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NP205 and NV4500 rebuild help

5K views 22 replies 3 participants last post by  Kmehr 
#1 ·
I've been tracking down a very loud gear growl/howl from either the trasmission or transfer case. I'm pretty sure it was the transfer case, since I drove about 300 miles in 4hi on the highway after I built the truck. Also the transmission was supposed to be newly rebuilt when I bought it and put it in the truck. Gear noise is loudest at highway speeds and can be heard when on the gas and also when coasting.

It's a "light duty" NV4500 that I put a 10 spline input shaft in. This means the mainshaft and input shaft of the NP205 are 23 spline units. Running stock power right now (175hp pump).

Rebuild kit for the transfer case should be here tomorrow. Managed to pull the transfer case solo today, man that sucker is heavy! When I was separating it from the NV4500, a bunch of fluid came out of the FRONT of the transfer case... the area between transfer case and tranny that houses the coupler, was full of fluid. Is this normal? there was no seal around the coupler in the rear of the transmission. What I mean by this is there was about an 1/8th in gap between the outside of the coupler and the transmission. This seems odd to me, as it allows tranny fluid to leak into that part of the transfer case. Should there be a seal around the coupler?

I'm concerned that the real culprit for all of the gear noise is actually the transmission. It had the same color fluid, with the same metallic glitter in it... I put Syntorq in it when I put the truck together. It could have been leftover fluid from the previous NP435 that was in front of that trasnfer case (that thing was definitely smoked), as I really haven't touched the NP205.
 
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#2 ·
When you changed the input shaft on the NV4500 did you re-set the end play on the mainshaft assembly ? If you didn't then you probably have caused some damage internally.

Here is a thread I wrote up on converting the NP205 from 23 to 29 spline....but covers the rebuild as well.

http://www.cumminsforum.com/forum/8...25-np205-rebuild-23-29-spline-conversion.html

As for the NV4500 rebuild, I ordered the rebuild manual from Quad4x4....and found a few threads on-line that covered partial rebuilds as well. You can look through my build thread...I do show some of my rebuild in there, and I think I might have linked to those other threads?

Crewcab update... - Dodge Diesel - Diesel Truck Resource Forums
 
#3 ·
Well dang. I definitely did not set end play on the input shaft, I just pulled the old one, then set the new one and slapped a new bearing retainer on there. Truck only has about 600miles on it since assembly. What sort of damage should I bee looking for in the transmission?
 
#4 ·
Well 600 miles you are probably not going to see a ton of damage yet....but if those were high speed, on the hwy miles, then perhaps a bit more. The mainshaft has to only have a slight amount of end play....can't recall the exact number...think under .005" ? If this is not achieved the mainshaft can walk out of alignment on the counter shaft and cause the gears and bearings to wear.

At the very least I would pull the tranny apart, if the counter shaft looks good, bearings seem smooth, and the end play on it is correct then leave it in place. But I'd pull the mainshaft and replace the syncros, and bearings....you can get a decent rebuild kit for under $150. Make sure you order a shim package, since your current set-up will probably be wrong.
 
#5 ·
Started tearing down the transfer case. The "well" (connection between the case itself and the rear of the transmission) had a very thick sludge with a lot of metal in it packed in the bottom- this was definitely left over from the old NP435. I'm struggling with a snap ring, but everything has looked good so far. Bearings have all looked and spun really nicely. The thing that I can see that was incorrect is the rear output bearing looks like it was installed backwards- not sure if that even matters though. There was a lot, probably 1/8th- 1/4in of back and forth play on that shaft. That definitely didn't seem correct.

thrashingcows- I'm a little confused- the mainshaft is output shaft right? But you set it's endplay by setting the input shaft up correctly? Can I check the endplay of the mainshaft from the rear so I can potentially avoid pulling the transmission?
 
#6 ·
there are only the input shaft and main shaft. main shaft is output shaft. to set pre load you will have to remove 5th gear, there is a plate behind 5th gear with shims under it. the plate and shims set pre load on rear bearing. this sets preload on main shaft and input shaft. if its to tight it will burn up the Torrington bearing that sets between the input shaft and main shaft. look up crazzyrunner33 sticky on nv4500. its very good.
 
