Gear whine normal?

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Matt Harkis
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Gear whine normal?

#1 Post by Matt Harkis »

Recent purchase of a 61 t5 B.
Working through things one at a time.
I have a not terribly loud whine in the differential. No noise in 1st,2nd or 3rd gear accelerating or decelerating in gear. There is noise in 4th gear but not crazy. The noise is louder decelerating in 4th or coasting in neutral.
The transmission was supposedly rebuilt a couple of years ago. However, there is no documentation.
The question is: is a certain amount of noise normal in these transmissions

Norm Miller
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Re: Gear whine normal?

#2 Post by Norm Miller »

Yes & no however it's not desirable.
Likely a bearing, a mismatched gear set, or?
I have a whine in my dare I mention unpopular 911 in 3rd gear only but luckily I don't spend much time there.
I suggest you get a 356 pro to take a ride with you.
 

Jon Bunin
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Re: Gear whine normal?

#3 Post by Jon Bunin »

Matt harkis wrote: Fri Nov 01, 2019 8:22 pm...No noise in 1st,2nd or 3rd gear accelerating or decelerating in gear. There is noise in 4th gear but not crazy. The noise is louder decelerating in 4th or coasting in neutral...
The question is: is a certain amount of noise normal in these transmissions?
Matt, these cars and their gears are now over 50 years old, and most have well over 100k miles. Even when these transmissions are rebuilt, the gears are usually re-used if not damaged.
Many 356 transmissions have lost oil at some point, due to leaking axle boots, and the upper gears might show some degree of scuffing or increased wear. This often results in gear whine.
The sound of a bad bearing will usually be heard in all gears, not just one, so what you're describing is probably a gear issue. If so, it might not be a cause for concern, but merely an annoyance.

You should check the oil level, or drain the oil into a clean pan and inspect it for metallic glitter, and inspect the plug magnet for any suspicious bits.
If you drain the oil and it looks fine, then you can add new oil and drive the car, unless you feel that the noise seems to be getting worse. Or if you wish to be safe, you can have the transmission opened and inspected.
Jon Bunin

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Vic Skirmants
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Re: Gear whine normal?

#4 Post by Vic Skirmants »

Jon Bunin's advice is ALWAYS spot-on. I would add that 4th gear is the first gear that goes "dry" if the oil level gets too low. It is also the gear that sees the most miles. If oil level continues to drop, then 3rd gear starts to suffer.
One additional comment on what to find on the magnetic drain plug; lots of fuzz from the synchros; perfectly normal.

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Re: Gear whine normal?

#5 Post by John Ward »

Not being the transmission experts that Jon Bunin or Vic Skirmants are, I might also suggest looking at the trans mounts.
If there gone, they can transmit gear noise thru the tunnel.
BUT !!! I would listen to Jon Bunin or Vic Skirmants.
 

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Matt Harkis
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Re: Gear whine normal?

#6 Post by Matt Harkis »

Thank gentlemen.
The transmission was very low when bought it. Both axle seals and one boot were leaking.
Magnet was pretty full of fur.
Again, it only makes some noise in 4th.
If it was warmer and the windows were down, you would probably barely hear it.
The car is going into a body for 8 to 10 mos.
I am taking the motor and trans out next month to rebuild the motor.
I hate to put it all back together and have this thing get worse.
However, it sounds like I may be ok for awhile.

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Wil Mittelbach
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Re: Gear whine normal?

#7 Post by Wil Mittelbach »

Matt harkis wrote: Fri Nov 01, 2019 8:22 pm Recent purchase of a 61 t5 B.
Working through things one at a time.
I have a not terribly loud whine in the differential. No noise in 1st,2nd or 3rd gear accelerating or decelerating in gear. There is noise in 4th gear but not crazy. The noise is louder decelerating in 4th or coasting in neutral.
The transmission was supposedly rebuilt a couple of yrs ago. The question is: Is a certain amount of noise normal in these transmissions.
Gear noise may be typical when loafing at about 50-70 mph without either accelerating or decelerating, per my 65C cab with currently less than 80k original miles and original transmission. The gear noise was also evident when I obtained the the car when two yrs old in`67 with less than 15k original miles.

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Wil Mittelbach
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Re: Gear whine normal?

#8 Post by Wil Mittelbach »

Wil Mittelbach wrote: Sat Nov 02, 2019 11:40 pm
Matt harkis wrote: Fri Nov 01, 2019 8:22 pm Recent purchase of a 61 t5 B.
Working through things one at a time.
I have a not terribly loud whine in the differential. No noise in 1st,2nd or 3rd gear accelerating or decelerating in gear. There is noise in 4th gear but not crazy. The noise is louder decelerating in 4th or coasting in neutral.
The transmission was supposedly rebuilt a couple of yrs ago. The question is: Is a certain amount of noise normal in these transmissions.
Gear noise may be typical when loafing at about 50-70 mph without either accelerating or decelerating, per my 65C cab with currently less than 80k original miles and original transmission. The gear noise was also evident when I obtained the the car when two yrs old in`67 with less than 15k original miles.
Additionally; typical pinion/ring gear noise may be due to factory excessive clearance adjustments, or most likely the result of the pinion/ring gear tooth profiles.
Wonder what the opinions of the more experienced may be?

