First Gear Fix - Alfa Romeo Bulletin Board & Forums
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post #1 of 151 (permalink) Old 08-25-2006, 09:49 AM Thread Starter
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First Gear Fix

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:



Quote:
Originally Posted by bianchi1
how is it working? you stated that the 1st gear sort of stands alone without a syncho ring of it's own..also when you rebuild the gear box, what parts do you reaally need? the ring, the hub,the sleave, the quarrant? etc. thanks for any help.
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.

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

Last edited by 60sRacer; 02-28-2014 at 10:26 PM.
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post #2 of 151 (permalink) Old 08-25-2006, 11:09 AM
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Very Interesting Post.

You can bet I will be trying this out on my gear box during this winter's rebuild !

*****George: Take note of this idea!*****

......... Bud Feigel ........<Oo \*/ oO>....... Lexington, Kentucky ........
'82 RED GTV6 / 2.5 - '86 WHITE Spider Veloce 2000 - '71 GREEN GTV 1750
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post #3 of 151 (permalink) Old 08-25-2006, 06:54 PM
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Hmmm.... I think I'll have to play with this idea, too. Sounds promising!

Bill / 1977 Alfa Romeo 4C2000 / 2012 BMW S1000RR / 1975 BMW R90/6
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post #4 of 151 (permalink) Old 08-28-2006, 05:40 AM
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This also solves the problem when the dog teeth from first are worm and you need to replace and finding a good fist gear hub is difficult. Just use any one available together with the appropriate parts. Always wondered why first was different but never really thought too much about it.

Thanks for the tip.

Ciao

Ken

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1965 GTA, RHD, Stradale
ex- 1965 GTA, RHD, Corsa, Trans/Am 66-72
1964 Sprint GT, B-Sedan in 70's
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post #5 of 151 (permalink) Old 08-28-2006, 11:06 AM
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It wouldn't be an Alfa if I didn't have to do into second gear first Don't you miss doing that

Loud pipes save lives.

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1969 GTV, #AR1530021 - sold 10/72, guess didn't intend to keep forever
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post #6 of 151 (permalink) Old 08-30-2006, 01:49 PM
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I've got used to dipping into a higher gear before shifting to first, but I wish I had thought of this when I rebuilt my transmission a few months ago. I could have stolen the parts from any of the synchros in my donor transmission.

By the way, I always dip into fourth, rather than second, seeing how the second synchro wears so easily.
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post #7 of 151 (permalink) Old 08-30-2006, 10:10 PM Thread Starter
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Quote:
Originally Posted by jmshyla
..I always dip into fourth, rather than second, seeing how the second synchro wears so easily.
It really doesn't matter much. All you are trying to do is stop the rotation of the gearset. its only the mass of the gears on the mainshaft and the mass of the rigid countershaft that you have to stop. You really don't engage the syncro - never even come close to the dog teeth whatever gear you touch. The point is that the output shaft is not moving at all, and you use that to stop the few parts that are rotating with the clutch disc and the input shaft. That's the countershaft, driven off the input shaft, and the individual gears that are all in mesh with that.

Of course it's important that you push the clutch fully in first.

I used to touch second since I pull the shift lever to the left to the 1-2 slot, then pulled back to touch the 2nd syncro to stop the gears, then pushed forward to engage 1st. With the mod, just push gently forward to 1st and the gears stop, then push furthur to engage the 1st gear.

Robert
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post #8 of 151 (permalink) Old 08-30-2006, 10:27 PM
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NOW I find out...hahaha! I just rebuilt my transmission 3 weeks ago and have it installed in the car. However...there is another transmission in the wings waiting for me. I will definitely do the modification to this one. I even have some parts laying around here that I can pull from. Thank you for this tip!

Christopher

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post #9 of 151 (permalink) Old 09-02-2006, 12:44 PM
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Robert,

Is it best to replace the dog gear on 1st with a decent dog gear from 2nd through 5th, or can the original dog gear be used (assuming it isn't worn out)?

If I understand this correctly, these parts need to be swapped onto 1st Gear:
  • Synchro Ring
  • Both Sectors
  • The two "half rings" need to be used in place of the single "half ring"
  • Dog Teeth Gear (optional?)
  • Snap Ring?

Thanks. I'm doin' it !!!

Bill / 1977 Alfa Romeo 4C2000 / 2012 BMW S1000RR / 1975 BMW R90/6

Last edited by Bill77; 09-02-2006 at 01:02 PM.
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post #10 of 151 (permalink) Old 09-02-2006, 01:44 PM
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Dog Rings

Quote:
Originally Posted by Bill77
Robert,

Is it best to replace the dog gear on 1st with a decent dog gear from 2nd through 5th, or can the original dog gear be used (assuming it isn't worn out)?

