Engine/Transmission (1994 - 1998) Broke 5th Gear

[R.ebel]

Last summer at 155K miles I had my clutch done and 5 speed overhauled and in an attempt to make my truck bullet proof I upgraded to the fully splined mainshaft from Standard Transmission. Note I NEVER had the stock fifth gear nut come loose!



Driving home from a long trip (3000 Miles) with Toy Hauler in tow while going down a slight grade I started getting a bad noise or rattle from the Transmission, thinking I'd been bitten by dreaded 5th gear nut backing off I downshifted to 4th and drove the remaining 200 miles home. Hmm... I'm thinking how Ironic that after upgrading to the fully splined main shaft I'd have the 5th gear nut come loose. Oh well maybe the transmission shop didn't torque it to spec. Miles on rebuilt transmission 10K.



Dropped the truck off at the same shop that did the install, a few hours later I get the call. Them "you broke your 5th gear", me "what?... . WTH! ", Them "tore up the companion gear to 5th as well", Me "What the heck caused it?, Them "possible abuse or a bad gear".



Abuse is out of the question, High HP is a factor. I'm the only driver and I don't beat on my truck, its used for towing and thats about it. I don't even let my wife drive it, telling her it has way too much HP for her to handle :-laf



I've got the busted gears back from the shop and under close examination there is a slightly stained area under one of the 5th gear teeth that broke, which tells me the suspect tooth was cracked for some time. So I called STANDARD TRANSMISSION to see if they would warranty the parts, no such luck!



Moral of the story, If IT'S NOT BROKE DON'T FIX IT :{

 

[Missouri Mule]

I'll second that and make sure your not getting used trans parts.

 

[GAmes]

The sad truth is that high HP and towing in 5th gear in a 4500 doesn't mix. I know, I've trashed three of them, and I'm not that high in power. Every catostrophic failure I've had started with 5th gear starting to make noise. A downshift to 4th (the only direct drive gear) stops the noise. However, it is only a matter of time before 1st, 2nd and 3rd also start to go. I now do not ever exceed 20 pounds of boost in 5th gear, in fact I usually shift down at 16 if it is evident that 20 is coming. I am also going to replace the trans at 100k even if it is still working. My failures occured in UT, OR and ID which made replacement that much more expensive being far from home.

 

[R.ebel]

GAmes-I hear what you are saying in the HP department. The old adage "If you wanna play your gonna pay" does indeed bear some weight. I tow about 6000 lbs in valet mode at 385 HP.



The funny thing is the factory original 5 speed was fine at 155K (half of which it was bombed), I just decided to "upgrade" (in my case a downgrade) to the fully splined mainshaft from STANDARD TRANSMISSION thinking it would improve reliability, the Trans was already removed for clutch work so I figured "nows the time" for a rebuild and upgrade.



Buy the looks of the now broken "new" gear it clearly had a crack at the base of a tooth that allowed the gear oil to penetrate and slightly stain the underlying metal. How it managed to last 10k is beyond me.



Makes me wonder if the "new" gears are being "outsoursed" from China :-laf

 

[GAmes]

My 5th gear fell off at 88k. Standard trans did the rebuild and the transmission lasted 165k, the longest of any transmission I have had in it. You may have gotten a bad gear, but I have had nothing but good service from ST.



I believe the problem is the countershaft (I think that is the correct term) bearings. Every gear except 4th is driven by this shaft. I can literally watch the trans heat build up in 3rd (climbing a steep hill) and 5th on a slight incline. If I shift down to 4th the temp drops 20 or 30 degrees rather quickly.

It's too bad the 5600 isn't made any more. If I had known I would put this many miles on the truck I would have converted years ago.

 

[surfbeetle]

So I was going to post NV4500 Rebuild and Overhaul Kits for your info as a place to get parts and service. But when I read his page, I see that they are no longer rebuilding the NV4500 due to parts shortages. As I am at 180,000 + miles on my original trans, I am not pleased to see that rebuilding it may be an issue. I feel that I may be on borrowed time.

 

[Mokerz]

Mid Atlantic Gear (Harrisburg, PA) has or can get the parts for a nv4500. I rebuilt two at my shop this year so far. One required a new 3rd gear, the other was just a strait rebuild. Had the parts at the shop in a day or two.

 

[CumminsPower98]

My 5th gear fell off at 91k while running empty and caused no damage or noise. I put a new nut on and ran it up to 97k with no problems and then swapped in a 5600. I'm sure glad I made that move because a few months later I went OTR towing. I have put 304k on it with many miles of heavy towing in 6th and so far its holding up well.

 

[Signal73]

arent the 5600 parts more scarce then the 4500's?

 

[GAmes]

arent the 5600 parts more scarce then the 4500's?

A year ago 5600 parts were almost non-existant. I'm not sure of their status now.

 

[CaseySmith]

This was unloaded going for a pass. The gears had 175k miles on them. New ones have lasted another 100k. Got the replacements from standard transmission.

 

[PToombs]

And how'd that sound when it let go? :{

 

[CaseySmith]

Not Very Good. I had to drive a mile or two to find a safe spot to pull over. Even in a lower gear fifth got completly trashed.

 

[Boomer II]

I lost 5th 4 times, paid to have upgraded parts on the last re build only to discover when I lost 5th for the 4th time that it was bone stock. Of course I had no way to prove anything since the receipt was generic. Got fed up with all that and went with one of the last new 5600's available. If you're going to tow, that's the only way to go. The 4500 is in my Jeep, if I lose 5th there it won't ruin my vacation.

 

[surfbeetle]

So lets assume that the 4500 has gone away like the 5600 as far as parts and rebuilding are concerned... What is the next logical replacement trans that isn't automatic?