Gearbox Rebuild
Turbo Mini Forums

So after killing my standard Spi box on a trackday, I clearly need a new one. I want to have something to fit ready when in take the bottom end off, but can't afford the £1300 for the MED setup I really want at the moment. Hence a move to plan B; buy a second hand standard box, rebuild and get back on the road while reconsidering options for an SC box. By this I mean make/buy which will depend on my ability to do this rebuild.

So, got a second hand A+ box tonight, allegedly off an 1275 A-Series of some sort. It's pretty grubby, but to my untrained eye, pretty salvageable. Plan is to strip down, get up close, and see what I can make of it.

Gears move sweetly enough, despite the dirt and grime, and there is no obvious bearing wear. First concern though for me is the slight indent to many of the centres of the teeth in all gears on both the main and layshaft.

So, pics below to share and would welcome any opinions. I'll keep this thread updated with this side project.

My build thread: http://www.turbominis.co.uk/forums/index.php?p=vt&tid=440970

Looking at the clubman gear set on minispares, that scoring down the middle of the gears is normal isn't it? Don't you just love a newbie!

My build thread: http://www.turbominis.co.uk/forums/index.php?p=vt&tid=440970

fully recommend the ms clubman gear kit, alot of us have been running them for years and more than enough are pushing 200+ bhp through them

the 'scoring' is from the factory i think it indicates something to do with gear type

box looks dirty as hell, you want to get that ALL out or the engine will pay,
main bits you want to check imo
first motion shaft bearing, main double roller and the 2 diff output bearings

Yes i moved to the darkside

Instagram @jdm_brett

Rediculously long time since my last post. Bit of an update today though.

Managed to purchase a Mini Spares Clubman s/c gear set and drops during the Minispares January sale and also a bunch of other stuff, including KAD Quickshift, complete gearbox refurb kit and x pin diff.

Have stripped down and cleaned the old box and Started the rebuild. The main shaft and lay gear are complete and now Ready for the differential build. I took a 3.44 out of the refurb box but think I have a 3.1 in the current one which I would prefer for some on-road compromise and also for those larger circuits.

Engine is out of the frog, no real problems there which was good. Need to replace the engine mounts and a the suspension arm ball joint covers. Flywheel is stuck solid now though so being patient and leaving some tension on for a few days before anything more drastic. I've already snapped the end off a breaker bar

Edited by daveg79 on 30th May, 2013.

My build thread: http://www.turbominis.co.uk/forums/index.php?p=vt&tid=440970

Edited by daveg79 on 16th Jun, 2013.

My build thread: http://www.turbominis.co.uk/forums/index.php?p=vt&tid=440970

More teeth than a Bee Gee!

If that flywheel wont move get some heat and a big hammer on it...

Hammer already done. Bit worried about heat and damaging the crank? Think it's rusted on :(

My build thread: http://www.turbominis.co.uk/forums/index.php?p=vt&tid=440970

i wish I had pushed to boat out and gone for the straight cut gearset...

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

Nah, just heat the shit out of the flywheel to expand it a little, then crank up the puller, leave for 5 minutes if it doesn't come off, then more heat and you'll find the puller will keep going as the flywheel moves slightly. I've used an impact gun on stubborn flywheels before, the shock helps to free it off.

Deffo took the key way washer out didn't you?

If something is worth doing, it's worth doing half of.

My build thread: http://www.turbominis.co.uk/forums/index.php?p=vt&tid=440970

The bolt is too short cos you have the puller assembled back to front. Flat side should face outwards.

If something is worth doing, it's worth doing half of.

That's the right way round for those pullers john, the bolt it's looks really short compared to the ones I've used. The minispares puller is far more up to the job imho.

I always use them the other way around as when I've done it the way pictured the centre bolt was too short like Dave is experiencing. I also use decent thick washers as the ones that come with them are shonky!

Edited by John on 27th May, 2013.

