4th gear tapping

[Big A]

This weekend I was pulling my 9500lb 5ver over the mountains, and the transmission would knock or vibrate a little in 4th gear. It would only do it if I was going up a steep hill. It would stop if I eased off it, and it would'nt do it again. It did'nt seem to affect performance.

Any thoughts?

Thanx

Big A

 

[MidwestMotorman]

rpm

What rpm were you running in fourth? The trans have been known for vibrations at rpms below 1800 loaded. But I would presume you would have been much higher than that.

 

[Big A]

Nathan,

I was running around 2300 and 2400 rpm. I cant really explain it, but the vibration or tap, was coming from the transmission. Like I said though, it has tons of power, and no adverse effects when it happens. This 5spd is a much better puller than my '99 auto,but I really dont want to have any problems with my transmission.

Thanx

Big A

 

[WLM_RAMMAN]

My 5-spd vibrates pretty good when I'm working it with a load on the 25 ft flatbed... . sometimes it worries me. I will stop if I let out of it... . think its too much power to the transmission?... ... NAH!!!, never...

 

[claymike]

This has been happening with my 6 speed. In 4th gear around 2400 rpm you start getting like a loud tapping or knocking sound. If you let off a little the sound goes away. In my case when the sound starts you can put your hand on the gear shift and it is still smooth. After doing some more checking I found it to be the air cleaner snorkel banging around in the fender.



Mike

 

[JyRO]

Me too!

Big A -



I'm glad you started this topic because I was almost ready to believe I had imagined it. My 5'er is also around 9,500# loaded. I just got back from going out to Mt. Rushmore and back about 2,600 miles towing (3,100 miles total).



I had a real hard pull up about a 8% grade (I guess), and at the bottom I got behind granny. She was running about 30 in a 55 zone (no joke). I could see the hill coming and I wanted to get a run for it but she was in the way. When we finally started up the hill the road split into 3 lanes (2 up, 1 down) and I got to go around her.



Basically 4th gear had just enough power to pull this grade, going into 5th would've resulted into going back into 4th. So I left in in 4th, running about 2,400 - 2,500 rpm. Mine started making a slight thumping noise. I couldn't feel it in the shifter or anywhere, only hear it. It sounded just like a tire going flat, as it got a little louder. I was mighty worried since I was pulling a 5th wheel with a 2500. When I let off it went away. I got back in the throttle and the noise came back. I let off the throttle again and by that time I'd slowed down enough to need 3rd. I put it in 3rd and it did just fine, no noises in 3rd.



Later I used 4th on some other steep grades on slower speed 2 lane roads. Some times it did it, some times it didn't. Never did it when not pulling the 5'er though. 5th and 6th never had this problem either.



- JyRO

 

[MidwestMotorman]

simple solutions

Sometimes the cause is way off the beaten path. Remember the old Coke bottle in the quarter panel noise???



I would check anything attached to the motor or trans. Exhaust, hoses, air tubes, and anything else that can rattle with the drivetrain.

 

[JyRO]

I don't doubt that...

Nathanbush - In this case, I would tend to agree with you. Because I (along with others on this topic) couldn't feel in the shifter, pedals, or floor what I was hearing. And it didn't seem to have any effect on power. It was only a noise that happened in 4th gear under heavy load.



I forget if 4th or 5th gear is 1:1. I was wondering if in the case that 4th is 1:1, could it be possible that due to the extreme load and the fact that a 1:1 gear puts the most pressure on the clutch, could the clutch be starting to slip? Or otherwise heating up the clutch and/or causing the noise in the clutch area versus in the transmission? Hmmm. Just something I've been pondering.



- JyRO

 

[MidwestMotorman]

noise

Yes, fourth is the 1:1 ratio and fifth the overdrive on five speeds. I would think that if the clutch started to slip, the owner would have immediately noticed it as they were towing something on a grade. I would think that once the clutch started to slip that it would do so again at progressively lighter loads, and one would be able to smell the clutch if it did. One could be hearing noise from the springs in the clutch disc as they get loose.



It is hard to say. My rig does not make the noise so I have nothing to compare it do. But I do hear the noise from the #6 rocker assembly quite clearly in the cab. One sound I do listen for is a "dinging" from the driveshaft, meaning the spider gear cross shaft is running around. Already had the experience with another truck of using the front end to drive home with. Sounded like someone was tapping the driveshaft with a hammer. After a week of the noise, KABLOOM, my rear driveshaft was laying on the highway with the rear end internally exploded.

