Grumbling transmission

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JohnLiles
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Grumbling transmission

#1 Post by JohnLiles »

I have a '57 356A T1 , original gearbox , it makes a noise like a food mixer fed with rocks when moving away in reverse , and also to a lesser extent when moving away in first . When up to speed there is a slight whine from transmission in all forward gears , synchro works fine up and down the gearbox .
I attach a link to a short youtube video , have posted this already on the Porsche 356 Facebook site , however I feel that the registry may have more chance of getting some helpful feedback on what might be the cause of the foodmixer noise !

I plan to hand the car over to an experienced 356 workshop here in the UK for any mechanical dissection !!

https://youtu.be/hN91wf4yfbM
1957 'A' and 1955 'Continental Outlaw'

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Jacques Lefriant
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Re: Grumbling transmission

#2 Post by Jacques Lefriant »

Hi
the reverse gears are straight cut and subject to face damage. Check your magnetic drain plug.
j
 

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John Brooks
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Re: Grumbling transmission

#3 Post by John Brooks »

Yes. And you probably need a new shaft. Here is what to expect, this a reverse & first growler.
Attachments
Bad first reverse great, needs a main shaft
Bad first reverse great, needs a main shaft
John Brooks

62 Roadster
66 912
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getting pushed around in porsches since 1965

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Vic Skirmants
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Re: Grumbling transmission

#4 Post by Vic Skirmants »

John Brooks wrote: Wed Jan 25, 2023 3:27 pm Yes. And you probably need a new shaft. Here is what to expect, this a reverse & first growler.
That really has nothing to do with reverse gear.

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Graeme Langford
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Re: Grumbling transmission

#5 Post by Graeme Langford »

I am no expert. But that noise when you are in the garage with very little forward movement. Could that be from the clutch assembly rather than the gearbox ?
1958 356A
1967 911S

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Martin Benade
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Re: Grumbling transmission

#6 Post by Martin Benade »

On a side note is that main shaft bearing inner race in normal decent condition? Mine looks just like that and I’ve pretty much decided that it’s ok. It’s a tiny bit noisy idling in neutral but otherwise makes no odd noises.
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Randy Mittelstet
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Re: Grumbling transmission

#7 Post by Randy Mittelstet »

If the problem is a bad clutch throw out bearing,
what would be the symptoms and sounds?

Would the grinding rock sounds occur with the clutch
pedal pushed down or with no foot on it?
Randy Mittelstet
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1960 early Roadster

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Steve Proctor
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Re: Grumbling transmission

#8 Post by Steve Proctor »

It sounds like you have a stock-weight flywheel, but friend Jack Allen had a flywheel that was lightened with both a circumferential cut and lightened further with dozens of large holes. It was literally swiss cheese. His transmission rattled like crazy until he replaced the flywheel. If I recall correctly, I believe a "street lightened" flywheel is usually about 11-14 pounds, so I have no idea how light his was.
STP
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Al Zim
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Re: Grumbling transmission

#9 Post by Al Zim »

I know you are THERE and do not have access to what is available here in the colonies. HOWEVER Zim's has used SWEPCO (exclusively) a gear oil for Close to 30 years. It was magic with the Porsche synchronizers. (also in the differential of my then ancient Volvo) Someone in England or Europe has a magic oil. DO NOT REMOVE THE TRANSMISSIION!!! There is a good possibility that the rear of the car will have to be aligned (front with it) which cannot be done on the floor of your garage with a piece of string. DRAIN THE OIL INTO A CLEAN PAN and see what is there. Stick a magnet into the drain hole (magnet on a wire) and see what comes out! DO NOT MAKE MORE WORK AND COSTS FOR YOURSELF. al zim
www.allzim.com 
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Martin Benade
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Re: Grumbling transmission

#10 Post by Martin Benade »

That’s a good point to check it out in place as much as possible. As for an alignment, it depends on who’s holding the string.
Al, this wouldn’t be commercially viable, but you are probably among the people that could get it spot-on with a tape measure and string.
Cleveland Ohio
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Graeme Langford
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Re: Grumbling transmission

#11 Post by Graeme Langford »

Al Zim wrote: Thu Jan 26, 2023 12:14 pm I know you are THERE and do not have access to what is available here in the colonies. HOWEVER Zim's has used SWEPCO (exclusively) a gear oil for Close to 30 years. It was magic with the Porsche synchronizers. (also in the differential of my then ancient Volvo) Someone in England or Europe has a magic oil. DO NOT REMOVE THE TRANSMISSIION!!! There is a good possibility that the rear of the car will have to be aligned (front with it) which cannot be done on the floor of your garage with a piece of string. DRAIN THE OIL INTO A CLEAN PAN and see what is there. Stick a magnet into the drain hole (magnet on a wire) and see what comes out! DO NOT MAKE MORE WORK AND COSTS FOR YOURSELF. al zim
Hi Al, Can you let me have the exact details of the Swepco oil that you use. I would like to try some in my gearbox as I occasionally get some strange noises from it
1958 356A
1967 911S

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David Jones
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Re: Grumbling transmission

#12 Post by David Jones »

Graeme, Google swepco 201. About 80 pounds a US gallon in the UK.
If I had known I would live this long I would have pushed the envelope a little harder.
Cymru am byth
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Graeme Langford
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Re: Grumbling transmission

#13 Post by Graeme Langford »

Thank you David, can you remind me how much oil the gearbox takes
1958 356A
1967 911S

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David Jones
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Re: Grumbling transmission

#14 Post by David Jones »

3.5 litres Graeme.
If I had known I would live this long I would have pushed the envelope a little harder.
Cymru am byth
David Jones #9715

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Graeme Langford
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Re: Grumbling transmission

#15 Post by Graeme Langford »

Much appreciated David
1958 356A
1967 911S

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