I think I have a TR6 gearbox in my Stag!?

[jpyke]

...and I don't mean a TR6 box with Stag innards, I think it is a completely TR6 box. Could this be the case?

The clues:

1. Between the engine and the gearbox there is a cutdown auto adapter plate, followed by the manual adapter plate followed by the gearbox. This has been very neatly done, it must be said and has the effect of spacing the gearbox away from the engine by an extra 13mm or so.

2. Despite being 13mm further back than normal, the gearbox input shaft mates nicely with the spigot bush in the centre of the flywheel, and certainly would not be able to go in any further.

3. There were no spacers or anything equivalent between the end of the crank and the flywheel.

James

[jpyke]

Hmm according to this site http://club.triumph.org.uk/cgi-bin/f...?m-1136204129/ it looks like its from a TR4 ...

[Rod1883]

I'm pretty sure it's not TR - they are TS (3 synchro) and CT, CC, CD, CF (4 synchro).
This Club Triumph site lists all the prefixes - it suggests that yours might be Dolomite Sprint?

http://www.club.triumph.org.uk/prefix1.htm#Dolomite

Alternatively that might be a date stamp - is there another number stamped anywhere else on either side of the bell housing or on the main case?
Rod

[dasadrew]

The input shaft nose certainly looks different to the Stag shaft nose

[Stagdad]

The input shaft nose certainly looks different to the Stag shaft nose

Just looked at pics of mine and agree the input shaft looks different.

Cheers Steve

[jpyke]

Hmm that must mean that I maybe have a dolomite flywheel too? Perhaps not if the end of the shaft is the same. Could anyone post a pic of a stag input shaft for a comparison?

Bit odd really - the car was originally auto but was changed to manual J type at some point. Really not sure why they'd have gone to such efforts to adapt it in this way rather than just put a manual stag box in, unless it happened when the car was still in Hong Kong and there wasn't anything else readily available.

I'm not sure what the best thing to do is really, I had it in mind not to touch the box, just replace the seals at each end because it worked perfectly and changed gear really well. I've always thought I must had had a "good un" because I've never really found it notchy or any of the other complaints about stag manual boxes that occasionally surface.

[Stagdad]

Here you go ,obviously ignore all the other bits that dont look like yours.If it works well wy not keep it.

Clutch bearing 029.jpg

[jpyke]

Cheers Steve... As it happens I was thinking not to ignore all the bits that don't look like mine as I was planning to pick your brains soon to do the same conversion

I've just look on rimmers and my input shaft certainly does look like a dolomite sprint one. Bugger, that will likely mean that my fancy new AP racing clutch and cover plate won't fit. Grrrr.... bought it a year or so ago now too, so unlikely to be able to change it.

[jpyke]

Well here's the last piece of the mystery... On the left/above, the clutch plate that came out. On the right/below a new Stag clutch plate. This would confirm that it is a dolomite gearbox and explain why the clutch would slip a bit if you pulled away hard!

[flying farmer]

The VA prefix on the gearbox confirms it is a Dolomite Sprint gearbox.

I think the Sprint clutch plate is 8 1/2 inches in diameter against 9 for the Stag.

If your new clutch cover fits the flywheel it will be a Stag flywheel.

IIRC the Sprint flywheel is pretty much an even thickness on the engine side whereas the stag one is recessed towards the ring gear, and is a lot heavier as is required for a 4 cylinder.

The odds are that a Sprint clutch plate will fit the Stag clutch cover, so one option would be a second hand Stag flywheel if yours is a Sprint item, then use a new Sprint clutch plate with the Stag cover. The Stag cover should have a
stronger spring and so grip the Sprint plate more tightly.

Neil

[jpyke]

The VA prefix on the gearbox confirms it is a Dolomite Sprint gearbox.

I think the Sprint clutch plate is 8 1/2 inches in diameter against 9 for the Stag.

If your new clutch cover fits the flywheel it will be a Stag flywheel.

IIRC the Sprint flywheel is pretty much an even thickness on the engine side whereas the stag one is recessed towards the ring gear, and is a lot heavier as is required for a 4 cylinder.

The odds are that a Sprint clutch plate will fit the Stag clutch cover, so one option would be a second hand Stag flywheel if yours is a Sprint item, then use a new Sprint clutch plate with the Stag cover. The Stag cover should have a
stronger spring and so grip the Sprint plate more tightly.

Neil

Hi Neil thanks for your response... I was hoping you may be able to offer some advice as you're probably familiar with the innards of both types of box!

So, the stag clutch cover won't fit so its definitely a dolomite sprint flywheel (which kinda makes sense given everything else in the conversion isn't stag).

It looks like the sprint clutch plate will work ok with the stag clutch cover, if I get hold of a stag flywheel, but I'd be reluctant to use my new AP uprated cover with a smaller diameter clutch plate as it will start to wear it and I'm not sure what this would mean if I wanted to change the box later on and go to a standard stag plate where the wear area wouldn't match the plate.

What I am wondering is how similar the innards of the box are; I think it would be too much to hope for to swap the input shaft and nosepiece(?)

[jpyke]

?..the stag one is recessed towards the ring gear, and is a lot heavier as is required for a 4 cylinder...

Did you mean that the stag one is heavier or should it be lighter?

cheers

James

[NickA]

What I am wondering is how similar the innards of the box are; I think it would be too much to hope for to swap the input shaft and nosepiece(?)

Parts catalogs have the innards pretty much the same; as least as gears 1-3 go. 4th is a different part but that's part of the input shaft so it might be just a case of swapping this one over.Main shaft has same part no as well. If you want scans of the two catalogs let me know

cheers

Nick

[jpyke]

Parts catalogs have the innards pretty much the same; as least as gears 1-3 go. 4th is a different part but that's part of the input shaft so it might be just a case of swapping this one over.Main shaft has same part no as well. If you want scans of the two catalogs let me know

cheers

Nick

Hi Nick.

I have a copy of the Stag parts catalogue, if I can have the scans of the Dolomite that would be most appreciated

James

[flying farmer]

Did you mean that the stag one is heavier or should it be lighter?

cheers

James

The Stag flywheel is a lot lighter as it has to carry the crank only half the distance between firings compared to a 4 cylinder.

I did consider fitting a Stag input shaft to my TR gearbox when I fitted the Stag engine to the TR, however I found I was able to buy a complete gearbox for the same price as a new input shaft. Then you need to add a new nosepiece and bearing carrier, plus the flywheel.
I wonder if it is possible to get uprated Sprint clutches that might handle the torque better and be the cheaper option?

Neil