I have the motor and gearbox out of our 1959 Frogeye for winter maintenance.

The Motor is a 948, head casting number ties up with this, but the gearbox is a rib case variant, of which the build number is 13796. Is this a 948 box (9CC) or a later box, how can I tell.

I would as ever appreciate some guidance from the experts out there.

If the case has ribs it's not a trans that came with a 948, it came from a later car. This is a good thing actually, as the rib case gearbox has a number of improvements over the smoothcase transmission.

OK, I thought so but the improvements are not totally clear to me.

Biggest improvement is you can rebuiild a Rib Case Gearbox and they are built with better materials.

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Jim Gruber - Tampa/Riverview FL
Bugsy I - '68 Sprite w BE Bonnet - Gone but not forgotten
Bugsy IV - '60 Bugeye - 1,275+.040 and a 5-Speed - CA Car - 2nd Owner from new -
A truly rust free, garaged in Los Angeles for 57 years Bugeye

OK, all out there, I have the gearbox a part, but I am still confused as to whether I am ordering parts for a ribbed case 948/998 or 1098.
The gearbox casing has the number 13796, I have just take the numbers from 3 gear sets as follows; laygear cluster L22G76, reverse gear 22A453 and the 1st motion shaft 22G172.

So the question is do I buy parts for a 948 or 1098??

Await your expert responses.

Gearbox identification for Sprites and Midgets can be very confusing. The following is my understanding of what you have (80% sure):

From your parts numbers of the internals, your parts are from a Mk111 Sprite, ribcase 1098 which had engine numbers from 10cg to 10cg H4641.
These are designated at type A gearsets. 10cg H4642 and after were produced with type B gearsets which were not interchangeable with the earlier type A.

So, to answer your question, order for a 1098, with the above descriptions.
Good luck, Scott in CA

Hi Scott, many thanks, you have confirmed what I have also now concluded.
Have a great Christmas!

Stephen,

You have an A-cut gear set in that gearbox as fitted to Mk 11A, 10CG motored vehicles. There are some gear ratio variations between different A-Series cars. For example, the Mk 2, A40 Farina had a ribbed A-cut gearbox with a bigger gap between 2 and 3. All the later B-cut gears will fit in that case and the Mk 11A had the same ratio's as the the ones in Mk 3 Sprites onwards. However, the tooth form angle is different so the individual gears cannot be mixed and matched. They will make a horrible noise and chew out quickly. Sadly, parts for the 10CG ribbed case gearbox are very rare as they were only run for a little over one years production and you might have to buy a full set of the later gears unless you have access to old stock. I have some new (eg 12G76 cluster and 1st gear ring) and some second hand parts intended for future maintenance on a stock gearbox. Typically, the 1st gear sliding ring, 1st gear on the cluster and the reverse gear chop out first. Replacing synchro rings may 'restore' the use of second, third and top gear. If you have the ability, post photo's of the condition of your gears.

Early gearboxes used shrunk-on brass cone synchronisers and I know of no one who will rebuild them. The 11A 'boxes were the first to use 'modern' replaceable synchromesh rings and the Mk 3 B-cut gears were introduced to reduce noise levels but are probably no stronger. In my experience 11A gears wear and get noisy while Mk 3 gears work until they lose a tooth. To clarify, 'big crank' 10CC 11098 cc Mk 3 gears are the same tooth form angle as the 1275 gear sets. They are the same ratio's as the Mk 11A but a different tooth form angle.

Good luck!

Roger