Stag stag engine and transmission

[rockman]

I am working on resurrecting a 71 stag bought without an engine or transmission. I found an engine original triumph
I bought from the wife of a restorer that had tightened his last bolt,she had no idea of its origin, a friend assayed it and felt it was tight. Now I have access to what is described as a j type transmission or maybe J type overdrive and will have to act on it before I get the engine. My big question that I am leading up to is Are there any variation in the design of the gearbox in association with the motor and drive shaft any insight would be welcome Cheers Jeff

 

[TR3driver]

Hi Jeff :
If the motor was orginally setup for a manual trans; and if the transmission in question came from a Stag, then it should bolt right up to the motor & driveshaft. You'll need a different rear crossmember for the J-type OD, plus some other odds & ends like the lockout switch in the top cover, an angle drive for the speedo cable, and a different speedo cable. The original Stag OD setup used a special shift lever & knob with the OD switch in the knob, but you can put a switch anywhere you want. You'll also need to either modify or replace the exhaust. (For my most recent conversion to J-type, I just bent some brackets to go between the original pipes and the tail of the J-type. Seems to be working so far.)

Note that there is a separate aluminum "flywheel housing" that goes between the gearbox and cylinder block. Also a TR6 gearbox won't work, as the input shaft is too short. (There are also internal changes in the gearbox to handle the increased power.)

 

[rockman]

WOW Thanks for the reply very informative. I am still at a loss on what the motor was mated to. The motor did not have its flywheel I am still in search of that. Is the crankshaft mount different(manual-auto flywheel)? The big question is the bell housing bolt up different. I might be able to solicit a friend to obtain the engine #'s would they give me some insight.
The box does have the bell and the cross member and there is wiring in the shift lever left in the car so the exhaust may be set for an overdrive. Then again I don't know if that shift lever came with the car. its owner stated that it did not come with OD. It is a fun science to figure out. Thanks again Rockman

 

[WA1KWA]

Not familiar with the Stag V8, but, most manual transmission vehicles have a pilot bushing in the end of the crankshaft. Automatics do not. Hope this helps.

Colin

 

[Brosky]

<div class="ubbcode-block"><div class="ubbcode-header">Quote:] most manual transmission vehicles have a pilot bushing in the end of the crankshaft[/QUOTE]

Colin,

Every manual transmission that I've ever seen has one. That is what keeps the transmission mainshaft in alignment with the crankshaft. I wouldn't want to drive a car for long without it, which brings up another question.

Are the crankshafts installed(automatic vs. standard built car)all the same? Do they have a machined area to install a pilot bushing properly?

 

[TR3driver]

The crankshafts are the same between auto/manual I believe. Definitely a pilot bearing for the manual, which IMO you should replace as a matter of course, and I believe all cranks are machined to accept it.

The transmission bolts to the "flywheel housing" I mentioned, which is definitely different between the auto & manual engines.
Rear Engine Plate

Also worth noting that there are two special "dowel" bolts in that joint, which appear to be NLA. I made some from "drill rod" stock; or it's been suggested that there may be an aircraft (AN) bolt available that will work.

I'm not certain, but I believe the engine number would have either a "BW" or "A" suffix if the engine was originally built for an automatic gearbox. There are other suffix letters to indicate other options, but no special letter for manual/OD. If it's a US-spec engine, then the suffix should be either "UE" or "UEBW", with the latter being for the BW35 auto box.

Jeff, you might like to join us on the Stag forum . There are several people there who have gone through the conversion from auto to manual. I'm glad to help if I can, but I've only gone from 4-speed to J-type.

Here's a drawing that shows the non-OD exhaust :

 

[rockman]

Hero's The car was offered less the motor and box, I did not want it unless I could find the original running train.
Imagine I found the motor the next day on craigslist, who would have thought that was possible. I bought the car and the motor felling sure I could find the correct box with a little research, but within days a box with OD came available at a killer price"Yes" but lots of questions. Now I can fell like I am making an educated decision. Cheers! Rockman

71 Stag soon to be resurrected
52 MGTD driver 34 years going through a face lift
53 Triumph Mayflower resent acquisition in great condition

 

[RonMacPherson]

England has several Stag refit companies there. Tony Hart and Monarch come to mind. Might want to do a search for Stag transmission repairs. Might be able to contact a shop that can fill you in on any concerns/questions you have.