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TR2/3/3A OD Transmission vs 5 speeed conversion

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Scotsman said:
One source told me j type can be configured to give od in 2nd and that a j-tupe is preferable as parts are much more readily available. Also told that the j-type does not engage as fast. Any comments.....
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I have J-types on both Stags; and I don't like driving them nearly as well as the A-type. There are things that can be done to make the J-type shift faster, but it will never be as fast as the A-type. Both of my J-types shift so slowly that even if I let off the throttle, push the clutch, flip the switch, and release the clutch; the OD still hasn't shifted when I release the clutch unless I consciously wait for it to shift. And the speed at which they shift is tied to driveshaft rpm, so it would shift even slower in 2nd gear. By contrast, the A-type seems to read my mind, it shifts before the lever on the switch is done moving!

The difference is that the A-type carries an accumulator of high pressure oil all the time; while the J-type does not. With the J-type, once the solenoid moves, the OD clutch doesn't move until the pump has made enough strokes to move the dashpot, then lift the pressure and move the operating pistons. And the pump only runs at driveshaft rpm, so that can take awhile. The A-type just dumps oil into the operating pistons as fast as 400 psi will move it.

In fact, I've been trying to talk a friend into trading me a Stag A-type (which is slightly different than a TR A-type) for a J-type, but somehow he isn't very interested :smile:

But there is no doubt that the J-type is simpler, stronger, and easier to service on the car. Two filters instead of just one, and full time pressure lubrication to most of the bushings. The pump, dashpot and solenoid can all be serviced from under the car.
 
charleyf said:
TR3driver said:
"rebuilt OEM fully syncro TR4 transmission" seems clear enough to me ??

Randall it appears to me that the rebuilt TR4 tranny is a third choice.
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Ah, I see your point. Sorry, I took it to be the rebuilt A-type OD. My bad.

My opinion, unless you're talking 100 point concours restoration; a 4 synchro gearbox with OD is just as good as a 3 synchro box with OD. The non-originality of the 4th synchro just about matches the improvement in drivability, in most folks' eyes. (Both are pretty minor.) But YMMV, that's just my opinion (guaranteed to be worth everything it costs).
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charleyf said:
The only thing missing in the above discussion is whether the OD tranny has syncro in first gear. I am guessing from your choices that you do not. To me that lowers the value of the OD tranny a lot.
Charley
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Until the day I die, I'll never understand the almost universal disdain for gearboxes with non-synchro low gears! But maybe it's because I've been around long enough to have learned first on such gearboxes and also gotten reasonably good at double-clutching. ;) To each his/her own, though....
 
Andrew Mace said:
Until the day I die, I'll never understand the almost universal disdain for gearboxes with non-synchro low gears! But maybe it's because I've been around long enough to have learned first on such gearboxes and also gotten reasonably good at double-clutching. ;) To each his/her own, though....
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For me it is a remembering of the first gear going out twice on my first TR3 back in the 1960's. The first time was due to being stuck in snow and having the tranny pop out of first gear unexpectedly. Unfortunately my hand was resting on the gear shift lever which gave it just enough pressure to force the gears back together and chip a few teeth on their way. For me it is just a safety factor. I have no recollection of what caused the second incident.
Charley
 
One nice thing about the 3 synchro boxes was the large loose full complement needles fitted to the countershaft gears. They could sometimes be a pain to install, but hardly ever failed compared to the caged bearings fitted in later TRs. Or maybe the problem was related to more hp and driving style.
Berry
 
I wouldn't say have "disdain" for no synchro on first, but I would much rather have it, while it would probably not be a problem for me to drive a car without it these days, I too have bad memories of Sprites with chipped, whining first gears in my early years of driving, partly because of young and stupid on my part, but also if the car is not well maintained you can get the crunch at a stop from a bad throw out bearing (a graphite friction sort of thing that wore out quickly on early Sprites, not sure what it is on a non-synchro first TR never had one) or dodgy clutch hydraulics. Plus so many of the cars you may want to buy have the whiny first gear because of DPO abuse.

Lastly, even if you can handle the no synchro first, if you ever hand the car over to somebody else to drive...now some people never let anyone else drive their car...but if you do first you have to explain what it means, then you have to hope they understand, and pray they remember...
 
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I am leaning towards the J-type as it will maintain the "originality" of the car, and is easier to service with more readily available parts. Reg the shift speed on the J-type, I read the below about a "competition piston." What are your thoughts and does it compromise the transmission, or drivability factor? I don't plan to race the car but if it is possible to have the J-type shift faster similar to the "A" it will add to the fun factor.


Quote from https://www.ntahc.org/techtips/OVERDRIVE1.html "The competition accumulator piston is the same as the TR4 standard piston. It was used in the works rallye cars so it was dubbed the competition piston. The piston is larger in diameter (1.75 inches) so has about two and one-half times the surface area of the OEM piston. The result is that the push of oil from the accumulator piston reservoir is much greater in volume which causes the operating pistons to engage the O/D instantly instead of slowly engaging the O/D system. The result is a very positive engagement of the O/D like shifting into another gear and quickly releasing the clutch."
 
