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Author: Subject: MX5 gearbox on Pinto engine

posted on 1/3/16 at 12:41 PM Reply With Quote
MX5 gearbox on Pinto engine

Cant find much info on this, so can it be done and what are the challenges?

I am thinking:

Inclination of engine relative to the MX5
Output shaft splines
Gearbox width compared to the Type 9
Engine to gearbox adaptor plate

Does anyone have the knowledge?


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Paul Turner

posted on 1/3/16 at 01:03 PM Reply With Quote
When I was at Raceline a few years Pete was working on a solution to using the 5 speed MX5 box on a Duratec in a Caterham (no issue - same bolt pattern as newer MX5's since newer MX5's use a Duratec) and a kit to adapt to a Zetec.

Main problems as I remember them were size (forget the 6 speed) and ratios (5 speed ones were not great - 6 speed ones were really rubbish). Cannot remember anything about weight.

But why bother. Steve Perks at SP Components does rebuilt Type 9's with quiet helical synchromesh race ratio's (still OK on the road) and for cheapskates like me a kit that simply changes first gear.

On my modified V6 box I have the following ratio's:

1st 2.71
2nd 1.81
3rd 1.26
4th 1
5th 0.825

Its superb on the road and I would expect it to be the same on track. The 1st gear kit was about 250 (several years ago) and Steve's fitting cost was very reasonable. Call him on 01527 894232 but prepare yourself for a lecture.

Over the years I have had probably 4 other gearboxes 2 of which were strait cut Quaiffes and the other 2 standard Ford. The standard boxes had rubbish firsts and the Quaiffes were very noisy. This is without a doubt the best compromise and in reality is not really a compromise. Would not want anything different now.

[Edited on 1/3/16 by Paul Turner]

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posted on 1/3/16 at 01:19 PM Reply With Quote
Why not just go MX5 Engine?

I've made an adapter for my MX5 box to a Mazda V6 but most the research was already done so I knew a simple flywheel spacer would ensure things remained viable. I think there is a lot of work behind it working and I would never look to do one from scratch myself.

There is a guy who does RX8 gearbox adapters for a range of engines. He was at Stoneleigh so may be able to help (someone will have to come along with a name/contact info)

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posted on 1/3/16 at 03:13 PM Reply With Quote
The RX8 ratios are:

1st 3.760
2nd 2.269
3rd 1.645
4th 1.187
5th 1.000
6th 0.843

I have the Lexus variant of the AZ6 6 speed on my 3SGE engined car. The ratios are slightly different to the above but similar.
If you ignore 1st the remaining five ratios are very usable.
Its not the lightest of boxes, however.
In its favour, the RX8 box does accept the Ford propshaft.

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posted on 1/3/16 at 06:27 PM Reply With Quote
There is a company in Hinckley that makes a kit to bolt an MX5 box direct to the Ford unit, they do a lot with MX5 boxes including supplying Morgan with their gearboxes

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posted on 1/3/16 at 08:27 PM Reply With Quote
In theory its doable if you have a custom flywheel made (1.8 mx5 flywheel but with bolt pattern to suit Pinto crank) However the MX5 engine is lighter, runs unleaded, and in almost any version of tune outstrips the old 'boat anchor' Pinto.
Cheapest solution is to use a Pinto engine and a Ford box that fits or MX5 engine and box.
The is an RX8 conversion which I think was intended more for Ford V6 engines.


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