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Mazda 5 speed conversion

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My local group leader has had a major gearbox failure, it's with a repairer and will cost a good amount to repair due to the amount of parts damaged/required. 

As he's already got to spend a substantial amount he's wondering if it's worth spending a bit more to do the Mazda 5 speed conversion, I'm hoping to get some experience from members here that I can pass on to him and help him decide which way to go: repair/conversion. 

Many thanks

Gareth

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I've just arranged to exchange my gearbox & A type OD for reconditioned units, I briefly considered the Vitesse conversion but I couldn't see the logic in going from a 7sp 'box to a 5 sp one and paying a lot more for the privilege. You can pick S/H Mazda gearboxes up for peanuts, if Vitesse would sell a conversion kit it would be worth it, for £3k it just seems way too much money to me.

Ian

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I wouldn't 

It won,t be original anymore, so likely worth less when sold.

you are going from 7 to 5 speeds

his original, correctly repaired will last for years, likely longer than his TR ownership

it is accepted that modern gearboxes are not as strong as our old tank like ones, and are more complex

just for starters, sure more will comment.

 

John

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I would keep to the original Triumph box , 7 ratio's as against 5  for normal road use.

I had my gearbox repaired/ rebuilt a couple of years ago and later found that I could have bought and fitted a rebuilt warranted replacement off the shelf for less .

In my opinion unless you have a specific need for racing /sprints etc a standard box would be the best match for normal use.

Brian

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I can see the attraction of the Mazda (or Toyota) conversions, particularly for those that use their car as a daily (but that probably isn’t a big number).

As many will say, moving away from a recognised original box could have an effect on value - unless your prospective buyer values the same mod. Personally, I don’t find myself crying-out for an overdrive when driving a vehicle with a decent 5-speed.

The conversion cost is - in my view - quite high though, so would be some-way down my list of priorities.

there probably isn’t a right/wrong answer - their car, their choice.

...... Andy

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32 minutes ago, John Morrison said:

it is accepted that modern gearboxes are not as strong as our old tank like ones, and are more complex

Really John? Not sure I'd agree. They are generally better engineered and seem to last for hundreds of thousands of miles.

As far as the MX5 box goes, it is a fine choice as a gearbox (I have one in one of my Hurricanes), but as others have said, perhaps not right for an overdrive TR and I wouldn't willing swap an overdrive box for non-overdrive. If it's a non-o/d car, then that's a different question.

Jerry

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Used and broken lots of Mazda Mx5 Boxes over the years including those built with Quaife gear sets (don't bother waste of money).

Mazda MKII Sport has a six speed (£250-300) and the same bellhousing pattern so is 6 v 7 gears . Nice to use but the syncro's are the weak spot on 2nd and the cases can flex and snap the through bolts passed 200bhp esp on the MK1 (£50 -75) 5 speed but in normal use will go on forever.

Andy 

 

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The conversion kit is expensive on its own then you have to supply the box which is then an unknown, add that to the depreciation of final value its not really worth it, There are plenty of boxes around for outright buy for less than the total cost of the 5 speed conversion. I would get a proper box for it first as last.

Stuart.

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I've been ask to join a Mazda MX5 gearbox project but I'm double-minded.

Not solved is how to get a speedo drive for low effort and low cost on the Gazda gearbox to use the original speedometer.

The Mazda gearbox in the car and the working original as a spare part will lift the price

Edited by Z320

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A modern gearbox conversion is ideal for a car where the original gearbox is under geared or lacks synchronisation on all gears (Morris 1000 etc), I fitted a Ford type 9 to my 1952 MG which was a huge improvement  and added to the cars value. However a standard TR box with overdrive is as good as a modern box and I would think a conversion would devalue the car, a bit like swapping PI for SUs

George

Edited by harlequin

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This is great guys, I'm of the same feeling that a standard (od) box is the way to go. I'm pretty sure that's what he'll do, he just wanted to explore all the options before getting his rebuilt. 

Cheers

Gareth

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I have a very modified, road legal TR6, and can suggest a Stag derived gearbox, with some use of TR6 components, competition synchro rings, and good quality bearings.  Complete with a competition o/d unit, although not for the faint hearted, is a great package, and will absorb all the power you can throw at it, including the kitchen sink.

Something great about having an o/d box, and part of the character. Not much can beat the precise, riffle bolt, positive gear change, too.

 

Cheers.

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To rebuild a TR gearbox is a job that is not beyond an amateur mechanic, there is lots of guidance on t'interweb and here ofcourse, parts are easily obtainable and there is a great deal of satisfaction to be gained in a DIY job.

The overdrive unit is a different story, for me anyway and I would recommend getting that done by a professional 

George 

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