|Topic Review (Newest First)|
|05-31-2012 08:05 AM|
.... Okay guys it has been a while, but I feel I owe the forum (and future readers) a closing of this thread and the "resolve" of my issues.
This is what happened:
The mechanic returned the car to me after he tried to identify the source of the problem downshifting from 3rd to 2nd. He said, he couldn't find the problem and therefore split the tranny again. He said he did something to 2nd gear or Syncro, but didn't know if that was the cause of my issue. I asked if he also addressed the first gear issue - he plainly said no.
- The clunking is 95% gone,
- Strangely enough the first gear grind is fully solved - despite the fact that he didn't do anything to address the grinding issue / no work on first gear. I can always shift up into first from neutral, no matter if the car is cold or hot - NO GRIND, ever.
... after this whole discussion here, you all must agree that this is somewhat of a miracle. I guess a good miracle for me.
I do have my own thoughts about what he did to the tranny, but this is speculation I shouldn't share here.
I am a happy driver now - all I needed to do was wiping off the greasy fingerprints on my fenders and then hit the road !
Thank you all again for your interest and sharing!
|03-14-2012 12:13 AM|
Yes, I have them already removed, they are $60.00 ea. and anything else you may need call me (925) 200-1998
Old shop was in Byron, currently main parts car pile and shipping in Lodi, I am at the Tracy building, doing more service type stuff and special projects. I live in Pleasanton.
|03-13-2012 11:44 PM|
No issue with me Larry. I went through all this in '72 when I first did this "First-Gear-Fix" working in a one-car garage. Took me a few days of getting it wrong, then getting lost. Did it again when I made that write up. Got that wrong a couple of times too.
BTW - you (initially your dad) actually provided me with many of the parts! I was living in Palo Alto while you were in that old junk yard in Tracy, Then in Hayward in the early 80's? Now I see APE is in Pleasanton. Finally got my Duetto hard top from you a few years ago. Remember meeting in that Shell Station in Northridge?
BTW - I need a few dog teeth sets. Got any? ( I can pull them too if you have gears). Quantos dineros? I need to come by soon, I've a list of bits I need.
|03-13-2012 10:59 PM|
|larry||Yes, I got myself thinking of the mainshaft speed so much I did reverse the 1st speed. It is an upshift relatively speaking. The wedge shape on the nose of the main lock does do something to help the Up direction for what it's worth. Is that humble pie in the oven.|
|03-13-2012 10:23 PM|
In any case, replace the 1st gear dog set with one from a 5th, and use all the internal syncro bits, including both upshift and downshift sectors.
The GRRUNCH GOES AWAY!!
|03-13-2012 10:17 PM|
Here's a practical engineer's viewpoint:
Alfa has five gears, all the same except 1st; it's missing one syncro sector. It's either an upshift sector or a downshift sector. If it's missing the downshift sector, you can't get from 2nd DOWN to 1st. So it must be missing the UPSHIFT sector.
Interestingly, for the same thinking, they could have left out the DOWNSHIFT sector on 5th gear.
|03-13-2012 10:12 PM|
Driving down the road, the output shaft is directly connected to the differential, and is turning at road speed (wheel rpm times DIff ratio). If you're in third and UPSHIFT to fourth, you press the clutch in and pull on the shift lever. The third syncro disengages and the fourth starts to engage. You are moving from a high engine speed to a lower engine speed at the same road speed. It has to SLOW down the clutch-inputshaft-countershaft to match the output shaft. Then you release the clutch and the engine slows (it at least partially did with your foot off the gas) to match the road speed.
As you UPSHIFT, the clutch-inputshaft-countershaft - all firmly meshed together - SLOWS DOWN.
Similarly, as you DOWNSHIFT, the clutch-inputshaft-countershaft SPEEDS UP.
Sitting at a stop with the clutch engaged and the TX in neutral, the output shaft is stationary. The clutch, input shaft, and countershaft are rotating at the engine idle speed. Press the clutch in, and push the shift lever to first gear. The counter shaft, input shaft, and clutch SLOW DOWN, so that when engaged it matches the STATIONARY speed of the output shaft. You still are not moving after all.
SLOWING the countershaft is an UPSHIFT. But the Alfa TX does not have an UPSHIFT syncro, so it goes GRRUNCH. Brand new. The only time it doesn't is if the synchs are new and tight, so the small cone engagement before the dog teeth engage is enough friction to stop the countershaft. New bearings from the Throw-Out-Bearing in the clutch to the back of the TX can also add a bit of drag to help slow the countershaft. If you try to shift quickly into first from idling neutral at a stop, you will hit the dog teeth before all that rotating Clutch-input shaft-countershaft-mass can stop. GRRUNCH!!
|03-13-2012 08:57 PM|
In neutral input shaft spins counter shaft which turns 1st and all other gears, only the mainshaft is stationary (driveshaft not turning thus you are slowing 1st to match speed of mainshaft That is an Downshift.... In no case are you ever trying to speed up 1st for a shift.
If you need to see a trans apart to truly understand that dynamic I have them readily available for demo.
I think we should consider the engineers would not build a 1st gear syncro assembly that in essence does nothing according to the theory that 1/2 the locks are left out.
