NP435 3rd gear noise

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Mar 3, 2002 | 03:32 PM

highcountry

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Joined: Mar 2002

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From: Montrose USA

NP435 3rd gear noise

Hi all,

I have a 78 F150 4*4 that I am building for four wheeling. I finally got it on the road for the first time yestarday after a bunch of work. Everything is great except there is a noise fron the NP435 transmission in third gear (2nd if you don't count the granny). Is this a common problem? I have no problem with pulling the thing and tearing it down (it would be a great opportunity for a twin stick conversion) but I would like to have an idea if this is a common problem or not. Thanks for any help.

Mar 9, 2002 | 12:55 AM

Greybeard

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From: Tulsa U S

NP435 3rd gear noise

I've got a '77 Ford 4x4 with a '79 400M with the same trannie. It also makes a noise in third gear similiar to what you described.

Mar 9, 2002 | 02:35 AM

kspilkinton

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From: South Kitsap County, WA

NP435 3rd gear noise

Is the noise a high pitch whine? Has the tranny ever popped out of third? Is is a pain to get into third on occasion? Trying to narrow it down to the synchronizers or a rubbing shift fork.

-Kerry

Mar 9, 2002 | 05:50 AM

Greybeard

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From: Tulsa U S

NP435 3rd gear noise

My third gear sychronizer seems to be good.

This seems to be a very slight grinding, almost as if chains were softly rolling, instead of gears. It's not very loud, but can be felt through the gear shift. Something is rough. I expect the granny first to make a little noise, but not third.
I was about to change the fluid in it. What type of lube does it take?
While I am on the subject, what about the 9in rear end and front differential? what lube? The transfer case?

Mar 9, 2002 | 05:55 PM

kspilkinton

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From: South Kitsap County, WA

NP435 3rd gear noise

[updated:LAST EDITED ON 09-Mar-02 AT 07:00 PM (EST)]If you feel a grinding it could also have some thing to do with the reverse idler gear sliding up against something. I can't give you a definite answer on either the fluid or the problem since I don't know exactly what xfer case you have.

The NP208 and BW 1345 take Dexron/Mercon ATF and have uses a chain drive which I can definitely feel when I put my hand on either shift lever, the NP205 takes different gear oils for different years 50W before '78, 90W after and it's gear driven. The NP203 takes 50W in warmer climates and 30W in colder areas. The Dana 21 also takes a 50W.

The front and rear diffs should take the same fluids. I use 80W-90 in both diffs (one's a 9" the other is a Dana 44) and the tranny and I know an acquaintance that uses 85W-140 in all three. I've heard talk about 50W in the tranny, but I found reports that say 85W-90 in the tranny. I think that warmer weather warrants the use of a thicker oil, but not so thick it doesn't flow and can't reach all the gears. The 50W deal must be a far north thing. I'd use at least an 80W in OK.

-Kerry

Mar 10, 2002 | 06:44 PM

highcountry

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From: Montrose USA

NP435 3rd gear noise

I run (fresh) 80/90W or 85/90W in axles and in this tranny (not all trannies). And my noise is exactly what Greybeard says. Sort of a rolling chain noise. It doesn't happen in second either. just third. Hey Graybeard how long has yours been doing it? Has it gotten worse? I have only had this thing on the road a few times since I rescued it from someones yard (read: big project truck). Last time I drove it it sounded quieter, may have just been me though. Thanks for the input. If one that makes this noise grenades post it so I know. Thanks.

Mar 10, 2002 | 10:54 PM

GMFDBob

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Joined: Dec 2001

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From: USA

NP435 3rd gear noise

Hey, don't worry about it, i have a '78 f-150 4x4 with a 300ci. inline np435 and a np205 and it does the exact same thing as you explained. my truck does it and it hasn't gotten wrose either so i would say don't even bother trying to stop it, its normal.