np435 noise

[1971ford]

For those with np425's, can you hear it at all when you're driving?
talking about 2nd, and 3rd gears.

In my highboy, when in second and third gears it is LOUD. Then I shift into 4th and i can finally here my exhaust again, no more np435 noise.
Normal or have my gears seen better days?
It has fresh fluid


Also, how do you know when your clutch is warn. Never owned a stick shift before so I dont know if mine is warn or not but it feels fine to me.

[averagef250]

1st, 2nd, 3rd and reverse powerflow is through the countershaft. 4th gear it is straight through. Noise in all gears except 4th is caused by bad bearings or problems with the input gear.

Should be a bit noisy in 1st/reverse yet smooth and quiet in 2nd, 3rd and 4th. 435 bearings are easy to replace. synchros not as straightforward.

Clutches wear out in several ways. The disc gets too thin, the disc fatigues as in the damper springs come apart, the pressure plate wears out (different ways it can wear).

Clutches break in to your driving style. They can last almost indefinitely or just around the block. Lots of things factor in. No real way to know what shape it's in without inspecting it out of the truck.

[1971ford]

Thanks for the info Dustin.
It makes perfect since that it is making the noise in 1/2/3 and not 4 if 4 doesn't go through something the counter shaft. I didn't put it together that the final gear ration is 1:1 so 4th would be different.

If i get my brother and his super nice video camera in the truck, do you think you'd be able to tell if it's bearings or input gear?
Because if it's bearings and they're easy to replace then i'll do that, but if not then im going to pick up another np435 soon and get it ready to swap in.

Good clutch info. Thanks. I'll have to check it out sometime just out of curiosity.


One last transmission related question i have.
Half the time i drive my truck the clutch works great. Let the clutch out slow, a little gas and it VERY smooth.
Then sometimes it will randomly be a PITA. I work the clutch the same every time. But when it's not behaving, i let out the clutch and give it gas as i always do, but it will jerk like crazy! As in it's not smooth at all, the whole truck jerks/chugs as if it was a 5 year old learning clutch. I always think i might of let the clutch out too fast so i try it differently at every stop light/sign and its not me, just the clutch not behaving. What's up with that?? Could cold have anything to do with it?
I thought it was only when it was cold out (i'm talking 30-50 degrees) but it's done it when it's warm too.
Drives me crazy.

[averagef250]

The video deal is worth a shot, but it wouldn't be a long shot to assume the bearings are bad based on what you describe. If you have any questions about rebuilding it or sourcing parts give me a call. If it hasn't been run completely out of oil the gears inside are probably like new. Sometimes 435 reverse is beat up on the leading teeth edges, but it works fine regardless.

A few things come to mind in regards to your clutch issue. Leaking rear main seals, even valve cover and intake leaks can wet the clutch and make them grabby. Parking or driving uphill usually makes this worse. If your clutch is especially grabby on a hill that might be something to look at. My other thought is it's a bad motor mount or bad input bearings in the transfer case. I think I remember that you replaced the transfer case mounts with poly? If you haven't check them out too.

A bad driver side motor mount can get a small chain reaction going in these trucks. You let out the clutch, the engine loads and lifts, the engine lifting actually pulls the throttle open further making everything worse. Something to look at anyway.

[1971ford]

awesome info, thanks.

I will check the motor mounts tomorrow although the 390 was dropped in only 3 months ago. However they were re-used rubber mounts. I could of ripped one while offroading, who knows.
Your're correct, t-case mounts are brand new.
I'll get the video as soon as i can but it will be a little.
I'll get a video with my point+shoot and if that has decent audio then i wont need my brothers fancy cam.
I would be surprsied if the t-case was ever ran dry. It had a lot of fluid before i drained it and put all new fluid in.

Interesting you mention it could be a rear main because I know for a fact either my rear main or my oil pan gasket is leaking. I get about 5-10 drops a day. I've been waiting to get my race truck going so i can pull the 390 out again and replace rear main and oil pan gasket.
I'll have to assume this is the reason for the clutch jerk unless i find anything else. I have yet to start out on a hill in the truck yet so that's not it. I do park it on a "hill" which is my driveway, which is not steep at all.

[fireguywtc]

If you have ripped a motor mount you would almost certainly know it. It has a feeling like nothing else and when it happens it is very apperant that something is wrong. It kind of depends though on which side since it is my experience that the motor torques up and tends to pull the drivers side up. So depending on which side is broken it will change how it feels. I have had motor mount issues on both my trucks and each time I knew it immediately.

