NP435 Rebuild

Mike K · Apr 21, 2012

I recently purchased a used np435.

I pulled off the top plate of the tranny and here's what i see:

The rear most big gear has some wear on the rear side of the gears.
The senter gear has a small centered grove or uniformed notch on all the gears.

Lower in the tranny where the small gears are, the gear second to the back looks like the gears are rearing differently than the rest.

Obviously, i'm not sure what i'm looking at. Is there something with maybe pictures which will help me inturpet what i'm seeing?

Also, is there a good rebuild manul and kit you could recomend?

Thanks!!
Mike

beaux312 · Apr 21, 2012

I would put the cover back on and install it to see if anything is wrong. Those are some tuff trannys, not much to go wrong. I got a used one and have been driving on it for 6yrs now.

OX1 · Apr 22, 2012

First pic is of a 435 in really good condition, maybe new.

Second pic is my T-18 in good shape.
T-18 is very close in internal configuration to 435.
(some differences in gear ratios and synchronizers).
This trans is now in my 70 and works fine.

Wear on first gear is normal, it is not synchronized.
Lower small gears on bottom are reverse idler.
They engage first gear and countershaft gear to
give reverse direction. Same ratio as first gear, but in reverse.

Here is procedure for putting a 2WD output shaft in a 4WD trans.
Not a repair procedure, but it does show disassembly pretty good.
435 will be fairly similar.

http://luxjo.supermotors.net/70 EB SPORT/T-18 INSTALL/OUTPUT SHAFT SWAP/T-18 OUTPUT SWAP.htm

Also found this exploded view of 435..........

KyleQ · Apr 22, 2012

The rebuild kits are cheap and you can rebuild these transmissions with a hammer and a block of wood. I wish I would have gone through mine before I put it in, now its in, I hate the condition its in, but not enough to drop it and fight getting it back in again.

ugly74 · Apr 23, 2012

I'd double check the synchros to make sure they aren't wiped out. otherwise, a little wear is normal and okay.
over the winter, I made 1 good trans out of 2 bad ones for my plow truck. one had a cracked case and bad synchros, the other had a busted output shaft. took 'em both apart, used the best parts from each. smooth like butter now!
for such a supposedly strong transmission, I sure have a knack for destroying them!

DirtDonk · Apr 25, 2012

What's wrong with yours that's got you so miffed Kyle?
Is it making some noise, or hard to shift? Something else?

Just curious. Friend's is very hard to shift, but it was supposedly rebuilt too.

Thanks

paul

KyleQ · Apr 25, 2012

Mine grinds like I don't know how to drive a stick. It goes into gear easily enough, but getting into 3rd without noise requires double, if not triple clutching and 4th is so bad it refuses to go into gear unless I'm hauling balls fast enough that the teeth are lined up.

It's good enough for a trail slut and doesn't ever pop out of gear, I'm just a bit annoyed by it.

.94 OR · Apr 25, 2012

That doesn't sound right. My dad has an old plow truck with the NP435 and it has 180,000 hard miles on it and it shifts better than that. Sometimes you might need to double clutch to downshift into 2nd, but otherwise it flows ok.

bmc69 · Apr 25, 2012

.94 OR said:
That doesn't sound right. My dad has an old plow truck with the NP435 and it has 180,000 hard miles on it and it shifts better than that. Sometimes you might need to double clutch to downshift into 2nd, but otherwise it flows ok.

I've worn more than one 435 out to the point where the synchro(s) were about gone. If I recall correctly, the one in my '78 started being ornery around 180K miles...one total rebuild that included new synchros and its been happy for another 100K+ since..and still going strong.

KyleQ · Apr 25, 2012

.94 OR said:
That doesn't sound right. My dad has an old plow truck with the NP435 and it has 180,000 hard miles on it and it shifts better than that. Sometimes you might need to double clutch to downshift into 2nd, but otherwise it flows ok.

No it does not, I found some metal in the bottom of the case too and the gears look a bit worn. This is an old transmission for sure, when I'm in 1st gear the synchros get really noisy, like louder than the exhaust through the hole in my floor loud. I'll try and get some video of it tonight-

.94 OR · Apr 25, 2012

How well did it shift after being rebuilt with new synchros? I have a NP435 that I am tempted to put in mine, but would go through it first.

DirtDonk · Apr 25, 2012

What lube are you using?
I would think that, for our lighter trucks, a thin synthetic would still offer good enough protection and also help shifting.
A 75w/90 would be my first choice. Not that it's a cure-all, but it might help make those shifts a bit easier if what you're using now is an 85/140 or straight 140 weight.
If you're already at the thin end of things, I'm not sure what to recommend. If thicker though, it'd be pretty easy to test the thinner-lube theory.

Good luck.

Paul

beaux312 · Apr 25, 2012

This might sound odd but I changed gears to 5.38 from 3.50s and now my tranny shifts alittle harded and grinds alittle.

KyleQ · Apr 26, 2012

Ok, I took some video of me beating around my back yard while holding my phone on top of the windshield with one hand. Please excuse the poor quality, I was driving, shifting and recording

You can hear how noisy it is in 1st, there is a lot more engine/wind noise on top of the windshield - it's rather obvious through the Texas sized hole in my floor...

NP435 Rebuild

Mike K

beaux312

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OX1

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KyleQ

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ugly74

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DirtDonk

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KyleQ

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.94 OR

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bmc69

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KyleQ

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.94 OR

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DirtDonk

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beaux312

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KyleQ

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