Gearbox Seals

[Colin Byrne]

Hi Guys, building up my Close Ratio Gearbox at the moment, all going together well and will post some pics soon.  I've just noticed that there are three o ring style seals that seal the selector shafts as they pass through the gearbox case.  As there is a big hole in the bell housing for the rods to pass through this is a bit of a leaking point.  Does anyone know where i can get new ones from?  I'm going to try a normal seal supply shop during the week but they appear to be a strange combination of a square and a round o'ring.  Anyone else come across this problem?

[Barry Edmunds]

Col
Suggest you have a chat to Bruno, Vin or Hugh as they are very experienced with these units

Barry

[vin sharp]

Hi Colin,
Later gearboxes have shorter shafts that don't protrude and the bellhousing is cast closed in that window area; problem solved by the factory......not much help for early boxes though. In any case, I'm looking at the same thing at the moment with 2 original GTA 'boxes I have up for rebuild, so I don't want to change the bellhousing etc.
Firstly, the O rings started life as just plain round section: wear and squeeze fit cause the wierd shape. Not hard to source at seal place.
Secondly, I'm thinking of making up a small cap with gasket and attached by 2 screws into the bellhousing to effectivly close over the ends, with a minimal hole for the reverse light switch shaft.

[LaStregaNera]

Hi Colin,
Later gearboxes have shorter shafts that don't protrude and the bellhousing is cast closed in that window area; problem solved by the factory......not much help for early boxes though. In any case, I'm looking at the same thing at the moment with 2 original GTA 'boxes I have up for rebuild, so I don't want to change the bellhousing etc.
Firstly, the O rings started life as just plain round section: wear and squeeze fit cause the wierd shape. Not hard to source at seal place.
Secondly, I'm thinking of making up a small cap with gasket and attached by 2 screws into the bellhousing to effectivly close over the ends, with a minimal hole for the reverse light switch shaft.

That's a great idea. I've got to go through this on the box for my 66, Never thought to look there when I was chasing down the gearbox leak before I took it off the road...

[Colin Byrne]

Hi guys
Looks like the original O ring is an imperial one
Round
Code 113
Cross section 2.61mm
ID 13.76
OD 18.99

I also got some square section ones and am going to try them as the feel like they seal better, also looing into making a cap as Vin suggests but it is a complex shape to seal against.

Other leak points I have found
-   the drilling hole for the interlock pins is sealed up with a 40 year old rubber plug, mine was has hard as a rock and completely useless so I've tapped  a M10    thread into the hole and going to seal it with a grub screw and sealant
-   The long through bolts just pull up on thick steel washers that pull up hard against the ali case.  I'm currently turning up new steel washers with o rings on both sides to try and seal up this problem
-   Not sure how much oil comes out the breathers but planning on running some tubes off the breather to a catch can

[Colin Byrne]

When Vin Checked out my gearbox build he commented that the machined sphere on the output shaft I had used was very worn.  I had never really looked at this before but unfortunately I had to agree so I located a new one and rebuilt the main shaft.  Since I'd gone to this much trouble I thought I'd better check out the bush that the sphere locates in in my drive shaft.  Glad I did, it was really worn and wouldn't have provided much centre location at all.
After a bit of mucking around around getting the old bush out of the shaft (ended up welding a plate to it and bashing it out with large hammer) I machined up a new bush and pressed it in
   Once I receive my flex disc from the us I'll need to get the whole assembly balanced, anyone know a good place to get this done?

[pancho]

I once read/heard that the Beninca workshop has a '3 plane' balancing machine - not sure if that helps.

[Colin Byrne]

Thanks Pancho

Here's a couple of photo's of the gearbox, just waiting for the front and rear seals to arrive, then i can finish putting it together

[AikenDrum105]

Shiny !

[pancho]

So Colin, is this an off the shelf CR gearset?

[Colin Byrne]

It's an off the shelf item


http://www.spruellmotorsport.com/alfa-gearset-close-ratio-gearset-free-syncros-p-2380.html

It's a bit confusing as they stated it fits a 1750/2000 gearbox but it is for gearboxes with a circlip rather than a nut on the input shaft, and i think those gearboxes are from earlier cars.?, so i ended up getting 2 donor gearboxes to get all the bits i needed

[pancho]

Let us know how the car drives with this box in it, I am looking to go get one based on your fedback. What made you go with this gear set over others out there?