7 replies to this topic

[Robbie]

Mini Racing Green
1990
Engine revs too high in 4th gear!!!!



MG Metro engine fitted

Hello all, I've a question that could potentially sound quite stupid, but as I'm not the most mechanical person ever, I thought I'd ask.

At some point in its life, my car's original 998cc engine has been replaced with that out of an MG Metro.

Am I right in thinking that the MG Metro was fitted with 13" wheels, and that because my car has 12" wheels, this causes the engine to rev high in 4th gear consequently meaning that speeds above 65 are unrealistic due to both the noise and the amount of revs.

Because I don't want to lose the brilliant acceleration I have in 1st, 2nd and 3rd by putting a taller final drive in, nor do I want to fit 13's, I was wondering whether it was possible to just put a new 4th gear in which has a taller ratio, giving me a comfortable cruising speed (especially as I'll be heading off to uni soon).

I hope this makes sense, and that someone can give me some much needed advice,
Thanks in advance,
Robbie.

[Guess-Works.com]

simple answer, no...

Complicated answer, is still no, but the reason is, all A (and A+) series 4 speed transverse gearboxes have a 1:1 4th gear....

If you want a guide as to what final drive you're running, then play with the figures on here...


http://www.guess-wor...nical/ratio.htm

[Robbie]

simple answer, no...

Complicated answer, is still no, but the reason is, all A (and A+) series 4 speed transverse gearboxes have a 1:1 4th gear....

If you want a guide as to what final drive you're running, then play with the figures on here...


http://www.guess-wor...nical/ratio.htm

Thanks for the quick reply, I guess a taller final drive is the only option...

[bmcecosse]

Or a very expensive 5 speed box! For best economy - go for a 3.1 or even a 2.9 final drive. The acceleration will still be fine - the lower gears will 'hang on' longer .

[Robbie]

Or a very expensive 5 speed box! For best economy - go for a 3.1 or even a 2.9 final drive. The acceleration will still be fine - the lower gears will 'hang on' longer .

A five speed gearbox, I wish!!!!

Which one of these two should I be looking at then? -

This one .

Or this one? .

Thanks for your help guys

[Guess-Works.com]

You'll need a crown wheel and pinion, but would steer away from new, far too much money, second hand is the way to go... I seem to have 3.1's coming out of my ears at the moment... £40 + carriage.

However you do realise to change the final drive the engine is going to have to come out of the car.

[Robbie]

You'll need a crown wheel and pinion, but would steer away from new, far too much money, second hand is the way to go... I seem to have 3.1's coming out of my ears at the moment... £40 + carriage.

However you do realise to change the final drive the engine is going to have to come out of the car.

Yeah, I thought engine out would be the case.

As my driving test is a week today, (if the weather has cleared up by then), me and my Dad won't do it straight away as I'll want to drive it for a bit, but when the time comes, I'll give you a shout. Thanks for all your help Guessworks and bmcecosse.

Robbie.

[Ethel]

It should have a 3.44 diff, the same as many 10 inch wheeled Minis.