14 replies to this topic

[johnpaul]

 im partialy disabled (left leg) and i would like to build an automatic mini but how strong are the gearboxes when it comes to tuning?

ive got an auto a+ 1000cc as a starting point but how far is too far turbos,twin carbs or supercharging.?

many thanks johnpaul

 

[mini13]

Around about 100hp is the upper limit I belive, there were some uprated parts available through Mra minis, but they are now defunct, although the owner was on here still and doing specialist gearbox stuff so might be worth looking into.

I think in this instance a mildly supercharged engine might be best, I'm thinking it would have a smother power delivery and be less harsh on the box.

[Albannach]

The words Strong and Mini Automatic shouldn't be used in the same sentence. They are fragile creations at the best of times, and the 998 version is well past its sell by date. If you hate changing oil....then don't even consider an AP2 box.
I speak from experience, having literally owned and driven dozens of them over the last 5 decades.
Parts are getting hard to find now, such as Bands. Every 998/1275 Box I scrapped I would take the Bands out and send them down to Jpats, so some other Masochist would benefit. Sorry for your disability, but try a small Jap auto for reliability.

[slidehammer]

I wouldn't go mad with an auto box, maybe a stage 1 kit at the most. The other problem is if you change the engines characteristics in terms of power delivery the box won't change at the right points   in the new power curve.

[Homersimpson]

Could you consider an engine conversion, I know most of them are for manual but it may be possible to modify to take an auto?  The micra might be a good starting point as its a fairly small engine although i have no experience of this at all, might be worth finding and talking to someone who does conversions to see if its been done before.

 

I would avoid any form of tuning on a standard mini auto, they are just too fragile IMHO.

[mini13]

if the auto is out, then depending on the level of disability, I have heard of remote servos being used to make the clutch lighter.

[dyshipfakta]

AS strong a a strongish cheese Red Leicester

[Spider]

The other headache you'd run in to is the stall speed of the Torque Converter, when you start running Cams over about 265 degrees, it doesn't suit them too well.

[nicklouse]

A friend has a similar issue following a ski accident. He has the clutch as a hand operated conversion.

[CityEPete]

Maybe a hydraulic upgrade to make it super light then with the lever on the gear lever making it a single handed gear change?

The other option would be a bike engine with sequential 'box and a blipper up and down.

[johnpaul]

thanks for all the replys im letting it soak in.ive talked about a hand clutch on the gear lever for a while but would like to see one in operation or a magazine,

cheers johnpaul

[DomCr250]

In good condition they are a lot stronger than people think.  People have used them in motorsport with high HP numbers as semi-autos.  Keith Calver has referred to a couple of guys who visited Minispares in the 80's / 90's and put loads of power through them, they actually tried to break them and struggled to do it.

 

Like anything it's all to do with how good the individual parts are inside and how they are put together.

[alex-95]

Theres a bit of info in this thread ---> http://www.theminifo...gy-the-autocar/

[CityEPete]

thanks for all the replys im letting it soak in.ive talked about a hand clutch on the gear lever for a while but would like to see one in operation or a magazine,
cheers johnpaul

Modifications are popular in the motorcycle world 'for obvious reasons!' I'll bet there's a company that could knock up a good hand clutch out there, I've seen lots at the NEC motorcycle show. A button under the thumb controlling an actuator that quickly depresses the standard hydraulic clutch would be really trick!

[ACDodd]

I also think the autobox is good for more power if its built properly. And by this I don't mean a quick £1000 refurb job, I mean, new clutches brake bands valves the lot. I would have thought you would be looking at way I excess of £2000 for just the gearbox on its own. The problem is the autobox has suffered with lack of maintenance by owners and cheap rebuilds meaning they fail often giving rise to poor reliability. Using second hand is almost pointless, they are simply too old now.
I would do a big capacity build (1380 or 1430) and a mild cam(sw5-07 or my ACD - RT)torque pump type engine if you will, this would work well with a (very expensive) rebuilt gearbox. Should last 20 to 30,000miles before you need to rebuild again.

Ac

Edited by ACDodd, 27 December 2017 - 02:53 PM.