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A+ Gearbox Strip Down And Rebuild


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#1 JonnyAlpha

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Posted 15 January 2020 - 01:46 PM

As part of my 1275 - 1310 rebuild I need to tackle the Gearbox (Not touched it since I removed it from the engine)

It's from a 1275 Metro and although the Engine Number was all but obliterated and hard to read, I seem to recall that the Diff ratio was something like 3.44.

 

Anyway - I am off work today recovering from a minor op and thought I would put my downtime and do some research (not allowed in the garage).

 

I have spent the morning watching MED Engineering, Mini Mania and a couple of Home Made Videos on Gearbox Rebuilds, which for all intents and purposes, seems pretty straightforward. However, there there are not many videos on stripping down, which seems to be were the difficult areas are, especially when it comes to removing bearings and bearing races.

 

I have looked through the excellent guide from this forum here and removing bearings from the main gearbox seems straightforward and requires no special tools.

 

Flywheel Housing 

However what about the bearings in the Flywheel Housing, namely the First Motion Bearing and Idler Bearing and thier respective races.

in this video the guy talks about two different types of Flywheel Housings, one with a large First Motion Bearing and one with a small First Motion Bearing. May I assume that I can find the difference by looking at the MPN on the casing? 

 

What is the best way to remove and replace these bearings and races?

 

I'm sure there will be a lot more questions as this thread progresses.



#2 nicklouse

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Posted 15 January 2020 - 02:18 PM

first motion pilot bearings are all the same except for the Metro Turbo.

 

the idler gear bearings are small (early) and larger (later) 

 

you do have a Haynes manual please read it.



#3 JonnyAlpha

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Posted 15 January 2020 - 02:56 PM

first motion pilot bearings are all the same except for the Metro Turbo.

 

the idler gear bearings are small (early) and larger (later) 

 

you do have a Haynes manual please read it.

 

Nicklouse - Haynes Manual, Workshop Manual got both, and yes I will read them, but like I said not allowed in the garage and that's where they are :-) Can't get at them without moving the Mini and can't do that for fear of tearing some stitches in my back :-)

 

So this being an A+ Engine from a 1988/9 Metro would I assume be classed as "later" so large idler bearings.

 

Found some info on removing the bearings and races - pretty crude but adaptable, one by John Guess on here.

 

Bearing / Race Removal:

 

https://www.youtube.com/watch?v=VcKeF5E64W8

http://www.guess-wor...Tech/spigot.htm

 

So far I have put together this list of helpful links and videos:

 

http://www.theminifo...down-with-pics/

 

 

Part 1 of 4:

 

Part 2 of 4:

 

 

 

 

 

Part 3 of 4:

 

Part 4 of 4:

 

Idler Gear End Float


 

 



#4 BaronVonchesto

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Posted 15 January 2020 - 03:18 PM

here watch this series. Helped me a lot when i was rebuilding my gearbox.



#5 JonnyAlpha

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Posted 15 January 2020 - 04:18 PM

here watch this series. Helped me a lot when i was rebuilding my gearbox.

 

That'll be "Cole" from Classic Mini DIY. I'm subscribed to him on YouTube and found that video this morning. I had seen his Gearbox rebuild a while ago but not this part. That gearbox is in a right state isn't it :-)

I have just messaged him to see if he has or is going to do a video on the Flywheel Case. I know he's been busy fitting a SuperCharger to Bad Wolf :-)



#6 Moke Spider

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Posted 15 January 2020 - 06:21 PM

Flywheel Housing 

However what about the bearings in the Flywheel Housing, namely the First Motion Bearing and Idler Bearing and thier respective races.

 

What is the best way to remove and replace these bearings and races?

 

This is the factory's advice on this;-

 

avHlyoi.jpg

It's the same deal for the Idler Gear Bearings too.



#7 JonnyAlpha

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Posted 15 January 2020 - 07:24 PM

 

Flywheel Housing 

However what about the bearings in the Flywheel Housing, namely the First Motion Bearing and Idler Bearing and thier respective races.

 

What is the best way to remove and replace these bearings and races?

 

This is the factory's advice on this;-

 

avHlyoi.jpg

It's the same deal for the Idler Gear Bearings too.

