I have a Muncie M20 in my '69. It has a certain amount of whine in 1st thru 3rd gears. Not quite like an M22, but noticable. Is this normal? If not, is it caused by worn gears or worn bearings or? Otherwise its operation is fine, except for the 1-2 shift being sometimes being a little balky when speedshifting. The synchros are in excellent condition and bearings aren't "rough" when rotated. von

Von, I'm certainly no expert on Muncies. I have a whine in 3rd only, and a few experts decided it was a bearing. It would have been a different bearing if it had been more than 1 gear. Or so I was told.

Von, I wonder which bearing it might be, there are three, the front on the imput shaft, the center bearing and the roller bearing on the front of the main drive.

I don't know the history of the trans, but if any of the gears or the cluster were replaced, it might make noise. It won't happen all the time when these gears are replaced, just once in a while.

Another sorce of whine can be a drive shaft that is not aligned with the rear, it loads the output shaft and will make it whine.

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Wally
Gold #67
67 Malibu "Small Block"
90 SS454
71 Malibu "Small Block"
93 torch red vette

The three mainshaft bearings and the extension bushing. There are four runs of needles in the cluster gear, also.

Sounds like the mainshaft balls, and the rollers in the input to mainshaft are going away, since 4th is a direct linkup from the input to mainshafts, and doesn't use the rollers between the main and input shafts, or a broken ball guide in the input shaft ball bearing.

Could also be the trans oil is way too light or synthetic.

Only real way to know is to tear it down. Is it that bad yet???

I always use 90 wgt gear oil only in 4 speeds, no synthetics or lighter viscosities, even in cold weather.

Sorry Von I dont have an answer for You ,,,,,but I was wondering ,,,,,Walley how can the driveshaft be Out of line with the trans????? can You ummm be more specific on this?,,,,,as to how can it happen ? and how can a person check it? to fix the problem? what I am gettin at is how DO You check for the misalighnment,, Tintop55

I don't know the history of the trans before I bought the car 2 yr ago. I tore it down 1 yr ago and replaced the gaskets, seals, and rear bushing. Everything else appeared to be in good condition, but I'm not an expert on these. Reverse gear had a few chipped teeth. I'm using 75W90 gear lube. Like I said before, the whine is light and only in the 1st 3 gears. None at all in 4th. If my memory is correct, other M20's I've had many years ago didn't whine at all. von

Chipped reverse teeth are normal. Alignment from the trans mainshaft center to the pinion center isn't always a straight line, but offset to one side of the car, and this is normal (the u-joints make up for the mis-match.

4 speeds usually will not make noise in 4th gear unless bearings are broken, because the other gears that move on the mainshaft aren't in tension moving the car. 4th gear is a direct linkup from the input shaft to the mainshaft (output shaft) via synchro, and therefore, the cluster and 1/2/3 gears freewheel inside the trans when it is in 4th gear.

When the 1/2/3 gears are used, the input shaft turns the cluster gear, and depending on which of the first three gears is selected, engages that particular gear onto the mainshaft through its synchro, while the input and mainshafts freewheel on each other and turn different speeds.

For noise in 1st through 3rd, look into bearings in the input shaft, mainshaft, and cluster gear, and the thrust washers and spacing on all the gearsets, including the cluster gear.

75/90 is a little light, but shouldn't allow loud gear whine. I use straight 90 wgt only.

Hmmmmm, the rear yoke is not aligned with the rear of the trans? Hom much mis-alignment do you think it will stand? And, how do the universal joints make up for mis-alignment?

I understand what the role of the universal is, up and down movement is the primary domain, not to much side to side if any.

10 bolts and 12 bolt rears a centered pinion rears, unlike the 9 inch Ford, offset 4 inches, the Dana 60 offset 1 9/16. Both axles are the same length in the GM units, the rear and trans should be alinged, the straighter the better.

In response to an earlier post about how this can happen, several ways. The rear can be mis-aligned if the bushing are in bad condition, one or more of the link bars are bent or the frame is bent.

If the rear was meant to run out of alignment with the trans, why do chassis builders use a large precision ground shaft the aligns the center line of the crank with the rear? I have seen this done, once on my car.

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Wally
Gold #67
67 Malibu "Small Block"
90 SS454
71 Malibu "Small Block"
93 torch red vette

Von,
If it is a true whine, it is from the gear mesh most likely. If a bearing is bad (that is in a Muncie) it most likely will make some other noise (more like a growling front wheel bearing, and will buzz or vibrate through the shifter). If I were going to take a wild guess in the dark, I think it is possible that it has had a gear replaced (maybe the cluster) in its past. This is a common symptom (excess whine) when one or more gears are replaced. If everything else is OK about the tranny, then leave it alone.

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Tom Parsons

If you think all driveshafts are aligned side to side, you haven't really looked at a Ford van. They have a 2 inch side ot side offset from centers stock.

Depending on the crossmember, motor mounts, differential aligning pieces, the driveshaft can indeed be offset as much as a couple of inches.

Now, if the center of the front yoke is not centered in the rear of the trans, then this would cause a problem, bushing and yoke wear.
The rear yoke will never be centered in the car, but doesn't nescessarily center align with the center of the trans. Yes, the engine/trans is offset to the pass side for steering box clearance, buy it still doesn't always fully align with the center line of the diff.

I'd start just checking everything, as the main thing in side to side alignment is that both shafts are paralell with each other, but it isn't totally nescessary to get them in perfect alignment front to back.

I just follow DZ around and post replies about muncies after his! 65Z16 said it could be too light of oil or synthetic. My experience is that synthetic gear oil dramaticly QUIETS down Muncie noises, however, it tends to leak easier! Also, like Tom said, replacement gears will cause a whine due to the fact that the new gear(s) and old ones didn't "wear in" together.

I've NEVER had synthetic oils quiet anything I tried to use them in. Synthetics are always too light a viscosity for proper lube and it breaks down way too fast for me, and I simply will never believe that oil change intervals can be increased without having wear increase exponentially.

Sorry, I don't buy synthetic oils hype.

Thanks guys. It makes sense to me that gear mesh would cause it since it only occurs in 1st thru 3rd. Since everything else seems OK, I'll leave it alone for now. Maybe try some heavier lube. This 75W90 stuff does seem thin (Valvoline Hi-Perf). von

Von,
Unless you live in a climate where it gets super cold in the winter (teens/20s) and stays there for an extended period, why don't you put a straight 90w oil in your Muncie and leave it. If it does get cold and stays cold, then at least let the tranny spin in neutral for a while after you start the engine if you switch to 90w. (way, way back when, before I got my first Muncie for the 51 Chev, I put 2 cans of STP in my 3spds and filled them with 90w gear oil, a little stiff in the winter, but they were quiet).

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Tom Parsons

DZ, I live in the Indianapolis area, but don't drive the car in the winter. I will try the straight 90 wt next season. Thanks. von