Gear box question

[classic-alfa]

Hi all, can you help me identify my gear box. Car was raced last time in 1983 and since that time stored, so no new production....
Thanks, Rafal

[alfabender]

Rafal

First thing to do is count the teeth on each gear.

[classic-alfa]

Dents it's easy but construction of this gear box is limiting all ratios from 33%. Can you help me with manufacturer....my car was made in 69 but in 1971 was prepared by autodelta and than this gear box was instaled and raced from 71 in European Championship so this gear box or ratios should be homolageted by FIA. I attached picture of my GTA in seventies received from previous owner.
Thanks for help

[kengta]

Quote:

Originally Posted by classic-alfa Hi all, can you help me identify my gear box. Car was raced last time in 1983 and since that time stored, so no new production.... Thanks, Rafal

[classic-alfa]

Only one gear is not lightened and shaft is center drilled. Seal will check tomorrow. But it looks like later shaft so bigger seal.


Thanks for your help

[Alfar7]

On my box the side cases are stamped with an identifying #(from AD) & Autodelta emblem.AutoDelta id# /26\ 3945
This is gearcount for it.
Gears: 1st 35/18,2.54, - 2nd 30/23, 1.701, -3rd 26/27, 1.256, - 4th 23/30, 1:1, -5th 22/31, .882

All input gears (4th) are 23/30 (1.304 input ratio)

3rd
27/26 1.355
26/27 1.256
26/26 1.304
25/27 1.207

2nd
32/21 1.387
30/23 1.701
29/24 1.576
30/22 1.778

5th
20/33 .791
21/31 .883
20/32 .815
21/32 .856

Below is an excerpt from my website
101/102/105/115 Transmission Gear Comparison & Modifications

4th 3rd 2nd 1st rev 5th
GTA STD (M/L) 23/30 1:1 26/27 1.256 30/23 1.701 35/18 2.54 30/18 21/32 .856
GTA Intermediate 23/30 1.1 26/26 1.304 30/22 1.778 36/17 2.76 30/18 20/32 .815
GTA Short 23/30 1:1 25/27 1.207 29/24 1.576 34/19 2.33 30/18 21/31 .883
Racing TZ option (RJ) 22/30 1:1 26/27 1.310 30/23 1.770 35/18 2.64 30.18 22/31 .921
RacingTZ with 23/30 input 23/30 1.1 26/27 1.256 30/23 1.701 35/18 2.54 30.18 22.31 .883

By swapping out the input shaft from a 105 series 5 speed to the 4 speed along with the corresponding front half (4th gear lay gear) of the 4th/3rd gear cluster you get a much closer ratio gearbox as shown below. Simply press off both donor 105 & 4 speed cluster gears cut them into ,(in half cutting between gearsets as close to center as possible.) press on lay shaft being absolutely overall length is the same. weld up cut around the outer edge (penetration of .150 is adequate I always preheat the area being welded just before welding shielding the teeth by wrapping in aluminum foil after coating with antisplatter coating.)
I have done manytimes, makes a very pleasant track & street box.



4th 3rd 2nd 1st Rev 5th
Split case 4 speed & early 5speed (TZ or early Zagatos & 102`s)
Main shaft/Lay Shaft 22/ 31 1:1 26/ 27 1.35 31/ 22 1.98 37/16 3.25 30/13 20/ 33 .85
Std 105/115 23/ 30 1:1 27/26 1.35 32/21 1.98 38/15 3.30 30/13 20/33 .79
Modified early 4 or 5 speed box with 105 input/4th cluster gear half: 1st to 4th) (5th)
1:1, 1.25, 1.85, 3.0 23/30 :1 26/27 1.25 31/22 1.85 37/16 3.00 30/18 ( 20/33 .79)

[180OUT]

Quote:

Quote: Originally Posted by classic-alfa Serial number of my car is 775384. Only one gear is not lightened and shaft is center drilled. Seal will check tomorrow. But it looks like later shaft so bigger seal. Thanks for your help

[Little Italian]

That doesn't look like a normal ALFA gearbox. Better box it up and send it to me so I can get rid of it for you. I'll be a good guy and send you a good used gear box so you won't be off the road.

Could this be a Colotte Gear box?

[alfabender]

I don't think it's a Colotti trans. The Colottis that I've seen are dog boxes, they don't have synchros. This trans has synchros.

Doug Bender

[giulia_veloce]

Hey Classic Alfa.

Nice gearbox.
I have an old one here,with straight cut teeth,that was done here in Australia.
Your shift pattern is standard,where mine has 1st + reverse on one plane,2nd + 3rd on another plane and 4th 5th on another plane.Plane is H pattern.
I havent seen a straight cut gearbox for a 105 except for the one I have.
Did they make them for 105 series Alfas in the 60s ?
Can anyone else out there add to this ?
Pics are from the cluster shaft.The other gears I have here are disassembled.

Robert

[classic-alfa]

My ratios are:
I 1.95; II 1.37; III 1.11; IV 0.92 and V 0,806. First gear is different but can be practical; on rally -I was obliged to start with my 2000GTV from second gear to save time.
Seal is big but should be small because there is ring upgrading size of shaft.

Hope this will help.

[Andrew]

Confessing my ignorance: would a stock GTA gearbox have helical or straight-cut gear teeth? I assumed helical.

Andrew

[Alfar7]

Quote:

My ratios are: I 1.95; II 1.37; III 1.11; IV 0.92 and V 0,806. First gear is different but can be practical; on rally -I was obliged to start with my 2000GTV from second gear to save time. Seal is big but should be small because there is ring upgrading size of shaft.

[classic-alfa]

So please:
I 24/36;II 29/31;III 29/25;IV 35/25;V 37/23
but please look that this gear box has no rear...and that this gear box has slighly different construction than standard alfa and that 4'th is not locked with input shaft but has additionnal gear locking shafts 34/26, so I used this gear to count my ratios.
Hope this will give you some more details

[Alfar7]

Quote:

but please look that this gear box has no rear...and that this gear box has slighly different construction than standard alfa and that 4'th is not locked with input shaft but has additionnal gear locking shafts 34/26, so I used this gear to count my ratios.