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Is a Triumph overdrive tranny all that?

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Regarding the o/d in second gear. I have it in my TR3 (2nd,3rd and th4)but not in my TR4 (3rd and 4th). I seem to recall reading some place that after a certain serial number (or the A-type o/d) it is not recommended to have the 2nd gear option. Something to so with the strength of the unit to handle the switch at full power. But again I can't remember exactly where I read this. I just remember there was a reason that I did not add it when I converted my TR4 gear box to one with an A-type over drive, even though I had all the bits and pieces to do so.

I am interested in what others have to say on this.
 
Roger Williams talks about this in his books.
As the TR engines increased in power, the A type overdrive were not strong enough to hold up to the torque in second gears, so the factory disabled the ability to engage it in that gear.
 
I believe that S-T dropped the switch for 2nd gear when they came out with the 6-cyl engines with Petrol Injection giving 150 HP. The O/D was iffy in 2nd gear with all that extra power. It sounds like the O/D you installed came from one of the 6-cyl cars. The "A" O/D was used up to a certain point in the life of the TR6 when they changed over to the "J" type O/D.

With your 4-cyl TR4, you won't have any power problems in 2nd O/D if you were to add the missing switch.
 
New parts are readily available from two sources in the UK as well as some here in the US. A Volvo J-type unit can be adapted to work on the TR trans. While you may spend up to $2500.00 you can also shop on Ebay and can do the whole deal for less than $1000.00. John @Quantum Mechanics has everything you need.
 
Don Elliott said:
I believe that S-T dropped the switch for 2nd gear when they came out with the 6-cyl engines with Petrol Injection giving 150 HP. The O/D was iffy in 2nd gear with all that extra power.
Click to expand...
With respect to all, I don't believe that is correct. The early TR2 was the only TR with an A-type but not OD in 2nd gear. Even the 150bhp TR5 and early TR6 still allowed usage in 2nd.
The change to not allowing OD in 2nd happened with the switch to the J-type; and I believe had more to do with how slowly the unit would shift at such low shaft rpm, than not being able to withstand the torque.
 
The very early TR2s with the push / pull switch had their A type ODs operating on 4th gear only. That really makes it just a fifth gear cruiser rather than a street fighting, split gear on 2nd or 3rd. Very comfortable for the car and its occupants at 80 MPH and 3150 RPM.

Gad, it feels good to correct Randall!

Lou Metelko
Auburn, Indiana
54 TR2LD
 
I ordered a rebuilt O/D unit complete with the correct transmission mainshaft for my TR250 off of e-bay, it has not yet arrived, but the guy has 100% feedback so my hopes are high that it is a quality piece. He indicated he had several more, and is selling them for a very good price.

I think I am going to fit it myself, I have done most every other task on my LBCs over the years except tear apart a tranny, maybe time to try that.

If interested let me know I'll dig up his name and e-mail, he is in New Zealand.

Getting to the original question, the O/D does make highway driving better, but I use it around town as well anytime the speed exceeds 45 or so for any length of time. It isa fun accessory to use and you get thatnice feeling that the engine is relaxed instead of straining.

You can use a Toyota Supra/Truck etc. five speed for TRs and big Healeys, I think the ID is W57 or W58.

The 5 speed is probably more relaible and definitely lighter, but I just have always thought O/D on our cars is just downright cool, if you can do the work yourself it will pay for itself and maybe more when you sell the car.

Greg
 
glemon said:
I ordered a rebuilt O/D unit complete with the correct transmission mainshaft for my TR250 off of e-bay, it has not yet arrived, but the guy has 100% feedback so my hopes are high that it is a quality piece. He indicated he had several more, and is selling them for a very good price.

I think I am going to fit it myself, I have done most every other task on my LBCs over the years except tear apart a tranny, maybe time to try that.

If interested let me know I'll dig up his name and e-mail, he is in New Zealand.

Getting to the original question, the O/D does make highway driving better, but I use it around town as well anytime the speed exceeds 45 or so for any length of time. It isa fun accessory to use and you get thatnice feeling that the engine is relaxed instead of straining.

You can use a Toyota Supra/Truck etc. five speed for TRs and big Healeys, I think the ID is W57 or W58.

The 5 speed is probably more relaible and definitely lighter, but I just have always thought O/D on our cars is just downright cool, if you can do the work yourself it will pay for itself and maybe more when you sell the car.

Greg
Click to expand...


Can you please provide the contact infor for the seller
of the rebuilt tranny? I'm interested to know how it
goes once you receive and install the one you ordered.

Thanks,
 
Also, from your comment: "You can use a Toyota Supre/Truck etc. five speed for TRs and big Healeys, I think the ID is W57 or W58."

