Question on OD wiring harness 57 Smallmouth

How does the wiring harness get from the gearbox to the dash? I've never had the tunnel on this car and the tunnel is in tough shape.Sometimes I think this car had 3 inches of water on the floors for years.

Wiring from the trans goes underneath and up to a relay in the engine bay, then in through the bulkhead to the sw on dash.

Marv

My relay is mounted to the inside of the battery box putting it inside the car.

The cables from the top of the gearbox and for the solenoid come through the steel wall of the tunnel near your heel for the gas pedal. It's the grommet closest to the left of the photo. The other holes are for access to the solenoid from the top. Two holes up high for a very long screwdriver and the large hole to see what your doing and to replace the solenoid. This large hole is filled with a rubber plug also used in the floor pans for the floor jack.

My overdrive relay is mounted up under the battery box. It came that way in 1958 when I bought my TR3A brand new.

BTW, the 2 wires from the grommet shown above go in a sheath or vinyl spagetti tube along the floor under the carpet and then up vertically beside the gas pedal right against the firewall in the corner behind the RHS of the gas pedal.

Don is correct, as usual. But I don't like having the wires through the side of the tunnel like that, so mine run up the firewall inside the engine compartment and through the grommet visible to the left in Don's second photo above. The grommet in the tunnel is replaced with a plain plug.

Also worth noting, perhaps, that none of the published wiring diagrams match the original wires on TS39781LO. The diagrams show a wire from the isolator switches directly to the dash operating switch, but TS39781LO had the wire from the isolator switches to one side of the relay coil, then the other side of the relay coil to the dash switch. Function is the same, but there is one less wire from the relay to the dash.

I considered adding holes as Don has done; but in all the years I've driven an A-type, I've only had two solenoid failures. And I prefer to avoid the "swiss cheese effect" if possible.

Is it possible that the overdrive relay is installed upside down. The TR3 operations manual shows the 3 terminals in the down position. Apparently the Vanguards had the 3 terminals pointing up, and Laylock used a saloon car for illustration in their manual.
Robert

It has been too long, I don't recall for certain; but I think that TS39781LO had it mounted the other way over. Certainly that is the way it is shown in both the TR3 service manual and the OD service manual. (The OD service manual also shows it the other way for the saloon.)

Doesn't matter to me. It works. It's the original relay that was in the TR when I bought it brand new in May, 1958. I checked my sketches as I was taking it apart in 1987 and can't find any sketch for this. In 1990, that's the way I put it back in and I don't think any TRA or VTR judge ever took off a point because of this.

So, it'll probably stay that way for another 22 years. I'll let you know then if I have changed it around.

Well this like many other TR trivial details is subject to controversy or at least discussion. But, yes there is evidence that the side of the relay with three terminals points down, and not up as shown above. Here is an earlier version of my OD relay mounted like Don's car with comments from John Warfield, president of TRA.

<span style="font-style: italic">
Tags,check and see if your relay isn't mounted upside down...while the illustration in the Laycock handbook provided with early cars shows the 'three terminal side' mounted up, it's mounted in a saloon (likely a Vanguard). The TR2/3A Operations Manual has a section with a diagram/drawing that shows it with the 'three side' down. Not worthy of concours deduction at any rate but since we are all striving for perfection and it looks like you are getting close... J. Warfield</span>

Here's a clip from the Triumph Parts Manual which also indicates the single terminal pointing up.



I have since changed the mounting of my relay.

So did early TR2s come with a "Laycock handbook" other than publication 502274 ?

I am spooking around the internet looking for a picture of how the wires are ran for the OD dash switch, and came across some of Don Elliot’s old posts, but the pictures are deleted. Does anybody have the old pictures saved or something similar to share.

Here are photos showing the harness for my 1957 TR3. I laid them out to see how everything went together. One is the overall layout, the others are close-ups. You can see the wires for the OD dash switch. If you're asking how they were "run" behind the dash, it was "up and out of the way" from the relay, which is mounted on the lower left corner of the battery box (as seen from inside the car).

Thanks Keith that is kinda what I am looking for, the wire routing from the dash switch and where the dash switch meets the harness after relay. I wanted to see a picture of the original wire route, but it is starting to look like a rare bird. What I read from Don Elliot posts is he had made a sketch of his probably because cameras like today were not common when restored his car in 1989. He bought the car new in 1958 and it was probably no big deal to him.

I did find an old battery box that has one of those tie holder deals right behind the relay on the bottom of the battery box. I never knew what it was for, but know I think the tie held the wires on the bottom of battery box as the wires went away from the relay and back to the firewall to connect to the dash switch.

Just curious are the wires coming out of the OD dash switch gray?

thanks again --steve

Yes, Steve, the wires out of the OD dash switch are gray, no polarity. Attached is a photo of underneath the dash showing the relay and the wires out of it, which go to the gearbox top under the carpet and a grommeted hole on the left (driver's) side of the tunnel, with the others going up to the OD dash switch and the white and brown wires going to the ignition switch and the ammeter, IIRC. As my car is still with Macy's Garage, I can't check to see the routing, nor verify the presence or absence of clips for the wires.

You can also see where I've installed a new heater from T7 Designs in the UK. https://www.t7design.co.uk/products...w-lightweight-heater-with-side-vents-12v.html

Thanks Keith for your reply. I purchased an od switch a while back and it had a gray wire, but I believed the wire was incorrect because it was gray, but now I think not, and it is a gray wirer. Plus, I am starting envision a way to run the switch using some of those clips like on the temp gauge that should work out and look kinda original. There a couple of nice original cars that come to the large local show here and the guys are pretty cool, and I think they will let me look up under the dash.
Those newer heaters look like they come in and out easier than the old ones—plus the older heaters are getting difficult to find.
Thanks steve