5 speed manual Conversion information

[quarrymot]

Hi,
I am NEW to the forum, and wanted to know if there is a good manual 5 speed conversion for the stag with Stag V8 engine, i do have a TR7 and Rover 5 speed and wondered if anyone has fitted either of these 2 gearboxes to the stag before?
With thanks Neil.

[jleyton]

Hi welcome to the forum and I'm sorry nobody has come up with an answer to your question yet.

I'm afraid I don't know the answer either, but why do you want to fit a 5 speed box when, if you've got overdrive, you've already got a 6 speed box ?

That's said a bit tongue in cheek but overdrive top certainly gives you the equivalent of 5th gear and with around 25 mph/1,000 rpm that's pretty high gearing. My modern car gives about 35mph/1,000 but I wouldn't have thought that many 5spd boxes from that era will offer much better than the Stag's overdrive top.

Cheers

Julian

[Kevin Garrod]

There is a Toyota 5 speed conversion, but I think the boxes are a bit thin on the ground these days. Contact Bob Heritage on this forum, he may be able to tell you a bit more.

[mjheathcote]

Yes the Rover 5 speed manual gearbox has been mated to the Triumph V8 before, as long ago as in the 80's.
Have a good search on this forum for details, it has been covered before. It hasn't though been popular.
Cheers
Mike

[Peter Hills]

Hi Mr Quarrymot,

Once upon a time there were some adaptor plates made which were drilled to fit the Stag block and the Rover LT77 gearbox bellhousing. Unfortunately, I do not know the wheabouts of either a spare plate or a drawing from which you could have one made. However, maybe somebody on the forum might know of a source.

Hope this helps.

Happy New Year

Peter Hills
Modified Stag Co-ord, SOC

[flying farmer]

I have used a Dolly sprint engine backplate and adaptor ring to fit a Stag engine into a Toledo (I needed the box to be upright, not leaning), and several of the holes in the adaptor plate were common to the stag block, the rest I redrilled to suit. On this basis I reckon a TR7 backplate could be used to fit an LT77 box to the back of a Stag engine, I think the clutch plate is the same size as the rover V8, so a rover clutch plate would do the job.
Personally I don't like the LT77 box as I have worn out and broken them far more easily than the Stag manual box, the splines where 5th gear fits on the layshaft are a weak spot, and they seem to eat their bearings more regularly too.
If you are converting from an auto box or a full overdrive and box rebuild are required, then the LT77 might be a cheaper option, if you can find a good one. If the LT77 needs a layshaft, it used to be far more expensive to rebuild than the Stag box
Neil

[quarrymot]

Hi,
Thanks for the advise, i have a 4 speed manual without overdrive from a stag, that i can put in the car, but thought a 5 speed would be nice, however i guess my best option would be to fit the 4 speed for now and hope to find a good overdrive box at some point.
With thanks Neil.

[Peter Hills]

I have used a Dolly sprint engine backplate and adaptor ring to fit a Stag engine into a Toledo (I needed the box to be upright, not leaning), and several of the holes in the adaptor plate were common to the stag block, the rest I redrilled to suit. On this basis I reckon a TR7 backplate could be used to fit an LT77 box to the back of a Stag engine, I think the clutch plate is the same size as the rover V8, so a rover clutch plate would do the job.
Personally I don't like the LT77 box as I have worn out and broken them far more easily than the Stag manual box, the splines where 5th gear fits on the layshaft are a weak spot, and they seem to eat their bearings more regularly too.
If you are converting from an auto box or a full overdrive and box rebuild are required, then the LT77 might be a cheaper option, if you can find a good one. If the LT77 needs a layshaft, it used to be far more expensive to rebuild than the Stag box
Neil

Yes, the LT77 gearbox is known to be somewhat fragile, however there was a direct replacement - possibly a derivative - called the R380 gearbox, which is believed to be much stronger. This was used for the later MGB RV8 cars and also Range Rovers and Discoveries. Might be worth lookig for one of theses.

Happy New Year

Peter

[Guest]

Hi all, been away for a while just started work on my Stag again so I need a little help on this tranny question. How do I mate my TR7 5speed to my 73 stag.

[andy p]

ive never seen a manual stag without overdrive, I thought they all had it

[stagmuffin]

ive never seen a manual stag without overdrive, I thought they all had it

quite a few early stags were fitted with 4speed non overdrive box,s. must of been a headache cruising at 70 ..............

[jleyton]

quite a few early stags were fitted with 4speed non overdrive box,s. must of been a headache cruising at 70 ..............

Hi Steve,

I agree, but it wouldn't be any worse than an auto. The mph/000 in 4th, without overdrive, is the same as an auto in 3rd.

Thank heavens for overdrive

Cheers

Julian

[GDPR]

No Andy, overdrive was optional on early cars - the Mk1 engine I rebuilt last year had non-overdrive transmission. Early Dolomite Sprints were all non overdrive (and all mimosa yellow!)

[davidf]

My Stag was registered April '72, commission number in the LD11900 range, and had a non-overdrive 4-speed manual box when I bought it in 1997. That it was originally built like this is confirmed by the commission plate; there is no letter 'O' on the end. I read somewhere that overdrive only became a standard fitting on manual boxes from late 1972.
I rebuilt the car with an overdrive gearbox left over from a previous write-off (fire).

[Guest]

Five seed conversion

ive never seen a manual stag without overdrive, I thought they all had it

Hi, I did a lot of research last year before getting a side tract with family matters; then heart surgery to top it all my COPD was aggravated with three bad infections: Found that all cost mega bucks or like the overdrive unit were almost unobtainable so got a TR7 tranny.

The TR box will mate up to the block which I had to bore out to 40 grand owing to water damage as the intake manifold manifolds were badly fitted and coolant water flooded the cylinders then left idle for decades. To bad as all the car is in great shape with absolutely no rust that includes the floor pans.

Questions I have, although the box has most of the bolt holes to block in the right place not all but most, I understand, I think that I need a spacer which came with the manual Stag trans, also a Stag flywheel.
What else do I need? pedal box, master cylinder, slave cylinder, etc. Anybody got parts and or advice.

Some head scratching guys this is my first foray into the beautiful Stag.

John