I can sow you an Alfetta 1st, GTV-6 1st which are just like a 105-115. I jumped to fast on the inclusion of the Milano( yes it is very different and prone to breaking)
As I said I use 2-5 readily on 1st. after someone changes to a good carrier with new syncro of course "it works good now" you just fixed it just as if they had a good original 1st carrier with new syncro etc.
|03-13-2012 03:48 PM|
I never understood whyu Alfa made !st different. It had to cost more to make the two unique pieces than to use the ones on all the other gears. I know this started back in the 50's with the Gulietta 4-speeds, but really.
In addition to the 1st gear sector, the 1st gear is really heavy. Lightened gears are great for a slick shifting transmission, though they are hard to do because they are so hard. Induction hardening is fairly deep, and it takes carbide tools to cut or drill. You can save a few bucks by just milling the first gear, which has the greatest syncro load.
|03-13-2012 03:33 PM|
Another point is that the Milano/GTV-6 are NOT set up the same way. Pic #1 below is from the Spider service manual. There is only one arc piece in 1st gear (L) to transmit force. All the other gears have two arcs.
The second pic is the first gear synchro assembly from the Milano/GTV-6. Here in 1st gear the second arc piece (#4) is there. But for some reason they buffer it from the key with a spring assembly (#5-#7) for first gear only. So the parts are there already but they don't work as well (in my experience) as in other synchronized transmissions.
Alfa had many years to get this right and they kept farking it up
|03-13-2012 03:15 PM|
See this thread; the issue was addressed and solved a few decades ago:
|03-13-2012 03:09 PM|
Larry, I've got a ton of respect for the expertise you and your dad have. But I'm afraid you're incorrect in this case.
Without the missing side of the synchro carrier, the synchro cannot engage in this case to slow down the input shaft. Thus you get the Alfa first gear grind.
The Alfa transmission can only engage the 1st gear synchro to speed up the input shaft because the synchro only has one side to the carrier. That's why on the Alfa at a stop you need to either wait for the spinning to slow on its own or touch another gear to use the synchro in that gear to stop the spinning.
The fact is that every other fully-synchronized transmission has a double sided synchro carrier for first. There's a good reason for this.
|03-13-2012 12:29 AM|
The boots have to be removed for rebuild and replacing them is a must if ripped. the tower to shift rod boot keeps the oil in the trans. those leaks are bad for a fresh rebuild. how much is leaving while driving?
First gear syncro carrier
They are "one sided" due to the fact that you cannot upshift to first, only downshift( milano and GTV-6 transaxles are set up same way) all the other gears can be subject to needing syncro effect for speeding up and lowering the speed of a gear relative to output shaft.
All the "need to" pause or touch second is usually due to worn 1st, cold trans oil and the fact that 1st is spinning 54% faster than second thus to do a good down shift into 1st from 2nd at 1500 RPM's you need to blip throttle to 2310.
At 2000 RPM's you need to hit 3080 RPM's to slide into 1st.
I think most people don't throttle up enough on downshifts to 1st and blame the trans.
When sitting at a light in neutral and car idling, engine 850 RPM approx.
and you step on clutch and shove into 1st at that instant the slider is not moving, 0 RPM ( connected to output shaft i.e. drive shaft) 1st gear is at 262 RPM's and you expect it to instantly engage.
I often put 2-5th carriers on first only for the reason that it is hard to find a good 1st carrier. Not for any improved syncro action.
Any questions feel free to call
Alfa Parts Exchange (925)200-1998
|02-24-2012 07:36 PM|
Originally Posted by Gubi View Post
If it is mechanical and the TX has to come out, then definitely do the "First Gear Fix". Print out the entire thread for your mechanic if you have to, but DO IT next time the case is opened!
Larry and others are right -almost- in that first gear doesn't grunch in normal life. Only if you shift to neutral while at a full stop AND let out the clutch while still at a stop do you even come close to hearing it. Further, if you move the shift lever almost any direction except directly into first gear, you will touch some other syncro and stop the rotation of the countershaft, and again the issue will not occur. Long time Alfisti are so habituated to touching some syncro that they don't even notice. Also, a newly rebuilt TX with new bearings still has enough drag in the bearings that the countershaft rotation is reduced; you actually notice it later, as the TX gets well broken in and the bearings become free rotating. That will make a novice Alfisti think something is wrong as it gets worse soon after a rebuild, but not immediately.
It really is a n Alfa-unique quirk. And can be completely eliminated.
|02-24-2012 03:07 PM|
Originally Posted by Atlantic View Post
Now, Robert's modification will fix this issue, but it's not widely known and unless you discussed making this change before the rebuild it would not be considered a "standard" part of the job. So I don't think the fact that it still does this should be considered a mistake by the mechanic. On the first gear grinding, suggest you either:
1) Do what most Alfa guys do and touch another gear before shifting into first, or:
2) Have the mechanic add the parts per Robert's instructions, but pay for the labor/parts on this as an extra item
The poor shifting, on the other hand, sounds like a real issue. If I were you, I would focus on having him fix the "clonk" since that isn't good. Did he ever test drive the car? What did he say about the issues you reported?
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