T3 final drive gear set options

[glenm64]

Hi Folks
A bit of context. Ive had old faithful for around 40 years, she has a lot of mods and still pulls like a train. When I build her (1000cc, 40mm PHM, P3 cam, 38mm Marzocchi front + more) the final drive gear set wasnt a good match as it felt like I needed another gear. I fitted 8/33 and besides needing a bit more feathering of the clutch it suited my riding here in the wide open spaces of Western Australia. As time goes by my speed has come down a bit (age, speed cameras, morons on the road etc).
On a recent oil change there was a bit of metallics in the oil. I opened it up and there is pitting in the gear set, so I think sooner rather than later I will need to rebuild it.
I am thinking to increase the ratio a bit but dont want to go back to 7/33. Will the 8/35 from a V7 sport fit in the later T3 final drive. My initial enquiries say it will, but I would like confirmation from the brains trust here please.
Thanks in advance

[bmc5733946]

I'm pretty sure that all the Tonti gear sets will fit any Tonti housing. The only caution is number of splines on pinion shaft. An expert will be along in a few moments to give correct information.

Brian

[guido guzzi]

Beautiful bike!
If you want to use a drum brake final drive (complete unit) you will need something like this https://www.mgcycle.com/index.php?main_page=product_info&cPath=72&products_id=5249
because the drum brake final drive housings were shorter. Not sure what's needed if you want to transplant the gears from a drum brake model into your existing housing... 

[John A]

The reason for the difference in the length so a spacer is needed is they went to wider pinion support bearings on the bevel box. It’s about.040”, which I use when I make my own.

[Antietam Classic Cycle]

The reason for the difference in the length so a spacer is needed is they went to wider pinion support bearings on the bevel box. It’s about.040”, which I use when I make my own.

It's not the pinion bearings, it the thickness of the flange of the pinion carrier. It's 2 mm thicker.

[guido guzzi]

So can 'drum brake' gear sets be used in 'disc brake' housings?

[Antietam Classic Cycle]

So can 'drum brake' gear sets be used in 'disc brake' housings?

Yes.

[glenm64]

Thanks Gents
I dont want to fit an early style rear drive, only change the gear set. I think the 8/35 will be a perfect match for the old girl (and me).

[John A]

It's not the pinion bearings, it the thickness of the flange of the pinion carrier. It's 2 mm thicker.

I thought that with the larger ujoint, I think some later T’s had them but the pinion carrier bearings collectively were the .040 wider, starting about then.

[glenm64]

Could someone confirm the number of splines on the earlier V7's pinion shaft versus the newer models please?
Again TIA

[Antietam Classic Cycle]

Could someone confirm the number of splines on the earlier V7's pinion shaft versus the newer models please?
Again TIA

They're the same. The only ones that are different are Convert/Cal II Auto and some rare Californias (IIRC) which have 20 splines.

[John A]

It's not the pinion bearings, it the thickness of the flange of the pinion carrier. It's 2 mm thicker.

This am I remembered a conversation with Dave Hewitt ( tech rep) where he told me that they had done testing on that flange and had made it thicker after finding it did flex. I wonder if the thicker flange came with the wider bearings?

[glenm64]

They're the same. The only ones that are different are Convert/Cal II Auto and some rare Californias (IIRC) which have 20 splines.

Excellent, thanks Gents.

[moto-uno]

  Given any thought to a different wheel, tire combo ?