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adding overdrive to standard tr6

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osbourne William G
Salmon River, NS, Canada   CAN
Hi, I am in the process of purchasing a tr6 but it does not have overdrive. I would really like to have it so my question is just what is involved to add overdrive to the car and where would I look for the parts. Any info would be greatly appreciated.
Thanks

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davem Avatar
davem dave m
vancouver island, BC, Canada   CAN
step 1 - what year is your car - they changed form an A-type to a J-type in 1972 i believe

a type has o/d in 2nd 3rd +4th j-type has o/d in 3rd +4th

osbourne William G
Salmon River, NS, Canada   CAN
Thanks for the quick reply.
the car is a '74 with no o/d

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Darth V8R Avatar
Darth V8R Vance Navarrette
Beaverton, OR, USA   USA
1980 Triumph TR8 "Wedgie"
In reply to # 1392857 by osbourne Thanks for the quick reply.
the car is a '74 with no o/d

William:

You can get used and rebuilt OD gearboxes on eBay, or rebuilt from John at Quantum Mechanics. This is expensive, but simplest for a shade tree mechanic. If you want to tackle this on your own (as I did) then....

You will need the following parts

Laycock J-Type overdrive - As found on Volvo or Triumph - Ebay has them used starting at $100, Quantum Mechanics has them rebuilt (www.quantumechanics.com) for a lot more. BE CERTAIN you get one that has the provision for a MECHANICAL speedometer. Later Volvos used an electronic speedo and will not work with a TR6 speedo. Volvo used a slightly different mounting system, so you may need to drill a couple holes and tap them to accept the mounting studs.
J Type adapter - quantum mechanics. I got mine on eBay.
Speedo Gear set - If your OD is a Volvo unit. Available from Moss Europe last time I looked. If the unit is a Triumph unit, you do not need them.
Right Angle drive for speedo cable - available from Rimmer brothers or on eBay.
Overdrive Mainshaft - I got mine from the roadster factory, also available from Quantum Mechanics
Overdrive switch and plinth for steering column - I got mine on eBay, you can try the big three
Overdrive wiring harnesses. I got mine from Moss.
Overdrive output flange. You cannot reuse the output flange from your four speed gearbox. If you get a Volvo OD, there are two different styles of output flange, be sure to get the LARGER round style, and it will bolt right up. The smaller flange will need to be machined to fit, and the Volvo X-type flange is scrap. If you can't get one, eBay or Quantum mechanics, perhaps Rimmer brothers.

I have a complete set of instructions, PM me if you want them.
You will also need a complete set of gaskets, seals, etc.
You need to disassemble the transmission and remove the gear clusters, then reinstall them on the new mainshaft and reinstall the whole kit and caboodle back in the transmission case. So you will want to inspect and replace any chipped gears, worn synchros, bent shift forks, worn bearings, etc. in your gearbox while you are at it.

You can do it yourself for about half of what a rebuilt OD gearbox goes for. But great care is needed as gearboxes are very sensitive to tolerances and so you will need feeler gauges and some shims to get it back together correctly.

If you get a used Volvo OD, you will want to measure the thickness of the cone clutch material. Anything less than 0.050" and the clutch is worn out and will need to be rebuilt. Once again you can get a rebuilt clutch from Quantum.

Cheers,

Vance



1980 Platinum Metallic TR8, navy blue interior
Bare metal respray, Crower cam, raised compression
ported heads, modified Zenith carbs, 0.060" overbore

clifish Avatar
clifish Cliff Deger
St. James, NY, USA   USA
Hi William,

If you are not too far into the process it might be easier to go out a find one with OD.. I was in your position a few months ago and ended up spending a little more for my 74 that was converted to an OD car by quantum in CT by a previous owner. It is getting tougher to find the OD units or the proper Toyota 5 speed conversion. Also it will cost 2 grand plus to do it. On the plus side I agree with you wanting an OD car, I love mine, could not imagine doing 60+ with out.

No matter what you decide, good luck and you will find a wealth of info from the members on this forum.

-Cliff



74 TR6 - Carbs by POOLBOY
81 Corvette

davem Avatar
davem dave m
vancouver island, BC, Canada   CAN
so you need to look for a J-type + switch and housing + wiring harness
-used units usually run $1000 -1200 but no telling how good they are
-rebuilt ones run $2000+
-then there is the install as well

-all in all i think it is well worth the outlay and the next owner will certainly appreciate it as well (much easier to sell )
good luck
-buckeye triumphs has a really good informational website on most things tr6

TR3driver Randall Y
Confusion, Los Angeles, USA   USA
FWIW, I own both and I much prefer the A type od. Instant shifts plus od on 2nd gear make it more sportier, IMO.

If you are going to go to all that trouble, you might want to consider using the earlier unit. I think you'll need a ratio adapter for the speedo drive (which any speedo shop should be able to make up), otherwise it should drop right in.

ORS in the UK is another source for od parts.



Randall
56 TR3 TS13571L daily driver
71 Stag LE1473L awaiting engine rebuild
7? Stag awaiting gearbox rebuild

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osbourne William G
Salmon River, NS, Canada   CAN
Thanks guys, I did purchase the car; just couldn't leave it alone for the shape it's in. Now I have to get my head around all of this stuff. If I could find one, just which Toyota unit would I look for?

davem Avatar
davem dave m
vancouver island, BC, Canada   CAN
i heard somewhere that you need a tr4a flywheel for this conversion ??
-if you find you need one let me know, i have a newly refaced tr4a flywheel for sale

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TR3driver Randall Y
Confusion, Los Angeles, USA   USA
In reply to # 1393434 by osbourne If I could find one, just which Toyota unit would I look for?
Were you asking about a Toyota 5 speed gearbox, instead of a TR6 box with Laycock OD (as original)? The Toy box requires a rather expensive conversion kit, so you should start by finding which kit (not sure if the kit from NZ is still on the market or not), and then ask which gearbox that kit uses. If you go with Herman's kit, you can find information about which Toy gearbox on his webpage
http://www.hvdaconversions.com/products.html



Randall
56 TR3 TS13571L daily driver
71 Stag LE1473L awaiting engine rebuild
7? Stag awaiting gearbox rebuild

tirebiter Jeff Garber
Dighton, MA, USA   USA
The rear axle ratio can also be changed to drop the revs on the highway.

osbourne William G
Salmon River, NS, Canada   CAN
I was looking on some other sites and found a 5 speed from a tr7. Does anyone know if that would fit the tr6? Just looking for all of the options.

TR3driver Randall Y
Confusion, Los Angeles, USA   USA
In reply to # 1393905 by osbourne I was looking on some other sites and found a 5 speed from a tr7. Does anyone know if that would fit the tr6? Just looking for all of the options.
Almost anything can fit, with enough work. But it definitely won't just bolt up. You need that Edapter kit.




Randall
56 TR3 TS13571L daily driver
71 Stag LE1473L awaiting engine rebuild
7? Stag awaiting gearbox rebuild

pathman98 Gary Assarian
Bloomfield Hills, MI, USA   USA
WHY BOTHER!!!

gozto11 Avatar
gozto11 Todd Bermudez
Cincinnati, OH, USA   USA
Wow shouting and not very helpful??

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