9 replies to this topic

[adam c]

Has anybody ever rebuilt a gearbox and is it a diy job?? I have the early type of gearchange so the box's are much more expensive ready done. Minispares do a kit for 120 quid odd would this be suitable??;

THIS IS A FULL SET OF BALL BEARING.BAULK RINGS GASKETS AND SEALS FOR REBUILDING YOUR GEARBOX PROPERLY INCLUDING DIFFPIN AND COMPONENTS

Presume it needs a full rebuild?? - its makes a noise in every gear and in neutral when the clutch is engaged (i.e. pedal up)

Also think i might have a go at the engine myself. Rich has explained many a time the process (thanks :grin: ) so I won't ask again but how will i know if i need a rebore as this would require new pistons and more expence (yes?). Also when would i need my crank regrinding - how will i know if it is OK??

Oh and by the way the engine and box has done 91k...

Thanks in advance guys....

[dklawson]

What are you calling "early"?

The earliest gearboxes were 3-synchro boxes with bronze baulk rings. In the early 1960s this design was changed to a 3-synchro design with steel/iron synchros. Of this type there were "A" and "B" gearsets. Parts for all three of these are getting harder to find and are quite expensive. I don't believe MiniSpares has kits for these boxes. These early gearboxes were finally replaced with a 4-synchro design sometime in the mid- to late-1960s. Parts are a little more available for these. Finally the rod-change gearbox arrived on the scene for which parts are much more readily available. Make sure you buy the right parts for whichever type you have.

As for DIY... yes, it can be done but you need some big socket wrenches, a strong work bench, good measuring tools, and a clean place to work. I would say the hardest step is getting the final drive pinion off the mainshaft. This is torqued to 150 ft-lb [200 N-m] and getting it loose involves a few tricks.

What you may wish to do is locate a later gearbox, rebuild it at your leisure, then swap it out for the one that is currently on your car. That way you can take your time and you can select a core for rebuild for which there are parts.

[adam c]

By early i meant the 4 synchro with the early type of gearchange (i.e. the massive tunnel thing from the gearbox to under the gearstick). I have a later type of gearbox but want to try to keep the car original. Are there any other advantages of the later box? By measuring tools do we just mean like feeler gauges and stuff??
Should be able to cope with the nuts, am used to working on tractors and wagons and stuff...
Cheers dklawson :grin:

[dklawson]

It sounds like you have a 4-synchro, remote shift box. More parts are available for it than my 3-synchro box but you still may have to do some searching. Between Mini Spares, Mini Sport, and a couple of other sources I found in the U.K. you should be able to find all that you need either good-used or NOS.

Feeler gauges, big sockets, dial calipers, perhaps some tin snips for making shims, and a dial indicator if you have one are the tools I would expect to use. There are a number of places to check endfloats and clearances. Some places you can use feeler gauges others it's better to use a dial indicator.

One of the seemingly simple but awkward tasks inside the gearbox is assembling the shift hubs over the gears. They have spring loaded detent balls in them which love to shoot around the inside of garages. You can probably improvise assembly tools using hose (Jubilee?) clamps or similar but count on loosing a couple of the balls. There is some additional information on this at Mini Portal (http://www.miniportal.ca)

[adam c]

Thanks again mate :grin:
Anyone else got any suggestions or ideas??

[siggy]

Adam, to be honest if you have no experience of rebuilding gearboxs, then leave it to someone who does, its expensive if you get it wrong.

Siggy

[Tucker SP]

Cant help with the gerabox (sorry)

dklawson mate, you seem to have plenty of knowledge, where did you get it all from??

Cheers
Tucker

[bluebottle]

i've known friends rebuild gearboxs' ok in their garage, and they worked fine for years. not sure i'd have a go myself, but if you are feeling brave ...go for it!

the haynes book and the proper workshop manuals give you plenty of information on stripping down, inspecting and rebuilding, although i don't know if they tell you everything you need to know.

if you go for it, i'd recommend taking plenty of photos as you go,so you know where bits go back to, and where they came from, and i'd bag the bits up as they come off, so you dont mix them up


good luck!

[dklawson]

Thanks for the compliment Tucker. I started working on British cars about 30 years ago... a 1964 MGB. I've worked on them off and on ever since. I'm the kind of person who will not be told "you can't do that". I had a few mechanics give me that answer when I was a kid and it drove me to do all the repairs myself that I could. Electronics in new cars are beyond me but I love working on older machines of all types.

I agree with Bluebottle about doing transmission repairs. On the surface they can seem intimidating but if you have a service manual, document what you are doing, and work on the parts as sub-assemblies, the gearbox is not any different than any other repair. If you would ever attempt to rebuild your engine yourself, you shouldn't be any more intimidated by a manual gearbox. Careful work and attention to detail will give you quality results. Regardless of whether you do it yourself or pay someone to do it gearbox rebuilding is expensive.

[adam c]

Thanks guys - might leave it for now as have seen an exchange one for £300 and am gonna ask around locally to see if a local company can do it cheaper. I normally find that a friend of friend will do it out of hours for a bit of cash, might be cheaper and easier than doing it myself.
Siggy I see your point but oneday want to be able to have done and be able to do every possible job on a mini and have gotta start somewhere. When I've finished my project and have more space and cash I might get a scrap one and strip it down and put it back together again just for fun!! :grin: