• Hi Guest!
    If you appreciate British Car Forum and our 25 years of supporting British car enthusiasts with technical and anicdotal information, collected from our thousands of great members, please support us with a low-cost subscription. You can become a supporting member for less than the dues of most car clubs.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

BN1 transmission

Share this page

J

JTSchmid

Freshman Member
Offline
Hi,

I'm in the process of restoring a BN1, although I have the original 3 speed transmission I also have a side shift 4 speed. Would it be best to stay with the 3 or opt for the 4 speed? This car will be a driver, not looking for concourse. Any past experiences will be helpful.

Regards,

Jim
 
If you are not staying strictly concours, I would much prefer the four speed. Some modifications would be required. The major one would be replacing the four speed bell housing & clutch linkage. There are new 4 speed clutch housings available from Denis Welch
https://www.bighealey.co.uk/section.php?id=7&page=3.

I think most folks are just going for a Toyota 5 speed conversion. Not as original but possibly cheaper.
D
 
DR's advice is excellent, as usual.

For me it would be a tough call. Many BN1s have been converted to the BN2's four-speed box, and frankly I don't have a lot of experience with the three-speed, but it is obviously somewhat awkward. The shift pattern is so peculiar that it almost constitutes an anti-theft device!

However, it was what it was, and it is what it is: a vintage car. Do you really want to sacrifice that unique, vintage feature for a later gearbox, perhaps even for a modern five-speed? Good "driveability" is a wonderful thing. So is an original, vintage car complete with all of its unique vintage quirks still intact. There is a school of thought that says if you want a modern car, buy one; don't try to make a vintage car into one.

I'm not condemning the idea of transplanting a four- or five-speed gearbox into your BN1. I'm just offering perhaps a little food for thought about these rare cars and their rare features, and what may be lost by changing them.

Your car, your call.
 
I would put the BN1 gearbox back in because it doesn't require any modifications or extra parts to get it going. Drive it until the box explodes then replace it with the 4 speed. With average luck that will be a long way away and your three speed will serve you well for many many years. Just make sure to keep it full of oil at all times.

I have the three speed in my BN1 and also the same gearbox in my Atlantic and it is a joy to use. In fact, I would argue the synchros on the 3 speed gearbox are better than on the 4 speed, it shifts more smoothly for sure.


Yes, the gear pattern is weird, but you'll get used to it in short order....

Alan
 
Here I am all set to reply to Reid's post, agreeing with him about one of our greatest resources, Dave Russell, and to go on to say that the synchromesh on the BN1 gearbox was of a more antiquated design (certainly more difficult to replace them) when Alan remarks that his 3sp shifts better.

I can only think that the BN2 (or later) Healeys you've driven have had compromised synchro rings, or that your own cars must've lived a fairly easy life.

In any event, it's always left up to the owner to decide what is best for him/her. My own car currently has a non-overdrive MGC gearbox, but my plan is to revert back to the original side-shift/ovd transmission.

Funny how your priorities can change several times when you own a vehicle for over thirty (>30) years :wink:
 
Went back and forth with this question myself and decided to go with the 3 Speed for the following reasons....

-No modifications
-Resell (in case that became an issue)
-Not a commuter car so drivability was not the highest order bit
-Might do a show for fun
-Best way to experience what a 55 BN1 was like - the good the bad and the ugly
-Slightly lighter trans
-The upside down pattern really confuses people


I would suggest you go with what works best for you.

Michael
55 BN1 (currently solving the oil crisis one leak at a time)
 
I think the 3 speed is part of the BN1 character. I have no trouble switching between my BN1 and my BT7 and/or, for that matter, my 6 speed Mini Cooper. The synchros are OK, not great, but I'd say the same about the BT7. I'd probably feel differently about it if the BN1 was my daily driver or if I was going to track it. I should add that I'm older than dirt and enjoy a taste of the "Old Ways". And. in the interest of full disclosure, I should admit that I am restoring a BN1 with a 4 speed.
Marv J
 
By all means change what you will, however keep the original bits, as the next owner may wish to run it in original factory specs, and modify the bolt ons to match the original, not vice versa, as an original classic is worth more than a junkyard bitza,went down the thoughtline as you are doing, came to the conclusion that if I wanted a fast hotrod then buy a AC Cobra 40 lookalike and get my thrills that way, so my BN1 '53 is stock and now worth far more than a modified BN1 with a V8 with all the go gear, (my apologies to the modified healey crew! :smile:)
 
My current car is my first 100 (BN-1). Had numerous BJ-8 and 7's. I love the original tranny in my car It shifts smoothly, quitely and the synchros are a pleasant surprise.The gear ratio is fun ,peppy and enjoyable to shift through. It is better than my 70 E-type! My friends 65 Morgan has a "crashbox" and it is horrible to drive in the city.

