20 replies to this topic

[Jordy869]

Hello,

I’ve got a 1992 classic mini neon that I’m going to change the engine to a 1275 A series engine which I will get repaired and rebored to a bit bigger but not sure yet. I was wondering if I was able to change a 4 speed gear box with a 5 speed?

Or is this a ridiculous idea and should never and Cannot be done. ?

Regards

[sonikk4]

Yes you can fit a five speed box but they are expensive, rare and not that strong. Plus getting spares for them is difficult.

 

A decent overhauled 4 speed with the correct final drive suitable for what you want to do is more than enough.

[Jordy869]

Is there anywhere that refurbs them. If it needs to because in the future I want to add a supercharger.

[DeadSquare]

Buy a proper workshop manual.

 

You will then be able to "refurb them" bits your self.

 

If you are going to fit a supercharger, keep your rebore to the minimum, as in a 1300, there is not a lot of metal for the head gasket to sit between.

[sonikk4]

Is there anywhere that refurbs them. If it needs to because in the future I want to add a supercharger.

 

Like i said spares for them are rare, John Guess aka Guessworks should be able to do a refurb. He refurbs standard 4 speed boxes all day long. He did my lads for us.

 

As mentioned if the block needs a rebore then go +0.020", that will give you 1293cc's with plenty of life left in the block for more rebores.

 

Going straight to 1380 will mean only one thing if the bottom end wears and thats fitting liners. Not a cheap thing to do.

 

So all of this will mean a decent budget will be required.

[Jordy869]

Okay, I get it. Small increments on the boring will is probably what I will do because I was aware that go to max then it wears out it’s then knackered.

Okay I’m just waiting to go on with it. To be honest I could refurb them myself to save a bit of money. Thanks

[croc7]

Not a fan of a 5 speed gearbox, they are expensive and from what I've read, what you get with a 5 speed is a four speed close ratio box with an 'overdrive' 5th gear, 3.1:1 final drive.  Save your money and build an engine with tons of low end torque for driving around town and a final drive ratio of 3.1:1 for the highways.  That's what I did and have no regrets.

Edited by croc7, 23 August 2019 - 11:27 PM.

[Magneto]

You can buy a complete 5 speed box from MiniSpares, about $2500 and they will build it to your spec....they will put in any final drive you like but depending on what spec your engine works out to, the std 3:44 which will give you about 3:1 in 5th is a good spec.

 

A lot depends on what kind of driving you'll be doing. I agree with the others, build a nice torquey engine and a 3:1 ratio final drive and you'll have a nice combination for most road conditions.

 

Here in the states we have huge distances between our events, so a nice tall final drive is a good move, having the extra ratio for acceleration and the hills is a good move too.

Edited by Magneto, 24 August 2019 - 04:01 AM.

[Ethel]

You'll have less need of extra gears with forced induction as you get more power without increasing the rpm.

 

The amount of power is also down to how big the combustion chamber is and how compressed the charge is in it. It doesn't matter so much if it's been compressed by a bigger piston or a supercharger. Especially true for the A Series as the limit will be when something breaks, usually the transmission, there's no point in finding the most expensive way to get there. 

[mab01uk]

Minispares 5-Speed Gearboxes:-

http://www.minispare...Speed.aspx?1501

[nicklouse]

What are you hoping to active with 5 gears that you can’t with 4?

[Dusky]

Nothing wrong with a good 5 speed. There is a reason they have 6 speed manuals and 8 speed autos now.

[Ethel]

Yes, heavier cars that can do much higher speeds than a Mini.

 

The most important thing is to have good ratios to match where your engine makes the power you need to drive at the road speed you do.

 

There's nothing that wrong with a 4 speed Mini that justifies splashing out £2k, at least that's my opinion.

[Magneto]

Depends on what kind of driving you do....here in the states it's 500 miles between cities, so not having the engine wound out to 4-4500 for 8-9 hours is nice. Being able to drop the revs down to 32-3500 really makes a long trip more comfortable, but of course you need the engine set up right to pull those lower revs. It's not hard to do tho…..I've built a number of engines that run at those rpms very happily, without resorting to forced induction. Supercharging just makes it easier tho….

[Dusky]

Even the most basic Ford Ka has a 6 speed box. It's technological advancement. We couldn't keep using the good old powerglide transmissions.