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TR4/4A Changing from 4 speed to Overdrive on a TR4

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rnpennington

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I've read several threads about people with OD of the A-Type vs a Toyota Conversion. However, mine does NOT have OD, but I want it for touring.

What are the thoughts about going with an A-Type from Quantum Mechanics vs the Toyota 5 speed. Cost for both is about the same. Mine is not a concours car, nor will it ever be, but I use it as a driver all the time. My concern is going long distances - especially highway's - with just the 4 speed. It seems the reduced rev's either way will be a good thing for the car.

Let the opinions begin!
 
Bob, it's a more or less straight swop, with a added relay, wiring harness and switch on the column. The other has good reviews also, but not plug and play. Just me, but I would stay with Triumph parts. I'm putting in a "A" type in my TR6, a get round to it sort of thing.

Wayne
 
I'd have to say that the 5 speed conversion is probably more reliable, in the long run. But my preference runs strongly to the Laycock OD. Period correct and uniquely British (American overdrives were much different to drive as they lacked the electric controls and hydraulic clutches). Plus the extra gears add significant flexibility when driving twisty mountain roads (tho I guess you don't get too many of those around Houston :smile: ).

Here's an old ad that I like. Written for a Healey, so some of the details are different, but right on the money as far as the OD experience.

LaycockODkicklikeamuleBW.jpg~original
 
Mines a driver that I added an A Type and enjoy it very much. Defiantly worth the work and expense for the enhanced driving experience for me. I just can't see putting anything Japanese in the car except maybe a bento box to go.
 
Bob - I did that exact swap about 9 years ago using an overdrive from John E at Quantumechanics. It has been totally reliable and trouble-free for the 30,000 or so miles since.

Installation was just a straight-forward wrassling of out with the old and in with the new, John provided everything including the relay and steering column stalk switch. He also sent a plastic nacelle with a hole for that switch but I preferred to keep the orginal (metal) so I made the needed D shaped hole in it.

As Randall notes, in mountain driving the 3rd OD is often just the right gear for a twisty uphill road.

Plus (as I've mentioned before) which would you rather say... 'Toyota' or 'Laycock d'Normanville'?
 
Another vote here for overdrive. I upgraded my first TR4A to an A-type overdrive when I restored it and loved it.

Scott
 
I have two TR4's with Toyota trannies because I could not locate a OD tranny for them. My current project has a OD tranny waiting for it. That said I do like the "quiet" Toyota trannies compared to the TR trannies.
Charley
 
How difficult was it to run the OD wires up the steering column? Any hints would be useful, as I will be making the change in about 2 weeks
 
Bob, you will be running them down the sleeve. Just loosen the bolts that hold the column after taking off the steering wheel, use a stiff wire, (cloth hanger), stagger the bullet connectors and tape it to the wire, shove down.


Wayne
 
I do not recall having to remove the steering wheel for the OD wiring and switch (but it has been 8 or 9 years ago). The TR4 has that metal 'dagger' that comes off and the wires run through it. Of course the two halves of the nacelle are removed to get at the insides & the switch mounts to the right hand one.
 
Geo, You are right, the wheel can remain on, but much easier to go right down the column. Pull the wires through the echelon and hole in the column then run them down. I have replaced a few light and signal switches and it was just easier to get to the bottom of the column.

Plus the steering wheel is in the way every way you try to shove the wires. Oh, clean the horn ground and lub with dielectric while in there.

Wayne
 
One more thing to think about when removing the steering wheel. Use some type of marker to mark the position of the wheel on the shaft. If you don't do this before you remove the wheel you are not likely to get the wheel back on the shaft in the same position. That means that your wheel will be in the wrong alignment for your front end. Or the wheel will not be in the straight ahead position when you are going straight ahead. Just one of those "Oh why didn't I think of that when I took it apart!!" things.
Charley
 
Good one Charley, now the why didn't I think about that. Bob, just take the wheel off before you start, much easier to get to or remove all the stuff to get that sucker in and out, (tranny bolts, tunnel, and dash support.
Better add, wrap a towel around the end of the shaft, don't ask, just do it. LOL
Wayne
 
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On a TR4 it is very simple to pull the wheel with the shaft by just undoing the clamp in the engine compartment. Position is preserved as the big nut is left in place. Perhaps this is an alternative. I usually do this by removing to two bolts on the clamp and not disturbing the set-screw / lock nut.

Also - on a TR4 I find it easier to get the gearbox out & in through the (LUD) drivers side provided you have the steering wheel out of the way - due to the handbrake being on the (LHD) passenger side of the tunnel.
 
Geo, well now that we have Bob convinced it's a piece of cake, he should just jump right in there. Couple little things, it's heavy as ****, if you are changing the clutch, get an alignment tool and clean the threads on the bottom tunnel support caged nuts with a tap if you have one.

Wayne
 
Even better than an alignment tool is (if you can find one to borrow) an old input shaft.

InputShaft_zpsa674af1c.jpg


Some of the alignment tools sold are undersize and inexact, a spare input shaft is, of course, perfect.

Yeah, it's a bit heavy. I recall once seeing an adaptor someone made to enable the use of an engine hoist to dangle the gearbox into place. The trick was getting the center of gravity (which is pretty far forward) just right.
 
I'm sure its a piece of cake like everything else Should take one hour, allow for two and it takes four!
 
rnpennington said:
I'm sure its a piece of cake like everything else Should take one hour, allow for two and it takes four!
Click to expand...
Oh but the joy of it all. Just think you got to spend four hours fiddling with your Triumph rather than the short hour after which you might have to do something a lot less fun-- like mowing the lawn.
Charley
 
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