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Caving In [5-speed conversion for BN2]

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roscoe

roscoe

Jedi Knight
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For a variety of reasons, not the least of which is that I ain't gettin' any younger and I'm not sure how much longer I can " do it all myself" in terms of the bigger jobs, I have made the plunge to put a Toyota 5 speed in my BN2. I've had a few gearbox issues and although I can likley fix them, the long term prognosis is that parts are hard to get. By parts, I mean wrists, shoulders and back parts that I unfortunately can't fix myself. Also, I've been trying to get my wife to drive since I put it on the road. She is 5 foot 1 and has a hard time being comfortable with the mechanical clutch. Having the hydraulics and not having to twiddle the OD might make it more attractive for her. If I create a monster and she starts to think of it as "her car", well that's OK too.

Before anyone asks, I'm going to keep the original gearbox and OD and leave the bits in the engine bay and the dash switch for the person who gets the lot when I leave this mortal coil. Maybe I'll really miss flipping the OD on and off.

I have managed to find a very nice W58 gearbox and have the Smitty/Delaney kit on the way. As Pete Delaney recommended, I am going to put in a BJ8 diaphram clutch and lighten the flywheel a bit. I know it isn't rocket surgery to do the latter, but in a way it is, in that the physics of what is being done are beyond my intuitive abilities. So, I will ask the forum to suggest by how much to lighten said flywheel? I do not rally or race and my enginge almost never sees more than 3200 rpm. Yeah, I know I'm missing some big fun.

As with all of my mechanical endeavors I strive to do no harm and I know the flywheel is on there for a good reason but I have no idea if the original weight was specifically designed or someone just said " mate, don't forget to put a heavy flywheel on there". I'll have it balanced, with the new clutch if possible and I know that ideally you balance the rotating components, including the crank, slap a real balancer on the front in place of the rubber band and so on. Not going to go that far and I have previously installed a rear crank seal kit. As always, thanks for your input.

Jon
 
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Re: Caving in

Jon, to satisfy your desire to use the OD switch, occasionally filp it when you shift in/out fifth gear!
 
Re: Caving in

When I moved my OD switch to the shift knob, I put the headlight dip switch in its place and made a dead pedal for my left foot when not using the clutch.
 
Re: Caving in

Thanks Steve. I have read Michael's article and it is a very good piece. I'll wait and see how the kit goes together but I'll contact Dave Dreamer as I'm all in favor of making things out of aluminum angle. With all the scrap I have I won't be surprised if I have something suitable that bolts up.

Yes, it'll be hard to not blip the throttle in 3rd gear slowing for a stop, might as well flip the switch too. I was also trying to decide what sort of cool thing I could wire to that switch. Perhaps a nitrous oxide injection system or some wheel well LEDs. I used to work for a guy who was pretty much of an unpleasant sort. He asked me to install an a switch in his RX7 that would allow him to turn on his back up lights to make people who were tailgating him back off. Kind of a nasty trick and likley unsafe at night. Oh, wait, no back up lights....
 
Re: Caving in

I like the dip switch idea. I do have to say that having one car with the foot switch takes me back to when everyone had a foot switch. I have good memories of that place.
 
Re: Caving in

pictures courtesy Dave Deamer, who just installed the 5-speed on his BN1.
Stock bracket:

screenshot.2271.jpg
screenshot.2272.jpg


Dave's bracket under construction:

screenshot.2277.jpg
screenshot.2276.jpg
 
Steve, thanks for posting those. I'm sure it will make sense when I have the kit in front of me.
 
Though the present mis/malalignment of the clutch linkage in my car's setup has never given a moment's pause since first installation I will certainly opt for Deamer's upgrade if for no other reason than it looks so nice.

Jon, I cannot tell you how much to lighten the flywheel but you are on the right track with all of your proposed changes. While you're at it think about either putting in a remote hose or create a small access door in the vertical panel to make clutch bleeding easier. I replaced the OD switch with a large red light tied to a low oil pressure switch. And start sticking your foot in it--there is a whole world of performance and excitement above 4K rpm's.
 
The answer to how light to go with your flywheel is: lighten it as much as you can. The stock flywheels for the 6 cylinder cars vary slightly between 28 and 29 pounds. Don't know the stock weight of the 100 flywheels are but they are also too heavy. The trick to lightening as much as possible is in addition to shaving material off the back side but to also scallop out material on the face, or front side, around and to the inside of the circle of the pressure plate mounting bolts. Again, with a 6 cylinder flywheel, you would be lucky to shave off seven pounds and that is still a heavy flywheel. A lightened flywheel will feel like you have 10 more horsepower. You will love it!
 
Thanks so much for the information. I'll report back but it will be a while. I might wait until rainy season to do the work as right now my gearbox is pretty happy.
 
One more question ( for now). The 100 flywheel has two dowel pins that are 180 degrees apart. The BJ8 clutch housing is a 3 dowl pin assembly and I assume the pins are 120 degrees apart. So I'm assuming I will have to drill 3 new holes or at least two holes using one of the original ones, in the flywheel. Can anyone tell me if this is correct? Are the dowel pins on the BJ8 flywheel evenly spaced? Are the dowel pins threaded or are they a press fit?
 
roscoe said:
Thanks so much for the information. I'll report back but it will be a while. I might wait until rainy season to do the work as right now my gearbox is pretty happy.
Click to expand...

Jon -
Dave Deamer had mentioned he had a Jule frame on his BN1 - it occurs that maybe the mis-alignment of the MC mounting bracket is due to a difference from the stock frame.

At some point it would be helpful if you could verify this one way or another.

Re: the flywheel - suggest speaking with British Car Specialists and see if they could sell you a used BJ8 flywheel and possibly lighten it.
 
I had my 100 flywheel trimmed a bit, as I recall the motor was first used in trucks or vans, so starting under load was more important than acceleration.

The flywheel has a big ring protruding out the back, this can all come off, I had that and a little more taken off my car. I think it went from 30 some pounds to a little over 20. No drivability issues at all, big torque of the Healey made for smooth starts even with the higher gear of the BN1 3 speed. I can't really say what it did for performance since I rebuilt the very tired motor to higher spec at the same time.
 
Martin Jule probably found something that was tweaked on every big Healey ever built and said, " I can make that right". I will give a full report when the job is done.

Thanks for the flywheel info. I'll probably decide when I see what it weighs and consult with the engine shop I'm going to have do it. I'll have to change my signature to "Do it mostly yourself, you'll be glad you hired an expert when you need one".
 
Regarding flywheels. The standard 6 cylinder is about 28 lbs, the DWR steel replacement I installed weighs 13 lbs and is still perfectly driveable on the road and idles without any problem. You can easily take off 10 lbs, removing weight closest to the perimeter will have the biggest effect.
 
Mike Salter, with considerable 4-cyl racing experience, may have an opinion about how light a flywheel to go on the un-counterbalanced and breakable 100 crank. it's not the same thing as dealing with the 6-cyl cars.
 
Re: Caving in

John, I did the same thing ... pic enclosed.... Jags had a nice addition for that.

IMG_5921.jpg
 
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