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 Posted: Apr 29, 2020 10:05AM
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Save your money and go for a 3.1 final drive.  My engine has plenty of torque and on 10" tires, is easy to drive around town.  60 MPH = 3400 RPM, a slight drop from 3750 RPM using the 3.44, but noticeable.

 

"To catch one, you need one"....John Cooper

 Posted: Apr 29, 2020 02:51AM
 Edited:  Apr 29, 2020 02:55AM
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It's too bad the 5 speed gearboxes for A-series Minis are oriented to performance applications instead of street. By that I mean the gear ratios are chosen to give an even rpm spread between gears. Good for competition, but limits how tall 5th gear can be. On the current 5-speed boxes, 5th is .882.

Ideally, I'd like to have my cake and eat it too - cracking acceleration in 1st and 2nd gears, and a easy cruising 5th. But if you run a 2.76:1 final drive, 1st and 2nd are neutered because the tall final drive bogs these gears down.

For a 5th gear to match the nice cruising of a 2.76:1 final drive on a 4 speed, you need to run 3.1:1 final drive. But because 1st and 2nd gears of the 5 speed are taller than those of a A+ 4 speed box, running a 3.1:1 FD on a 5 speed gives no real advantage in 1st or 2nd.

Either I'd want a 5 speed with A+ 1st-3rd gears matched to a 3.1 FD, or a 5th gear with a .8 ratio on a 3.4 final drive. It wouldn't be ideal for competition and keeping the engine within a narrow powerband rpm range, but great for the street.

If such a thing could be done, I'd have already bought a 5 speed. But after running the ratios over and over, I just can't see the 5 speed, as they're offered now, actually improving my street driving experience. Especially when considering the cost of same.

DLY
 Posted: Apr 28, 2020 08:15AM
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Give or take twenty years ago I bought several 5 speeds new in the boxes. I was busy building a street, classic mini.
As much as I wanted fit one in my personal car I had the sinking feeling that just like the JKD dog boxes, spares on
going was going to be an issue.

As I have been reading about the 5 speeds currently out there they suggest not using with a turbo. I'm not sure I'd
want one under my autocross engine.

In the mid to late 70s I was an active SCCA Solo 2 A S/P competetor in a 67 Cooper S. I managed a 3rd in NE/Div, 1st
SE/Div and a 5th Nationals. Power by a 1330 Cooper S, 13.3 to 1 CR, SC/CR 4 synchro, open diff with 4.35 CWP. Rolling
on 6X10 Revs with gumball slicks. Weber 45 DCOE and straight exhaust with megaphone.

As for street mini I also like the idea of low RPM producing high MPH. I have been running and building ultra wide ratio
gear sets with 2.76 CWP and two O/D drop gears. Ends up with 69 MPH at 3000 RPM. With 145/10s or 145/12s wheel
spin in first is a issue. I have one in my car and three in customer cars. Engines are built for torque 1000-4500 as
there is a 1000 RPM drop with each up shift. I currently have the parts to assemble another tranny or complete power unit. 

I also have SC/CR 4 synchro, standing start JKD involute dog box NOS with shift forks. A NOS Swift rolling
start dog box set with forks for rod change and lay gear shaft. I also have cross pin diffs, Tranex posi and some
posi CWP sets. If you want something special in a tranny contact me. Steve (CTR)


 Posted: Apr 28, 2020 06:54AM
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I know how to get a 5 speed into a Mini. Of course it's attached to a Honda engine.....

 Posted: Apr 27, 2020 09:54PM
 Edited:  Apr 27, 2020 09:55PM
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I considered a 5-speed in the early stages of my restoration. After reading several posts on different forums including a video from Jamal, I concluded they were a bit wonky. I passed. Perhaps if I heard from folks who were happy w/ their 5-speed I might reconsider. It sure would be sweet cruising at 65 mph @ 3200 rpm.

 

Michael, Santa Barbara, CA

. . . the sled, not the flower

      Poser MotorSports

 Posted: Apr 27, 2020 01:36PM
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CA
A standard diff has 4 tapered gears in a circle, two of which connect to the output shafts. The two other gears (If I recall correctly) are kept in alignment opposite each other with a straight shaft or 'pin'. Under heavy use they wear or break. A cross-pin has 4 ends instead of two, and keeps all four gears properly aligned, providing better transfer of force and a lower likelihood of breakage.
A limited slip diff generally has an arrangement of clutch plates between the output shafts, allowing them to turn at different rates only by slippage.

.

"Hang on a minute lads....I've got a great idea."

 Posted: Apr 27, 2020 01:32PM
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The cross pin diff is not the same as a limited slip.  Take a look at an exploded diagram of the differential and you will notice the standard configuration has 2 spider gears.  The cross pin diff uses a couple of new/different parts so you can have 4 spiders.

As Chuck said there are a few possible 5-speeds but they are seriously expensive. 

Doug L.
 Posted: Apr 27, 2020 11:35AM
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Well I should have just looked myself but thanks.  So what is a X pin differential?  Is that what we would call Limited slip?

If I ever get to run an autox this summer I'll find out if the rear sway bar helps keep the right front tire down.  If so I might just start saving for that 5 spd.

I'm having a 5 spd TREMEC put into my 65 corvette next week so that will spoil me for sure.

 Posted: Apr 27, 2020 09:36AM
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A SEARCH for PARTS here will get you at least three.

 Posted: Apr 27, 2020 09:33AM
 Edited:  Apr 27, 2020 09:33AM
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Yes, MiniSpares sells a 5 speed gearbox, you can spec the diff ratio and whether you want a crosspin diff or a limited slip. I know of a couple of people that have them and really like the extra gear for highway cruising.

 Posted: Apr 27, 2020 08:53AM
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I guess I have to specify that as the newer Bini's probably have them.  
So is there a modification, upgrade, to install a 5 speed in the classic??  I would even consider a limited slip, after I run this new sway bar at an autox.