105 gearbox differences

[Colin Byrne]

As I've posted previously I've go a new close ratio gear set so I'm looking for an old gear box to use as a basis.  The gear set I have is supposable for a 2Lbox (as the current gearbox I have is a 2L).  Yesterday at the club night we were discussing what the actual differences between 105 gearbox's are, and we weren't to sure so I though I'd open I up for discussion

As far as I know the 1750 and 2000 gearbox are the same, except the bearing on input shaft of he 2000 is larger so a 1750 bell housing will no fit on a 2000 gearbox (learnt from previous experience of chasing an oil leak for 12 months)

What about 1300 and 1600 boxes?

[pep105]

Colin Ive got a Gt Junior 1600 box and a 2L box Im pretty sure they are the same, ill check and confirm this weekend but from what Ive seen so far they look identical. Given they are both approx of the same vintage 1600 is 74 and 2L is from a 72 model. Just need to have a better look.

Cheers
Pep

 

[ItalCarGuy]

This was a snippet I took from the AlfaBB a while back which I found helpful.

I don't think that there is any difference in transmission gear ratios between 1600, 1750 and 2L cars, at least on U.S. cars. The 1300 Jr. is the one with a different 5th gear, 0.86, I believe. We didn't get that car in the U.S. but you guys in Canada did. If you plan to use your car on the track you may prefer the shorter gear of the 1300. It would cut down slightly on your top cruising speed though.

Another thing to look for is the "long rod" vs. "short rod" version. The long shift rods protrude through the bell housing when engaged in 2nd, 4th or reverse and the one for reverse engages a pivoting lever which in turn engages the reverse light switch. The short engagement rods (which replaced the long rod version around '72) don't protrude through the bell and the reverse light switch screws into the housing right in front of the reverse rod. As long as you have the correct version of bellhousing to go with the transmission, you could use either version with your car. Your original would be the long rod version but most people prefer the short rod version - less oil leaking into the bellhousing, more needle bearings, etc.

I don't know what exterior numbers correspond to which transmission but the transmission cases are different between the two types as the short rods no longer needed a casting for the o-rings. You should be able to tell what he has by looking into the bellhousing for the reverse switch location and by counting the input to output turns ratio. Send us some pictures if you're not certain.

By the way, this info pertains to hydraulic clutch bells and trannies. The "push to reverse" sticks and non-moly syncros of the the earlier transmissions are a whole nuther can of worms.

[Colin Byrne]

Thanks for the info guys, looks like where getting a bit closer to understanding the situation.  So looks like I was incorrect about the difference between 1750 and 2000 rather its just a chronological change.  Sounds like the bearing difference I mentioned goes with the selector shaft length change.

So can we say there are only 2 different hydraulic clutch gearboxes regardless of engine size?

[aggie57]

Colin - according to the  1974 Rapido parts manual the part numbers vary for:

- the gearlever (non-reverse lockout vs later reverse lockout)
- the input shaft (2000 vs all the rest as you mentioned)
- speedo drives (for different diff ratios)
- sump and filler plugs (don't as me why!)
- the lay shaft (2000 vs all the rest; can't say for sure but looks like the shaft and bearings are different)
- the main shaft bearings (2000 vs all the rest)
- the rear seal (two part numbers listed, one for earlier cars to 1750 and another for later cars incl. 2 litres)

That's not everything and I've only ever used it as a guide and a starting point.  It's certainly not a perfect reference and nothing compares with holding the two parts side by side (as you would know!).  However it does suggest there are quite a number of detail differences between, particularly, the 2000 and earlier gearboxes and more specifically around the bearings throughout.

Alister

[vin sharp]

Cable/hydraulic clutch option aside, most of the differences early to later are regarding revisisions of bearing sizes for stregth and method of retaining the bearings, so how the gearshafts and diameters have been made and sized is what is important to know to put it all together. Most of the O/S gear sets are made to pre-revision sizes and need to be changed accordingly, if you use the wrong design bearing for the application (and yes, the WRONG bearing will fit in some places!), the you will have problems.......which is one of the reasons for locally producing close ratio "kits" that can be used universally across the model variations, (not to mention the odd gear tooth angles that preclude the use of any actual Alfa or original Autodelta gears components in the 'box...)
Col, give me a call if you want and I'll have a look at what you have and sort you with what combination you need to put it together sucessfully........for the honour of all Alfisti, you need the beat that ugly Volvo!
Cheers,
Vin

[aggie57]

Here's an interesting related thread from the alfaBB that I saw this morning:

http://www.alfabb.com/bb/forums/transmissions/176353-74-transmission.html

I can't start my 911 unless the gearbox is in neutral and the clutch is fully, and I mean fully, depressed.  Lawyers!