Engine/Transmission (1998.5 - 2002) nv4500

[KATOOM]

Welding the nut has also been attempted by the shade tree folks, but proven to not work either. Plus welding changes the metallurgy of the nut and gear.

 

[SAndreasen]

Yes I have seen welded nuts still come off but if you welded the retainer to the nut neither could move . all welding the nut to the shaft does is ruin the shaft so it has to be replaced

 

[SAndreasen]

About ready to install

 

[SAndreasen]

Got the transmission back in with 200 miles on it so far and it is working beautifully shifts are smooth no noise coming from the transmission and it seems to be running the same Temp as it was before the damage . I will run a few more miles and change the oil and filter while I had it out I put a drain plug in as well

 

[KATOOM]

Drain plug is a great idea. I'm not sure though why you didnt drill out the already bung in place under the fill plug. For that matter, I'm not even sure why NV didnt utilize their obvious intended spot either.....

 

[SAndreasen]

The early transmission had a drain plug in the spot you can see where yhry cast . thr only reason I do them this way is so the plug Is on the lowest possible spot in the case

 

[KATOOM]

I was thinking more for potential housing casting strength by using the existing bung. I didnt know if drilling a random hole could allow for cracking.

 

[SAndreasen]

I have not seen one crack but I suppose it's a possibility

 

[JAlford]

I have had 5th gear issues for the last 60K on my truck (4 rebuilds + now a new trans), but I tow a rather heavy trailer (15.5K). My opinion currently is to purchase a "new" NV4500 from Midwest Transmission. He still had some left a few months ago. I have a new one in my truck and have towed over 3K miles with it so far. Seems to be working well, time will tell.
My 2nd ST rebuild 5th and 5th countergear looked exactly like yours, similar situation, was driving 60mph pulling a very slight slope and then KABOOM, no more 5th gear. The rebuild had 6K miles on it, less than 4K towing. I was running Amsoil GL4 at the time.
My next rebuild was Midwest trans, and the ST mainshaft was re-used. All gears were Cryo treated and it lasted for 25K miles (but about 4-5K miles towing again). Only broke 3 teeth off 5th, none on countershaft. 5th nut did not back off, but the 5th gear was worn severely (could rock it back and forth on mainshaft) and there was 0.015" space between nut and gear.

If you get a new trans, there isn't a core and you could have your old one rebuilt as a backup spare. That is what I have currently. The NV4500 isn't a reliable trans if you tow heavy, so a backup keeps the truck available with only a trans swap. I have gotten to the point I can swap mine in the garage in about 6 hrs.

The alternative is a G56 conversion - but the cost is $$$$$. It figured to just over $6K total cost, which is why I had to just get a new NV4500. I talked with several TDR members that have done it, and it would be worth the $$ if you can afford to put that much into your truck according to all of them I spoke with.
Jeff

 

[KATOOM]

Thanks for that information JAlford, but did you ever monitor your transmission temps? I ask because not only does towing in 5th gear in the 4500 build immense heat, especially 15k pounds but the 4500 transmission is also a solid chunk of iron offering very little heat dissipation. In stock form normal driving temps run in the 175* - 225* range and people who have towed heavy with this transmission and also use a temp gauge have reported temperatures up around 275* - 300*. Thats simply way too hot to expect reliability and will always result in internal mechanical problems. Not too many hotshoters using the 2ng gen trucks anymore so therefor less 4500 trannys are used for that too, but years ago there was a hotshot driver who talked about how many 4500's he went through until he discovered that excessive heat was his problem.

Learning from all the shared information I've read over the past 10 years or so regarding this situation, when I started towing a 14k+ 5th wheel regularly with my truck, I found that running Fastcoolers, blanketing the exhaust by the transmission, and staying no higher than 4th gear results in fluid temps of around 175*. I might reach 200* on looong grades in 3rd gear but as soon as I shift back into 4th the temps start to drop back down. Oh yeah.....thats in triple digit summer weather too.

 

[JAlford]

Thanks for that information JAlford, but did you ever monitor your transmission temps?

Depends on how accurately the temp measured is. The outside of my FAST cooler has never measured more than 210*F with an infrared. I also have much less power than most trucks, it peaks out at 250HP and 530ft lbs on the dyno. I have never towed the trailer in more than 80*F weather as well. I have run RP fluid, Mopar, and Amsoil. Fluid never looks "burnt" at a change. I change it every 20K miles.

