I posted a thread about fixing the famous 'First gear Grunch' a while ago. Just send a PM off to a member that asked about it, and thought some others might be interested.
The issue is that when sitting at idle and not moving, the first gear will grunch when shifting from neutral to 1st. It's because of the way alfa saved 3¢ in assembling the transmission. It'll cost you about $15 in little bits of alfa parts (or free if you have a spare gear or two), and a lot more agrivation than it should. I did this almost fourty yeas ago and it is still working fine:
Friction on the molly ring from the brass syncro slider pushes the top key, which pushes on the arc piece, that then pushes on the bottom key. The bottom key fits in a notch in the gear and so pushes on the gear. All this occurs before the teeth of the brass syncro engage the dog teeth on the gear. So all this serves to speed up the gear to match the rotation rate of the brass shift slider.
The second arc piece inside the gear is for the 'upshift' case, where you need to slow down the gear to match rotation rates.
Except for first gear. This gear only has one arc piece, and the top and bottom keys are different. The result is that the 1st gear will sync only on a downshift, when you want to speed up the gear. Well, of course you say. Who would ever 'upshift' into first? But that's what you do when idling in neutral with the car at a standstill; the gear is rotating, and you need to slow it down - or 'upshift' - to engage.
We all have learned to lightly touch second before engaging first when standing still and in neutral. That syncs second on the virtual 'upshift' from neutral ( that is, the rotating gears stop), and then 'downshifts' into first.
I got tired of the obvious grunch almost four decades ago. I just took all the bits for another gear (they are all the same after 1st) and put them in the first gear too. There is a slightly larger notch in the first gear; I thought about welding it up, but didn't and there has been no problem.
For 37 years!
AND NO MORE GRUNCH! Just do it.
Robert
BTW - you can remove the dog teeth bit from the gears. It's tricky, but it's just pressed on - very tightly. This is how you renew a worn second gear syncro. Take a dog ring off a spare fifth gear (they are all the same) which rarely wears much.
Enjoy
Robert
The issue is that when sitting at idle and not moving, the first gear will grunch when shifting from neutral to 1st. It's because of the way alfa saved 3¢ in assembling the transmission. It'll cost you about $15 in little bits of alfa parts (or free if you have a spare gear or two), and a lot more agrivation than it should. I did this almost fourty yeas ago and it is still working fine:
If you take those awfully strong snap rings off each gear, you would see the pieces that make up the syncro mechanism inside the moly ring. There is a small key at the top, and a longer one at the bottom, with two arc shaped pieces on either side. The top piece keys into the outer molly ring (that's why there is a gap in the ring), and the bottom piece keys into a notch in the gear itself. The two arc pieces essentially connect the two keys.bianchi1 said:
Friction on the molly ring from the brass syncro slider pushes the top key, which pushes on the arc piece, that then pushes on the bottom key. The bottom key fits in a notch in the gear and so pushes on the gear. All this occurs before the teeth of the brass syncro engage the dog teeth on the gear. So all this serves to speed up the gear to match the rotation rate of the brass shift slider.
The second arc piece inside the gear is for the 'upshift' case, where you need to slow down the gear to match rotation rates.
Except for first gear. This gear only has one arc piece, and the top and bottom keys are different. The result is that the 1st gear will sync only on a downshift, when you want to speed up the gear. Well, of course you say. Who would ever 'upshift' into first? But that's what you do when idling in neutral with the car at a standstill; the gear is rotating, and you need to slow it down - or 'upshift' - to engage.
We all have learned to lightly touch second before engaging first when standing still and in neutral. That syncs second on the virtual 'upshift' from neutral ( that is, the rotating gears stop), and then 'downshifts' into first.
I got tired of the obvious grunch almost four decades ago. I just took all the bits for another gear (they are all the same after 1st) and put them in the first gear too. There is a slightly larger notch in the first gear; I thought about welding it up, but didn't and there has been no problem.
For 37 years!
AND NO MORE GRUNCH! Just do it.
Robert
BTW - you can remove the dog teeth bit from the gears. It's tricky, but it's just pressed on - very tightly. This is how you renew a worn second gear syncro. Take a dog ring off a spare fifth gear (they are all the same) which rarely wears much.
Enjoy
Robert