If something is worth doing, it's worth doing half of.

Yeah I've had them pull through before :/
If you get the chance to get a minispares one, get one. You'll never look back!

As it was rather late tonight decided to remove the differential and speedo housing rather than persist with the fly wheel. Good news is that the crown wheel looks in good condition and it and the pinion do give the 3.1 ratio I was after. Did find laygear teeth in the bottom of the case though, as suspected. no fine fragments which was good so hopefully no significant uptake into the engine. Wondering how I'm going to remove the pinion without an intact laygear though as won't be able to lock it, unless i lock on other gears? Hmm.....

Will probably build up x pin diff tomorrow night.

My build thread: http://www.turbominis.co.uk/forums/index.php?p=vt&tid=440970

Tonight's efforts. Thinking I may have to invest in new diff bearings though as the old ones didn't come off too cleanly...

My build thread: http://www.turbominis.co.uk/forums/index.php?p=vt&tid=440970

So bought the Minispares puller and the flywheel came off a treat. Good tip! Last time I buy shoddy second hand tools. You can see in the pic below the the teeth on the input gears on the first motion and lay shaft are totally stripped. I collected a bunch of teeth unsurprisingly!

Rest of the box has now gone together a treat. I also found a replacement speedo gear to make sure the match is correct for the latest setup. Plan to drill and tap the speedo housing to add an oil temp sensor as others have done.

Also purchased a MED ST1 Ultralite clutch assembly, as was taken by the acceleratin benefit such and upgrade gives and I don't have much weight left to shed. Sadly I had to disassemble this as I forgot to add the clutch hosing seal guard (optional I know) and the flywheel washer was stuck solid and I had to disconnect the pressure plate to get access to remove. In the process the bolt sheared in the pressure plate! Non too pleased. Have shipped back to MED for repair.

Spending the time cleaning up the engine now prior to replacing the engine. Next post will hopefully be a test drive. Few pics below.

My build thread: http://www.turbominis.co.uk/forums/index.php?p=vt&tid=440970

State of input gears...


Sheared MED Pressure plate bolt.

My build thread: http://www.turbominis.co.uk/forums/index.php?p=vt&tid=440970

Complete, and all reassembled, cleaned and painted. Hoping to drop it in and test on Friday. New Flywheel and oil temp in speedo as planned.

Shot of the reassembled unit.



Close up of the knackered input gears. Not a bad job!

Edited by daveg79 on 26th Jun, 2013.

My build thread: http://www.turbominis.co.uk/forums/index.php?p=vt&tid=440970

So it's all back together, and with all the other electrical work I've done, I was please it fired up first time. However, can't help but think that the slight metallic noise coming from around the clutch casing isn't quite right. I've replaced the clutch and flywheel with a lightened MED ST1 assembly, added minispares straight cut drops and a new oil pump. Oil pressure is fine. I haven't attempted to drive it yet. Wasn't sure if the noise was just the nature of the new parts.

Any thoughts? Sorry, difficult to tell from the video.

http://youtu.be/d6DHi0xscpk

My build thread: http://www.turbominis.co.uk/forums/index.php?p=vt&tid=440970

That's just straight cut drops.

Good work on building your own box. It will be very satisfying when you get it out on the road.

Sounds like drops, should go quiet when you dip the clutch.

My build thread: http://www.turbominis.co.uk/forums/index.php?p=vt&tid=454802

Flickr: http://www.flickr.com/photos/85313398@N02/

Had to bleed and adjust the brakes today before the test drive, but good news is I have all gears and it appears to have worked! Only minor things are I have a slight oil leak on the left hand side gearbox to block seal and also I think the clutch needs bleeding again as it isn't quite disengaging enough for a smooth change.

Most significant thing though - s/c gears a flippin noisy! Wow! Awesome! :)

My build thread: http://www.turbominis.co.uk/forums/index.php?p=vt&tid=440970