Jeff

 

[KATOOM]

Measuring 210* on the outside of the cooler means everything is definitely hotter on the inside of the cooler just by the basic principles of dissipation. So you're probably running much hotter fluid temps than you think. Just curious too but did you ever shoot the laser temp at the iron housing and in various areas of the housing?

Also, your fluid doesn't have to look burnt to be running too hot. For oil to reach the point of coking means temps exceeding 300*, but thats not the direct issue either. The real problem is oxidation which rapidly takes place once oil reaches 180*-190*. The oxidation then reduces lubrication properties and attacks the soft metals. Over time, depending on the average sustained temperature, the oil becomes compromised and needs to be changed. Not a big deal for most conditions but when you're averaging in the 225* - 250* range then you need to change it more often. I would presume changing the oil every 20k is often enough but again, I'm not really sure how hot your fluid is getting under certain situation. Nonetheless, point being is towing in OD will always generate high heat in the transmission simply by the virtue of increased output leverage inside the transmission through the compounding process. I notice the temperature change running in 4th as compared to 3rd gear.

 

[JAlford]

The iron case always measures 50-80* lower than the FAST cooler, typically 130-150* or so. When I have had conversations with ALL trans shops, NONE recommended any more than adding the FAST coolers and NONE could tell me that there had ever been a failure due to temps. My issues are gears breaking cleanly along fracture lines - and I have always suspected the metallurgy. I have yet to have any bearing failures or seal failures, both would be much more likely with excessive temps.
Does towing in 5th create more heat? Possibly, I don't know since I don't have the option of towing in 4th, due to the trucks miles are on interstate highways.

SAndreasen - I apologize, I didn't intend to hijack your thread, only to offer a possible option for a 5spd trans. The reason I purchased the "new" trans is that the parts were made to New Venture specifications, and most likely made here in the USA. The fully splined main shaft was an exception, as it must be changed from GM to Dodge. Midwest Trans is sourcing the mainshaft from Italy instead of the far east. I don't know if it will survive long term, but so far it is doing better than any previous rebuild.
Short of purchasing a newer truck or doing a conversion to a 6spd, it is the only other alternative I am aware of aside of a rebuild.
Jeff

 

[KATOOM]

Good to know. I cant fully state about the heat issues in regards to any transmission shop input, as all I know has come from members sharing their experiences. But one thing I have become more aware of from transmission shop talk is the lack of OEM componentry for these transmissions. Its literally non-existent anymore and everything now comes from China or Thailand or Taiwan. One place told me specifically that the replacement fully splinned shafts are more problematic than the OEM partially splinned shafts simply because the metallurgy from the orient is so poor quality. Maybe thats one reason why you've been having so much trouble with the rebuilds. I know people have tried cryogenics but maybe its just not enough help.

 

[OakViewJeff]

I've been following this thread and want to add my observations to the transmission oil temp and failure cause discussion.

I monitor both the NV4500 and differential temperatures since installing the Fast Coolers on the transmission and MagTec cover on the diff, and rarely see the temps go over 200F on either component. I haul a 9,000lb 5th wheel for CGW of just under 19,000lb over some steep passes in the west during the summer. Recently pulled the load up a 13% grade to Cedar Breaks! I use the OEM spec oil in the transmission and RP in the differential and change it every 50K. Current mileage is 275K.

I am on my second ST rebuild as I detailed in my earlier post, and want to share the comment from Richard Poels, owner/engineer/mechanic of Standard Transmission in Tucson, regarding NV4500 failures. He said the transmissions were never designed for the reverse thrust load created by the aftermarket exhaust brakes that most of us have installed on our trucks. Before the last rebuild, I used my exhaust brake all the time. in all the gears to slow down, with or without my trailer. Now, I downshift to 4th before engaging the exhaust brake (using the handy button on my gearshift knob), and rarely use the e-brake when driving without the trailer. Brakes are cheaper than transmission repairs.

 

[KATOOM]

OakViewJeff, I too fully monitor my drivetrain vitals with gauges. And I only use OEM Syntorq in the 5 speed and RP 75-140 in the differential. With the Fastcoolers I have about 7 qts in the transmission and 8 qts in the differential. Under normal driving the average transmission temps towing in 4th gear are about 150*-175* depending on weather. The differential runs warmer at 175*-190* simply due to the hypoid action with the thicker 140 weight.

