13 replies to this topic

[fikus01]

what are the standard ratios for mini gearboxes? 4 synchro rod change, i know there were diffrent types of 'box for this type gt ratio, cooper, turbo, jsut would like a list of what had what ratio. i found guesworks calculator which tells you already what speed you'll be doing in each gear but it wont give the actual ratios!

i just want them for referance material as i have several gearboxes available to me that i have collected over the years and id like to be able to count the teeth and find out what gearsets im running!

[Guess-Works.com]

There are loads...

**** 3 Synchro Boxes ****
3.627 2.172 1.412 1.000 MKI Mini Pre '64 (Magic Wand)
3.520 2.210 1.430 1.000 MKI/II Mini Post '64 (Magic Wand)
3.200 1.916 1.357 1.000 MkI/II Cooper & MkI/II/III Cooper 'S'
2.573 1.722 1.255 1.000 MkI/II/III Cooper 'S' (Close Ratio / Straight Cut )

**** 4 Synchro Boxes ****
3.330 2.094 1.353 1.000 MkIII Cooper 'S' & 1275 GT (Close Ratio)
3.525 2.218 1.433 1.000 MKIII/IV Mini & Metro (pre A+ <'84)
3.647 2.185 1.425 1.000 MKV/VI/VII Mini, ERA Turbo & Metro (A+ >'84)
4.004 2.307 1.435 1.000 Metro 1.0 HLE

**** Aftermarket gear sets ****
2.583 1.711 1.250 1.000 Minispares (Clubman ratios CR/SC) C-STN39
2.544 1.731 1.258 1.000 Minispares (Abingdon ST ratios CR/SC) C-STN77
2.313 1.567 1.187 1.000 Minispares (Metro Challenge CR/SC) nla?
2.544 1.731 1.258 1.000 Minisport (Abingdon ST ratios CR/SC) GRBMS4014
2.544 1.731 1.258 1.000 TRAN-X (Abingdon ST ratios CR/SC)
2.583 1.711 1.250 1.000 TRAN-X (Clubman ratios CR/SC)

to work out the gear ratio of set follow the formula

Number of teeth on the wanted gear, divided by the corresponding number of teeth on the laygear, multiply by the number of teeth on the largest gear on the laygear, divided by the number of teeth on the first motion (4th gear)

[Sprocket]

And to throw the spanner in the works the MPi gearbox used a different second gear ratio

[icklemini]

indeed, the MPis do have a different ratio setup. though, confusingly, this doesnt seem to exist on every single mpi (have done a fair few mpi boxes and its not the case on every one thats for sure)
tis not just 2nd gear thats different, the ratios work out as:
1st - 3.44
2nd - 2.06
3rd - 1.35
4th - 1

ttfn,
Dave

[Sprocket]

Ok then, will the 26 *edit* 25 tooth MPi second gear work with a common garden A+ lay gear? Now that is a question id like answered, as its an easy step to a close ratio box if it will. Mini spares are selling them new.

Edited by Mini Sprocket, 23 April 2007 - 10:35 PM.

[benpopham]

iv got a 3.44 final drive in my box... what are the advantages of this?

[Sprocket]

LOL

Thats another subject again, Best try the search on that one as its been asked a few times. Quick response is, generaly accepted as the Final drive to use to get the best of acceleration and crusing speeds in one

Edited by Mini Sprocket, 23 April 2007 - 09:43 PM.

[benpopham]

oh awesome.. all is good then

[icklemini]

Ok then, will the 26 tooth MPi second gear work with a common garden A+ lay gear?

hmmm - no idea, not tried it so wouldnt like to comment...

give it a go - would imagine a careful bit of comparison and building up would soon work out if its a goer or not...
am thinking it probably wouldnt though, as am sure the teeth angles will be different.... :s


Sory dude
lol edited the wrong post, undone what i did.

Edited by Mini Sprocket, 23 April 2007 - 10:32 PM.

[Sprocket]

Ok then, will the 26 tooth MPi second gear work with a common garden A+ lay gear?

hmmm - no idea, not tried it so wouldnt like to comment...

give it a go - would imagine a careful bit of comparison and building up would soon work out if its a goer or not...
am thinking it probably wouldnt though, as am sure the teeth angles will be different.... :s

I'll give it a go. I'll tag it on the end of the next order, should be here by next week. Keep you posted

OOPSIE, its a 25tooth, doh! not the 26, thats a standard one, lol

Edited by Mini Sprocket, 23 April 2007 - 10:33 PM.

[Dan]

confusingly, this doesnt seem to exist on every single mpi

Weren't loads of MPi boxes changed under warranty because of poor quality lay gears failing or something like that? Maybe the warranty replacements were standard Unipart boxes, I can't imagine Unipart keeping track of a detail change like that when they were making so many other supply mistakes!

[Guess-Works.com]

I too have heard of this said difference... not yet seen one tho' n a box...

[Rob7620]

If anyone stumbles across this thread and wonders like me if you can use the mpi second gear with a standard layshaft.
Unfortunately not was the answer I found ?‍♂️

[Spider]

If anyone stumbles across this thread and wonders like me if you can use the mpi second gear with a standard layshaft.
Unfortunately not was the answer I found ‍♂

 

The original thread here was started before I joined up here and yes, I found this quite a few years back.

 

You can only fit factory gear sets as the sets that they were fitted in originally. They don't mix and match in terms of trying to make different individual ratios.