#7 ·
1070 is correct on the location of the shim pack and how to set it up, but to actually check the end play I think I remember having to set up the dial indicator to measure the movement in the mainshaft.....so the top would have to come off regardless I think.
 
#8 ·
damn, I reeeeaaaallllly didn't want to have to pull the tranny, but I guess its best to do now before I trash it. Give me a chance to check out my clutch and flywheel install too I guess.

Got the case all torn down. Bearings all appeared in good shape, there was definitely some wear on some of the gears, is it enough to warrant replacement? Also the oil home in the idler shaft was totally plugged with mud looking stuff and the idler shaft is seriously worn down.

wear on the front output shaft- need replacing?


wear on one of the gears- replace?



where the spacer was wearing through the idler shaft because it was plugged with mud
 
#9 ·
Your idler is fine....that is how they are machined. I thought the same thing when I pulled my NP205 apart for rebuild and conversion. After some research and phone calls I found that this is the way they are supposed to be. The sleeve/spacer rides just on the outer edge of the nice machined surface.

As for the rest....I'd run it. These T-cases are pretty tough, and I doubt that a couple chips in the teeth and the small amount of wear on the output shaft will really cause and long term problems. But on the otput shaft I would install the new bearing and see how much play there is ad make a judgment call then.
 
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#10 ·
I'm very glad to hear that. I starting adding up what a new 23 spline input would cost, plus the idler gear, plus the idler shaft, plus bearing kit. After all that I'd be better off just getting a new one!


Once It gets above 30 degrees here and I can track down a transmission jack, the NV4500 is coming out. I'll be sure to post up more questions on that.
 
#11 ·
The input shaft and the idler gear it matches up with are really the only two gears with visible wear on them. Which makes sense because that had a ton of back and forth play, other side was pretty tight. I think I can replace those two and come out ok money wise. I'm going to call ORD today and see if they have them. Here are some more pics of those two gears:













 
#12 ·
Looks like all that in/out play was from the bad bearings....man those things look toasted!
 
#13 ·
ORD can sell me a 23 spline input for $350; where as a 29 spline is only $220. Or a complete rebuild 29 spline transfer case for about $1000. Either way this ain't going to be cheap!

Thinking pretty hard about doing a 29 spline conversion. Since I have to take the NV4500 apart anyway, I can through a 29spline main shaft in there for about $125. Add bearings, then everything would be rebuilt and up to diesel manual transmission spec. Worries me quite a bit that Dodge didn't even trust the 23 spline setup behind a 160hp manual Cummins... When I get this whole thing dialed in I'll be pushing around 350hp.
 
#14 ·
you will have to machine the case for the large bearing. no big deal just did not want you to forget.
 
#15 ·
I'm leaning pretty heavy towards swapping everything over to 29spline. A used 23 spline input for the 205 is $350! USED! Hell the 23 spline couplers are selling for $250 on ebay right now! And if my mainshaft in my tranny is still good, that's another $150. I can replace the 23 spline stuff for about $150 more than that and have a much stronger setup.

Thrashingcows- you're running the 23 spline mainshaft in your NV4500 right? Hows it holding up? Would you say you have 300hp in your truck?

Taking my NP205 guts to a highly recommended local pro tomorrow for an in-person opinion on what needs replacing.
 
#16 ·
No, my NV4500 was a factory 2nd Gen cummins 2wd unit. I drove it like that for about 3 years, then did the 4wd conversion to the truck. I converted the 2wd NV4500 to 4wd, so it got the 29 spline mainshaft. And with doing all that I used my donor 1st Gen auto/23spline NP205 and converted it to 29 spline. My motor is probably only about 200hp.....if that....the mods I've done are pretty tame really. ;)

My NP205 conversion thread should help you out. I was only into it for a few hundred extra dollars, and then I knew I would not have any issues down the road. I hate doing things more then once....but sometimes that's the only way I/we learn. ;)
 
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#17 ·
Took all of my guts to a highly recommended local transmission place and he gave everything a good bill of health. He said all of the gears are just fine, and some of those strange looking spots that look like they were hit with a dremel are just that- factory blemishes from grinding down burrs.

