Engine/Transmission (1998.5 - 2002) Manual Transmissions ......

[GIT-R-DONE]

I have had this question for a while and finally remembered to post it... . lol For the manual transmission guys out there:



1. Besides the clutch, pressure plate, and input shafts, have you ever had anything else go wrong with your trans? In all the post over the years, I dont remember a post where there was any problem, other than the 5th gear nut, that would be related to the actual gears themselves.



2. Are the gears basically indestructible ?



3. How much power can the gears take in these transmissions. You see some people on the dyno making awesome power and I dont ever remember hearing about any gears on the trans going south. TIA

 

[JFinke]

Blew sixth gear all apart on my 5600 at 260,000. Jake

 

[nps]

Had the clutch pressure line separate from the slave cylinder and leak out all the brake fluid at 7K miles because a rolled pin holding the line into the cylinder fell out. I started in gear and drove home to inspect. The line could have been reattached but there is no air bleed on this system. So I waited for the Ford roll on to show up so the dealer could put a new master/slave assy on. After getting it back, I put a cotter pins through a spare hole, and threaded safety wire through the rolled pin hole. to prevent the line from ever separating again.



Also recently been looking for some additive for my 5600 - Gear Lube or RP. Ever since putting a centerforce clutch on about 10K miles ago, getting it into gear at a stop is getting difficult and I don't like the amount of stick force that is necessary. The local auto parts stores don't have it so I need to stop by the local truck stop.

 

[Supermod56]

The gear oil is not the problem I'm afraid, did you replace the pilot bearing? Real common on these things for them to hang up, several guys make improved bearings for these. Better get it checked or it will damage the syncros



Tom

 

[surfbeetle]

Also recently been looking for some additive for my 5600 - Gear Lube or RP. Ever since putting a centerforce clutch on about 10K miles ago, getting it into gear at a stop is getting difficult and I don't like the amount of stick force that is necessary. The local auto parts stores don't have it so I need to stop by the local truck stop.

Your problem is that the clutch is not completely disengaging. You still have moving parts when attempting to put it into gear. You will notice this more in the lower gears like first and reverse when you are stopped and attempting to get into gear. You will eventually blow out the synchros and wear the clutch down.



As for additive, I have Prolong in my 5 speed.

 

[SRadke]

Stripped fifth gear spline, stripped fifth gear syncro hub, fifth gear nut, broken imput shafts... ... These are all things I've heard about The NV4500 is not a heavy enough box for the torque of the Cummins. I have personally rebearinged 4 of them and put fully splined shafts in two.



-Scott

 

[TStinson]

No transmission parts breakage - BUT, synchronizer on 3rd gear has all but gone away @ 250,000 miles. Been running Amsoil 75W90 for over 200,000 miles, plus Geno's filter kit hanging off the side. Mostly highway miles. See my profile for current mods.

My guess on the synchronizer failure is combination of the following - 250,000 miles, lot of low speed up & downshifting in Houston traffic, hydraulic clutch linkage failure (twice) causing excessive reliance on the synchros to downshift until could get new parts in and, oh yeah - more than a few hard shifts @ the dragstrip.

 

[Larry Willard]

5th gear synchronizer at 99000 miles

 

[GIT-R-DONE]

In 98, I bought one of the first 24 valve diesels, ended up with 2 (two) times replacing the 3rd gear syncro as when I would tow, and be going downhill, it would jump out of gear. They never did fix it, so I got rid of it.

 

[SRadke]

Jumping out of gear is not caused by the syncro. There are three small springs wiht little grooved steel plates on each gear that hold it in. Sounds like you had wear in the pates or weak springs or..... Probably not a syncro problem unless it was grinding into gear.



-Scott

 

[NIsaacs]

The manual transmission gears are tough, but not indistructable. The weak link in the manual trannys is overdrive. In the old days, the little 4-spd's lasted for ever. This was mostly because 4-th, the gear used the most is direct drive. Direct drive is straight thru, main shaft locked to the output shaft no gears being used. Usually when you break the gears themselves, the bearings have become somewhat loose, allowing the gear mesh to ride more on the tips of the teeth. If the 5 and 6 spd's were direct drive and we could get real high axle gears,(3. 00 or higher) then yes the manual trannys would almost be unbreakable.





"NICK"

 

[SConklin]

Does the BD short shift kit leaking like crazy all the time before count?

 

[Luke Warmwater]

How much HP will an NV4500 take before something gives and what breaks at what HP levels? I'm around 500 now and am thinking about 575 level.

 

[GIT-R-DONE]

I was also wondering what the ratios are between the old 5 speed trannys and the 6 speeds. What are the ratios of both and where did the 6th gear come into play. Is the 6th gear in my 5600 the same as the 5th gear in the 4500, ( ratio ) ? Always wanted to ask that too. Damn, my memory is getting better... .