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1967 Mustang Convertible - 200 Six - 3 Speed Manual Transmission
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Discussion Starter #1 (Edited)
The 3 speed manual transmission in my 1967 Mustang is noisy at idle with the clutch engaged (pedal up). If I push the clutch pedal to the floor it is quiet. It also is noisy while driving in 1st and 2nd gear but not much in 3rd. When I'm driving slowly in 1st gear (for example) there is a lot of whirring noise as I give it a little gas and then let off, gas let off, gas let off etc. Definitely coming form the trans area. I made another post about it here a while ago and did some other research and it seems likely that my input shaft bearing is making the noise. The car runs and shifts great. If not for the whirring noise I would not have any idea anything was wrong. It is loud enough that it is killing some of my cruising joy. The car is a weekend cruiser. I hate to get into taking out the transmission on a vehicle that otherwise runs great.

I'm thinking of changing the gear oil. Is there anything I can put in there that would help to quiet it down some?
I'm going to go under the car tomorrow and look around. Is there anything (an adjustment maybe) that I should check?

Thanks for any help!
 

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As easy as it is to get that trans out, why not just pull it an fix it properly? Before you do though, I'd recommend taking it to a reputable (typically means old) tranny shop and have them give you their opinion 1st. It sounds obvious enough that they should be able to tell pretty quickly- then base your strategy on that..
 

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1967 Mustang Convertible - 200 Six - 3 Speed Manual Transmission
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Discussion Starter #3
As easy as it is to get that trans out, why not just pull it an fix it properly? Before you do though, I'd recommend taking it to a reputable (typically means old) tranny shop and have them give you their opinion 1st. It sounds obvious enough that they should be able to tell pretty quickly- then base your strategy on that..
Thanks for the response. You're right...but I have pulled the tranny before on this car and to call it easy is a bit of a stretch. Maybe with a lift. I'm doing it with jack stands...not real fun. The car is running great just noisy. Surely I can milk it for a while? How about some thick gear oil? Also finding a qualified mechanic seems just about impossible!
 

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The bearing is making noise because metal is rubbing on metal instead of balls rolling on races. It's going to progressively get worse and, most likely without warning, is going to fail completely. When this happens it's probably not going to be a simple bearing replacement.....
 

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I've heard that putting sawdust in a noisy transmission or rear end is an old used car dealer cure.
 

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I suppose you could ensure the clutch is adjusted properly and you have good fluid level in the transmission. Outside of that, I think your best option is to pull the transmission. While it is not an especially fun job, its the best approach before things get worse. It could be the input bearing which is not that hard to change once the transmission is out. I rebuilt my 3 speed several years ago with a relatively inexpensive kit full of everything needed from NPD.

I would just go ahead and replace the throw out bearing while you have everything apart as it could be making the noise. With the bulk of the work done, it would be hard to justify not checking out the clutch too. Maybe you get lucky and see the problem before you get everything taken apart.
 

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1967 Mustang Convertible - 200 Six - 3 Speed Manual Transmission
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Discussion Starter #7
Thanks for all of the great advice. As usual, you guys are right and I should probably go ahead and get the transmission fixed properly. I'm going to take the car to a transmission shop this week and get their opinion before I do anything else. I actually have another 3 speed transmission (the original one out of this car) in storage that I could have rebuilt. I could then swap it out and probably not have to much down time on the car. I have been through this before. I bought the transmission in there now from a local Mustang guy (sadly not around anymore). It had been rebuilt not to long before I got it. That was nearly 20 years ago so I guess it is time.
 

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There is no easier trans to pull out than a Mustang 3-speed. You can have it out of there, on the ground, in an hour, with hand-tools, even faster with air tools. You can have the input shaft out in another 15-minutes. Changing gear oil is just going to be a waste of good gear oil. Pull the trans, replace the bearing and front seal. Replace the throw-out bearing while your there.

Strong guys can bench press that trans back up in there. The rest of us use a trans-jack on the ground. I now have a hoist and a tall transmission jack but before that I had a used Blackhawk transmission jack for working on the ground. I thik I paid $100.00 for it at a swap meet.

Get four used big-truck brake drums, I'm sure you can get then for free and by big I mean air brake truck big. Jack the car up and slide a drum small opening up under each tire. It gets the car up higher than you can with jack stands and gives you room to work. Its solid as a rock, no mater how much shoving and pushing you do under there the car cannot fall off of those drums. The only downside is finding a place to store them.

Grind the heads off of two bolts and use them as temporary guide pins to slide the trans back into place. Not a must but it makes it easier.
 

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I've heard that putting sawdust in a noisy transmission or rear end is an old used car dealer cure.
Oddly true, it does make worn-out gears and bearings run smooth and quiet. Trouble is, you can measure the life expectancy of the transmission in days after doing it.
The bearing is making noise because metal is rubbing on metal instead of balls rolling on races. It's going to progressively get worse and, most likely without warning, is going to fail completely. When this happens it's probably not going to be a simple bearing replacement.....
This is absolutely true. If it is running well, apart from this noise, fixing it now is imperative. There are actually two possibilities- The main input shaft bearing, or the pilot roller bearings between the input and output shafts. The rollers are in use in neutral, reverse, 1st and 2nd, but do not roll in 3rd. If you still have the noise in 3rd, it's the main bearing. The main bearing should cost you about about $35, plus $5 for the front seal.
 

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1967 Mustang Convertible - 200 Six - 3 Speed Manual Transmission
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Discussion Starter #12 (Edited)
Oddly true, it does make worn-out gears and bearings run smooth and quiet. Trouble is, you can measure the life expectancy of the transmission in days after doing it.
This is absolutely true. If it is running well, apart from this noise, fixing it now is imperative. There are actually two possibilities- The main input shaft bearing, or the pilot roller bearings between the input and output shafts. The rollers are in use in neutral, reverse, 1st and 2nd, but do not roll in 3rd. If you still have the noise in 3rd, it's the main bearing. The main bearing should cost you about about $35, plus $5 for the front seal.
I'm starting to think it could be the pilot roller bearings? I hear it in neutral (with the clutch pedal up), 1st and 2nd but not in 3rd.
 

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I don't know how it would help your worn bearing but some of the old farmers would put a chopped up cork gasket into a trans/diff to quiet noisy gears.
 
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