• Hi Guest! Being a Paying Supporter is NOT a requirement to participate at BCF. However, subscribing will help ensure we can continue to serve the LBC community for years to come. If you enjoy BCF and find our forum a useful resource...Please consider supporting us by **Upgrading**
    (PS: Subscribers don't see this banner)
Tips
Tips

Overdrive wiring

autoheart

Freshman Member
Country flag
Offline
Hello all. I'm installing an A-type o/d, recently rebuilt by John Esposito, in my TR4A (which never had one before). I have all the bits, but I can't figure out where the o/d relay is supposed to mount in the engine bay, and where the harness is supposed to go from the o/d to the relay. And while I'm at it, where does the speedo cable route?
 

pa297pass

Jedi Trainee
Country flag
Offline
Hi Joel, welcome to the Forum.

I can't speak to the TR4a, but on my 1962 TR4 which came with overdrive from the factory, the OD solenoid is mounted in the interior, on the passenger side.

Here is a picture taken looking up into the passenger side footwell... the OD solenoid is to the left side of the picture with the yellow wires coming out of it.

HoodRelease.jpg


Hope this helps.

Matt
 
OP
A

autoheart

Freshman Member
Country flag
Offline
Thanks, Matt - especially for the photo. I suspect this is the same on the 4A. So there's a harness that penetrates the firewall in front of the relay? And the wire bundle from the o/d itself goes ???. I'm totally befuddled.
 

pa297pass

Jedi Trainee
Country flag
Offline
Joel:

Unfortunately, my car didn't still have the OD transmission when I bought it, so I don't really know where the wiring goes from the solenoid. There is no hole in the firewall in front of the relay. I will take another look at my car tomorrow and see if I can decipher anything.

Matt
 

TR4nut

Yoda
Country flag
Offline
Assuming a 4a is just like a 4, the wiring goes through the trans cover itself. On my 4, there is a grommet on the cover about 9" off the floorboard, and 2.5" from the firewall. I have the same location for the relay as in Matt's picture.

Welcome to the forum, by the way!

Randy
 

MichaelG

Senior Member
Offline
Yes the 4A and 4 are similar.. Solenoid as shown in the picture and wiring harness through grommet in the transmission cover. No wiring goes through the firewall.

Are you replacing the transmission tunnel? There are a couple of mods you might need or want to make. I had to cut out a small area over the 90 Degree speedo connector coupling in order to make the plastic replacement cover fit. Also, the workshop manual shows a cutout that provides access to the solenoid from inside the car...access to both of these would make it much easier to diagnose future O/D performance issues.
 
OP
A

autoheart

Freshman Member
Country flag
Offline
Thank you everyone - this is most helpful. I assume the grommet is on the right side of the tunnel? I'm not replacing the tunnel. I have a plastic one, and plan on making an access panel for the solenoid, as well as any other mods that may be necessary.

I also assume the speedo cable goes over the top of the tranny then down into the right angle - is that correct?
 

TR4nut

Yoda
Country flag
Offline
Yep, grommet is on passenger side. On the TR4 (and I think on the TR4a) speedo cable is quite a bit longer than the non-od cable. Cable routes from speedo to outside firewall, then behind engine, then down the right side underneath to the tranny. I believe there usually is a clip on the cable that mounts it to the outside firewall right behind the engine, but that one is a real pain to install and I don't think is critical.

Randy
 
Similar threads
Thread starter Title Forum Replies Date
ckeithjordan TR2/3/3A Overdrive Wiring Triumph 5
R TR2/3/3A Overdrive wiring installation Triumph 14
S TR2/3/3A Triumph tr3 overdrive wiring Triumph 9
C TR6 TR6 Overdrive Wiring. Triumph 2
S Overdrive Wiring Check Austin Healey 12
Got_All_4 TR2/3/3A Quick Overdrive Wiring Question Triumph 6
BillyB62 TR2/3/3A Type A TR3 Overdrive Wiring Triumph 13
M Stag Wiring plugs for gear lever knob overdrive switch. Triumph 1
Gerry M TR6 Overdrive Wiring Triumph 5
Gerry M TR6 Overdrive Wiring Questions Triumph 10
T TR4/4A Any tips on running the overdrive switch wiring down the steering column? Triumph 11
R TR2/3/3A TR3A Overdrive Wiring Harness Installation Triumph 19
Coyote1 Overdrive wiring question Triumph 8
hondo402000 TR6 Need Help on 71 TR6 Overdrive Wiring Triumph 9
KLUTZ Confused with my Overdrive wiring.. Help please MG 3
R BJ-7 overdrive relay wiring problem Austin Healey 1
S Overdrive Wiring Austin Healey 2
Mickey Richaud Transmission/Overdrive Wiring MG 3
S Removing Overdrive Shaft Lever Pin Austin Healey 7
nevets Reversing With Overdrive "On" Austin Healey 8
Healey Nut Overdrive Relay Austin Healey 1
T Clutch or Overdrive Slip Austin Healey 8
G TR4/4A "Engine seized after engaging overdrive at low speed. Triumph 26
A TR4/4A TR4 Overdrive Solenoid Triumph 19
H TR4/4A A-type overdrive pump Triumph 4
B COMPLETE DROP-IN Rebuilt 1975/6 MG Midget 1500 engine PLUS rebuilt Spitfire Overdrive trans NEVER INSTALLED Spridgets Classified 0
Rob Glasgow New Fangled Electric Overdrive Austin Healey 9
Got_All_4 TR6 Refurbishing gearbox with A type overdrive Triumph 7
J Transmission and Overdrive Rebuild Austin Healey 6
C Overdrive Failure Austin Healey 18
D TR2/3/3A Overdrive question. Triumph 49
D TR2/3/3A Type A overdrive not engaging Triumph 0
D TR2/3/3A Type A overdrive not engaging Triumph 16
BN6_2197 Overdrive engaging with time delay Austin Healey 39
P Broken Overdrive Switch in Gear Knob Austin Healey 14
T Overdrive Problems Austin Healey 18
T TR2/3/3A overdrive solenoid Triumph 3
T Spitfire Overdrive again and again... Triumph 5
BN6_2197 Replacing gearbox switch of the overdrive system Austin Healey 10
G Wanted Non Overdrive gearbox wanted Austin Healey Classifieds 0
T General Tech Spitfire overdrive, the sequel Triumph 3
T General TR Overdrive problem Triumph 4
R Gearbox and Overdrive Oil Level Austin Healey 18
C Overdrive Electrics Austin Healey 8
R gearbox and overdrive Austin Healey 1
M TR4/4A A type Overdrive Oil Leak Fix Triumph 3
M TR2/3/3A TR3 Overdrive filter drain plug Triumph 7
R Overdrive dummy mainshaft Austin Healey 1
J Overdrive Cuts Out when... Austin Healey 11
J Overdrive Cuts Out when... Austin Healey 2

Similar threads

Top