Gearbox shifting problems - Page 3 - Alfa Romeo Bulletin Board & Forums
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post #31 of 50 (permalink) Old 08-13-2019, 11:31 AM
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Chas is referring to the OP where the trans and synchros are Alfa, which uses the Porsche servo type, not the later balk ring type. It was Alfar7 that conflated the 2 and in effect hijacked the thread.
This is an Alfa site, not a Porsche site and this thread has little to do with semantics.
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post #32 of 50 (permalink) Old 08-13-2019, 11:37 AM
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PM sent on the fuel pressure...
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post #33 of 50 (permalink) Old 08-13-2019, 04:18 PM Thread Starter
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Grtting back to MY problem...

Not to put a clamp on this discussion, but the reason I started this post was to solve my shifting problems.

So here is the update: I drained the oil, flushed with kerosene and let the car run in neutral for 3 minutes drained it and then added RedLine 75-90 NS. My driving experience is that is still crunches going into second from first. If I shift slowly or blip the throttle, no crunch. Downshifting from third, no crunch. My guess is second gear syncro is now toast because of my previous problem and they probably should have been replaced. looking through the filler hole they look dark gray, not brass. Any new thoughts on THIS subject?

Thanks,
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post #34 of 50 (permalink) Old 08-13-2019, 05:29 PM
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Quote:
Originally Posted by alfabits View Post
Not to put a clamp on this discussion, but the reason I started this post was to solve my shifting problems.

So here is the update: I drained the oil, flushed with kerosene and let the car run in neutral for 3 minutes drained it and then added RedLine 75-90 NS. My driving experience is that is still crunches going into second from first. If I shift slowly or blip the throttle, no crunch. Downshifting from third, no crunch. My guess is second gear syncro is now toast because of my previous problem and they probably should have been replaced. looking through the filler hole they look dark gray, not brass. Any new thoughts on THIS subject?

Thanks,
There are no brass synchro parts in your trans. I offered some experience with Pennzoil Synchromesh earlier in response to your shifting problem. It's not expensive, but it did take some miles to restore synchro function.
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Last edited by Chas H; 08-13-2019 at 05:38 PM.
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post #35 of 50 (permalink) Old 08-13-2019, 05:36 PM
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I mean, even on a good Alfa you need to shift slowly from 1st to 2nd? So not sure you have a problem?

Tom

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post #36 of 50 (permalink) Old 08-13-2019, 06:08 PM
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I have had some luck using 80-140 gear oil in split case box's not syn but old dinosaur
crude cheapest money can buy and have had it bring worn box's back to usable.
just my experience. There is a clue in Bits box that upshifting with a blip is OK, down shifting is better.
RML
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post #37 of 50 (permalink) Old 08-13-2019, 06:13 PM
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They don't shift like Datsuns. That's for sure......We used a 50/50 mix of 90W gear oil and ATF for high performance stuff.

They were baulk/Warner brass synchros though.

It's Giuseppe's giubos, not Guido's guibos, on my 78 Alfas
REFRESH CONNECTIONS BEFORE REPLACING COMPONENTS
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post #38 of 50 (permalink) Old 08-13-2019, 09:39 PM
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When I was data logging WOT test runs with the Spider I measured the shift intervals at about 1 second and it was the same between all gears. That was with lightened gears and a lightweight flywheel. Perhaps gear lightening has a greater impact on shifting between the lower, heavier gears.
I fill the gearbox with 3 pints of Redline 75W90NS as Richard suggests.

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post #39 of 50 (permalink) Old 08-13-2019, 10:39 PM
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This is the style used in the Alfa split case transmissions.