 

 

Hmm - and where might I borrow an 18GA617 - nothing on the web?



#8 alex-95

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Posted 15 January 2020 - 07:35 PM

This is how I removed the idler gear in this thread - http://www.theminifo...ng-replacement/

 

The 1st motion one I've used a hot air gun warming around the bearing from the back and then "thumped lightly" the casing onto a bit of wood and it came out. Don't get it too hot though as this can crack the casing, Don't weld a bolt to it to pull it out as this can crack the casing too.

 

The mini-mania videos are sort of useful but some of there techniques of doing things are a bit rubbish, like on the third video fitting the bearing...



#9 floormanager

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Posted 15 January 2020 - 07:59 PM

I've recently stripped and rebuilt two gearboxes.  All fairly straightforward.  Trouble I had was undoing the main nut (had to take it to a gearbox specialist).  First motion outer race came out easily when heated in an oven and dropped onto wood.  The A+ idler gear bearing is easier to get out than the A series ones as there's more room to work in.  There's a video of someone making a puller out of washers.  I have an internal puller which worked.  No problem with replacing any of the bearings.  Something to be aware is getting the first motion shaft bearing out of the box.  Be careful not to twist it as you are removing it as it can lock and you'll be there for ages with it not moving.  I watched all the videos, including Guessworks, mini mania etc.  Well pleased with the result.  Oh and do not buy the cheap bearings.  Get the best ones you can (RHP).  Happy to offer any advice. I've decided I love build gearboxes :-)



#10 JonnyAlpha

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Posted 15 January 2020 - 08:52 PM

This is how I removed the idler gear in this thread - http://www.theminifo...ng-replacement/

The 1st motion one I've used a hot air gun warming around the bearing from the back and then "thumped lightly" the casing onto a bit of wood and it came out. Don't get it too hot though as this can crack the casing, Don't weld a bolt to it to pull it out as this can crack the casing too.

The mini-mania videos are sort of useful but some of there techniques of doing things are a bit rubbish, like on the third video fitting the bearing...


Agreed, whilst the videos are ok with regards to the process, he doesn’t treat the gearbox with any compassion, far to rough smacking in the bearings and doesn’t use a soft hammer!!

#11 Rorf

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Posted 16 January 2020 - 05:31 AM

Haynes manual has a section on gearbox stripping - that is a new one as all the Haynes manuals I have seen that section has been omitted as it was deemed too complex for the DIY dude.

 

These are very easy boxes to work on and tons of info on the net on how to do it. Simple Google search :lol:



#12 super6al

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Posted 16 January 2020 - 05:04 PM

Hi Rorf

The earlier Haynes manual ('69~91) has a detailed section on the gearbox strip down. The later Haynes are little better than service manuals, however as you said most of the detail can be found on the net. I think (could be wrong) but Guessworks did a detailed strip down & rebuild somewhere on here?

Alan



#13 floormanager

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Posted 16 January 2020 - 07:33 PM

Yup the early haynes are useful, one of these

https://www.ebay.co....WoAAOSw8bteGg5V

 

or

 

https://www.ebay.co....rgAAOSwhbZd9o9R

Not my sales

With the online videos the gearbox becomes quite easy.



#14 nicklouse

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Posted 16 January 2020 - 08:31 PM



Hi Rorf

The earlier Haynes manual ('69~91) has a detailed section on the gearbox strip down. The later Haynes are little better than service manuals, however as you said most of the detail can be found on the net. I think (could be wrong) but Guessworks did a detailed strip down & rebuild somewhere on here?

Alan


all mine do here is page from the 69-94 one. it is the only last service one that is crap hence the comment Haynes workshop manuals.

 

oZbq8f1.jpg

xGyjgRn.jpg


 


 



#15 Rorf

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Posted 17 January 2020 - 05:18 AM

OK I see, must be the copied pirated manuals available on the net which have all omitted the gearbox and clutch sections.

 

The manual I have is the Autodata - Austin Mini 62-89 and has an excellent section on gearbox tear down and rebuild.  Strangely the clutch section does not give detail on how to set the clutch up properly.






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