Is a Triumph overdrive tranny all that?

[jjbunn]

I actually prefer having the switch on the steering column: it adds to the novelty value, not having to touch the gear stick. Maybe once I've used it for a while I wont be so sure.

 

[Guest]

Actually, the stock location for the OD switch is quite convenient. Be warned that the aftermarket switch that is available (all from the same Taiwan manufacturer, I believe) is wired backwards, that is, down is on/up is off. My OE drivers manual shows up is on/down is off. I had to modify my aftermarket switch to work backwards. (Geez, I wonder now if I could'a just reversed the wires?) Also, you might consider bending the arm a bit for it to be comfortable for long-legged drivers, the knee often will activate the switch.

 

[2wrench]

Thanks, gentlemen.

Great pics, Julian. I appreciate the extra effort.
As you go, do you think you could find the time to
photo document this tranny upgrade/rebuild? I am
asking personally (tranny rebuild for dummies), but
the Forum would appreciate it as well, as I do not think
such tread, in photo detail anyway, exists.

If it were, we both would probably appreciate being
referred to it.

And, yeah, wherever, I do need to find the speedo angle
drive.

 

[2wrench]

Found two speedo angles on line. One $75; one $150.
Bought the more expensive (get what you pay for?)

This is what I got. Tell me again where this
thing goes......

 

[jjbunn]

Found two speedo angles on line. One $75; one $150.
Bought the more expensive (get what you pay for?)

This is what I got. Tell me again where this
thing goes......

I think you maybe got the wrong size ...

But srsly ... in fact the angle speedo drive I received, and shown in the photo, is in two parts. There's the angle drive itself, which looks identical to one I fitted on my MGB, and then there is a connector piece (that screws onto the knurled brass ring) that is attached to the J O/D. I suspect (but haven't checked) that the connector piece is more difficult to come by. The MGB angle drives are regularly on Ebay. E.g. this one:

https://cgi.ebay.com/ebaymotors/1976-MGB-...1QQcmdZViewItem

Can anyone confirm or deny that this is the same as the one we need?

Perhaps your best bet is to go to the Quantum Mechanics people.

I don't know when I will start in on the O/D fitting ... it very much depends on how quickly I complete all the other jobs on the TR6 first. My plan is to get the car on the road, and drive it a while, and then fit the O/D when I'm happy with the mechanics.

One other piece I know I need, and don't have, is a mounting for the O/D, to secure it in the transmission tunnel, between the floorpans. I'm expecting to be able to follow the Buckeye Triumph instructions and fabricate my own.

 

[TR3driver]

There's the angle drive itself, which looks identical to one I fitted on my MGB, and then there is a connector piece (that screws onto the knurled brass ring) that is attached to the J O/D.

Right.<div class="ubbcode-block"><div class="ubbcode-header">Quote:] I suspect (but haven't checked) that the connector piece is more difficult to come by.[/QUOTE]No, it's also readily available. But it's also clearly part of the OD, so should be included with it.<div class="ubbcode-block"><div class="ubbcode-header">Quote:] The MGB angle drives are regularly on Ebay. E.g. this one:

https://cgi.ebay.com/ebaymotors/1976-MGB-...1QQcmdZViewItem

Can anyone confirm or deny that this is the same as the one we need?[/QUOTE]That's it.

 

[TRDejaVu]

Close up of speedo angle drive, and where it fits on the O/D:

I am getting ready to convert my non-OD TR4 to OD with a TR6 A Type transmission that I recently got on eBay. I also bought an angle drive from a BCF'er that was from a TR4A (shown below). The TR6 OD has an external thread (male fitting about 5/8ish) and the angle drive has 2 male fittings. As you know the setup is different on the J Type, so does someone have a picture of whatever adapter I am going to need to get this angle drive to connect to the A Type OD?

As always, I appreciate your help.

 

[TR3driver]

Ian, that is exactly the same angle drive that Julian showed, it just has the adapter from an A-type stuck in it while Julian's has the adapter from a J-type stuck in it. Just remove the adapter (the brass piece with the external threads) from the cap (the brass piece with the knurling on it) and you should be good to go.

