20 replies to this topic

[smileytony]

Hi all,

While I'm waiting for my engine kit delivery I thought I'd set about rebuilding a gearbox I have lying around.

I know the casing etc is in good condition because it was in a runner, but one of the bearings is knackered so can't reach 4th (I think this was the problem anyway).

So I was looking at the Minispares or Minisport rebuild kits: MiniSpares or MiniSport (I think the latter includes differential rebuild parts whereas the former doesn't although there is an alternative kit that does).

The car is going to be a 1380 road car. I'm not a racer although like most people....need I say more!

I'm also going to install a central oil pickup.

I'm going to check for any serious wear and replace where needed, but what I want to ask is whether it's worth uprating the differential at the same time. I was looking at this MiniSpares which I know Guessworks recommends, or this MiniSport.

Is it worth me spending the extra dosh? Is there anything else I should/you'd recommend replacing?

Also what's the different between those two diffs? One has the splines for the pot joints pictured whereas the other hasn't?

Cheers

[Nightrain]

The Minisport diff, started life as the 'Mini Torque Diff' this was the first twin crosspin diff on the market. I got one of these when they first came out supplied by Mini-it's. Managing to break it only after about 3 months, one of the cross pins came out, taking the out both the diff housing and the gearbox casing.
Mini-it's were fantastic and after a lot of hassle from the Manufactures managed to get me a replacement a few months later. Which turned out to be the mk2 version, but seeing as it was the start of the summer and over the years of messing with minis I've bust several standard diffs plus Minispares had started to produce there own twincross pin diff. And after examining this was what I went for.
Later the diff was purchased lock stock and barrel by minisport, must say I don't think the Mk2 version would fail in the same way as it now has allen screws preventing the pin moving.
If you examine the 2 diffs side by side, the Minispares diff designed by Neil Booth is a much better proposition, the pins been locked together by there offset design so they wont/can't move.

[smileytony]

Thanks mate that's really useful!

With regards to the different crown wheels available, how do I work out what's best for road use. Is it worth changing what I have? Also how do the different wheels make a difference?


Thanks!

[Nightrain]

This is always a difficult question to answer there are so many different ideas, that people have of how their car should perform. Plus everyone drives there car in a different way. You need to be honest about what you use the car for and what you want from the car. Wheel sizes effectively alter your final drive ratio, a 3.44 on tens is a lot lower geared than a 3.44 with thirteens.
To give you a general idea, make a note of the rev's you use on a normal journey, particularly not the speeds you achieve in each gear. Now find a final drive calculator pretty sure there is one on here. Now enter your details which will give you what speed you do per thousand rpms then compare it to what you've got now.
The other thing to consider is whether or not you run a close ratio box, this is probably the most important aspect with a standard box go to low with your final drive and first and second become useless to high a final drive with a normal box and you'll drop out of the powerband changing from second to third.
On this last point your cam will play a part, so what is the full spec of your present engine and box ?

Edited by Nightrain, 20 February 2009 - 11:41 AM.

[smileytony]

Hi mate,

Well I'm looking to fit it out with 13"s (all the modifications to arches and rack etc have been made for this). I don't have a built engine for it or another similar specced car that I can drive to give me my 'normal' RPMs on an average drive.

This will be delivered to me in about 4wks: Engine kit

I'm just about to rebuild the gearbox - it's standard from a 1300 metro. I was looking to use the overhault kit and central pickup.

I wasn't looking to go for a close ratio box as I'm looking for this to be a normal comfy day to day drive, and not a speed demon!

So if I'm looking for the Minispares diff, what crown wheel would you recommend and why?


Thank you!

[Nightrain]

Hhmmm Had a Minisport 1380 many moons ago, personally don't think I'd go down that route again there cheap for a reason. At the time the CA4 was a copy of the 731/800 cam, or at least that was what I was told. They may have improved, but you need to be asking questions. For instance the pistons where quarter of a inch down the bores, the block wasn't offset bored. It was a serious disappointment after the standard MG metro engine it replaced.
Now I believe the CA4 is a copy of the 544/286 and with a cam like this to get the best from it you really want a close ratio box. Im not talking straight cut, just the standard A series helical S/GT gearset. Tight'ish corners that should be taken in second will be a pain, use third and your out of the powerband exiting the corner and second is just too low to be of any use. Diff wise I'd recommend no higher than a 3.44 but if you prefer A&B roads to motorways a 3.6.

[smileytony]

Hello mate,

Well that's always painful to hear after you've committed to buying something! It's tough with the number of different pieces of advice people give - some people have said this kit will be fine.

