11 replies to this topic

[TopCatCustom]

Hi all, I'm nearly at the stage of sorting out a gearbox, in an ideal world I'd love to call Guessworks and order a nice new straight cut one, but I made the mistake of spending way too much on my last mini a couple of years ago and it went wrong leaving me a bit depressed and in debt! Hence this time I'm trying NOT to buy things unless I need them, (I have more money available now but I'm trying to forget that).

So- with a nice high final drive of about 3.9 or 4.1 and a cross pin diff, will I see a major benefit from a close ratio gearset? I'm going to be doing very small scale rallying, small twisty stages etc, and the engine is a 1310cc A+, with a 286 cam, flowed head etc so should make good power, but I've been given a standard A+ gearbox by a friend, and I just really shouldn't spend a small fortune on a gearbox which may only make a tiny difference.

I'd like some thoughts and advise please!

[AndyMiniMad.]

Hi all, I'm nearly at the stage of sorting out a gearbox, in an ideal world I'd love to call Guessworks and order a nice new straight cut one, but I made the mistake of spending way too much on my last mini a couple of years ago and it went wrong leaving me a bit depressed and in debt! Hence this time I'm trying NOT to buy things unless I need them, (I have more money available now but I'm trying to forget that).

So- with a nice high final drive of about 3.9 or 4.1 and a cross pin diff, will I see a major benefit from a close ratio gearset? I'm going to be doing very small scale rallying, small twisty stages etc, and the engine is a 1310cc A+, with a 286 cam, flowed head etc so should make good power, but I've been given a standard A+ gearbox by a friend, and I just really shouldn't spend a small fortune on a gearbox which may only make a tiny difference.

I'd like some thoughts and advise please!

Hi. Will you be useing the car on the road aswell? Could make a difference to your overall enjoyment of the car. It would be fab on a short twisty stage with a close ratio, straight cut box with S/C drops and a limited slip dif. But would you be able to live with it on the road? High revs all the time even at moderate road speeds, all that noise. My mates got a 1380 rally clubman. Not for road use, although road legal for getting betwen stages. its an absolute beast off the line with a gearbox as described above, but is just no fun on the road unless you drive it like a lunatic all the time. So most of the year it sits in the garage only coming out for rallys and sprints. It depends what you want to use the car for 90 per cent of the time. Im not trying to put you off at all, just saying that a car prepared for rallying is a different animal to a fast road car.

[TopCatCustom]

Yeah it has a Weber 45 and with the 286 will be quite lumpy and not traffic friendly, I'm not fussed about it being comfy on long trips as it will be for a bit of fun on the road too, the diff ratio will determine my top speed and revs in 4th for cruising, so something around 4:1 will be quite loud anyway, its just the difference of having a first gear that is going to be a bit short with a normal box or a long gear in a SCCR box more suitably for the cam and making 2nd and 3rd more suitable for rallying.

[AndyMiniMad.]

The 286 cam is very useable on the road, and should allow 7200 revs. Wont come on cam till around 2500revs so its giong to be noisy for normal driving. A longer 1st gear is the way we have gone when preparing the clubman for this years Snowman rally 4.2 final drive gives 93mph flat out at 7500ish revs. 296 cam comes in around 3500rpm.. If its short/tight rally stages you are doing then it sounds like your spec will be quite good and still be drivable on the road.

[TopCatCustom]

Any other opinions?

[dfmini]

Should go for a close ratio gearset. No doubt about that.

standard 1st and 2nd gear are way too short especialy with 3.9 or 4.1 final drive.

[wardyxxx]

Give Guessworks a shout. He's the gearbox guru!

[TopCatCustom]

Yeah I know and wouldn't hesitate for technical questions, but was hoping to get answers from people who have been in the same boat as me and tried using a normal box before changing to a SCCR box or similar!

[Ethel]

The gearbox ratios won't stop it screaming - 4th is the highest gear.

With a high ratio diff you're effectively increasing all the gear ratios so 4th is closer to the old 3rd, 2nd closer to where first was...

First could become redundant, as you could get the car moving just as easily in 2nd, hence the reasoning behind a close ratio box - it bunches the ratios closer together and closer to 4th, which has to be 1:1

Find an online gear calculator (thanks Guessworks) and have a play. You may find a slightly taller final drive and standard gearbox is a more usable option.

[Guess-Works.com]

The long and short of it ( oh bad punn ) is the gear ratios you use need to enable you to keep in the power band of the engine when changing up and down...

so a close ratio gearset may actually be detrimental to your forward progress as you're forever changing gear, and vice vera, a std gearset may leave you 'off cam' when changing up...

in my experience a 286 equipped engine will serve you best between 3000 and 6500 rpm, which is quite a wide band. You then need to work out the ratios, from those available, which will keep you in this band, up and down, and also provide you with your desired top speed, flat out in 4th, the shorter the final drive the closer the ratios will appear to be..

[TopCatCustom]

On the ratio calculator a standard box will be on cam through every gearchange (in theory), but I'm aware it isn't as simple as that because you arent just accelerating like in a drag race! As pointed out- the short first gear is the downfall as it will be practically useless- 28mph flat out!

Oh what to do! Even the S boxes aren't much different, maybe I'll have to put myself to the test and build a SCCR box, I've been competant enough to build pretty much anything so far, I'm an engineer and use my hands and brain designing and making stuff every day but never had a gearbox in bits!

[dfmini]

Buy a S/C gearset and rebuild the gearbox yourself, it is easy.

I have standard gear ratios on my car (fastroad 1293 with 286 camshaft and 3.44 final drive), and close ratios kit is on the top of my shopping list next time i'll take the engine appart.

Like you said, for a drag race it wouldn't be much difference of performance between standard and close ratios box.

But on twisty roads, most of the time, you'll find 2nd gear too short to use it. So you'll feel like having a 2 speeds gearbox