 

[glemon]

I had one of those angle drives and ebayed it a few months ago--oops guess I'll have to get another /bcforum/images/%%GRAEMLIN_URL%%/wall.gif

 

[TRDejaVu]

Thanks Randall; it was all gunked up and looking like a single fitting.

So does this mean that different adapters were used through the A Type production run or maybe the speedo drive shaft inside the OD had been replaced with a newer design; the red nylon gear looks too modern? I have included a picture of the drive assembly with the brass fitting from the angle drive next to it. As you can see the brass fitting has a larger OD than the aluminum drive piece.

Edit - just saw an original inner speedo drive on eBay with the metal gear teeth. However there is still the question of the outer aluminum drive sleeve and the different size thread.

 

[2wrench]

Regarding installation of overdrive to upgrade from
standard four-speed tranny, I post the following
information as provided me by the seller of my
rebuilt overdrive upgrade unit regarding installation:

Dennis, ok

1/ make sure oil is drained, Remove lid/remote 8 bolts 1/2' AF spanner.
2/ with screwdriver select 3rd or 4th gear and also reverse gear.
3/ trans should now be locked so undo nut holding on flange at rear and remove flange.
4/ remove speedo drive gear from side of tailhousing.
5/ undo bolts holding on tailhousing and remove housing.
6/ remove speedo drive gear off mainshaft, also circlip holding on large bearing.
7/ remove front clutch bearing carrier, 4 bolts. Inside bell housing, goes over input shaft.
8/ remove small plate at front, covering layshaft hole, 2 bolts.
9/ remove plate at back, retaining layshaft and reverse gear shaft.
10/ push out layshaft, push from front with screwdriver, out back.
11/ Drive mainshaft forward through large bearing, this will push out input shaft, (do not let it drop on your foot.)
12/ remove rear bearing off mainshaft, mainshaft will now lift out top of trans with gears on it.
13/ remove front circlip off mainshaft and take off gears and bush,s.
14/ put all these gears onto the mainshaft I supply, and assemble trans opposite of stripping down.
15/ fit overdrive adapter on to back of trans, then making sure the cam lines up with the cam follower hole, push on overdrive. Turning flange all the time until overdrive slips on easily, (do not force it ).
Reading this might look confusing , but when you get started it will all be clear.

My comment: Sounds like a piece of cake, right?

 

[TR4nut]

I am getting ready to convert my non-OD TR4 to OD with a TR6 A Type transmission that I recently got on eBay. I also bought an angle drive from a BCF'er that was from a TR4A (shown below). The TR6 OD has an external thread (male fitting about 5/8ish) and the angle drive has 2 male fittings. As you know the setup is different on the J Type, so does someone have a picture of whatever adapter I am going to need to get this angle drive to connect to the A Type OD?

Ian-

You may know this but I'll add it just in case:

The angle drive is fine if you have one, but if the floorboards on your TR4 are original you don't have to use the angle drive as the cable connects straight through. There is space to accommodate the cable with the rubber seal that you have for the emergency brake. The angle drive, if it works, is probably easier though.

Randy

 

[TR3driver]

IMO, I wouldn't use the angle drive unless absolutely necessary (which should not be the case on a TR4). They are expensive and fragile compared to the extra-long cable that the factory used instead. And while it's bad enough to have an angle drive fail for no apparent reason, it's even worse to discover that it failed because something else was binding (thereby ruining the replacement angle drive as well). BTDT (well, to be precise it was a PO who replaced the angle drive without realizing that the speedo binding was what ruined it).

I believe the all-aluminum carrier shown above is from a later A-type (as used on TR6 and other cars). The earlier units were brass and used the adapter piece (with or without the angle drive).

 

[TR3driver]

My comment: Sounds like a piece of cake, right?

Yup, that's what it <span style='font-size: 14pt'>sounds </span>like !

 

[2wrench]

Randall: I catch your drift. I'll likely sub this one
out, though through my ignorance, I tend to gravitate
to the do-it-yourselfer.

Anway, my car is a '74 TR6. So just to clarify, what's
the verdicit? Do I need a speedo angle or not? Maybe
I'm just dizzy, tired or something.

