Possible Toploader 4sp Gear Whine
#1
I have another thread with a gear whine noise I initially thought was coming from my rear axle. Before I commit to disassembling the rear axle I'd like some input on my thoughts. Is it possible this noise is coming from my transmission? It's a close ration Ford toploader 4sp. It is filled with Valvoline 80W-90 Gear Oil.

- The noise occurs on acceleration and only in 1st and 2nd gear.
- The harder I accelerate the louder the noise is.
- The pitch also increases with speed.
- The pitch changes with each gear. (Is this a clue?)
- The noise stops when I push the clutch in.

I'm not certain if its trans noise or rear axle noise that coincidently occurs at speeds of 1st and 2nd gear. I don't recall the noise before I changed the ring and pinion gears but I rarely drive the car.

I changed from a 3.89 to a 3.70 rear axle ratio so now under acceleration there are more loads on the transmission. So I'm thinking it could still either be rear axle noise or the increased loads on the trans during accel uncovered a trans issue.

If there are any members here more experienced with a toploader trans.
- Do they normally have some gear whine?
- Do they only have gear whine when something is wrong?
- It has Valvoline 80W-90 gear oil in it. Will Lucus 80W-90 gear oil be better?
- I've read some use 85W-140 gear oil. But does that make it harder to shift?

The trans was rebuilt by a local trans shop. All needle brearings, front and rear main bearings, thrust washers, seals, blocker rings, and the input shaft were replaced. No gears were replaced in the process.

Mike
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#2
I have not personally experienced noise from my top loader transmission but I have a friend whose 3 speed transmission did make a whining noise. It drove him bonkers so he ended up putting a T-5 in his car.

To rule out the transmission making the noise, from a stop position, try coasting down a hill with the transmission in neutral. The hill should be long enough to get the car up to at least 50 MPH. This way you will be able to tell if the gear noise is coming from the transmission or the rear end. Coasting is a great way to listen to your car for noises and or vibrations that you wouldn't necessarily hear during normal driving.
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#3
Gear whine is produced by load. while coasting will sometimes help pinpoint a heavily worn issue bearing or gears. As to whether it's the trans or rear end. I believe the whine he is talking about is a load only situation, and can be very difficult to diagnose, as the drive shaft is like an amplifier and will transmit noise from the rear end to the transmission, very efficiently. I rebuilt the trans, and put 2 used ones in my 87 Ranger years ago. Only to eventually find out, the rear end had a cracked main cap and it was flexing under a load, drove me absolutely nuts!
I wish I had better knowledge, but I talked with many professionals, and gear heads over the years and the only way I've seen it done was to have someone use a mechanics stethoscope and actually hold it against the trans to see if they could pinpoint the noise I've even checked the rear end the same way but that was on a Semi truck with one guy driving, and the other one laying on the chassis. Yeah real dangerous. Here's a thought take a long piece of hose and attach it to the vent for you rearend. The hose will transmit the noise almost as good as a stethoscope and a lot safer. Hope it helps JTS 71 Mach1
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#4
Thanks for all the input. The only thing I can add is the noise is not there while coasting. And is also not there in third or fourth gear under any condition. But that can still be coincident and simply speed related not trans gear related.

Since going into the trans is worse than the rear axle, I think I'm going to have break down and pull the third member back out. More than likely go back to the 3.89 gear set that I had in there before.

I agree, distinguishing rear axle noise from manual trans noise is difficult. A wheel bearing is easy to pinpoint. But anything else, the noise transmits so much from one place to another.

Mike
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#5
Out of curiosity did you happen to feel if the rear end seemed extraordinarily warm to the touch where you are unable to keep your hand on it?

Second, eluding to JTS' comments, is it possible to get your car SAFELY off the ground on jack stands and go through the gears to see if you hear the whining noise? It would be nice to rule out one or the other before tearing something down only to end up with the same result.

I thought you mentioned that you don't recollect hearing the noise prior to installing the new gears.
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#6
I just finished running it on jack stands to listen for the noise with my Stethoscope. The trans made a small noise but not the high pitch whine I hear while accelerating. I ran it in all 4 gears, the trans noise was the same in all gears.

