How do you tell an A+ Gearbox ?

I had someone over here the other night, puzzling over my gearbox ... I thought it was a stocko Clubbie rod-change... but he seemed to think it was some whacko Pommie thing...

He was getting hung up about the "Steel" plate on the bottom.. he said most aussie cars had a Square metal plate.. mine is round ....

Is he Dribbling? (Wouldnt suprise me ....)

J

_________________

a+ head isint flat behind the thermostat housing, the ribbing is on the block, down arround the dizzy. theres a post in the how-to section on how to post pics

_________________
speed costs....how fast do you want to go...

Ok, my bad, Aus did get some A+ motors in mokes.

The A+ gear box has different helix angle to the gears. It is steeper to reduce noise so that minis could pass drive by noise tests. The axial thrust is larger so they aren't really an improvement. Identified by a little notch in the top of each tooth.

The A+ engine have: Different dist clamp arrangement, no tappet covers, alternator mount holes closer to the water pump, different dip stick hole arrangement with no tube coming out of the block, vents on the timing cover and the MG Metro one I've got had the heater take off in the head not drilled and no bypass to water pump from head (yay!). Heater take off is by sandwich piece under thermostat cover. (I've modded mine to be as per old style)

Here is an Auto A+ (belonging to Brickworx) Ignore the auto stuff like box and oil filter placement and oil pipe and you can see teh block shape and alternator mounts.


M

internally different also:
lighter rods,
pistons have narower rings

The A+ head also has bigger valves, but my guess is the moke didnt get that as per pom gt. (a+ head also has no by-pass hose)

_________________
speed costs....how fast do you want to go...

There were 3 A+ heads I know of- all surprisingly called a 12G940!
Std Metro or common A+ one: 35.6/29.4 valves
MG Metro: 35.6/29.4 valves
MG Metro Turbo: 33/29.4 valves (exhausts sodium filled, with 5/16" valve stems).

Allegedly all had better porting than our old Mk2 S, Morris 1100S and 1275LS heads did.
Chong has a standard MG Metro one that I've had a squiz at, it's not bad inside but I'm sure GR will improve it some.

<edit> Here's a pic of my A+ showing the dizzy clamp setup, you can see the block ribs too. Dizzy is a Nissan Pulsar D4R83 with A+ drive dog, and 10 secs extra filing for the clamp to fit.

_________________
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.

that sounds right. mg/vdp metro also got a nicer cam similar to a 544? ive read stuf about the turbo having smaller valves due to likleness of the a plus head to crack.
ive seen my mates a+ head beside my stock 940 and the valves/ports do look nicer (valves are quite large really)

_________________
speed costs....how fast do you want to go...

MG metro had:
> Alloy inlet manifold with water heating passages
> Cast iron exhaust manifold
> HIF6 carby
> Big valves
> Electronic distributor with ignitor screwed onto the side and vacuum advance
> Slightly warm cam
> different engine number from others. Mine's a 12HD24
> standard crud single row timing chain with brittle plastic follower.

There were changes through the years though. I think compression changed in mid 80s.