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Mazda 5 speed gearbox


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Over winter I will be swapping my non-overdrive gearbox.

Initially my thoughts were to buy and fit an overdrive gearbox but have seen recently the availability of the Mazda 5 speed box conversion.

Although this sounds like a good option, I can't find anywhere that reports on the driveability of the car with the Mazda gearbox.

Has anyone carried out this conversion & if so, how does it drive - is it worth doing the work?

Thanks

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Well my tuppence worth would be to go the Triumph route,

A simple straitforward original fitment, that will enhance the value of your car, and will make it eminantly more drivable and fun, 

and you 6 or even 7 speeds instead of 5, All you need to know, wether you plan to do the job yourself or pay others is in these pages.

John.

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Hi Pete & John

Thanks for your replies.

Pete, I had a read of fitment of the Mazda gearbox but it didn't help on it's driveability and seemed to wander off on various tangents - gearstick positioning & the amount of BHP the gearbox would handle - not really what I was looking for.

John, your comment is definitely worth tuppence. I agree re. sticking with originality. We all know that the original gearbox is agricultural but that's part of it's 1970's appeal.

It doesn't seem that too many people have gone down the Mazda route so may stick with plan A and buy an overdrive gearbox.

I had an early TR6 in the 70's and quite enjoyed flicking in and out of overdrive.

Regards

Brian

 

 

 

 

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Brian,

I also think the standard gearbox and overdrive give a good combination.  All weaknesses and foibles to one side…..

I have a friend who swears the Ford Sierra gearbox route, that he has gone, is the way to go.

Peter W

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Hi,

I will come to a detailed and mainly positive summery later this year.

But in short words: I'm pleased.

My reason for the MX-5 gearbox was the challenge to do / fit it,

the need to buy an overdrive because I do / did not own one,

and my mistrust against the overdrive itself at its control switches.

Another point of interest is the concentric clutch slave cylinder:

we all get older and it's LOVELY to use the TR clutch with lady-effort like on modern cars.

Ciao, Marco

Edited by Z320
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On 9/12/2021 at 1:03 PM, Brian Turner said:

Over winter I will be swapping my non-overdrive gearbox.

Initially my thoughts were to buy and fit an overdrive gearbox but have seen recently the availability of the Mazda 5 speed box conversion.

Although this sounds like a good option, I can't find anywhere that reports on the driveability of the car with the Mazda gearbox.

Has anyone carried out this conversion & if so, how does it drive - is it worth doing the work?

Thanks

Take the easy known route and take your gearbox to ORS who would convert your original box to an overdrive one and overhaul your gearbox and ask them to do their layshaft mod to 3 needle rollers? In my view this is your best choice!

Bruce.

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+1 from me,

if you can't make this your own project and if you do want to puzzle how to solve  not expected challenges.

Because I suppose with the Vitesse gearbox anyway you have some of the problems like I had with my DIY project.

For example how to get it in car.

 

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Hi Fellah's

Thanks for you suggestions and advice.

Overdrive is certainly the cheaper and authentic way of adding more gears but, with the Mazda option it would have a light, smooth gearshift.

The main advantage of the overdrive route is that, living in South Yorkshire, I'm not far away from Overdrive Services, Sheffield who will overhaul my box + fit an overdrive for around £2000. 

As it's a winter project, I may be able to pick up something in the meantime.

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From memory, I think the earlier A series overdrives with big “ jam pot” piston comes in with such a bang that fitment to “later cars” ( TR4a onwards) leads to various failures at the rear, diff mounts etc.

To avoid this they then replaced the big boy piston with 2 smaller pistons which sssslllluuurrr into engagement rather than the snap of the earlier engagement. If I’m wrong correction from others will follow shortly.

Mick Richards

 

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14 minutes ago, jerrytr5 said:

Wasn't the A type on all 4A. 5 & early 6?

I thought it was just the CR series that went to J type.

Jerry

Yes, that's my understanding too. My 1970 CP series '6 has an A type overdrive.

Nigel

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Brian, 

two things for you to consider, buy a complete unit, they are about and can come with a warranty, quicker, and gives you your original box to sell on.

Also as you have no column switch at the moment, consider the O/D switch mounted on teh top of the gear lever, as Stag, Saloons and others.

I've driven lots of Tr's equipped this way, and the switch does fall very readily to hand, I think if I was starting from scratch, then this is the way I would go.

John.

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14 hours ago, Motorsport Mickey said:

From memory, I think the earlier A series overdrives with big “ jam pot” piston comes in with such a bang that fitment to “later cars” ( TR4a onwards) leads to various failures at the rear, diff mounts etc.

To avoid this they then replaced the big boy piston with 2 smaller pistons which sssslllluuurrr into engagement rather than the snap of the earlier engagement. If I’m wrong correction from others will follow shortly.

Mick Richards

 

Triumph had to change the A type to J type as Volvo did not like the Wham Bam engagement of the A type as Mick pointed out above and Volvo were their biggest customer?

Bruce.

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I well built Triumph gearbox with o/d is all that is required here.

If you have an uprated engine, consider a Triumph Stag derived one, again, built with quality bearings and synchro rings.  If your chassis is in good order, in particular, where the diff mounts, that will also be fine for an A-Type unit.

A competition o/d unit is rather harsh, but providing you're committed on the throttle (wide open), engagement is smooth and ultra fast.  I always use the clutch to disengage though.

 

Cheers.

 

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16 hours ago, Brian Turner said:

Hi Fellah's

Thanks for you suggestions and advice.

Overdrive is certainly the cheaper and authentic way of adding more gears but, with the Mazda option it would have a light, smooth gearshift.

The main advantage of the overdrive route is that, living in South Yorkshire, I'm not far away from Overdrive Services, Sheffield who will overhaul my box + fit an overdrive for around £2000. 

As it's a winter project, I may be able to pick up something in the meantime.

Make sure that you have your lay shaft bearings modified to 3 needle rollers as per Stag. ORS can do this mod not certain about OS? This will double the life minimum of your box as this is the weak point of a TR gearbox as it whines in 1st, 2nd & 3rd and goes silent in 4th. This the sure sign that a TR gearbox is on the way out.

Bruce.

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Wow, so many suggestions, so much advice!  Thanks Forum.

A reply to John Morrison - John, I have managed to buy a gear lever with an overdrive switch in the knob - I agree, it is much easier to use than the stalk mounted switch. Interestingly, during the mid '70's I owned a '69 TR6 with overdrive on 2, 3 and 4 and the switch was on the gear lever knob, I thought this was a standard fitment at the time but have now found that it was an aftermarket fit - certainly a good move. So really, this has made up my mind, reading the advice above re. the A type I will get my box refurbished and have a J type overdrive fitted. I have spoken to Overdrive Repair Service who will do the job.

Many thanks

Brian

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Brian - in case you weren't aware, a standard J type set up only works on 3rd and 4th , whereas the A type works on 2nd as well.

However it's a very simple modification to convert the top cover so that you can have OD in second as well on a J type set up - ORS should be able to do that very simply and at minimal cost when building the unit.

If you already knew all this, then apologies!

Cheers Rich 

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