What must be done to make them work? Does this require
great amounts of mods?
 
That would be basically the HVDA conversion. It's pretty involved. No changes to the box itself, but a custom bellhousing (which has to be precision machined to maintain alignment), shift housing (the Toyota shifter isn't in the right place), driveshaft joint, etc.
 
Lou Metelko said:
Gad, it feels good to correct Randall!
Click to expand...
Glad you enjoyed yourself, Lou.

You'll perhaps note that I carefully did not mention whether early TR2 had OD in 3rd gear or not, because I felt it would further cloud the issue rather than clarify it.

And while we're on the topic, the change to the toggle OD switch was slightly later than the incorporation of OD on 2nd & 3rd.
 
I have the J-type overdrive in my 6 (Quantum) and use it strictly as a highway cruiser. Even though it works in 3rd and 4th, for the life of me I cannot figure out why I would want to use it as a 6-speed. The overdrive 3rd is awfully close to the regular 4th, and so on. I will play with the tranny in 4th and 4th-overdrive but that is about it. Whatever. The location of the overdrive switch in proximity to my left index finger is soooo much easier than clutch/shift into a 5th gear.
 
TR6BILL said:
...for the life of me I cannot figure out why I would want to use it as a 6-speed. The overdrive 3rd is awfully close to the regular 4th...
Click to expand...

Granted it's close but 3RD OD can be useful. In the summer live at 7,000' and every drive ends with a climb up that mountain. It's mostly big sweeping curves with a steady 6% grade and that 3rd OD is just ideal for running up there at 45-50 mph.
 
Bill,

I never use mine as a six speed, but I LOVE the the 3rd O/D for the hilly back roads here in New England. You can run the curves like a bat outta ---- and just flip the switch in and out as you keep the pedal to the metal.

Yes, it was expensive, as others have said. John at Quantum does a great job and for the three summers of driving fun so far, it was definitely worth it. It just gets cheaper by the mile as time goes on.
 
I believe the Laycock-de-Normanville Type A overdrive is all that and more. It truly will be a sad day when parts are no longer available to rebuild these hydraulic head snapping wonders. No offense meant but I don't think a five speed Toyota conversion would do it for me. Yes, I use all seven forward speeds but only to Impress myself with how well the thing works. On the twisty roads around here I personally like using third gear OD on the straights, then disengage down to third for the turns, then stomp on the pedal and /bcforum/images/%%GRAEMLIN_URL%%/savewave.gif good-bye to those behind.
 
It is definately neat to have 7 forward speeds. I use 4th OD all the time. There are lots of times when 3 OD is useful, like when you want to do 45 and the car in front you is doing 39. In this way, it works like a speed limiter.

The best is 2nd OD. What an interesting use that is. I got stuck behind a bunch of bicyclists taking up the road. This gear was perfect for it.

I can't imagine the car without it.
 
Have a 58 TR3 I'm finishing for a local guy. It has an A type OD.
Need the basics of the tranny. What RPM does the tranny activate? Does it activate at low cruise speeds?
Besides the adtivation of the solenoid how do you know it is working? It works in 2nd, 3rd and 4th, correct?
Have a bead on another OD how can I tell if it is good or needs to be rebuilt? Is there a nice manual available for information on parts and operation?

Any help in addition to this post would be appreciated.
 
Larry,

The OD is normally controlled only by the combination of the dash switch and the gear lockout switches; it's not directly rpm-sensitive; except that it has to have built up hydraulic pressure in order to shift into OD. And since it has an accumulator to store the hydraulic pressure, at least in theory it can engage with the shaft not turning at all.

To test on the bench, you'll need some way to spin it enough to build up pressure (and indeed, checking the pressure is one way to gauge the health of the unit). I've found that a 1/2" drill motor is adequate, barely, to demonstrate that the OD works. (When it shifts into OD, the momentary extra load on the drill as it accelerates the output shaft is very noticeable.)

But having it hooked to an engine makes it easier even if the car is not drivable. One method I've used is a timing light hooked to the engine and shining on the tailshaft flange : in 4th direct the flange will appear to be stopped, while in overdrive it can be seen to turn (under the timing strobe).

I know I should have your email, but I seem to've lost it. If you'll PM it to me, I can send you several articles (including the factory manual) on the A-type.
 
When I repaired my O/D I used a 1/3 HP motor and a belt to drive the output. I used corks to plug all the holes in the forward part of the overdrive and that way I was able to test it before I even attached it to the gear box. It worked great. I tested it the same way once the unit was mated to the gearbox as well, just to make sure.

I have some pictures of this if you are interested let me know.
 
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