He did tell me that I'm asking for trouble running 23 spline stuff behind the cummins with a manual transmission. Told me I might get some years out of it, but that it would eventually wear out. Sooo I'm getting a new input shaft, bearing, new mainshaft for the NV4500, nut, seals, coupler, and fifth gear from him for a grand total of.....$355. Pretty screaming deal compared to what's listed online! I'm pretty sure I can sell all my 23 spline stuff and probably come pretty close to breaking even once I include machine work!

On another note, I was telling him about my gear howl- he said it could really be anything- the driveshafts, being hollow, can transfer noise really well and make it sound like it's coming from the transmission/transfercase area, but could actually be a wheel bearing or differential.
 
#18 ·
That's a darn good deal on all those parts. Make sure your bearing for the 29 spline input shaft has the outer snap ring....mine did not and it took me quite a while to eventually find a used one, and then had to pay dearly for it. Also the 29 spline coupler....make sure it also has the snap ring in the center....to stop it from walking back and forth on the input/output shafts.

This guy sells all the parts for the conversion....you can at least see all the pieces required.

np205 np 205 transfercase dodge 29 spline input nv4500 g360 getrag g 360 | eBay

I would also add this to the 5th gear nut.....

DODGE UPGRADE 5TH GEAR LOCK NUT RETAINER NV4500 5 SPEED 4X4 TRANSMISSION | eBay
 
#19 ·
Ended up having PST do the work replacing my mainshaft and they found significant wear on both my input shaft and cluster gear on the countershaft.... so all that got replaced too. This ended up being a lot more than I hoped it'd cost, but hopefully I won't have to open the tranny or transfer case up again. Ever. Still waiting on some bearing shims and a snap ring to finish assembly of the transfer case. Supposed to be cold this weekend, but hopefully not too much snow so I can get it all back together. I'm also really hoping this fixes any gear noise I had. The Dana 80 is the only thing left untouched at this point. I opened it up when I bought it and it looked great despite 200k miles on it. I have a bearing kit for it sitting on my shelf, but I reaaaaalllly don't want to do another axle and especially don't want to pay someone to do it.
 
#20 ·
Glad you are getting things sorted out. Sucks that there was all those additional costs....but lessons learned I guess. ;) Once you get it back together and on the road you'll quickly forget. :D
 
#21 ·
Definitely lessons learned, 1) pull stuff apart before ordering whole rebuild kit- could have only replaced one bearing and a reseal kit in the T-case and been fine! Can't wait to be jammin gears again, especially with all this snow we've been getting! My little commuter Corolla ain't what the ole Dodge is in the snow....
 
#22 ·
Here's a little tip for others running an NV4500 and NP205 combo- the "well" meaning the adapter between the transmission and transfer case, will hold about a quart of fluid. When you are filling your transmission, you need to account for this extra capacity since there is no seal in the rear of the transmission to keep fluid from spilling into the "well." My transmission guy said the damage I had in my transmission was because it looked like it had been run low on fluid. I'm pretty sure I put in the recommended 5 quarts when I installed this transmission, I think 6 qts is what is really needed. I know the stuff is expensive, but I only ran this transmission for about 600 miles and that was enough to cause significant wear. I'm going to buy a couple extra quarts and make sure that the level is up to the fill port after running for a while.
 
#23 ·
Finally got everything back together! Runs and shifts great. Even hauled a couple of trees off this afternoon. I didn't get it on the highway today, but the gear noise/howl is gone so far. When I put the transfer case back together it was muuuuch tighter than when I took it apart. I think whoever built it last time put the rear output bearing on backwards and that was making a ton of slop/play. Hopefully I'll never have to touch the transmission, transfer case again.

I rebuilt the front axle with a new DC joint and all new U-joints, So much smoother and quiter!

Still need to hook up the grid heater, windshield washer bottle, and HVAC. After that, truck will NEED nothing, just fun modification and repairs from here on out. I mean ive damn near rebuilt the whole thing at this point. Only the rear-end and the 27K mile cummins haven't been rebuilt! (well and paint and body, but I can't let this girl get too fancy or she won't want to work!)
 
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