Hey all, sorry another topic but I thought I would make another one for this specific questions as I'm getting mixed answers.

so I've decided to go for a 1275 and keep it auto in the minimatic. From what I've read here it appears I cannot change the diff ratio in it? is that correct?

I was looking at a rover a+ 1275 auto. Which would probably sit better on a highway.

but at the same time I was offered an a series 1275 that needs a freshen up for a cracking deal.

I was talking to len read and he isnt too sure but he reckons the diff ratio can be changed out? apparently the autos had two ratios they came out with. I forgot the exact he said. 3.1 and 3.2 or 3.3 I think. SOmething lik ethat atleast.

I'm not looking for something to go speeding it. just something that can sit on a highway and not be screaming its head off.

I'm rather tempted to go for the a series (period correct? lol) and hot it up a little bit. If worse comes to worse I cannot change the ratio then so be it. I'll just get to the top speed quicker. But are they indeed changable?

from the minimatic website

Differential
In Australia there was only ever one diff ratio in auto boxes. It was about right for a 998cc 700kg Mini on 10" wheels or a 1098cc or 1275cc. A 1275cc auto mini with 10" wheels (or later 12" low profile tyres which are roughly the same outside diameter) will be undergeared and will be quick off the mark, but noisy at motorway speeds. Manual diffs won't fit auto gearboxes.


hmmmmm. so it sounds like there is hope. But not much lol

Some one else asked about this. I think there's a 2.9:1 available, or something like that

The output ratio of the Matic box has the same revs per 1000rpm as the Mini Deluxe.

There was two different diff ratios in the Australian Minimatic/Morris 1100 Auto.
3.48 in the early cars and 3.27 in the later cars.

The output ratio of the drop gears is 1.15:1.
So that means the 3.27 = 3.76:1.

+1 on what Morris 1100 said, so you could try and find an early Morris 1100 auto diff, or buy one from UK and get it fitted.

But having driven minis with 3.76:1 diffs (& morris 1100S, which is 1275, with 4.13, which works out like a 3.76 on a mini), it's really not too bad. Yeah 4000+rpm on the highway, but if the engine is a good 'un they sing pretty well up there Still enough rpm left in reserve for a quick squirt as well

cheers,

Jacob

_________________
'72 Clubman Van - 1022cc, 295 head, 731 cam - Daily Driver
'69 Morris 1100 S - Dinged by a bus, in shed under repair
'64 Morris 1100 - Early 1100, long term project

You don't want the early auto diff. You want to go the other way with the ratio if possible.

The crown wheel and pinion set in an autobox is of totally different design and size to all the manual ones. They are bigger, because the centre spacing of the gears is greater.
The auto's diff output shafts & flanges fit a Cooper S, that's about it for interchangeability.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Ahh crapola, brain fade there - yes totally arse about, sorry about that.

And yes I should have added the manual & auto diffs are not interchangeable, but the later UK auto diffs should be.

There's a mob in UK manufacturing a lot of parts for these, I'll dig the site up.

cheers,

Jacob

_________________
'72 Clubman Van - 1022cc, 295 head, 731 cam - Daily Driver
'69 Morris 1100 S - Dinged by a bus, in shed under repair
'64 Morris 1100 - Early 1100, long term project

I posted this in your other thread. Looks like the A+ had the option of two diff ratios



Final Drive Gears, Automatic Transmission
22A1003 GEAR, final drive, 72 teeth 3.273:1 ratio (with 22 tooth 22A1300 pinion).
DAM7362 GEAR, final drive, 72 teeth, A Plus type 3.273:1 ratio (with 22 tooth DAM7365 pinion).
DAM4130 GEAR, final drive, 69 teeth, A Plus type 2.760:1 ratio (with 25 tooth DAM4128 pinion).

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Ok these guys in UK stll do parts for mini/1100 autos :

http://www.jpat.co.uk/

Look for "Automotive Product (AP)" as the brand, they have PDF catalouges.

cheers,

_________________
'72 Clubman Van - 1022cc, 295 head, 731 cam - Daily Driver
'69 Morris 1100 S - Dinged by a bus, in shed under repair
'64 Morris 1100 - Early 1100, long term project

I spent years looking for a 3.48 diff for my Auto. It would have suited the big wheels of my Moke better.

_________________
Brett Nicholson
Greendale (near Ballan) VIC.
1971 Morris Mini Moke
1966 Austin Mini
1965 Morris Mini Traveller
1973 LR Series 3 88
2007 LR Freelander 2

Rightyo. I have found myself a a series 1275 auto in Melb.

Len read will be rebuilding it for me. Not sure yet of what diff ratio is in it but he said from what he's seen its higher than a cooper s? dunno. lol


should atleast keep up with traffic better as a start.

Now to decide what mods I want on it.