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Triumph TR6 - Transmission replacement- OD A vs. the Toyota

Hi,

I need to replace the transmission on my '72 six, and I'm contemplating a few options:

1. Another four speed Triumph transmission.
2. An A-type overdrive Triumph transmission.
3. A Toyota Transmission with the kit available.

I'm wondering if anyone who has experience with the last two options can comment. For example, I've heard the A type overdrives can be unreliable.

Thanks very much,

-Bill.
W. Wright

The Laycock DeNormanville overdrives have their idiosyncracies, but I don't think that I would categorize them as unreliable. It is imperative that they be set up and adjusted properly or you can count on problems, but that is about it. If it ever does seriously break, be prepared to part with some cash.

On the Toyota conversion, I assume that you are talking about Herman van den Akkens conversion kit. I have not done one of those myself, but there is another person on this board that has taken the plunge and seems happy with. I can also say that two people that i know here locally have purchased the kits, but have not installed yet. Finally, I visited with Mr. van den Akker at his house/shop and am very impressed with the kit. It is well thought out and very straight forward. If I need to put a transmission in either my TR6 or TR250, the Toyota route is probably the way that I will go.
SteveP

Bill- Please note, if your trans is not an A type already the choice to go to an A is quite expensive and difficult to come by. My thinking it is the prefered choice verses the "J" type. But for my money go the Toyota.
Don
DON KELLY

I've had Herman's kit for about three years now. Outstanding! I'm using a Celica transmission which feels geared lower in first through fourth than the stock Triumph trans. And then hit fifth and everything smooths out.
NFI, just a very satisfied customer.
John

Hi folks,

Thanks very much for your comments. Seems like the Toyota conversion is really well liked. Is there no downside to it? Is there nothing to be missed in the Toyota compared to an A-type OD? (I think I've located one and may be able to go either way.) Its been very helpful to read your opinions, thanks again.

-Bill.
W. Wright

If your present TR6 gearbox does not have an "A" type overdrive attached to it now, you will need to also change the mainshaft in your gearbox to accept your newly acquired "A" type overdrive. These run about $300 to $400 for a good used one.

Then you or someone else will have to put it into your existing TR6 gearbox to accept the overdrive unit.

Don Elliott, Original Owner, 1958 TR3A
http://mysite.wanadoo-members.co.uk/trebor/don3a_big.JPG
Don Elliott

I'v run Hermans kit for three seasons and recommend it. Dealing with Herman is better than any other vendor I'v experienced - just a really good guy.

The Toyota Supra 5 speed gearbox combined with a hydraulic throwout bearing will transform your car into something that is much more "user-friendly" to drive. The first 4 gears of the W58 Supra gearbox are nearly identical to the TR6. 4th Gear is identical at 1:1.

The only downside I can see is the "originality" issue and perhaps a slightly reduced market for resale although some have said the 5-speed conversion increases the marketability of the car.

Check the archives.

John Parfitt
73 5-Speed.
John Parfitt

Hello,

The other downside is usually the high price for such transformation. I prefer to buy a good used one with overdrive.
Cheers,



JGC
J. G. Catford

The only comment I can add is that I owned a 1978 Toyota 5 speed pickup. I don't know if the W58 Supra trannys are related to what I had. So my experience may not apply. Anyway, the '78 pickup tranny had the overdrive go out. The 5th gear is kinda like an add-on on the back end of the box, with splines to the shaft. The gear and shaft splines failed with about 80K miles on them. The parts to fix, including throwout bearing and pilot bearing and a few other parts not related to the overdrive failure was about $450 back in the early 80's. Someone with more knowledge of Toyota trannies can tell us if this is a weak spot in all, or just the one I had.

I'm just saying that finding a used Toyota transmission and stuffing it in without a teardown might not be frugal. The box worked smooth as silk, it was a fun truck. I have always wondered why they never made a kit car out of those SR5's. It was close to a Triumph pickup.

As long as parts are available to rebuild TR trannies, I think we should continue to use them.
Tom

Can anyone give me an ideal in cdn dollars what shipping and duty charges are to Toronto area.
M SIDDALL

M.

You can find all infos you need there:

http://www.blindmoosefab.com/hvda.htm

cheers,

JGC
J. G. Catford

There is no duty to pay on automobile parts coming into Canada for a car which is 25 years old - or older. Have the shipper print that on the papers - to the effect :- "Auto Parts for a 1972 TR6 Antique car". But you will have to pay the GST and the prov. Tax.

Don Elliott, 1958 TR3A
http://www.zen21606.zen.co.uk/Forum%20Gallery/don3a2_big.jpg
Don Elliott

Tom - no the W58 5-Speed gearbox is used in the Supra. The Toyota Trucks run a completely different gearbox.


John Parfitt
73 5-Speed
John Parfitt

On a related question, all else being equal certainly the more gears available (within reason) the better. But is the attraction of the 5 speed / OD related to the taller overall gearing for cruising or keeping the engine within its powerband? Or all of the above?

I can understand that with a high reving engine with a narrow powerband one would want a big bunch of closely spaced gears to keep it in the powerband. And that engine description certainly does not match one for a reliable street performance long stroke engine. On a related note I think my kid brother's Corvette with 350 has enough torque to probably get away with a single gear, but with some loss in performance.

If taller gearing only is the desired outcome, then an alternate would be to save the weight and complexity (and cost) and go with the 4 speed and change the final drive from the stock 3.70:1 to 3.45:1 (or higher?), equivalent to about a 0.93 overdrive ratio. Would that not provide the close to the desired results?

What am I missing in my analysis?

Len
Leonard G Middleton

Len,

One problem with your solution is that it would require those of us in the NA market (unless we gray marketed in a ROW car)to have to either get a different speedometer or go to some correcting factor drive. Another is total drive gearing would only result in a about a 7% reduction in engine speed in a steady state highway operating condition.

I can't speak for everyone, but feel that for myself and probably most, that it would be about getting a reasonable gearing match through the first four gears with an overdrive ratio to boot. The A-type overdrive is .82 overdrive while the J-Type is .80 (OK, .797 for those that want to take it out to three places).

Considering the W57 and W58 boxes as used in the Supra, you have fifth gear overdrive ratios of .86 and .78 repectively. Considerably better than the .93 that would come about from changing out the differential gear set and as a bonus you don't have to fiddle with the speedometer. As to ratios on one through four, the W57 and W58 are the same. Compared to the TR6 gear sets, they are wider between first and second, but closer on second to third and third to fourth.
SteveP

Speaking of speedometers, since I haven't looked at the conversion site, do they supply a cable with the kit? And are there different speedo gears available for the Toyo tranny?

I guess I should just go look for myself, eh?
Tom

Tom - You will have to ask Herman that question. Mention my name. I met him about 15 years ago.

BTW, if you phone Herman, I hope you have long distance at $0.05 per minute. Herman is such a nice guy (lived 10 years in the Toronto area) he will take half an hour to explain all about the answer to your question.

There is a site with all the info on Toyota gearing :-

http://www.toysport.com/Technical%20Information/Transmissions.htm

Don Elliott, 1958 TR3A
Don Elliott

This thread was discussed between 25/05/2005 and 31/05/2005

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