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Can I rebuild the NP435?

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nilknarf007

Can I rebuild the NP435?

Apologies if there is already a thread for this, but I couldn't find it. I know that YOU can probably rebuild the 435, the question is, can I? The only two things I haven't tackled on a vehicle is an engine rebuild and a tranny rebuild. I'm curious as to how difficult it is, and what special tools I will need.

I replaced my clutch a few months ago, and I noticed I had quite a bit of slop in the input shaft, but things were running fine so I didn't worry about it. Now I have a significant rear main seal leak, so I'm going to have to pull the trans out again. I'm thinking I might as well rebuild it while I have it out to fix the slop. It has 140k on it, and 110k of that is from the original owner.

I'm sure it's possible to just replace the front bearing, but I want to do all I can while I have it out of the truck.

Is this something a shade tree mechanic can do?
Any recommendations on rebuild kits?

Rob F.
1985 4x4 4.9 i6 NP435, HEI distributor, smog delete, Clifford intake, twin Weber 38/38s.

Gary Lewis

Re: Can I rebuild the NP435?

Administrator

I haven't rebuilt an NP435, but you can look at the factory shop manual on it here: Documentation/Driveline/Transmissions/Manual Transmissions/NP435.

Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI

nilknarf007

Re: Can I rebuild the NP435?

I think my eyes started to bleed about halfway through that read. But, I think it can be done. I guess I'll take a ton of pictures during disassembly and give it go.

Rob F.
1985 4x4 4.9 i6 NP435, HEI distributor, smog delete, Clifford intake, twin Weber 38/38s.

Dyn Blin

Re: Can I rebuild the NP435?

Novak has a lot of good resources to plumb:

https://www.novak-adapt.com/catalog/transmission/transmission-parts/np435-parts

And a helpful set of notes here:

https://www.motortrend.com/how-to/np-435-rebuild/

Nice folks, too. Offered a lot of help to a friend working on a Jeep T90 last year.

Sonoma County,CA
1982 F150 Flareside XLS
NP435 4x4
351W Motorcraft 2150

StraightSix

Re: Can I rebuild the NP435?

Im planning to rebuild mine in the next few weeks and my buddy and I rebuilt his in November. Im fairly confident itll go without a hitch. it would be really nice to have a second set of eyes on it when you do it! If you can build an axle or a transfer case Im sure you can do this. you will need a press, a set of calipers, standard shop tools, and nothing else really special comes to mind tool wise. I was "in the passenger seat" as "shop help" for his rebuild, but as far as I remember there is only one terribly critical measurement in the 3rd/4rth synchro area, and it does need to be right. If you cant get it to shift gears on the bench and get both the input and output shaft to spin, dont put it in the truck. he made that mistake of thinking the synchros were just too tight from being new (wouldnt shift on the bench) and he thought speed on the input shaft would help. that turned out to be incorrect. We pulled it out again and got that one critical measurement right and after that it was all smooth going.

1984 Bronco, mild built 300-6, Np435, 3.55 gears, 8.8 rear with Eaton TrueTrac, D44 TTB front, 31" tires, Duraspark II, Offy C, EFI manifolds, Holley 390, No AC, 3G alternator, front receiver

ArdWrknTrk

Re: Can I rebuild the NP435?

Administrator

Don't forget a good set of snap ring pliers.

When I was stuck up in Vermont a year ago with a smoked transfer case I couldn't find anything that worked, locally.
Chain auto parts and hardware stores had nothing available.
Fortunately Amazon delivers Knipex, and I was able to get some in a day or two.

I haven't been inside a NP gearbox but if it is anything like the T-19 I had good pliers are going to save you a lot of headache.

Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.

Gary Lewis

Re: Can I rebuild the NP435?

Administrator

ArdWrknTrk wrote

Don't forget a good set of snap ring pliers.

Amen, brother! I struggled for decades with the one-size-fits-all (but never fits anything) snap ring plier sets. The ones with the little hex-shaped inserts that turn, or flex, or break. I finally bought the KNIPEX Tools 00 20 04 SB, Precision Circlip Snap-Ring Pliers 8-Piece Set and love them.

Gary, AKA "Gary fellow": Profile

nilknarf007

Re: Can I rebuild the NP435?

Thank you all so much. I feel a cautious optimism that I can do this. Ordering the pliers now....

Rob F.
1985 4x4 4.9 i6 NP435, HEI distributor, smog delete, Clifford intake, twin Weber 38/38s.

cjstaci

Re: Can I rebuild the NP435?

I used to work at UPS. We had NP 435 and NP 465 back then. The NP 435 is an easy rebuild. You should be able to buy a small parts kit along with blocking rings and bearings. I would look for SKF or Timkin depending on where they are made.

1981 F350 custom, std cab, 4X4, 400, C-6, 3.54 gears.

nilknarf007

Re: Can I rebuild the NP435?

Are you talking about the kits themselves or the bearings?

Rob F.
1985 4x4 4.9 i6 NP435, HEI distributor, smog delete, Clifford intake, twin Weber 38/38s.

StraightSix

Re: Can I rebuild the NP435?

I assume he was referring to the bearings. Im no bearing expert but what Ive been told is that its "Timken or nothing". I think Timken and Koyo might be the same manufacturer now.

1984 Bronco, mild built 300-6, Np435, 3.55 gears, 8.8 rear with Eaton TrueTrac, D44 TTB front, 31" tires, Duraspark II, Offy C, EFI manifolds, Holley 390, No AC, 3G alternator, front receiver

nilknarf007

Re: Can I rebuild the NP435?

My rebuilding efforts were successful. I admit I was ready to throw in the towel at one point because the shifting required way to much effort. Then I read through the directions again, and checked some tolerances. One ten thousands spacer in between a syncro and the gear next to it did the trick. Shifts real nice and crisp now.

Rob F.
1985 4x4 4.9 i6 NP435, HEI distributor, smog delete, Clifford intake, twin Weber 38/38s.

Gary Lewis

Re: Can I rebuild the NP435?

Administrator

Congrat's!!! Glad you found the issue with the spacer. Do you have the tranny installed?

Gary, AKA "Gary fellow": Profile