My main problem is (I posted this in another post) that if I get all the machining work done locally/even a little way away, it works out a LOT more expensive than buying in kit form like this. I enquired at a number of engineering shops and it just wasn't doable within my budget.

With regards to the close ratio gears, are you talking this Option 1 or this Option 2 ?

Either way both are out of stock at the mo. What's the difference between these? Could you link to the recommended one?


Thanks!

[smileytony]

The other option would be for be to retain existing diff (if usable), fit 3.44 crownwheel to it (and purchase relevant pinion), and fit close ration gears. However with regards to the differential from Minispares does it come with the crownwheel or does that need purchasing separately?

I'm just trying to keep the costs down really!

[Guess-Works.com]

X-pins are supplied without the crownwheel and pinion, the only reason the minisport one comes with the output shaft fitted is ( as you may have read ) they are a complete **** to put together.

[smileytony]

Hi mate, I did read your article about the minisport one and it's made me definitely NOT want to buy it!

It's interesting because I'm pretty much following the Ultimate Mini Builder DVD for my first engine/transmission rebuild. In the DVD he runs the gearbox as pretty much standard.

I'm just trying to get to a stage where I've got the best (whilst being sensible on cost!) gearbox for the engine I'm building....at the moment it's looking expensive:

Minispares diff: £157 Link
Crownwheel: £104 Link
Pinion: £21 Link
Rebuild kit: £160 Link - Looks like this one includes the parts for rebuilding the diff as well which I don't think I'd need
Close ratio gears: £95 Link - not 100% if these are the correct ones.
TOTAL: £536


Quite a lot! To be honest I'm getting to the stage where I'm not quite sure if I can afford this. I might have to just purchase the rebuild kit and rebuild as it!

Edited by smileytony, 24 February 2009 - 11:20 AM.

[Guess-Works.com]

Well you can reduce that cost fairly substantially....

3.44 final drives (cwp's) you can pick up for £40 or less, 2nd hand are just as good a new.

Close ratio gears, you'll not buy new at all... the 1st motion gear ( the input one ) has been unavailable for a number of years now... so again you'll be looking for a 2nd hand set.

The x-pin is worth every penny..

As for the rebuild kit, you'll either need MSG22 or MSG20 depending upon the gearset you actually do get hold of, most of the GT gearsets will be A series and not A+, which means you'll be running a different layshaft and 3rd motion shaft.

Finally, don't disregard the importance of the gearbox in relation to the engine... however much you spend on an engine rebuild, you should consider spending the same amount on the gearbox...

[smileytony]

Thanks mate,

I've just sent you a PM RE parts but I'll post here in reply.

Unfortunately I don't know many people in the mini scene here in London and parts on Ebay seem few and far between. If I could pick up second hand I would be happy with that.

Totally understand the importance of the gearbox, especially when the engine is going to be 'as new'. This is why I am thinking about sticking with the standard gearbox, install the rebuild kit and the x-pin diff, but stick with the standard final drive.

Unfortunately my knowledge of how this would perform in relation to the rest of the engine setup is limited...

Thank you!

[Nightrain]

Never converted the A+ box, looking at the links it's option1, but I believe you need additional parts. As used in the early A+ boxes which had the A series gear set fited. Personally I'd try to find a A series gearbox secondhand and go from there, you'd need the drop gears and bellhousing as well. Which is what I run in mine and had absolutely no problem with it. Can't guessworks sort you out a gearbox ? There is or at least there was last night a 3.44 crownwheel and pinion on ebay.

[smileytony]

Hi mate, I can see this on Ebay, and it's actually not far from me at all.

Is there actually a difference between the A and A+ casing or is it just the gear assembly inside? When you say bellhousing are you referring to the clutch housing?

Thanks mate

Never converted the A+ box, looking at the links it's option1, but I believe you need additional parts. As used in the early A+ boxes which had the A series gear set fited. Personally I'd try to find a A series gearbox secondhand and go from there, you'd need the drop gears and bellhousing as well. Which is what I run in mine and had absolutely no problem with it. Can't guessworks sort you out a gearbox ? There is or at least there was last night a 3.44 crownwheel and pinion on ebay.

[Nightrain]

Yep that'd do, doesn't matter whether it's A or A+ as long as you keep them matched and don't mix them up. You couldn't just bolt that diff in your box as the output shafts are the wrong size if your keeping the pot joints. Changing to the rubber couplings would be a bad idea.

Here the one I saw http://cgi.ebay.co.u...a...A1|240:1318

Edited by Nightrain, 24 February 2009 - 01:24 PM.