I have always been an "original" type of person.....

Good luck on you decision.

Pete
 
I drove my BN1 with the original 3 speed for 8 years, including a rebuild early on in its career. Even after the rebuild, by a very experienced and competent British car mechanic, but certainly not an AH tranny expert, it still leaked and it still had somewhat slow, beatable synchros.

That being said I liked the box--never was fond of non-synchro firsts, despite all the "reputation" the gearbox had, never grenaded or gave any problems.

The reverse pattern is surprisingly easy to get used to, even switching back and forth between it and my modern 5 speed cars.

I personally like the uniqueness and conversation starter factor as well as the originality as well.

They are hard to find parts for.

Not major, but certainly more than minor, but if you do swap to the BN2 tranny you also need to swap out your tranny tunnel and carpet, or at least modify them.
 
It took about two days' work to install the Smitty's conversion and Toyota transmission in my BN1. Adapting a Moss FG tunnel, fabricating a new bulkhead and installing new carpeting took far longer and was more challenging.

About the only thing I miss about the BN1 3-speed is the appearance of the low-profile tunnel with the peculiar molding around the side-shifter.
 
Thanks for all the input. I'm leaning towards keeping the three speed and hopfully will learn to get use to the shift pattern. (senior moments?)

Thanks again.

Jim
 
Another vote that you stick with the BN1 tranny. Enjoy its nearly silent synchronized low gear that's tall enough to take the car well over 25 mph. No need to row a BN1 through the gears in traffic.

Also note: I think the BN1 first gear was blocked out partly because the spiral bevel BN1 rear axle was too weak to handle the load of hard acceleration in first. If you put the BN2 tranny in there you may overload the axle if you like to burn out in first gear.

Finally: when in doubt, why not keep it original? Your Healey is an old collector car, not being prepped for the Monte Carlo rally or Monterey. If it were, I would probably opt for the Smitty conversion rather than a BN2 tranny.
 
I like this thread as it highlights the uniquenes of the BN1 gearbox. It is only difficult to get parts due to the lack of demand. Perhaps this thread will generate some demand.
I have experienced failure of second gear and live in fear of it happening again.
The "cone" type synchro is not as positive as the BN2's "baulk ring" but I think the ratios are spaced more suitably to the torque of the four cylinder motor. Driving in a left hand steer car with the wrong way round pattern would be interesting (we have right hand steer here in Australia). Sort of a complete mirror reverse activity!
Healeyjag's friend's Morgan would have had a "Moss" gearbox, not a crash box, although it would be hard to tell the difference. To me "crash box" refers to a non-synchomesh gearbox. I once had a Mark II Jaguar and a friend asked me to road test another Mark II. My 1966 car had a Jaguar "All synchro" transmission, the car to be tested had the Moss unit. I could barely drive it! Awful!
 
....and furthermore, in response to Healey 100: Why the bottom gear on the Austin transmission was blocked out on the Austin-Healey is a difficult question to answer. It is too low to be of any use with the standard 4.125 axle ratio. The higher ratio 3.6 was listed as an option which would make the BN1's "first" (2nd in the gearbox) very tall indeed.
As to the strength of the spiral bevel, don't forget the 100S has this axle.
 
pan,

I acquired a Hampshire as a donor car last year, came with 16" rims, same as listed on my cert, non O/D box, however I've been told cogs are same ratio, just different angle on teeth. ie replace as a total not individual, I bought it in the hope the brass synchros are interchangeable
 
I have the same transmission... only to move the 'big' girl, they use the actual 1st gear.... you can drive yours knowing there is another gear in there, it just not needed for such a light car!

Be glad you don't have the 'linkage' I do.....

wol2.jpg
 
Hi gblawson,
I am afraid I cannot identify your car! Is it an Austin? The gearchange lever at the left of the seat is interesting. The Austin saloons which used the similar transmission to the 100 all have column shift, operated by cables.

zblu, I also have been advised that it is necessary to use the gear-set from an A70 type trans. I have one but as yet have never had to resort to using it.
 
Back
Top