[70_F100]

I agree with Dustin, it could be bad bearings.

However, if it were the input or output shaft bearings, you should have noise in all gears.

Countershaft bearings and the bearing in the end of the input shaft (where the output shaft couples to it) would PROBABLY not make a noise.

The best bet is that there is gear wear that is causing the noise you're hearing.

Your best bet, IMHO, is to find another transmission.

[averagef250]

I agree with Dustin, it could be bad bearings.

However, if it were the input or output shaft bearings, you should have noise in all gears.

Countershaft bearings and the bearing in the end of the input shaft (where the output shaft couples to it) would PROBABLY not make a noise.

The best bet is that there is gear wear that is causing the noise you're hearing.

Your best bet, IMHO, is to find another transmission.

That is simply not true. I've repaired plenty of sticks that were minus input and mainshaft support bearings and made very little to zero noise in direct. Probably had 10 W56's that the balls would fall out of the races were they not held in by cages and they drove into the shop, 4th was quiet.

The bearing inside the input is known as the pocket bearing.

[70_F100]

Dustin, let me qualify what I'm about to post by saying that I respect what you've said.

Not to belabor a point, but I said "should" have noise.

In direct drive, the bearings on the input shaft, output shaft and countershaft are all turning. If one of these is bad, there will MOST LIKELY be SOME noise. The input shaft bearing, if bad, will generally be noisy when the truck is stopped with the engine running, clutch engaged and the transmission in neutral. The output shaft bearing will only make noise when the truck is moving. The countershaft bearings can make noise under any of these conditions.

Lots of times you won't hear any of these bearings from inside the cab (especially with the truck moving), but it is possible that you could hear them, dependent upon the condition of the bearings and things like sound deadener in the cab.

"Pocket bearing" is a "common name" for the bearing in the end of the input shaft. The proper name for it is "Input Shaft Pilot Bearing", but that's really not important. I described it as I did to avoid any confusion with the crankshaft pilot bearing/bushing.

The point is that the noise Ryan is hearing is, MOST LIKELY, gear noise, since there is gear engagement and pressure on the input shaft, countershaft gears and the individual gears on the mainshaft in all except direct. Since the input shaft is coupled directly to the output shaft in direct, there is no pressure on any of the helical cut gears. There is also the possibility that ANY of the bearings could be bad and could be causing a misalignment of the gears/shafts, which could result in noise.

The only way to tell for sure where the noise is coming from is to disassmble the transmission and check the condition of all of the internals. On the other hand, if there is significant gear wear, it will, most likely, be apparent and visible just by removing the top cover.

[1971ford]

I did have the top cover removed for a while and i'm pretty sure i took pictures, because i take pictures of everything i do to the trucks. I'll look for them.
I looked at all the gears i could see from the top when i had the cover off and i remember thinking they looked pretty darn good. I know that atleast one of them the corners were getting rounded but other than that, nothing caught my eye
I tried doing a video with the point+shoot camera but it turned out bad.

Just by the way it sounds i'd say gears, but could be the bearings, the higher i rev the more hideous it gets (louder). Not a smooth noise but rapid clatter.

i wish i could give more info. Maybe my buddies camera can capture it better

[averagef250]

In your initial posting you said gear wear was the cause for the noise. Gear misalignment from bearing wear yes, gear wear, NO, or atleast highly unlikely. There are specific transmission models that have gear wear/metallurgy issues, but the 435 is not one of them.

When most sticks are in direct there isn't any side loading of the gears, input and mainshaft output bearings can be really bad shape and you'll have little to zero symptoms of an issue in 4th gear.

[1971ford]

At last...

http://www.youtube.com/watch?v=hk8np45s3qU

[Redcap]

The NP435 is easy to rebuild.

[fordman]

i can hear it. but i dont know enough to tell you anything. you sure are getting bigger though.

[1971ford]

The NP435 is easy to rebuild.

How fast do you think someone who has never torn one apart (and doesnt know anything about how they work at all) can rebuild one? The truck is my daily driver so it would need to be a fairly quick thing although that WOULD be a great excuse to drive the race truck for a solid week.

Rebuilding mine would save me the time of cleaning up and painting another transmission but rebuilding it might take a while. Either way, my engine and transmission need to come out. Engine's rear main is leaking. Transmission chattering. Might as well swap a np205 in while i'm at it. Then might as well get my hands on the d44 HP i've always wanted...