 

[TR3driver]

On a TR6, you need the angle drive. TR2-4 (but not 4A) have a cutout for the cable to come straight off the OD, but the later cars don't.

I'm not saying you can't install the OD yourself, just that it's nowhere near as easy as those instructions make it sound. Just removing that circlip has been known to bring strong men to tears ... or threats of mayhem. Definitely a 4 wrench job in my book. In fact, I think I'll take another stab at duplicating Churchill 20SM69 (the circlip removal tool) before trying it again.

 

[2wrench]

Randall, you got to know I respect you. I'll likely
hire it out, although I have been known to do some pretty
dumb things in my life, nonetheless.

 

[Norton47]

FWIW, here is some other transmission rebuild info.
https://www.tr6web.com/Documents/tr6/TranIntro.html and this link is to the Greasy Hands guide.
use the files starting with TR, https://www.vintagetriumphregister.org/maintain/TransRebuild/
you may have seen already.

 

[2wrench]

By the way I thought I might install the OD on my current non-OD transmission main body. It works great with no noise and is fully synchro.
Can be done, correct?

If your current box is 4-synchro; and the OD one is 3-synchro, then you will need a different mainshaft for the swap. Exactly which mainshaft depends on exactly which gears your 4-synchro has. If the gearset is from a post-73 TR6, you may need to either buy a custom mainshaft or convert to an earlier gearset.

May also need some minor modification (with a die grinder) to the adapter plate. ISTR the early plates didn't have clearance for the countershaft end & retainer, but I could be mistaken on that point.



Although within the DIY realm, swapping an OD is not for the faint of heart, as it basically involves a complete teardown of the gearbox (in order to replace the mainshaft). The TR3 workshop manual shows the 3-synchro procedure (which is similar for the 4-synchro box).

Likely you'll also need to do something about the lockout switches, since the later non-OD top covers were usually not drilled & tapped for them. You can either drill & tap your 4-synchro cover, or rebuild the 3-synchro cover using the rails & forks from the 4-synchro.

Randall and Forum Family:

Took my tranny to a mechanic for rebuild/overdirve
upgrade. He has contacted me asking for specs as to
where to drill to place the lockout switch. He also
mentioned to me something about forks...whatever. I didn't
wholly understand his needs and/or comments re forks.

Can you figure just what his concerns might be regarding these sorts of things? Can anybody out there help us? Sorry if I'm unclear with the problem, but I'm a bit ignorant myself, as you likely well know. I think the
tranny being upgraded is a four-speed synchro, but not
even positvie about that....except to say it's a TR6 April
'74 with four-speed. Does synchro come part and parcel?

Also, he asked if something was missing, like the
terminal switch. So I suppose I need to buy the
switch that goes onto the steering column from Quantum?

And is there more, like a wiring harnass or some other
such things to complete upgrade and installation? Do you
think the on/off switch on the steering column is what he
is addressing when he says terminal switch or is this
antoher part? I think the "terminal switch" mentioned
by him is a different thing than the lockout switch, because
he has that and wants to know where to put the little
devil.

Yikes!

Any help is appreciated, thanks,

 

[Geo Hahn]

Column switches are available from the usual vendors as well as Quantum. Quantum also sells the harnesses for the ODs. As I recall there are 2 harnesses, upper and lower.

You could fashion your own out of stock wire but some FO will curse you if the wires aren't color-coded correctly.

I believe that isolator switch will have him drilling at tapping a hole in the boss on the cover that is just above the 3-4 selector shaft. There may also be some fussy adjustment to the mounting of the switch so it operates properly (vaguely recall seeing a diagram of the clearance between the switch button and the selector shaft.

I cannot say if it is simply a matter of centering the switch on the correct boss (though that seems likely) and setting the depth so the shaft closes the switch when 3 or 4 is engaged.

As for other questions, the gearbox you describe would certainly have a synchro first. I know of no particular reason why this change would require forks replaced but he may have seen something that indicates they are bent or whatever (do TRs suffer from bent forks? I know Fiats are plagued by this).

Appeared before but here is the top cover of a TR4 box showing its pair of isolator switches (and no reverse light switch).