I believe the comments from the Healey article refers to the A type OD. Healeys used the A type, also the J type doesn't use an accumulator.
Berry
 
Right. The mod described is basically taking an A-type OD from the TR IRS configuration back to the TR solid axle configuration. A J-type has no accumulator and will hence will never shift as fast as an A-type (even an A-type with the small accumulator).
 
Regarding Conversion kits I spoke with Herman at HVDA and learnt that when installing his kits into a TR3 it requires you to switch out the pressure plate for a TR6 one (apparently the TR3 plates are to “thick” or tall and because of that there isn’t enough room for the hydraulic slave cylinder inside the bell housing). In order to mount the TR6 pressure plate to the stock TR3 flywheel new holes need to be located, drilled and tapped due to a different bolt pattern, and then it would have to be rebalanced.

Questions:
1. Has anyone put this kit into a TR3A? Any thoughts, comments, challenges?
2. Do the locating pegs for the TR3 and TR6 pressure plates match up? If not I would think positioning of the new bolt holes will be a challenge.
3. It was suggested I use a TR4A flywheel to eliminate the need to drill new holes and balance. Would this work, and would it then require me to switch out the starter due to the # of teeth in the ring gear being different.

FYI: Just got off the phone with Eaglegate LLC. He is no longer making kits, and is looking for a buyer.
 
Having had to re-drill flywheels in the past (not LBC), the trick was to mount the flywheel on a drum lathe, use a sharpie to line where you think the holes will be, set the plate on it, see if the lines go right through the middle of the plate holes. Adjust as necessary...you'll immediately see if the diameter is too small or too big. Then we set up the cutting arm, and scribed the flywheel.
Remove, and mark the center of each hole through the plate on the scribed line.
Centre punch, and drill. Best bet is a drill press, but if that fails, a helper to observe the bit perpendicular in two lines, and you should be fine.
Our application used special bolts with long unthreaded portions (no a shoulder...just unthreaded shank) that needed to be clearanced drilled.
We did that after drilling the hole to tap, then tapped it out, using the same observer to ensure perpendicular orientation of the tap.
Never a real problem...just make the holes far enough away from the old holes to not have any issues if you're right next to one of them.
Our applications had four (at least) plates and if you didn't have the correct flywheel, that's what you did. If you went with a later plate, holes could be anywhere.
If at least two of the originals line up, bolt it down and just drill the rest.
 
I have not done it myself. But the pressure plate locating pegs are in a different circle, so none of them line up. They will all have to be redrilled, in addition to the holes for the PP retaining bolts. Any decent machine shop should be able to handle this, but it needs to be done accurately.

If you have the early flywheel and starter, then yes you would need to convert to the later starter to use a TR4A flywheel. But the production starter change was in April of 59, so there is some chance you already have the later one. The late TR3A starter will work with the 4A flywheel.

Might be worth asking Herman if the TR3 pressure plate will fit if you forgo the hydraulic TOB and use the original release mechanism. I don't even know if he still offers that option, but he used to. And I suspect (again check with Herman) that going that route would let you use a TR3 clutch. Of course lots of folks seem to like having the hydraulic cylinder buried where you have to pull the gearbox to even adjust it, so you may not want to investigate.
 
One other thing about your choice. The Toyota transmission produces less heat, the shift stalk does not get as hot as the stock Triumph transmission.
Also weighs less.
I have driven both types. I have driven both types. I like the OD , but if no OD, I would take a Toyota.
jerry
 
TR3driver said:
...Of course lots of folks seem to like having the hydraulic cylinder buried where you have to pull the gearbox to even adjust it, so you may not want to investigate.
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Droll... very droll.

Can't contribute anything here as my only experience is with the stock OD, but what would you rather say aloud: 'Toyota' or 'Laycock de Normanville'?
 
When i did my conversion I took the flywheel to a machine shop to do the drilling and balancing. cost around $300 that was unexpected, and it took at least a week to get it back. I would have the TR3 flywheel done and while itbis at the shop have them remove a few pounds.
 
If it ain't broke don't fix it is my answer. But I have been lucky enough to find A o/d units locally. Guess I need to hold on the the remaining units I have. Sounds like the 5 speed is not as easy to change out.

Marv
 
After driving the 250 with o/d I would rethink the HVDA conversion. I would tend to lean towards buying a over drive set up. Just my own opinion. You will spend about $3000 for the conversion, flywheel, drive shaft etc.
 
Marvin Gruber said:
If it ain't broke don't fix it Marv
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Good advice. I put in an A type, huge job requiring in a longer main shaft in the gearbox so complete disassembly. Cussed myself more than once for what I had myself in for. Thought it wasn't broke why did I take it apart. I could still be driving without OD and be fine. I wouldn't put in a foreign conversion and couldn't have a bigger grin every time I flip the switch. Just like driving the real deal.
 
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