Amazon: Re-gearing an M40 gearbox

[P1800Ray]

Through ownership of another make of car I'm aware that some gearbox specialists can replace the gears in the box to owner requirements. Has anyone ever done this on an Amazon?

Would be nice to spread the gearing to give an overdrive on 4th without having to search for an M41.

[Derek UK]

Not a good idea and would be detrimental to your driving experience. You call yourself P1800Ray but what car are we talking about here?

[P1800Ray]

Hi Derek, my P1800 has overdrive, this was referring to my Amazon (without OD).

Just a thought.

[grumpydad]

Hi
I have never heard of this
you would need a complete new gear set
all gear boxes i have come across have 4th gear as a ratio of 1 to 1
you could swap out the diff for a lower ratio
this would make the revs drop in all gears
the cost slower of the line so no tyre smoking possible

[P1800Ray]

Henry 😂

Road and Race do it for Caterham 7s so I just wondered - I called them, they’re not interested.

I have officially abandoned this seemingly mad idea 😁

[grumpydad]

Hi

https://www.volvoforums.org.uk/showthread.php?t=303459

have a look it seams to be about the going rate

[Volvo_133]

If you are contemplating dismantling the gearbox to do modifications, you could fit a M41 longer shaft, spacer, overdrive unit, to your existing M40 unit. Apart from the overdrive i think i have all the other parts.
Chris

[Vintagewrench]

Close ratio ratio gears are used in these cars for racing and rallying. Quaife offered a set for the M40-41 until just recently. It still manufactures a gear set for the 240 M45-46.

[Bracpan]

Has anybody fitted a more modern 5 speed box from a Ford, BMW or Mazda MX5 ? Its the higher 5th you need.

[c1800]

Originally Posted by Bracpan

Has anybody fitted a more modern 5 speed box from a Ford, BMW or Mazda MX5 ? Its the higher 5th you need.

Seen a lot of T-5’s , have a reputation for noise, and some models of T-5 the gearing is inappropriate. also T-9’s, which are more plentiful in Europe as they were used a lot more in production cars there. Better fit as they are smaller.

T-5 requires a larger tunnel for (I think) pre 68, unless it was originally an automatic.

Overall much easier to convert to an M41, which is plenty robust fir a B18. Lots of info in this and other forums, not exactly plug and play, but not difficult. needs a modified driveshaft, which has been done a thousand times. I suppose you could fit anything in there, just more work and challenge getting/fabricating a bell housing.