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TR2/3/3A Question on TR3 trans top cover

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TR4nut

TR4nut

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I picked up a cheap TR3 trans for spare parts - I'm interested in retrofitting the trans cover to my TR4 box to take advantage of the oil fill/dipstick on the cover.
3dea_1.jpg

I'm fairly certain I need to swap at least the 1st/2nd fork because of the syncro differences. Aside from that, I'd be interested in adding a reverse switch. Does anyone know if the plug on the rear of the top is for that purpose? It looks like a pressed in plug so I don't want to disturb it unless I know I can add a switch at that location. Being an early transmission I don't see a spare boss on the top of the cover to drill and tap as an alternative.

Randy
 
You'll also have to swap the shift shafts for both 1-2 and reverse, plus the reverse fork. As I recall the 3-4 shaft & fork will work, but I swapped mine anyway.

I don't believe the plug on the side is for a reverse switch. Instead it caps the bore where the shift interlock goes. The factory put the reverse light switch in various places over the years, but when it was on the LH side, it was maybe 1-1/2" to the rear of the interlock plug. The shaft was also modified to operate the switch.

I think when the factory fitted later TR3s with the (optional) reverse light, the switch was on top near the OD switches. However I've also seen a bracket that hangs the switch out in space, where it can touch the selector casting (where the shift lever engages with the shaft). You might want to investigate using a modern "microswitch" with a custom bracket instead.
https://www.mouser.com/microswitch/

Good luck with those taper pins. They seem to break easily. I recommend buying an 8-point socket to fit (don't recall offhand if it was 1/4" or 5/16") and then using a T-handle to turn the socket (to reduce side load on the pin while undoing it). The pins are NLA (or at least were when I did mine), so care is definitely called for.
 
Randy,
Suggest you measure the clearance between the cover and the heater box on the TR4 as there might not be enough room to fully remove the dip stick. Don't ask me how I know. If there is extra "stick" you might be able to shorten it and have a functional dip stick.
Bob
 
Oof, I hadn't thought of that. I think it will be worth a rough fitting first to see if I have a problem. I absolutely hate having to pull everything just to check and top oil on this setup so I am going to keep my fingers crossed.

Randy
 
TR4nut said:
I absolutely hate having to pull everything just to check and top oil on this setup
Click to expand...
Huh ? Don't you just jack the car up and do it from underneath, like on the later TR3s and Stags ?
 
TR3driver said:
Huh ? Don't you just jack the car up and do it from underneath, like on the later TR3s and Stags ?
Click to expand...

Very true, but I just don't like being under the car that far doing a contortionist act to get to the side fill plug. And to add insult to injury the oil syringe/plunger setup I have isn't leakproof. The last time I did this service work I needed to replace the drive shaft u joints which is why I pulled the cover.

I guess one way would be to get a funnel setup in the engine bay, with a hose fed into the transmission. And then patiently adding and checking fluid levels. But the enticement of a top fill location, with suitable access plug on the tunnel cover sounds good to me.

Randy
 
TR4nut said:
...But the enticement of a top fill location, with suitable access plug on the tunnel cover sounds good to me.
Click to expand...

Why not just add an access plug on the drivers side of the tunnel to allow you to get at the fill plug to check & top up?

That's what I did -- used the same rubber plug as the TR3A uses for the dipstick (and U-joint).

Very easy to do on a '4 with the fibreboard tunnel.
 
Thanks for the explanation, Randy. I never filled the transmission on the only TR4 I ever owned (never drove it either) so I wasn't sure.
 
If this top cover proves to be a pain (and the excellent advice so far suggests it just might be!), then Geo I think that sounds like a very good way to do it. I'm surprised that it wasn't designed that way given the grease access point for the u joint, but Randall's point is well taken on access from below in that the dealership would have had a lift setup and a nifty oil pump to handle everything.

Randy
 
Randy,

AFAIK, Triumph never changed the top cover casting. The bulge for the dipstick should be on your TR4 tranny topcover, although you'd have to drill it out so the TR3 dipstick could be inserted. Would take some fiddling but worth a look anyway.

Jeff
 
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