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Old 05-27-2020, 03:32 PM   #1
DRG-ler
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Default Scratching first gear?!?!

Hi guys,

yesterday I had to drive my A for about 20 minutes in a traffic jam / stop`n`go. The gearbox didn't really like that. The first Gear could only be engaged with scratching noises.
I mean the gearbox is out of sync is well known. It is understandable that the shafts in the gearbox turn a little longer for domes. But yesterday, in my opinion, was no longer normal. Sometimes it was so bad that I was already considering installing a synchronized gearbox. But the Mitchell also has no synchronized first gear ...
But I also think that this is not normal, and maybe the clutch does not separate properly. How can I check this and what can I do about it?

Greetings from Berlin
Andy
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Old 05-27-2020, 04:00 PM   #2
Jim/GA
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Default Re: Scratching first gear?!?!

Please check the oil level in the transmission. It might be low, allowing the gears to keep spinning. Use a very thick oil, not like modern transmission oil.

Also check to make sure that your clutch is completely disengaging when you step fully on the clutch pedal.

But because this happened more when you drove for a time, and got everything hot, I suspect it is the oil.

Thin oil does not do what you need.

Also air trapped in the oil makes it not slow down the gears as well.

You should not try to put the selector into 1st gear until your road speed is quite low, say 2-4 KPH. Almost stopped. Maybe that is your main problem.
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Old 05-27-2020, 04:10 PM   #3
DRG-ler
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Default Re: Scratching first gear?!?!


I bought my oil from a Model-A parts dealer here in Germany called 600W. The dealer should recognize the correct oil. Oil level in the gearbox was checked two weeks ago. Is at maximum.
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Old 05-27-2020, 04:19 PM   #4
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Default Re: Scratching first gear?!?!

Check your idle speed also. Mine doesn't like to go into 1st if the idle is too high.

For the clutch I set the pedal for ~1" free play.

I always get a chuckle when we are following each other and come to a light. The light turns green, First car, scratch. Second car, scratch. Third car, scratch. Me, scratch...

Last edited by Y-Blockhead; 05-27-2020 at 05:02 PM.
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Old 05-27-2020, 05:09 PM   #5
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Default Re: Scratching first gear?!?!

Your clutch is not releasing completely, especially when everything is hot. Adjust it when everything is hot. If you run out of adjustment range, fix it.
As long as you have proper oil in the box, oil is not the problem.
If everything is adjusted right, idle speed has no effect.

Consider this. It had no problems from the factory. It should have none now if everything is adjusted properly.
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Old 05-27-2020, 05:58 PM   #6
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Default Re: Scratching first gear?!?!

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Quote:
Originally Posted by Pete View Post
Consider this. It had no problems from the factory. It should have none now if everything is adjusted properly.
Consider this. How many 90 yo cars are in the condition they were when they rolled off the assembly line... It would be nice, but it ain't gonna happen'
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Old 05-27-2020, 06:15 PM   #7
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Default Re: Scratching first gear?!?!

Quote:
Originally Posted by Y-Blockhead View Post
Check your idle speed also. Mine doesn't like to go into 1st if the idle is too high.

For the clutch I set the pedal for ~1" free play.


Yes. See if you can lower idle RPM.

Confirm that the throttle assembly (mounted to the back of the engine) is really moving freely. They like to stick open a tiny amount. There are 2 holes on the top of the mechanism that need a few drops of oil when you change the engine oil. Then work it free to confirm it closes fully.

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Old 05-27-2020, 07:41 PM   #8
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Originally Posted by Y-Blockhead View Post
Consider this. How many 90 yo cars are in the condition they were when they rolled off the assembly line... It would be nice, but it ain't gonna happen'
Roger on that....

As far as freeplay the various books give a certain amount in inches. That was with the floorboards that the car left the factory with and everything was new.
In engineering it is called accumulated tolerances and that is what you have in a 90 year old car. The floor is not always a complete release.
Set the freeplay so that the clutch releases COMPLETELY with the pedal about 1/2 inch off the floor. (as long as the throwout fork doeas not touch) This way you will be certain if you are lazy and don't push to the floor each time, you still get a COMPLETE release. 90% of the peopple driving any stick shift DO NOT push the clutch pedal to the floor when they shift.

Last edited by Pete; 05-27-2020 at 07:53 PM.
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Old 05-27-2020, 07:44 PM   #9
Chuck Sea/Tac
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Default Re: Scratching first gear?!?!

You can pull the throw out cover above your bell housing and observe if the clutch is fully disengaging.
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Old 05-27-2020, 11:29 PM   #10
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Default Re: Scratching first gear?!?!

Quote:
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In engineering it is called accumulated tolerances
Haha, I am going to have to remember that one.
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Old 05-28-2020, 02:43 AM   #11
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Default Re: Scratching first gear?!?!

Quote:
So check your idle speed. Mine doesn't like to go into 1st if the idle is too high.
Hm ... I say, the idle speed is not very high. It is a little too high, but not much. This is because I also have the problem that the engine partly dies when stopping. It seems to be a most common problem, but I haven't been able to find out about it yet. I guess the speed is 50-100 rpm above normal.
Well, if you consider that the engine only makes 2200-2400 rpm, these are already worlds !! Do I have to take care of it ...

Which makes me think now ... If the clutch wears out over time, the clutch play should increase and not less.

The throttle valve works very smoothly. That fits so far.

Andy
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Old 05-28-2020, 05:06 AM   #12
Werner
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Default Re: Scratching first gear?!?!

Andreas,

if it only scratches on gear # 1 at standing car and not at # 2 u. 3, then disconnects the clutch right.

As written above:
Low idle <500 RPM or a half second time between the clutch pressing and engage gear shifting.
Thick oil. The SAE "600" oils are thinner than the then the old US "1500 weight!.

I use the thickest oil available here, 680.


(Anm.: Gibt es in Deutschland nicht über den Kfz-Handel. Ich habe das als Industrieöl 'Tribonol Renogear CLP 680' von Fuchs bezogen.)
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Last edited by Werner; 05-28-2020 at 06:32 AM.
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Old 05-28-2020, 06:13 AM   #13
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Default Re: Scratching first gear?!?!

It's probably your pilot bearing. Start the engine in gear with the clutch pushed down. Slide it out of gear and after a few seconds try to put it in gear. If it grinds a little, your pilot bearing is driving the input shaft of the trans. This happens a lot.
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