The Porsche/Schmidt style of synchronizer incorporates five main components; a brake band, an anchor, a stop, a friction ring and “dog teeth.” An operating sleeve, which is fixed to its respective shaft, first contacts the friction ring which has a surface that has a rough spatter coating. As the operating sleeve grabs the synchronizer, it turns until it hits the stop. The stop, in turn, then energizes the brake band, which then applies more tension on the synchronizer ring. This action is all to either speed up, (in the case of downshifting), or slow down, (in the case of upshifting) the gear that is going to be engaged. As the gear speed matches the spinning shaft, pointed “dog teeth” allow the operating sleeve to lock the selected gear to the shaft. All of this is happening in split seconds and the integrity of the individual components is key if a clash-free gear shift is to occur. The system is effective only if the key components are working properly and not worn. If the operator misses a shift, or doesn’t fully de-clutch when moving the shift lever, stress is put on one or more of these components.

The rough coating (like a cat's tongue) on the synchronizers eventually can be worn smooth with normal use, which then can cause the dog teeth and operating sleeve to clash and wear down the points which are there to assure clean engagement. The effect of improper use, or a missed shift, will begin a “snowballing” effect as wear on one component compromises others. This is why it is key during an overhaul to carefully assess each component for wear or damage due to past use. If the transmission is relatively high in miles, all synchronizer rings should be replaced as a matter of course, as these are the front line of the entire shifting process. Always pay close attention to the dog teeth as well as the teeth on the operating sleeve. Slight wear or evidence of minor contact to the teeth are okay, but the points of the engagement dog teeth should be distinct and relatively sound. The operational caution here is: if in doubt, replace it.

Schmidt was the transmission designer that worked for Porsche.


This s the style used 1900, 750 and 164 manual gearboxes.

In 1987 Porsche solved many of its gear shifting issues by switching to a Borg-Warner cone style synchronizer ring. This device, which is used widely in the industry now, has far fewer parts than its Porsche-engineered counterpart and is extremely effective and reliable. Porsche started using this with the 3.2 liter 911’s and has stayed with it through the 964, 993, and 996 models. The dog teeth on the cone-style synchronizer are shaped much like those on the Porsche style counterpart. The friction component, however, is on the inside of the synchronizer cone and it is pushed by an operating sleeve directly onto a corresponding cone on the gear that is about to be engaged. As the friction does its magic, the gear about to be engaged is either sped up or slowed in order to match the shaft speed before the dog teeth of the synchronizer locks onto the dog of the gear itself. Wear is much more easily measured on the cone rings, as there is a specification for the distance between the synchronizer ring and the face of the dog teeth on the gear.

1969 1750 Spider Veloce w/dual webers, 1969 1750 Berlina, 1971 1750 Spider Veloce w/ dual webers, 1985 Spider Veloce 23,000 orig. miles, {Two} 1986 Spider Veloces, 1987 Spider Veloce bought new, 1988 Quadrifoglio, 1991 164S, Plus several more. I think they are breeding.
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I just got 2 more. Now I have a Matta. I must be crazy.
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post #40 of 50 (permalink) Old 08-14-2019, 03:31 AM
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Geo.. my guess from here ... only a guess. The early tranny pre-105 Syncho rings ( cones) had circumferential grooves (non-moly) and had specifically mated sleeves that look identical to the 105 except for a groove on the inside.. non -moly and moly were different by the groove and I can't remember which was which... I had some NOS sleeves in AR packages that were mis-marked. Anyway the 105 rings (moly) had a pebble finish. It's possible your mechanic just switched out the ring and not the sleeve and if he did mixed the two components. I have no history of this mistake and the consequences... only throwing it at the wall to see if it sticks. It is also possible to have BOTH types in the same box depending on the nature of the rebuild.

here is a non-moly example.......... https://www.alfabb.com/bb/forums/giu...n-synchro.html

The non-moly type pairs required DENTAX ... Alfa had so many screw ups with this spec that they switched to the more forgiving and less sensitive moly type ring set in the 105 which didn't require Dentax..

Last edited by divotandtralee; 08-14-2019 at 03:55 AM.
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post #41 of 50 (permalink) Old 08-14-2019, 07:02 AM
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Originally Posted by alfabits View Post
It feels more like the clutch is not disengaging fully
I think this may be the root of the problem, so I will cast my 5c worth of speculation here.

