TR4/4A Checklist for installing A-type O/D in TR4a

[tdskip]

Just doing some planning here - is there a punch list of items/bits I'll need to put the an A-type O/D in the TR4A solid axle?

To beat Don to the punch,

1) Acquire A-type O/D (done)

Next would be?

2) ......
3) ......
4) ......

 

[TR4nut]

Tom-

Are you splicing the od onto a non-od trans, or doing a full trans exchange? You'll need to worry about getting an od mainshaft for whatever box you are using if you are splicing things together. If its a whole box you are transplanting, I think it should be a pretty smooth drop in, at best maybe a little adjusting of the rear trans mount if needed depending on the year of the transmission.

With a 4A and a diaphram clutch, you want to check the input shaft cover length and throwout bearing setup.

Only other thing I can think of is sorting out the electrics and getting the 6RA relay for the solenoid. But that isn't hard - certainly not harder than welding in a replacement TR6 valance!

Randy

 

[tdskip]

Hi Randy, sorry for not being more specific.

I am doing a full transmission exchange. Is there a specific clutch set up and throw-out I should be using?

Thanks!

 

[TR3driver]

This might help (click for full size):

 

[TR3driver]

Is there a specific clutch set up and throw-out I should be using?

Doesn't matter so much, as long as all the components match. A 4A would originally have had the diaphragm style clutch, which takes a shorter front cover on the gearbox than the earlier finger style clutches did (the diaphragm fingers will hit on the early front cover when the clutch is depressed); plus the later TOB with the curved face.

The later setup is smaller and lighter (which helps performance a bit), but seems to wear a little quicker (smaller friction surface) and be somewhat more troublesome than the earlier setup. Not worth the pain of redrilling (or changing) the flywheel either way, IMO; so just make sure things match.

 

[TR4nut]

Tom-

I think Randall covered it above - but just to add, I'm assuming you have a diaphram style clutch in the 4A just like in a TR6. If that is the case, use the correct throwout bearing for that setup, and check the length of the front cover that bearing assembly rides on. If your replacement od transmission has an earlier and longer front cover it would probably be a simple thing to just swap it out with the shorter one from the original 4A transmission.

I've had to throw away two ruined pressure plates because of mismatched throwout bearings (finger plate style ground away with curved style throwout bearing) - and a friend in our club had to repull his transmission when they accidently put a Gunst bearing in an early TR4 setup which allowed the clutch to permanently slip. So the golden rule is get the components to match as Randall said.

Randy

 

[tdskip]

Thanks guys!

 

[TR3driver]

If your replacement od transmission has an earlier and longer front cover it would probably be a simple thing to just swap it out with the shorter one from the original 4A transmission.

Or just hacksaw off about 3/8".

 

[tdskip]

Thank picture you posted is a fantastic resource Randall - thanks.

So it looks like I need;

1) Angle drive speedometer adapter?

Ideas on sourcing?

2) O/D switch for the steering column

This is the same as for the TR6, right?

3) O/D relay

Got one already

4) Solenoid for the O/D

Anyone have a good used on, or is the Moss aftermarket supplied one OK to use?

 

[CinneaghTR]

Would this be a good deal?

Triumph: TR4 and TR6 A type overdrive car installation kit

This is a complete car kit to install an A type overdrive transmission (not supplied with this kit!) into a non overdrive TR4 or TR6 car. It contains the upper and lower wiring harness set, the overdrive relay, the steering column overdrive switch and escutcheon and the speedometer cable right angle drive and spacer. All new parts. Price is $200. Shipping is $10 In USA.
https://www.quantumechanics.com/categories.php?op=newindex&catid=7

(I'm preparing to do the same thing...)

 

[CinneaghTR]

Oh, and Quantum sells the solenoid, too, in the overdrive parts section...

 

[TR3driver]

1) Angle drive speedometer adapter?

Well, if you keep that TR3 tunnel, you could do without; by routing the speedo cable through the cutout on the right rear. That's how the TR3-4 did it, takes an extra long cable that loops way out against the frame rail. Might be worth a thought, as the angle drives are kind of expensive and fragile. They're by far the weakest link, so if there is a problem with the cable or speedo head, it usually destroys the angle drive as well. (One of my Stags had just had a new angle drive installed when I bought it; less than 100 miles later the speedo head got hot, bound up, and broke the brand new angle drive.)

Should be available new from the usual suspects, or sometimes used from eBay.

<div class="ubbcode-block"><div class="ubbcode-header">Quote:]
2) O/D switch for the steering column

This is the same as for the TR6, right?
[/QUOTE]Ditto the usual suspects. I vaguely recall that the original 4A switch was slightly different than the TR6 version; but most likely the TR6 switch will fit and work. My 4A SPC shows P/N 139793, which TRF has listed for $50 (until Jan 30).

I've not heard anything bad about aftermarket solenoids, so the Moss unit is probably fine. I got mine from Quantum Mechanics, just because he had them for sale cheaper on eBay.

BTW, I do advocate adding a fuse to the solenoid circuit. The solenoid has a pull-in coil inside, with contacts that are supposed to open as soon as the plunger moves. If the contacts don't open for whatever reason (misadjustment, grit, etc.), the pull-in coil will quickly overheat and ruin the entire solenoid. Adding a fuse that will eventually blow if the contacts don't open gives you a chance to solve the problem without having to buy a new solenoid. I used an MDL-8 (8 amp slow blow) just because I had them on hand, but an ordinary 5 amp fuse should work fine. Early Stags were equipped with A-type OD fuses from the factory.

 

[Geo Hahn]

I think you'll also need a different RH nacelle that allows for the OD switch next to the headlamp switch (if going for the original look).

 

[tdskip]

I think you'll also need a different RH nacelle that allows for the OD switch next to the headlamp switch (if going for the original look).

Good point!

 

[TR4nut]

minor nitpick, and probably wrong - but wasn't the overdrive switch on the left or turn signal side of the column on the 4A? Thought I saw that on a parts car once.

 

[bgbassplyr]

OD switch on the right side. You can drill a hole for the switch through the existing nacelle.

 

[TR3driver]

4A Owner's manual seems to agree with Randy:

 

[HerronScott]

Randy is right. Both of my 2 TR4A's have the overdrive switch on the left side behind the turn signal. TR6's followed the same pattern. The only difference between the column switches for a TR4A and a TR6 are the TR4A's had chrome stalks while the TR6's were coated with black plastic. At the time I restored my first TR4A, TR6 parts were plentiful and cheap so I used all TR6 column switches (used or NOS). And it is a different escutcheon with 2 mountings spots as Jeremy and Geo indicated.

The TR4's had it on the right as their headlamp switch was on the dash versus on the right-hand side of the column like the TR4A's and TR6's. If you didn't have overdrive then you got a blanking escutcheion which could be drilled to install an overdrive switch like Jim indicated. I believe at least the early TR4's had metal escutcheon's too based on a friend's very early model. Not sure when they switched to plastic.

Scott

 

[sail]

TRF has chrome # 139794 4A only, fits left.

 

[tdskip]

Interesting guys - the Original Triumph Book has it on the right hand side, although that is a RHD car.

So, in summary then;

TR4 = right side

TR4A = left side like TR6

Yes/no?