If I understand this correctly, these parts need to be swapped onto 1st Gear:
  • Synchro Ring
  • Both Sectors
  • The two "half rings" need to be used in place of the single "half ring"
  • Dog Teeth Gear (optional?)
  • Snap Ring?

Thanks. I'm doin' it !!!
Bill:
It is my recollection that the first gear dog ring is different from the other gears. First gear has two cut outs on the inner circumference of the dog. One cutout has a slight cut at an angle. All the dog rings for the other gears have one cut out. The sements lock into these cutouts.

......... Bud Feigel ........<Oo \*/ oO>....... Lexington, Kentucky ........
'82 RED GTV6 / 2.5 - '86 WHITE Spider Veloce 2000 - '71 GREEN GTV 1750
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post #11 of 151 (permalink) Old 09-02-2006, 02:57 PM Thread Starter
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If you make the first gear fix I described above, one of the other dog gears would be a better choice. The 1st gear dog does have an extra cutout at the bottom, and for the original first gear, the bottom syncro piece has a hook tha engages this opening. But that is exactly what causes the grunch from standstill that I fixed.

When I first made he change, I left the original dog piece in place, notch and all. But I put the internal syncro pieces form another gear in, curing the grunch. I wondered if one of the little pieces would hang up on the extra notch, or fall in and jamb things up but I've never had a problem.

If your 1st dog gear is worn and you are going to replace it for that reason, use one of the other ones - 4th or 5th are usually the least worn dog teeth. the lack of that extra notch is not a problem as you will not be using it anyway; probably better anyway.

If your 1st dog teeth are fine: first of all I congratulate you on incredible shifting skills; second, I'd not worry about it and just change the other bits; third, if you've gotten more careful with age as I have, I'm gonna change to a 4th or 5th dog gear when I O/H the TX next time. But I have 35+ years with it as is, though probably less than 20,000 miles.

Robert

Last edited by 60sRacer; 02-28-2014 at 10:30 PM.
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post #12 of 151 (permalink) Old 09-02-2006, 03:41 PM
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Thanks for the info. I'll post the results soon.

Bill / 1977 Alfa Romeo 4C2000 / 2012 BMW S1000RR / 1975 BMW R90/6
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post #13 of 151 (permalink) Old 09-05-2006, 06:32 AM
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Quote:
Originally Posted by jmshyla
I've got used to dipping into a higher gear before shifting to first, but I wish I had thought of this when I rebuilt my transmission a few months ago. I could have stolen the parts from any of the synchros in my donor transmission.

By the way, I always dip into fourth, rather than second, seeing how the second synchro wears so easily.
I've tried 4th 1st instead of 2nd and it works better - it's easier going into
4th and the slip into 1st works fine.

Loud pipes save lives.

1973 GTV - bought 3/06, intend to keep forever
1969 GTV, #AR1530021 - sold 10/72, guess didn't intend to keep forever
Current project: '69 Corvette bought in '73, DD '73 - '80, in storage 1989-2002, now apart
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post #14 of 151 (permalink) Old 09-08-2006, 08:56 AM
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Dog Gear Replacement

This makes such good sense, I just wish someone would make replacement dog gears. The replacement process is surely going to deplete the total number of rebuildable transmissions out in ALFA Land as trannys are scrapped for parts.

......... Bud Feigel ........<Oo \*/ oO>....... Lexington, Kentucky ........
'82 RED GTV6 / 2.5 - '86 WHITE Spider Veloce 2000 - '71 GREEN GTV 1750
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post #15 of 151 (permalink) Old 09-08-2006, 09:31 AM
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Quote:
Originally Posted by Little Italian
This makes such good sense, I just wish someone would make replacement dog gears. The replacement process is surely going to deplete the total number of rebuildable transmissions out in ALFA Land as trannys are scrapped for parts.
Agree and,

I've said this before, Porsche Synchro Hubs (dog gears) are similar looking, but not the same, to the Alfa part and are available aftermarket.

An entrepreneur needs to make the necessary contact and investigate remanufacture.

FWIW

Ken

Ken Geiger, Toronto
1965 GTA, RHD, Stradale
ex- 1965 GTA, RHD, Corsa, Trans/Am 66-72
1964 Sprint GT, B-Sedan in 70's
1970 Giulia Super (CDN Spec)
1976 1600 GTj (Italian Spec)
1966 Harley Sprint (Aermacchi) 250
2000 Catalina 320, Hull #765 Northern Dream
2001 BMW Z3 3.0i
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