noisy 3rd gear

Tuko · Post by **Tuko** » Thu Sep 13, 2012 6:46 am

I finally got my truck out on the road at the beginning of the week, took it for a 2 or 3 mile spin. One thing I did notice was 3rd gear was ALOT noisier then the other gears, and if I messed with the winch control lever putting pressure on it towards the driver side it would quiet the noise but it would not go away completely. Any ideas what I should check to try to eliminate this noise? Ill try to get a vid posted a little later on.
thanks-
Tuko

RMS · Post by **RMS** » Thu Sep 13, 2012 4:37 pm

you may not be able to get rid of the noise you hear when in third gear without an overhaul(new rollers and thrust washers).
in topic post: http://www.g741.org/PHPBB/viewtopic.php?f=3&t=3722 m15256 mentions that the PTO is meshed with third speed gear.
so pushing on the pto lever to the drivers side would push on the shifter rod towards the passenger side, that pushes on the fork, that pushes on the gear, that meshes with third, putting presser on the counter shaft taking up the slack created by worn out rollers. if it was loud in every gear i would think the pto was improperly shimmed.
Is she the most quiet in fourth(1:1) ?

Tuko · Post by **Tuko** » Thu Sep 13, 2012 6:33 pm

i didnt get it into 4th on them backroads yet, but if i get a chance tomorrow ill try. what would that say if it were quietest in 4th?

RMS · Post by **RMS** » Fri Sep 14, 2012 8:37 am

in 4th( 1:1) there is no load on the counter shaft

MSeriesRebuild · Post by **MSeriesRebuild** » Sun Sep 23, 2012 4:21 pm

Tuko wrote:I finally got my truck out on the road at the beginning of the week, took it for a 2 or 3 mile spin. One thing I did notice was 3rd gear was ALOT noisier then the other gears, and if I messed with the winch control lever putting pressure on it towards the driver side it would quiet the noise but it would not go away completely. Any ideas what I should check to try to eliminate this noise? Ill try to get a vid posted a little later on.
thanks-
Tuko

Just a hunch here with lots of experience in M37 behind it, pushing right or left on the PTO control lever does absolutely nothing inside the PTO unit or the transmission, as the PTO shift shaft works in either a forward or reverse motion only. With that said, most likely what you are doing when you move the shift lever in a sidewise direction that quieted the noise to some degree; all you did was stop the lever from vibrating and making noise is my hunch. Vibrations are all over these old trucks until you literally go through everything doing repairs and updates to cure all this. I'd be surprised if there is a 3rd gear issue at all unless you are seeing evidence of that in gear clashing when shifting into 3rd or a tendency to jumping out of 3rd gear. There are no rollers between the 3rd gear and the mainshaft. It runs on a bronze bushing in the early series trans, and directly on the shaft in the 420.

If you feel the need to check further, simply remove the PTO shift lever and go for a drive, if the vibs stop, then you'll know my hunch was correct. High frequency vibrations are all over more than anywhere else, loose bolts, worn panels, weather seals that are missing allowing metal to metal contact, cab mounts worn out, engine mounts worn out, etc. The list is endless.

Tuko · Post by **Tuko** » Sun Sep 23, 2012 5:49 pm

I like the sound of that post (money saving) haha! the few times it popped out of 3rd i had my hand resting on the shifter probably with just enough pressure for it to pull out of gear. Without my hand on the shifter it wont pop out. since I got it I only have about 10 miles on it, bunch of small stuff needed to be done, Ill get it registered one of these days so I can start driving it around more and starting to enjoy it instead of just wrenching on it in all my spare time

MSeriesRebuild · Post by **MSeriesRebuild** » Sun Sep 23, 2012 8:45 pm

Tuko wrote:I like the sound of that post (money saving) haha! the few times it popped out of 3rd i had my hand resting on the shifter probably with just enough pressure for it to pull out of gear. Without my hand on the shifter it wont pop out. since I got it I only have about 10 miles on it, bunch of small stuff needed to be done, Ill get it registered one of these days so I can start driving it around more and starting to enjoy it instead of just wrenching on it in all my spare time

The early series trans had some issues with the snap ring on the front of the mainshaft popping out of its groove allowing the gears on the mainshaft to float forward. The early symptoms of this issue are 3rd gear clashing and or jumping out of 3rd gear. If you have this going on, don't ignore looking into it as obviously when left unchecked more serious problems will result all the way to total destruction. It can be easily checked for this disorder by simply removing the trans top cover and checking to see if there is lateral movement of the mainshaft gears. If the gears will slide more than a few thousandths fore and aft on the shaft, the ring is broken or out of its groove. You can't see the ring until the mainshaft is pulled from the unit. This is a common problem with the early series trans. Since you have shared that it has jumped out of 3rd; my suggestion is to be on the safe side, pull the top off and check things out, better safe than sorry.

Tuko · Post by **Tuko** » Mon Sep 24, 2012 7:39 am

ill be buttoning up some things on the M this week I will find time to check into that and report back

noisy 3rd gear

noisy 3rd gear

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