Did you have the flywheel resurfaced all those years ago? Often shops take a mm or so off the driven face of the flywheel but do not grind the clutch mounting surface by the same amount. Then they adjust the clutch plate forks to compensate,

Sometimes when rebuilding an old clutch plate the surface is skimmed and the forks are adjusted to compensate for the thinner plate.

I both cases it all works like a charm -- as long as the same clutch plate is used.

Now if you later replace the clutch plate with one that has a 'standard' fork setting and 'standard' plate thickness, the result is that with it all bolted up, the TO (release) bearing face on the clutch plate is set too far out. As a result the clutch pedal mechanism does not have sufficient travel to press the TO (release) bearing face in far enough to fully disengage the driven plate (in a worst case scenario the clutch fork stops up against the slot in the cover plate before the clutch is fully disengaged).

If you have the 'box out is it quite easy to check, and if it all checks out ok, you can eliminate it from your troubleshooting.

From memory the measurement of the flywheel between thrust face and clutch mounting face should be 23mm (others please confirm ... I am not near a flywheel I can measure).

I have attached a diagram cobbled together from different parts of the manual with specs you can check. The distance marked C from the flywheel face to the TO bearing face is the critical one. (you will need to assemble the clutch with a spacer the same thickness as your driven plate to measure this).

As I said ... just my speculation ...

Mike
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post #42 of 50 (permalink) Old 08-14-2019, 07:40 AM
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wouldn't you recognize that right away?
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post #43 of 50 (permalink) Old 08-14-2019, 09:36 AM Thread Starter
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Quote:
Originally Posted by giuliettaspyder View Post
I think this may be the root of the problem, so I will cast my 5c worth of speculation here.

Did you have the flywheel resurfaced all those years ago? Often shops take a mm or so off the driven face of the flywheel but do not grind the clutch mounting surface by the same amount. Then they adjust the clutch plate forks to compensate,

Sometimes when rebuilding an old clutch plate the surface is skimmed and the forks are adjusted to compensate for the thinner plate.

I both cases it all works like a charm -- as long as the same clutch plate is used.

Now if you later replace the clutch plate with one that has a 'standard' fork setting and 'standard' plate thickness, the result is that with it all bolted up, the TO (release) bearing face on the clutch plate is set too far out. As a result the clutch pedal mechanism does not have sufficient travel to press the TO (release) bearing face in far enough to fully disengage the driven plate (in a worst case scenario the clutch fork stops up against the slot in the cover plate before the clutch is fully disengaged).

If you have the 'box out is it quite easy to check, and if it all checks out ok, you can eliminate it from your troubleshooting.

From memory the measurement of the flywheel between thrust face and clutch mounting face should be 23mm (others please confirm ... I am not near a flywheel I can measure).

I have attached a diagram cobbled together from different parts of the manual with specs you can check. The distance marked C from the flywheel face to the TO bearing face is the critical one. (you will need to assemble the clutch with a spacer the same thickness as your driven plate to measure this).

As I said ... just my speculation ...

Mike
New Sachs clutch, pressure plate and T.O. bearing! See my original post. Thanks.

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post #44 of 50 (permalink) Old 08-14-2019, 09:44 AM Thread Starter
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Originally Posted by Gubi View Post
I mean, even on a good Alfa you need to shift slowly from 1st to 2nd? So not sure you have a problem?
You may be right and I am beginning to think it is normal, but I remember 10 years ago when this gearbox was fresh and the car was newly restored, it shifted between 1st and 2nd fairly fast, no crunch. Now at that same pace it crunches, if I pause at neutral then into 2dn it's fine and downshifting is fine. Downshifting from 5, 4, and 3rd are all good, no crunch. Upshifting to 3rd, 4th, and 5th are all good.

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Last edited by alfabits; 08-14-2019 at 09:49 AM.
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post #45 of 50 (permalink) Old 08-15-2019, 05:40 PM
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I mean, even on a good Alfa you need to shift slowly from 1st to 2nd?
That is my experience also.

Edward
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