I'm guessing no drivetrain load so is why I couldn't reproduce the noise.

Yeah, I don't remember that noise. I rarely drive it so I'm second guessing myself. I guess I'll pull the third member and back to the 3.89 gears. That thing gets heavier as I get older. Still easier than the trans.

The only thing I can add is the noise diminishes a lot after driving it a while (5-8 miles or so) and everything warms up a little.

Mike
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#7
You are correct, on jack stands you have taken away the loading of the drivetrain. You said 2 things that come to mind and point to the most likely culprit. You said you could hear "noise in the trans" with the stethoscope, and you said it only happens in 1st and 2nd gear. Which involves the input shaft and cluster gear in the trans, and the bearings that support each. I'm willing to bet you have a worn or loose bearing on the cluster gear on the front of the shaft. it would be loaded the most, in first and second gears, third not so much and 4th is straight through the main shaft of the trans, and the cluster gear is simply along for the ride and wouldn't make any noise since there is no load on it. Second thing is if it were the rear end, it would most likely get louder as load/speed increased just the opposite of what you describe. I'm leaning toward the input bearing and the cluster gear bearing in the front of the trans. One or both of them are not happy due to wear, looseness or possibly they could have missed a shim, washer or lock ring when it was rebuilt causing the looseness and the whine. I hate to be the bearer of bad news But i'm afraid it's not the rearend. Have you taken an sample of the oil, and see if you have any glitter, in one or the other? If you do you will be on your way to finding the culprit. Hope it helps JTS 71 Mach1
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#8
You might be right. For my sake I hope not because that means remove the trans and take to another trans shop because I don't have the pullers to remove the rear and front bearings.

Maybe I wasn't clear on the noise. It definitely gets louder under load. Loudest at low speeds under hard acceleration then fades away to nothing at about 35-40 mph. The pitch gets higher as speed increases.

I wondered about the trans fluid. So I changed it this last Sunday. The oil was crystal clear. Plus I read on David Key's Toploaders web site to change the oil at 500 miles after a rebuild to get any metal shavings and assembly grease out of the trans. I'm guessing I have 350 miles on it since it was rebuilt. There were a couple metal shavings on the magnetic drain plug and also some grease. I refilled it with Lucas Heavy Duty High Performance 80W-90 gear oil.

I recently learned the input shaft snout length on a small block trans is a little less than 3/8" longer than on a big block trans. The tag on my trans indicates it was from a 1968 390 (not a GT). I hate learning this stuff after the fact. The trans shop replaced the input shaft during the rebuild. The original didn't look bad where the snout rides in the pilot bearing. I hope they replaced it because it was wrong for a 351W. I found a few old pictures without the engine in the car and the input shaft snout looks unusually long like the top one in this picture. Plus, I don't have any clutch chatter or odd vibrations.


Attached Files Image(s)
   
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#9
The noise in the rear end would get louder, and I've never seen one fade out at 35 to 40mph. As long as there is a load on them, they just continue to whine. I've never heard any get quiet. Once a "Whinner" always a "Whinner" LOL!!! Geez I wish I had better news for you. JTS 71 Mach1

But please take what I've said with a grain of salt, As diagnosing one over the computer is sometimes pretty difficult. Hope it helps. JTS
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#10
I guess I need to decide what to tackle first, rear axle or trans, and hope I pick the right one.

Right now I am leaning towards swapping out the ring and pinion for the set I know had no issues for a couple reasons. 1st, if the noise is still present then it must be in the trans. 2nd, with that high 2.32:1 first gear in the trans going from a 3.89 to a 3.70 rear axle made the car more difficult to get rolling from a start. I have to feather the clutch much more now which I don't like. I do however like the slightly lower cruise RPM.

After research I've discovered Ford put 3.91 rear axle ratios in the majority of cars with a close ratio trans. My service manual has a footnote next the specs for a close ratio trans that states "with 3.50 or higher rear axle ratio". Now I know why. In hindsight maybe I should have installed a wide ratio trans. But at the time I remembered my oldest brother put a wide ratio 4sp toploader in his 1956 F100 and hated it. Could never find a suitable gear for driving around town and too much RPM change between gears.

Thanks for all the help. any more ideas please let me know.

Mike
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