NP-435 Grinding in first. - Pirate4x4.Com : 4x4 and Off-Road Forum

Scrapper · 01-11-2009, 06:16 PM

My early Bronco has a NP-435 that was running fine until I pulled it out to fix a leak. Like a dumbass I grabbed the output shaft and pulled it to get the trans out. The shaft and the bearing both slipped out about 1-2 inches and then slipped right back in. Now I've got everything back together and it all works fine but has a grinding noise when I use first gear.

So what did I fuck up? And how do I fix it?

94stepsideford · 01-11-2009, 07:09 PM

First is a straight cut gear. It may make a whining noise, same with reverse. Now if it's actually GRINDING????

Scrapper · 01-11-2009, 07:27 PM

It never made this noise before I slipped the output shift out.

While I had it out it fell off the floor jack and landed on it's side as well.

It definately sounds like two gears are hitting each other. It only makes the noise when it is in first gear and the Bronco is moving. All other gears are fine and don't make any noise.

Could the shift forks/gears have become mis-alighned or something?

jopes · 01-11-2009, 07:42 PM

output shaft is also the main shaft. I am guessing when you pulled on it, you dropped the pocket bearings that go in back of the input shaft that the mian shaft rides on.

http://www.drivetrain.com/np435_p1.jpg

Scrapper · 01-11-2009, 07:42 PM

This diagram shows a "first-speed gear stop" on the mainshaft. Maybe that thing moved.

http://www.motorsport.wlrgroupco.com/np435fsmdiag.JPG

Scrapper · 01-11-2009, 07:45 PM

Quote:

Originally Posted by jopes

output shaft is also the main shaft. I am guessing when you pulled on it, you dropped the pocket bearings that go in back of the input shaft that the mian shaft rides on.

http://www.drivetrain.com/np435_p1.jpg

Sounds like the damn thing will have to go to a rebuild shop. I aint got the coin for that right now.

woodchuck2 · 01-12-2009, 07:18 AM

You can always try rebuilding it yourself. A friend of mine rebuilt his for around $165 in parts. He isnt that mechanically inclined either and his holds up to his built 460 and heavy right foot.

jopes · 01-12-2009, 10:34 AM

Quote:

Originally Posted by Scrapper

Sounds like the damn thing will have to go to a rebuild shop. I aint got the coin for that right now.

this is very easy to check out. drain the fluid and see if there is any roller bearings laying in the bottom from the pto cover. If there is, put them back in the input shaft. it is easy.

you might be able to lift the main shaft from the pto cover or you might have to take off the shift cover to lift it. Remove the input shaft put all the bearings back in the pocket, use grease to hold them in. reinstall input shaft using the same shims that were behind the retainer.

Quick & Dirty · 01-12-2009, 12:43 PM

The bolts that hold the tailhousing on are different lengths. If you put a long one in the wrong hole it will hit the gear in first.

Scrapper · 01-12-2009, 03:14 PM

Quote:

Originally Posted by Quick & Dirty

The bolts that hold the tailhousing on are different lengths. If you put a long one in the wrong hole it will hit the gear in first.

Wow, I hope thats it. Where do the short bolts and long bolts go?

Rockit · 01-12-2009, 03:48 PM

Quote:

Originally Posted by Scrapper

Wow, I hope thats it. Where do the short bolts and long bolts go?

That would be my guess too. It's the lower left it looking at it from the rear if I'm remembering correctly. It's been a few years since I did the EXACT same thing.

Scrapper · 01-14-2009, 04:43 AM

Quote:

Originally Posted by Quick & Dirty

The bolts that hold the tailhousing on are different lengths. If you put a long one in the wrong hole it will hit the gear in first.

It worked! I backed out the lower left bolt and drove it, no grinding!! I'm very stoked! I was ready to take it out and have it rebuilt. Thanks Q & D I owe you a few cold ones, just let me know what flavor and where to send em!

And thanks to Rockit for telling me which bolt to shorten, that saved me some time too.

Now if I can just figure out my brake problem I can go wheelin!

01-11-2009, 06:16 PM	#1 (permalink)
Scrapper Registered User Join Date: Feb 2007 Member # 86651 Location: Mission Viejo, CA Posts: 74	NP-435 Grinding in first. My early Bronco has a NP-435 that was running fine until I pulled it out to fix a leak. Like a dumbass I grabbed the output shaft and pulled it to get the trans out. The shaft and the bearing both slipped out about 1-2 inches and then slipped right back in. Now I've got everything back together and it all works fine but has a grinding noise when I use first gear. So what did I fuck up? And how do I fix it?

01-11-2009, 07:09 PM	#2 (permalink)
94stepsideford Registered User Join Date: Oct 2004 Member # 36399 Location: Hinesburg, VT Posts: 3,147	First is a straight cut gear. It may make a whining noise, same with reverse. Now if it's actually GRINDING???? __________________ 94 F-150 Stepside. BGTL 12" lift, 1-tons, 39" 'roks 95 F-150 6" of lift, SAS 35" BFG's

01-11-2009, 07:42 PM	#4 (permalink)
jopes Registered User Join Date: Nov 2001 Member # 8469 Location: Douglas, Wyoming Posts: 3,191	output shaft is also the main shaft. I am guessing when you pulled on it, you dropped the pocket bearings that go in back of the input shaft that the mian shaft rides on. http://www.drivetrain.com/np435_p1.jpg __________________ 408ci SEFI, 70mm throttle body, 90mm mass air, stang harness, tweecer R/T waiting on a home.

01-12-2009, 07:18 AM	#7 (permalink)
woodchuck2 Registered User Join Date: Jul 2008 Member # 116651 Location: North Creek, NY Posts: 779	You can always try rebuilding it yourself. A friend of mine rebuilt his for around $165 in parts. He isnt that mechanically inclined either and his holds up to his built 460 and heavy right foot. __________________ 79 F-150 302,np435, rest of the truck has been sold and is now retired.

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01-11-2009, 07:27 PM	#3 (permalink)
Scrapper Registered User Join Date: Feb 2007 Member # 86651 Location: Mission Viejo, CA Posts: 74	It never made this noise before I slipped the output shift out. While I had it out it fell off the floor jack and landed on it's side as well. It definately sounds like two gears are hitting each other. It only makes the noise when it is in first gear and the Bronco is moving. All other gears are fine and don't make any noise. Could the shift forks/gears have become mis-alighned or something?

01-11-2009, 07:42 PM	#5 (permalink)
Scrapper Registered User Join Date: Feb 2007 Member # 86651 Location: Mission Viejo, CA Posts: 74	This diagram shows a "first-speed gear stop" on the mainshaft. Maybe that thing moved. http://www.motorsport.wlrgroupco.com/np435fsmdiag.JPG

01-12-2009, 12:43 PM	#9 (permalink)
Quick & Dirty Registered User Join Date: Nov 2004 Member # 38200 Location: Wisconsin Posts: 490	The bolts that hold the tailhousing on are different lengths. If you put a long one in the wrong hole it will hit the gear in first.