This in order to reduce the gearbox height in the center. Vitesse put in the necessary investment and made a completely new casting, transferred the whole Mazda gears.

I hope we can manage to find a "low-cost" solution....

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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 housings a second hand manual V12 Etype flywheel a Cosworth clutch and we just lined it all up by eye and got a mobile Ally welder to come in and weld it all together while it was propped up on bits of wood, it worked really well and we never broke it in several seasons of racing, The gearbox rear mount was the Jag one turned upside down. The gearstick came up nicely to hand and with a shortened stick you could change gear with just wrist action!

Stuart.

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Posted (edited)

The "center piece" is about 2/3 of the gearbox housing, in one piece with the bell,

to make and mill a new one is too much for a DIY project.

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The bell of the MX-5 gearbox is higher, but smaller in diameter and taller.

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And the bell is about 2 cm shorter to the pointed surface (stop for the release bearing).

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I guess the Vitesse work is worth the money...

Edited by Z320
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I don't know what power/torque your hoping to push through the Mazda NA box but I always found that the case bolts (10 IIRC) would shear after a race or two much over 220bhp/200ft/lbs with the end of the box not long after that if you failed to notice it, even after a period of road use. The solution was to replace them with 12.7 cap bolts to the same OEM torque or you risked pulling the threads out. Tried a Quafe semi dog gear set a few times with a longer 1st and 5th and they lasted no longer as the case flexes as the cogs pushed it apart . Otherwise a nice box to use.

The six speed is stronger all round but the ratios are very different and could take up to 350/300, last much longer bolted to a Turbo and is what I ended up settling on in the end as I got fed up having to carry a couple of spare NA boxes.

Look forward to seeing it working.

Andy

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The usual approach to this type of match up would be to retain the TR flywheel and clutch cover with an MX5 clutch plate. Will the Mazda bellhousing accommodate the TR flywheel or have you got a different plan? What are you going to do about a speedometer drive?

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Posted (edited)

Hi Andy and Spyder,

the car is omly my TR4A, no tuned engine, not racing, just sportive driving (if my wife let me do).

In my opinion the MX-5 gear box needs no stronger fixing than the TR gearbox.

Yes, the TR flywheel and clutch fits in the MX-5 bell housing, plan is to modify the Mazda friction plate.

What would you do about the speedo, indeed I have to speed it up.

Ciao, Marco

Edited by Z320
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Hi Marco.

For what its worth Vitesse use a Ford concentric slave cylinder. They use the existing TR flywheel. On the TR4a they use an 8.5 inch Helix clutch plate and an uprated MGB clutch cover.

Remember the prop shaft is also a made up special.

The speedo will need to be recalibrated in the usual way by a specialist.

Please let us all know how you get on. It looks like a very difficult job for the amateur?

Russell

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Posted (edited)

Uuups, thank you very much for telling me "Helix"

Google says Helix 70-3421 (215 x 24 mm x 22 teeth) is for MX-5 1.8 l, fits the TR standard clutch cover for 4A-6 (216 mm),

Mazda itself and other producers tell / do this 225 x 24 mm x 22 teeth, needs some modificationon on the lathe, MX-5's small 1.6 l is 200 x 24 mm x 22 teeth.

I would like to use the original MX-5 clutch mechanism, but I see this fits not with the TR electric starter.

Guess that's indeed the need for a concentric slave cylinder, perhsps from Opel , because I'm used to it.

Thanks again, Marco

Edited by Z320
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Does the MX5 box even have a speedo drive cable?  I would have thought it would have an electronic sender. I have a solution for this problem but I warn you, it's absurdly complicated.

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The Vitesse conversion lists a Speedo cable as one of the items included in the kit

...... Andy 

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1 hour ago, spyder dryver said:

Does the MX5 box even have a speedo drive cable?  I would have thought it would have an electronic sender. I have a solution for this problem but I warn you, it's absurdly complicated.

The MK1/II boxes have a cable.

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On 5/6/2020 at 10:23 AM, Z320 said:

peaceful moments at my garage yesterday evening

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just for my understanding....you plugged the holes at the starter mount ??

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Posted (edited)
1 hour ago, JochemsTR said:

just for my understanding....you plugged the holes at the starter mount ??

Hi Jochem,

yes, I "plugged" them all + the gearbox shaft, please have a close look on the plugs.

Ciao, Marco

Edited by Z320
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7 hours ago, trevor said:

Only a cable speedo drive on Mk 1 , electronic on Mk2.

 

Both cable. MK3 might be electronic

 

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