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Bn1 four speed?

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Daniel6364

Freshman Member
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Hi all, happy thanksgiving! In my BN1 that I'm currently restoring I've discovered that it has four forward speeds. Although I've yet to drive it on the road I'd like to know the possible reasoning for this and help identifying the current transmission. This is a project my father brought home in pieces about 26 years ago and about 2 years before I was born. He owns quite a few british cars-bj8, sprite, tr3, tr250, an mga coupe and one or two that I'm forgetting. Any help would be appreciated. Also he has never driven the Bn1
 
The correct "3-speed" xmsn for a BN1 was actually a 4-speed with 1st gear blanked off; that accounts for the goofy shift pattern.

People have tried "unblocking" 1st gear, by simply removing a plate where the selector rod is (myself included) only to discover that it really is useless! You'll hit the poor engines redline after about an eight foot (8') sprint. It just is not worth the effort, unless maybe you also swapped in something like a 2.73:1 final drive ratio.

On the otherhand, your car may be fitted with a BN2 trans. The BN2 "side-shifter trans for the Big Four cylinder engine looks just like this one for my BN6 6-cylinder engine, but with a different bellhousing, to accomodate the mechanical (versus hydraulic) clutch actuation.

IMG_7629.jpg


IMG_7633.jpg


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Randy's two scenarios are both correct and it would be easy to determine whether the transmission is a 3-speed with the starting gear unblocked or a BN2 four speed by simply determining what is the shift pattern. The original BN1 transmissions had the lower gears on the right side, with in this casse 1st upper right, 2nd lower right, 3rd upper left and 4th lower left, whereas BN2 transmissions would have a conventional H pattern with 1st upper left, etc. etc.
 
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