Jump to content


Photo
- - - - -

1275 A+ Gear Case Interchangeability

engine

  • Please log in to reply
9 replies to this topic

#1 Vudu

Vudu

    Stage One Kit Fitted

  • TMF+ Member
  • PipPipPip
  • 59 posts
  • Location: Asheville, North Carolina

Posted 22 March 2020 - 01:32 AM

I have a 1275 A+ from a 1988 Metro that I’m rebuilding into a high performance street motor. The stock gear case has some damaged fins and of course it has a verto clutch but I would prefer to run a non-verto setup. I also happen to have a 1974 998 with an undamaged case. My question is whether or not I can or even should swap gear cases between the two engines.

I’ve been reading a number of topics on this site as well as watching a bunch videos from MED Race Technologies, all of it very educational regarding high performance Mini transmissions. Unfortunately, I’ve not been able to find any info that answers my rather basic question. Hopefully someone here can supply some advice. Thanks in advance.

#2 Moke Spider

Moke Spider

    Crazy About Mini's

  • TMF Team
  • PipPipPipPipPipPipPipPipPipPip
  • 9,787 posts
  • Location: NSW
  • Local Club: South Australian Moke Club

Posted 22 March 2020 - 06:10 AM

Short answer here is no.

 

Usually 1275's have a Crankcase Breather on the Transfer housing. This can be overcome.

 

However the 1974 Transfer Houses won't interchange with the Metro one. The Idler Gear Bearings were considerably smaller than the Metro one.



#3 johnv

johnv

    Mini Mad

  • Members
  • PipPipPipPip
  • 226 posts
  • Location: Surrey
  • Local Club: FDMC

Posted 22 March 2020 - 06:36 AM

John Guess sells an adapter to overcome this I believe.

#4 GraemeC

GraemeC

    Crazy About Mini's

  • TMF+ Member
  • PipPipPipPipPipPipPipPipPipPip
  • 5,484 posts
  • Location: Carnforth

Posted 22 March 2020 - 07:53 AM

You mention damaged fins - do you mean you want to swap the whole gearbox between engines?

if so, the yes that is possible but the gearbox and transfer case must stay together for the reason Spider mentions.

 

However - damaged fins are not usually a problem as long as the case isn’t cracked.

And a pre-verto flywheel, clutch assembly and release mechanism can be fitted to an engine previously set up with a verto system.



#5 johnv

johnv

    Mini Mad

  • Members
  • PipPipPipPip
  • 226 posts
  • Location: Surrey
  • Local Club: FDMC

Posted 22 March 2020 - 08:31 AM

http://guess-works.c...play.htm?id=553

#6 whistler

whistler

    One Carb Or Two?

  • TMF+ Member
  • PipPipPipPipPipPipPip
  • 1,016 posts
  • Location: Cardiff

Posted 22 March 2020 - 11:28 AM

Check out minimania youtube video on this subject. I've just fitted A+ gears into an A remote gearcase. The idler bearing problem has already been dealt with by someone else.



#7 nicklouse

nicklouse

    Moved Into The Garage

  • TMF+ Member
  • PipPipPipPipPipPipPipPipPipPipPip
  • 13,460 posts
  • Location: Not Yorkshire
  • Local Club: Anonyme Miniholiker

Posted 22 March 2020 - 11:43 AM

as long as you use the correct transfer case and gearbox it is easy.



#8 Vudu

Vudu

    Stage One Kit Fitted

  • TMF+ Member
  • PipPipPip
  • 59 posts
  • Location: Asheville, North Carolina

Posted 22 March 2020 - 02:39 PM

Thank you to everyone for their responses...I greatly appreciate the community's experience and expertise. I should have worded my question and details better...

 

The damage to the fins on the A+ engine appear minor although I would absolutely check the gearcase/transfer cases for any cracks before proceeding with a rebuild. The Mini I'm building will be much more than a driver so the aesthetics of the case damage are a little bit of a factor  - although if I lower the car enough it'll discourage anyone from kneeling down to get a better look at the underside ;)

 

According to the Minispares site, my Metro A+ features a wide ratio box. I haven't been able to find specifics on the gearset yet but I strongly suspect it'll be less than ideal for the engine's performance although I don't know the specifics of the 998's gearset yet either. My thinking was that if it was better, I would swap the gearcase and transfer case assemblies to address the gearset, fins condition and clutch preference all in one shot.

  • If it turns out that neither gearset is desirable and I am faced with getting new gears, would it be better to work with the A+ and adapt the pre-verto clutch assembly? Or is there some advantage I'm not aware of in using the '74 gearcase/transfer case?

Thanks in advance for the additional help.

 

Is there a significant strength difference between the A and A+ idler bearing sizes? I would expect that the engineers made the change because their calculations suggested it was required but I don't know anything about other factors:

  1. Was there a history of wear issues in pre A+ bearings?
  2. Did it have something to do with the increased weight of the Metro vs the Mini?
  3. Was it related to the increased horsepower and torque?


#9 GraemeC

GraemeC

    Crazy About Mini's

  • TMF+ Member
  • PipPipPipPipPipPipPipPipPipPip
  • 5,484 posts
  • Location: Carnforth

Posted 22 March 2020 - 03:02 PM

Probably pros and cons to both.

The earlier box maybe better made in terms of tolerances and dimensions - Spider would advise better.

If the A+ is the later one with the 3 bolt centre bearing retainer then it is likely stronger.



#10 Moke Spider

Moke Spider

    Crazy About Mini's

  • TMF Team
  • PipPipPipPipPipPipPipPipPipPip
  • 9,787 posts
  • Location: NSW
  • Local Club: South Australian Moke Club

Posted 23 March 2020 - 07:08 AM

Cheers Graeme.

 

One way forward with this 'conversion' is to fit an adaptor bearing and use the earler drop gears

 

http://www.minispare...|Back to search

 

You'll also need an early 1275 Primary Gear. The idler Gear and Input Gears you will already have with your 998 Gearbox.

 

Overall though, these are an inferior gearbox to the 3 Bolt A+ types in most ways.

 

The Idler Gear is just one place, though, the machining tolerances were generally better in those days, but the bearings and shaftings were much smaller.

 

Personally, I always go to the later gearboxes, but I also have the 'luxury' of usually being able to sort out, the machining issues.







Also tagged with one or more of these keywords: engine

0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users

Mini Spares