moss gearbox identification

[Lino]

Hi, can anyone help me with a bit of information please, i am converting my mk2 to a manual gearbox, i have a couple of moss gearboxes how can i tell if they are for a 2.4 3.4 or 3.8?
numbers on box are GBN 24058 JS and GBN 72998 JS
MANY THANKS

[piman]

Hello Lino,

My spare parts manual only covers the 3.4 and 3.8 litre models. It lists the GBN for both engines.
It's just the 2.4 that I have no information on. Incidentally the JS suffix denotes 'shaved gears', whatever that means?

Alec

[Martec]

Hi,

GB and JS is on 2.4, 3.4, and 3.8 gearboxes, the N is for a suitable mainshaft for an overdrive to be fitted!

The moss box is an early synchromesh box with I think no syncho on first gear. The problem with them is that where as the later 'Full synchromesh boxes had a replaceable 'brass' syncho rings, the moss box had the syncho cone as part of the gear. So when the cone/gear is worn it can't be repaired.

I had a moss box WITHOUT overdrive and so a higher ratio differential, as it had 97,000 miles on it and was worn I had to try to learn double declutching, I gave up and fitted a later full synchro with overdrive box (a joy to use and as fast a gear change as you like).

If you wish to fit the moss box then engage first gear and count the input shaft turns to complete one turn of the output shaft.

standard box ratio 2.4 - 14.419 to 1; 3.4/3.8 - 11.954 to 1
Overdrive box ratio 2.4 - 15.365 to 1; 3.4/3.8 - 12.731 to 1

Best of luck
Brian

[Lino]

Hello Lino,

My spare parts manual only covers the 3.4 and 3.8 litre models. It lists the GBN for both engines.
It's just the 2.4 that I have no information on. Incidentally the JS suffix denotes 'shaved gears', whatever that means?

Alec

Thanks Alec,
at least it looks like im on the right path, i didnt really want to use a 2.4 gearbox if i can help it, apart from the gearbox i am trying to keep it as original as possible,(my first mk2 restoration) shaved gears sounds interesting though must look into it.
Thanks again much appreciated

[Lino]

Hi,

GB and JS is on 2.4, 3.4, and 3.8 gearboxes, the N is for a suitable mainshaft for an overdrive to be fitted!

The moss box is an early synchromesh box with I think no syncho on first gear. The problem with them is that where as the later 'Full synchromesh boxes had a replaceable 'brass' syncho rings, the moss box had the syncho cone as part of the gear. So when the cone/gear is worn it can't be repaired.

I had a moss box WITHOUT overdrive and so a higher ratio differential, as it had 97,000 miles on it and was worn I had to try to learn double declutching, I gave up and fitted a later full synchro with overdrive box (a joy to use and as fast a gear change as you like).

If you wish to fit the moss box then engage first gear and count the input shaft turns to complete one turn of the output shaft.

standard box ratio 2.4 - 14.419 to 1; 3.4/3.8 - 11.954 to 1
Overdrive box ratio 2.4 - 15.365 to 1; 3.4/3.8 - 12.731 to 1

Best of luck
Brian

Hi Brian,
many thanks for reply, i am still quite a way in finishing the mk2, i do want to use the moss gearbox though,against my better judgement, i love the old gearchange feel (sad maybe).
I want to try to use 3.4 or 3.8 box rather than 2.4, my next learning curve is flywheels starters and clutches for these.
Love it!!
Again thanks very much Best Regards Lino

[Martec]

Something for you to consider, there are 2 types of clutch fitted to these cars, early multiple coil spring clutch plate and the later more modern 'Bellville' spring washer type. The clutch only has to with stand the torque developed by the engine and stop it slipping and either clutch will do, but your flywheel will be drilled for one type of clutch and require centring and drilling for the later clutch.

I have an early original 3.8 with a multiple coil sprung clutch, I wanted to convert it to the later clutch, but was persuaded to fit an unrated (E type) clutch. A heavy clutch and hip pains made me servo the hydraulics for comfort.

good luck
Brian

[Lino]

Something for you to consider, there are 2 types of clutch fitted to these cars, early multiple coil spring clutch plate and the later more modern 'Bellville' spring washer type. The clutch only has to with stand the torque developed by the engine and stop it slipping and either clutch will do, but your flywheel will be drilled for one type of clutch and require centring and drilling for the later clutch.

