Help! I've got a rattling sound in 5th gear.

[LWilliams]

I've got a 96 12v 4x4 3500 with a 5 spd. 153k miles. It's been about 500 miles since I pulled a load on the highway and really worked 5th gear. I have the modified mainshaft with the new 5th gear. It's been in the truck about a year. Today I was starting off from a stop sign and when I shifted into 5th gear I heard a rattling sound. I clutched and slowed down, put it in 4th, normal, shifted into 5th and the rattling started again. When I am coasting in 5th I can barely hear it but give it throttle and the rattling gets worse. All the way home in all the other gears were normal but shift into 5th and the rattling starts again. The best way to describe the sound is like a loose metal gear that is spinning beside a stationary metal part and occasionaly it hits solid but not a real hard hit either. I would not be to afraid to drive it in 5th again to diagnoise but I definately know something ain't right in there. Do any of you have any ideas?

 

[moparguy]

No personal experiance yet, but sounds like the 5th gear nut has backed off. I'd contact the installer or rebuilder ASAP.



If you installed the fully splined mainshaft yourself, I don't know,,,,,,drive it untill it fails, or tear it down and check things out.



Good luck, Ronne

 

[Deezul1]

Mine made no noise, just like it popped into nuetral

 

[LWilliams]

Update

I've talked to two local shops and so far they are saying it sounds like a broken tooth on a gear. I am tied up on a job right now and can't get the truck in the shop. I will try to get it in there on Monday. I will keep you all informed.

 

[LWilliams]

Update

Well, it ain't good. Both gears, the one on the mainshaft as well as the one on the counter shaft have several missing teeth. They are in the bottom of the transmission. The nut was still tight. Nothing looks wrong except the missing teeth on the gears. ??????? Dunno! I guess it was time for me to spend some more money. I hauled a tractor on my trailer about 3 weeks ago but that is not unusual for me. It was not a hard pull either. I have been driving it every day since without a hint of trouble. Kevin at Standard Transmission in Fort Worth said he hasn't seen this happen before. I am installing both new gears, a new nut, new rear cover bolts and new fluid. Anyway for what it's worth to you, this is what happened to me. I am going to stay out of 5th from now on when I pull anything.

 

[Alaskaskiff]

My Standard Transmission rebuild did EXACTLY the same thing about 2 weeks ago. It only had 12000 on it. I didn't talk to Kevin, but one of the other guys. They couldn't get me a box fast enough so I went to Enterprise Engine instead. I lost seven teeth off fifth and about the same off the other gear. I only ran their bulk Castrol in the box and had only towed just over 300 miles. The GCVW was only 13700. Their rebuild was noisy from the day I got it, but since every transmission is different I didn't think much of it. I think otherwise now.



With 4. 10 gears I have to tow in 5th if I want to get anywhere.

 

[LWilliams]

update

I got my truck back from the shop yesterday. They put in a NEW 5th gear and a NEW 5th gear counter shaft gear, a new nut, new rear tailpiece bolts and new fluid.

The 5th gear that came out had 3 teeth broken off. They looked like all 3 had a crack in them for a long time and then finally broke off. This is evident from the smooth surface area and then the rough break area under each tooth. The counter shaft gear teeth were destroyed from the 5th gear.

Now that I have driven it with both new gears, the barely noticable whine is gone. When the truck was new it had no whine. When the upgraded mainshaft and new 5th gear only were added the whine appeared. Now it is gone. I theroise that a old gear riding against a new gear produced the whine and maybe some stress that led to the teeth failure. There appeared to be no other damage. The bearing in front of the counter gear was fine.

I'm just keeping you all informed. I think if I were doing the 5th gear upgrade with the new mainshaft I would put in both new gears instead of using an old counter.

If any of you have any other thoughts or advise I would like to hear them. Thanks.

 

[Strick-9]

Surely if cumminsgetme sees this thread he'll respond. I believe he too just went through the same dilema.



His 5th gear (updated) actually broke if I remember correctly, destroying the counter gear along with it.



I sure hope this isn't early stages of a series of failures.



Odd that Standard Transmissions says they haven't heard of this. We already have three instances and we are a very small minority. Are you guys describing the problems to them on the phone or are you just ordering new parts without any discussion?



-Chris

 

[jimk]

Steel gears

I am Sure that I will be correced But in PUMP SCHOOL that I attended about two weeks ago that the company I work for, the instructor showed the class a gear and asked what was wrong with It. The gear had some teeth missing, his question was what happened? The root cause, after some interested answers, the instructor said was cheap gears made in Japan. The metal was poor quality and weak.



I am not saying that the gears are made in Japan in the nv4500 or all Japan gears are bad, just food for thought.

loljim

 

[M Barnett]

I agree with changing out both gears instead of one new gear with the old counter gear. If it happened to me, I think I would take the broken gears to a machine shop to have a hardness test done on them just to be sure they aren't too hard causing the breakage. The test is easily done and shouldn't cost much. Its always a possibility.

Michael

 

[Alaskaskiff]

I had my failure 350 miles into a 4600 mile road trip (Rhode Island to Alaska). I had not pulled the case apart before talking to Standard trans but did describe the symptoms. I talked to Corey at Standard trans.



I was not real happy with the offer from Standard trans and they would have been too slow and more expensive than my alternative. Besides I had a box from them fail way early in its life so I wasn't giving them another chance when I had no room for error (military and I had to make the trip by a certain date).



They will receive a letter from me now that I am finally in Alaska (today) and when I can deal with the issues. I saved the gear teeth and have mutiple pictures.



My new transmission is smoother, quieter, and runs cooler than the one from Standard ever did. I am dubious of what was done to it, but don't have much that I can prove my case, and I had to turn in the core since I can not afford to send it to the rebuilder from Alaska.



Hopefully they are as stand up as folks have claimed.