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Jeff Adams
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Re: Gear whine normal?

#9 Post by Jeff Adams »

At least fifty percent of the 356's I have driven have some amount of fourth gear whine. It is a judgement call by the owner or mechanic to determine if it is a real problem or just annoying. For most of the transmissions I have built, we left it alone. I have seen gears that had ugly visual flaws and were dead quiet, and perfect looking gears that whined noticeably. Often times, the only alternative was to install another used set that looked nicer and hope for the best. The few times I did this, we gambled and lost. Noise can sometimes be diminished by changing gear oil and switching brands.

The factory currently offers new 4th gear sets, 4A (shortest) and 4C (tallest). For whatever reason, 4B and 4D are not offered. About $1900 each. I have installed both ratios in several transmissions, all were quiet as hoped and expected. Your results may vary.

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Vic Skirmants
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Re: Gear whine normal?

#10 Post by Vic Skirmants »

"At least fifty percent of the 356's I have driven have some amount of fourth gear whine. It is a judgement call by the owner or mechanic to determine if it is a real problem or just annoying. For most of the transmissions I have built, we left it alone. I have seen gears that had ugly visual flaws and were dead quiet, and perfect looking gears that whined noticeably. Often times, the only alternative was to install another used set that looked nicer and hope for the best. The few times I did this, we gambled and lost. Noise can sometimes be diminished by changing gear oil and switching brands."
From Jeff Adams

Jeff; I couldn't agree with you more. Some scuffed gears quiet, while some nice looking gears whiny.
It's a crap shoot. (Over 900 transmissions built to date)

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C J Murray
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Re: Gear whine normal?

#11 Post by C J Murray »

Vic told me he puts saw dust in all his rebuilds. JUST KIDDING!

Wil hit on a fact, the cars were hand built and you can be absolutely positive that some new cars made more noise than others.

I have rebuilt a few of these transaxles and have just finished doing one in a documented 68k mile C coupe that I bought to sell. All the gears in that one looked great. I got the car in not running condition so I didn't know what I would find when I went in to inspect and re-seal it. It didn't need much and now it doesn't leak. It shifts better and is quieter than any 356 trans I have experienced.

On the other hand another I did and have in our 63 coupe is pretty noisy in 3rd and 4th and wear was visible on those gear sets just as Vic has said is common. I've driven it 27k miles that way and have learned to ignore it.

One great thing about open cars with the top down is that you barely hear the gearbox.

Vic, do you have new production 3B, 4C and 4D gear sets and how good are they from a noise standpoint?
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Martin Benade
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Re: Gear whine normal?

#12 Post by Martin Benade »

Instead of sawdust I hear raw ground beef is the ticket.
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Vic Skirmants
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Re: Gear whine normal?

#13 Post by Vic Skirmants »

"Vic, do you have new production 3B, 4C and 4D gear sets and how good are they from a noise standpoint?"
Nope.

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Matt Harkis
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Re: Gear whine normal?

#14 Post by Matt Harkis »

Drained the gear oil and replaced with a quart of Lucas Oil Stabilizer with remainder 80/90 gear oil.
Drove the car about a hundred miles today. Again, not a terrible noise. Seemed a little quieter. It cold here now, but I can imagine with 5he windows down, you wouldn’t here much.
For now, I’ll leave it alone.
Thanks for the help guys.

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Re: Gear whine normal?

#15 Post by Greg Bryan »

I had my trans overhauled a year ago and put in very nice looking used R & P, 4C and 3rd gear (cant remember ratio). It works well, but I also have a whine noise that peaks at about 58mph. I drove a friend's car - another SC cab - and it seemed to have a similar noise at a similar speed, so I'm chalking it up to 'characteristic' - similar to the noise that Wil mentions at 50-70mph.
I can hear the noise and look down at the speedo and know I'm going about 60. It seems to go away if I go faster, but there is more ambient noise as well - at any rate, I can't hear it at 70-75 where I do most of my cruising.
My almost new car has a body drone at 1800 rpm and has been there since new. Sometimes you get a perfect storm of noises (vibrations) that will manifest when the frequencies line up in some fashion and the vibration amplitudes add to each other. I'm quickly getting in over my head, so maybe someone who actually understands vibration characteristics can speak up.
Greg Bryan

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