I have an early original 3.8 with a multiple coil sprung clutch, I wanted to convert it to the later clutch, but was persuaded to fit an unrated (E type) clutch. A heavy clutch and hip pains made me servo the hydraulics for comfort.

good luck
Brian

Thanks for info, i am currently bidding on a 3.8 flywheel with 104 teeth, so i guess the later clutch wont be a problem as you say if i get it drilled and centered, this has been very helpful and a good idea!
Thank you

[Lino]

Hi,

GB and JS is on 2.4, 3.4, and 3.8 gearboxes, the N is for a suitable mainshaft for an overdrive to be fitted!

The moss box is an early synchromesh box with I think no syncho on first gear. The problem with them is that where as the later 'Full synchromesh boxes had a replaceable 'brass' syncho rings, the moss box had the syncho cone as part of the gear. So when the cone/gear is worn it can't be repaired.

I had a moss box WITHOUT overdrive and so a higher ratio differential, as it had 97,000 miles on it and was worn I had to try to learn double declutching, I gave up and fitted a later full synchro with overdrive box (a joy to use and as fast a gear change as you like).

If you wish to fit the moss box then engage first gear and count the input shaft turns to complete one turn of the output shaft.

standard box ratio 2.4 - 14.419 to 1; 3.4/3.8 - 11.954 to 1
Overdrive box ratio 2.4 - 15.365 to 1; 3.4/3.8 - 12.731 to 1

Best of luck
Brian

Hi Brian
not sure if i am checking this correctly, i marked the input shaft and the output shaft,engaged first gear, the input shaft (shaft clutch sits on) turns three full and a one quarter turn to every one full turn of the output shaft (shaft the diff bolts onto).
Both the boxes do this so at least i appear to be two identical boxes.
Thanks again for any help and advice you can give me.
Best Regards Lino

[Martec]

I'm really sorry about that, I've looked at the Jaguar manual again and I gave you the figures for overall gearing, engine turns for one turn of the wheel.

It seems that they used the same prefix and suffix on 2.4,3.4 and 3.8 boxes, but also there is only one set of gear ratios quoted for the moss box of
3.377 to 1 first gear
1.86 to 1
1.283 to 1
1 to 1 top gear

The later full synchromesh box gear ratios are
3.04 to 1
1.973 to1
1.328 to1
1 to 1

Jaguar seem to have used 4 different diff ratios, two for the 2.4, overdrive and non overdrive box, and two for the 3.4/3.8, again overdrive and non overdrive. It maybe that they used the same box for 2.4,3.4 and 3.8???? and then used a different diff to get the overall gearing.

The manual says the later full synchro box is not a direct replacement for the earlier moss box. it requires a different bell housing, clutch release bearing and prop-shaft, can't remember what happened with the gearbox support.

Sorry for the confusion I caused, I hope the above helps.

Best wishes
Brian

[Lino]

I'm really sorry about that, I've looked at the Jaguar manual again and I gave you the figures for overall gearing, engine turns for one turn of the wheel.

It seems that they used the same prefix and suffix on 2.4,3.4 and 3.8 boxes, but also there is only one set of gear ratios quoted for the moss box of
3.377 to 1 first gear
1.86 to 1
1.283 to 1
1 to 1 top gear

The later full synchromesh box gear ratios are
3.04 to 1
1.973 to1
1.328 to1
1 to 1

Jaguar seem to have used 4 different diff ratios, two for the 2.4, overdrive and non overdrive box, and two for the 3.4/3.8, again overdrive and non overdrive. It maybe that they used the same box for 2.4,3.4 and 3.8???? and then used a different diff to get the overall gearing.

The manual says the later full synchro box is not a direct replacement for the earlier moss box. it requires a different bell housing, clutch release bearing and prop-shaft, can't remember what happened with the gearbox support.

Sorry for the confusion I caused, I hope the above helps.

Best wishes
Brian

Many thanks again for reply,
this is of help to me, it sounds like i can fit the moss gearbox and keeping the same axle i should be ok, i have now the flywheel (104 teeth), i will look for the starter and then i can start rebuilding the engine and fit the box, long way to go but going extremely well.
Again many thanks for your help.
Regards Lino