19 replies to this topic

[gkmini]

Hey all,

So I was just wondering. Is it possible to put the differential from a 998 on a 1275? I've got two and the one on the 998 has a lot less miles on it and a verto clutch.

Cheers!

GK

[gkmini]

Oh one more thing!

The 998 is from an 86 Mayfair and the 1275 is an A+ from a 82 Metro.

[Gremlin]

Differentails are interchangeable, but they do not really have anything to do with the clutch, unless you mean you were going to change the whole gearbox and clutch assembly?

[bpirie1000]

Have to take gearbox off the engine. Which means splitting clutch..
Not really that easy and I suspect if I you have to ask if you can swap them then you haven't done much mini engine building.

Engine out.....Split the box off take off the crown wheel from the main shaft and then switch diff. Then re assemble...
Haynes manual first and take lots of pictures but should be a good difference when your done.. Suggest take the car off the road for couple weeks..

[Gremlin]

Why do you have to split the box and block? The crownwheel is on the diff not the mainshaft

[gkmini]

Oh no problem. I'm doing a frame off restoration anyways. The 998 is the original engine and I'm swapping it for the 1275 A+. The clutch thing was kind of an added question so it's unrelated to the diff. All I really needed to know is if I can switch the whole gear box and clutch from the 998 onto the 1275 A+ and if it will give me any advantage or do any modifications.

[gkmini]

Oh and will there be a difference in gear ratio (transaxle ratio)?

[gkmini]

Ok I think I might of solved my own question. If the 998 is from an 86 Mayfair then it is definitely and A+ and so there is no difference between the two. The only difference I'll be adding is a verto clutch which will be an upgrade from the pre-82 AP system.


So that means...

I can just bolt the block directly onto the clutch and call it a day?

[Gremlin]

I would put the pre verto set up on providing you have all the parts, and yes, the block will bolt straight onto the box

[Cooperman]

Remember, when changing the crown-wheel, the pinion is a matched item with it, so they must be changed as a pair.

Check that the FDR is the same by counting the teeth on crown-wheel and pinion and dividing the pinion teeth into the crown-wheel teeth.

Always fit a new diff pin and planet gears.

[gkmini]

Gremlin: Why keep the pre vertical set up? What's the advantage? Just a simpler set up? Also. Someone drilled a breather hole into the top of it. Is that necessary?

Cooperman: Thanks. I'll look in to getting a new pin!

[Guess-Works.com]

As standard the one in your 998 should be a 3.1:1 and the one in the metro a 3.4:1...

 

If you want to change the diff ratio in either, you will need to change the pinion as well which will involve locking the gearbox. this can be done with a special tool without splitting the box from the engine, but personally, if you're going to pull the engine to change the diff you may as well split the whole thing and give it a once over while it's out...

 

Swap the flywheel and clutch cover from your 998 to the 1275, unless they are the same as this will mean you wont have to fiddle about with changing starter motors and possibly wiring.

[bpirie1000]

Aa above but I find splitting the box and engine you get loads more leaverage to slacken the very tight nut and make sure that the re assembly is tight enough..

Your choice.

[gkmini]

I'll have to do some serious thinking. Other than that though.

What would the hand drilled breather wholes on the clutch be for?

[gkmini]

And by clutch, I mean bell housing.