 

[Big A]

Thanx for all the input fellas. I'm going to check the air snorkel, and I'll check the drive shaft too. I'll let you guys know what I find.

Thanx

Big A

 

[claymike]

Ok throw out the snorkel theory. While pulling the 5er over Santiam Pass here in Oregon this last weekend the noise started again. At 2400 rpm in 4th gear the noise does not start right away but after about a mile the banging begins. Again I can't feel anything on the gear shift. This time instead of letting off I increased the rpms to 2600 and the noise stopped. Going to call Dodge today, my warranty is almost up.

 

[JyRO]

Never believed the snorkel thing...

Maybe that snorkel makes some noise on some peoples truck, but I've never experienced any noise from it. But right after buying my truck, I was messing with the air box and noticed the snorkel wasn't assembled with the intentions the engineers had. I could easily see how some peoples snorkels would get pinched almost closed and have a serious effect on the ability to pull air into the air box, by the way my snorkel was mis-assembled. I re-assembled my snorkel (I can't remember exactly how its supposed to work) back to the intention it was designed for. I remember that the tip protruded through the hole in the inner fender. I actually think this was some assembly person's idea to save them 3 or 4 seconds on their tack-time.



Anyway, my 4th gear noise is exactly like yours, ClayMike. Under heavy load, it doesn't come on immediately. But mine was more like a tire-going-flat thump, than a bang.



I bet it won't do you any good to seek help from DC. They won't be able to diagnose it. I'd hate to say this, but it would be easy to diagnose if something broke. Of course it probably won't break until after warranty . I don't know what it is, but I'm going to ignore it, for now. I'm going to try to do like you did and give it more throttle and see if it goes away next time.



- JyRO

 

[claymike]

JyRo I do not have a lot of faith in DC either. But my dealer has a real good transmission tech. I went by today to talk to him first. My truck is going in on Wednesday so we will see. Actually I have two problems. The thump, bang, knocking or whatever sound plus I can not get this thing in gear after putting it into neutral. I have learned that if I pull the gear shift while in neutral over to the left rapidly about four times it goes right into gear.

 

[JyRO]

Your truck on the rack...

Claymike,



Please let me know if they determine anything from your transmission. I bet mine has the identical problem and rather have it fixed while mine's still under warranty. I also notices that after pulling my 5th wheel, mine was extremely difficult to get into gear sometimes when I was at a dead stop and was shifting from neutral. Like when I would let it idle while out doing something to the 5th wheel, when I got back in it was hard to get into gear. Let me know what your dealer finds out about your truck.



Where do you live?



- JyRO

 

[claymike]

JyRo I sent you an email

 

[klenger]

I posted a similar problem on the main 24V forum a few days ago and got several responses.



The description of the sound like a flat tire is exactly what I experienced in 5th gear (6 speed). so much so that I thought that I did have a flat when I first heard it. Other times it is a grinding sound. Last night I heard a new sound, like a banking sound when I accelerate or decelerate going slow. At first I thought it was the 5er hitch pivoting, but I ty-wrapped it down and it still makes the noise. It's like something heavy is leading against the front of the bed and swinging into it when I move. Could this be drive train related? It this the tapping sound some of you have heard?



What's wierd about this, is that I have been watching this forum since January, and don't remember any posts about it. Now that I have the 6 speed, it seems that the problem is quite common. First person to correctly diagnose the problem gets a free six pack.



Ken

 

[klenger]

Drive train noise source verified

Well, I have discovered the source of my noise. The carrier bearing between the rear jack shaft and the drive shaft blew apart and the drive shaft is riding loose inside the hanger bracket. I will take it to the dealer tonight, and hope that they can get to it in the next few days. I think this accounts for many of the noises I was hearing while towing the 5er. I'll try to get a good picture to post.



I'd be interested to know if anyone else that is having funny drive train noises is having this problem. I guess that means I get the free six-pack.



Here are the pics:



#ad




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[claymike]

Ok maybe I have had to many beers whats a jack shaft?

 

[klenger]

Claymike:



My terminalogy may not be correct, but on the long wheel base trucks, the rear drive shaft is built in two pieces. What I am calling the jack shaft is the front piece that comes out of the transfer case, and what I am calling the drive shaft is connnected to the rear diff. I assume this is done (1) to keep the length of the drive shaft shorter to prevent twisting under high torque, and (2) to keep the drive shaft angle steeper to improve ground clearance. I'm really an electronics guy, so forgive my poor explanation. See pics in above post.

 

[claymike]

Thank you Ken just wanted to make sure I am looking in the right place.



Mike