That said, I too have heard about how the exhaust brakes can harm the manual transmissions in these trucks, but.....just pointing out that I've used mine for at least a decade. And I use it ALL THE TIME too. I understand that the excuse for issues is supposedly the reverse pressure placed against the internals from the retarding pressures of the exhaust brake, but I have to say that my opinion is most of this is uncertain knee jerk reactions to what those transmission builders cant fully explain or defend. And/or because people refuse to accept that the OEM fluid is necessary in the 5 speed due to the composite layered syncros and that the 6 speed is underfilled from the factory. What I mean is, I'm not professing to be as knowledgeable as those transmission guys but I've done my fair share of mechanical labor too. In taking that further, if every transmission shop was an expert then you wouldnt see any variations of information about fluid types and weights to run in them. Instead it seems to be personal preference per the builder and thus you'll be getting personal opinions in relation to failures. So for them to state that the transmission isnt designed for reverse load is strange to me because both shafts have a front and rear bearing and all gears have their thrust bearings as well. Meaning, even in 4th gear, just because power is direct in/out without compounding, there's still pressure against all those bearings and thrust bearings in forward and reverse load.

Again, I have no fight in this argument other than it sounds like wives tale talk that doesn't go away, like torn diaphragms in the VP. If exhaust brakes were the problem then I'd think there would be a lot more problems related over the past decade or so in the manual transmissions simply by virtue of exhaust brakes themselves. But there's not..... You hear more about incorrect fluid types or weights and levels, not using coolers thinking manuals dont care how hot they get, using cheap foreign parts, and people towing massive amounts of weight. Sounds like far more reasons for issues than exhaust brakes..... But thats just my opinion.

 

[JAlford]

OakViewJeff,
Thank you for the info, I had not heard about any issues with e-brakes and reverse loading. I would think it could contribute to the issues, for sure. I have heard from several trans experts that the nv4500 was really not ever designed for diesel applications period, and was why GM never used it except with gas motors. It only had a 450ft lb capacity rating from New Venture.

I can let you know that my failures have not involved an e-brake, as I have only had a functioning e-brake the last 6 months, and no trans failures during that time. I really personally suspect it is quality of parts available. My original trans lasted 98K miles before the nut backed off, and then the 1st rebuild I did myself and lasted 60K+. The 1st rebuild failed due to ground-up metal in the bearings, due to a defective casting of an aftermarket cast iron tailhousing that ST talked me into purchasing. Rebuilds 2-4, none have lasted very long.
Jeff

 

[SAndreasen]

The cheap China parts in the rebuilds is the main reason for the rebuilds not lasting very long I can't believe one of these companies won't get some parts made in the USA there is a market for the parts but nobody wants to do it . That's the main reason why I put this one back together the way I did how long it will last I don't know but even then I had to use China parts because that all quad 4x4 had #@$%!#@$%!#@$%!#@$%!

 

[KATOOM]

Well because 1) America is loosing its ability to "manufacture" as our the tooling jobs are outsourced, making its way overseas and across southern boarders. So much so that the financial loss America gives up annually from foreign manufacturing is in the trillions of dollars. And 2) its very expensive to manufacture in America thanks to various erroneous labor laws and unions stomping out competition, so unless the "market" is worthy of the investment no company has the means or will be willing to invest in a low or slim return. Dont like those answers then talk to your legislation and vote for those who are most geared around bringing manufacturing work back to American soil. Heck, even Obamy's recent economic adviser czar who was supposed to help deal with US unemployment numbers, Jeffrey Immelt, the chairman and chief executive of General Electric, just sent his company over to China..... WTF?

So, in point, dont get your hypes up for some American made components for these older transmissions. The likelihood is its not going to happen.

 

[surfbeetle]

I have had 5th gear issues for the last 60K on my truck (4 rebuilds + now a new trans), but I tow a rather heavy trailer (15.5K). My opinion currently is to purchase a "new" NV4500 from Midwest Transmission. He still had some left a few months ago. I have a new one in my truck and have towed over 3K miles with it so far.

What does a new one cost? Mine just started getting hard to go into 3rd gear. I'm going to change the oil and have been double clutching into 3rd. It's not my daily driver anymore but we use it to pull the fifth wheel almost every month.