Gearbox noise

[rupert's]

Good night friends! I am telling you.
I have only driven my mutt, and my mutt I have only driven after restoration. Taking this into account, there are times that I see behaviors of the car that I do not know if they are normal or are defects or breakdowns, that is why I resort to this forum that always helps me Thank you
I think I have play in the rear transmission, I know that the rear transmission arms may have wear, and in fact I know that there is a bit of play but, I think the problem may be in the gearbox.
Symptoms:
Gearbox pinion noise when I lift the throttle especially in gear 3 and 4
When I accelerate and release the pedal I notice the reactions a little sudden.
When I put the 4 wheel drive there is no jerk or noise in the gearbox.

I put a video to listen to the noise of the box
https://youtu.be/YlAA6lENF2M

Un saludo

[m3a1]

Everything sounds very typical to me.

You should be aware that this particular vehicle is a monocoque body (without a traditional frame) with large expanses of relatively unsupported sheet metal. Since M151 differentials are bolted directly to that without bushings of any kind, the body amplifies every noise those differentials make. The M151 series of vehicle is a VERY noisy little truck because of this..

The fact that when the truck is in 4 wheel drive that noise lessens, it is a good sign that things are in normal working order because both differentials are sharing the load.

However, if you are feeling particularly uneasy about your rear differential, consider swapping your differentials around (front differentials usually have far less wear than rear differentials) and then see how things sound in two wheel drive.

If you find the noise intolerable consider anything that lessens the vibration of the rear floor such as a heavy rubber mat, or anything similarly heavy, to deaden the vibrations.

The rear floor is not the only panel that acts as a sounding board, of course, but it is the easiest panel to deaden.

Cheers,
TJ

[rickf]

I know you had issues with the rear differential leaking before, is it possible that it ran low on oil and the pinion bearing was damaged? Other than that a lot of people have found that the rear output shaft bearing on the transmission going bad will sound just like it is coming from the rear differential. The main symptom of a bad pinion bearing is noise on deceleration but no noise on acceleration. In these vehicles it is very easy to check that by swapping the front and rear differentials as TJ has suggested. If you do that and the noise goes away then you know the problem is in the differential. If there is no change in the noise then either it is a normal noise or it is the transmission bearings. If it does turn out to be the differential and swapping them made it quiet then you have solved the problem, just leave them swapped. The front gets very little load on it and it will be fine until you rebuild it or find a replacement.

[lpcoating]

That sounds "normal" to me. As stated by others, these trucks are loud and make some unusual noises. Mine has NOS diffs front and rear and it's still loud. The best it's ever sounded was when the back of the truck was loaded from floor to soft top with coolers and camping supplies. It was actually enjoyable to drive because of how quite it was. Body harmonics. I have a rubber mat in the back of mine, doesn't really do much. I even put a trailer load bar between the inner fenders. That helps some. If you plan on driving your truck a lot and are going over 30mph for any amount of time, I'd recommend wearing hearing protection of some kind.

Guy

[rupert's]

Valley! One day when I have time I am going to change the position differentials and also the transmission arms, to see what happens.
Anyway, I'm going to try to make another video where the noise that the gearbox makes when the accelerator pedal is released is better heard.

lpcoating ... I recently did 300km (about 180 miles) in a weekend, almost all roads at 40 or 50 mph almost all the time, at this moment it is clear that it is necessary to have some hearing protection but it is not easy because you are driving and you need to hear everything that happens on the road.
I have in mind a possible solution that I think can attenuate the noise ... if I can make it less noise I will post it here.
All the best

[lpcoating]

20211017_185456.jpg

I started using this headset on our 151 trips. It's amazing how much more enjoyable the rides are. I highly recommend this type of unit for anyone that actually drives and enjoys their MV.

Guy

[m3a1]

Now, imagine being in a Gama Goat, which converts money into noise very efficiently...

[rupert's]

20211017_185456.jpg

I started using this headset on our 151 trips. It's amazing how much more enjoyable the rides are. I highly recommend this type of unit for anyone that actually drives and enjoys their MV.

Guy

I think that if the police see me wearing this they will give me a sanction. I'm going to ask a friend.

Now, imagine being in a Gama Goat, which converts money into noise very efficiently...

Headache assured

[m3a1]

I get hearing aids on Tuesday.

No, REALLY! I DO!

[Mark]

Ya, I have some too, but when I drive the mutt I put in ear plugs to save what hearing I have left