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4 Speed Tranmission in a BN-1

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T

TodE

Jedi Hopeful
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I have replaced the 3 speed transmission with a 4 speed transmission. I am getting ready to put the transmission in. I have the new cross member welded in place.

My question is with the new mounts I also purchased the "Rebound Rubber" (Moss number 021-345). I am assuming that this gets bolted to the transmission itself? Or is this not used with the 4 speed?

If someone could post a few good pictures of this and the mounts it would be most helpful.

Thank you,
Tod
 
I put a 4-speed in my '53 BN1 many years ago. I remember cutting out the cross brace & drill and taping holes for the 4sp mounts. Not sure what "rebound rubber" you're referring to.As I remember(maybe), the 3sp had round donut style. cheers Geno
 
If i recall the BN 1 had the Austin A 90 transmission in it and it was a 4 speed gear box but the factory decided to block off the 1 st gear because it was too low a gear for the healey 100. The second gear on the A 90 tranny was then used as the first gear of the healey 100. is it possible to make a BN 1 tranny into a 4 speed tranny by taking the plate that blocked the first gear off provided the effort was worth it because 1 st gear was so doggy and it was not meant for speed but power.?
 
I recall some people, on this forum I believe, did what you're asking about and determined that real first gear was too low and not worth the effort.
 
A friend of mine did that on his car back in the '80s. The engine was pretty built up so all it did was light up the rear tires if you used that first gear with any vigor. I remember him saying it would have been more worthwhile if you had a taller than stock rear end ratio.
 
Most of the BN1's I know including my own have the first gear block removed. I don't use the first gear often, but it is great for situations where you are crawling slowly in traffic, especially when pointed uphill. The stump-puller first gear is great for that, with the engine idling the car will mope along about 1 mph smoothly. The higher second gear is so high you either have to slip the clutch or constantly keep clutching and de-clutching to keep the car from moving too fast.

The first gear is a bit too low for much other use. And I always heard the first gear was blocked out to prevent damage to the non-hypoid rear axle. Too much torque for it if you accelerate hard in that first gear.

Bill S, NM
 
"Rebound rubber" Are you referring to the steady bolt assembly that keeps the engine/trans from moving forward under braking and causing the fan to hit the radiator. If so, you should install it. Not fully shown here is the bushing and bolt that attaches to a large round side-to-side hole in the bottom of the trans.
IMG_0733.jpg
 
Tim, if that's your car you're missing the two rubber bushings on either side of the 'bolt' attached to the chassis crossmember (they go under the large flatwashers).

I recommend the aftermarket polyurethane bushings for this; the stock rubber ones get oil-soaked and dissolve fairly quickly.
 
Thanks Bob, that was the before pic. I have since replaced all the bushings and reinstalled correctly. And yes I used poly as the old rubber ones did dissolve from the oil leaking from trans. I also replaced the trans mounts, one of which had also dissolve from oil.
 
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