I want to eventally rebuild my np435 when I do the resto. I want to be able to run Moble 1 synthetic in it. I tried it a few months ago and it had syncro issues and put back dino in all was well. Do they make a rebuild kit for the np435 with high friction syncros for synthetic oils?
Were can i get rebuild kit?
How hard are the np trans to rebuild/reseal?
how much money does the kit cost??
Thank you
Dustin

 

Most of the older transmissions are pretty straight forward. I've done them with nothing other than a sheet of torque specs. I don't see synthetic hurting anything after a rebuild. I don't know what a kit will cost you; I get all mine at cost. Really you cost will depend on the condition of the trans, does it need any gears or just seals and some syncros. It's hard to tell til you get it apart.

Matt

 

You don't want to buy those aluminum synchros unless you really need them they're not cheap besides they rarely wear out even when used over 900K miles. Sand the synchro drums, I used 320 sandpaper to break the glazed finish. You should get shims to set the synchro clearances and go to the minimum spec better yet slightly below spec, this allows more time for the synchros to work before the slider engages
Every time you have the shifter top off it would be a good time to replace the shifter forks nylon pads. Should the nylon pads be worn thru you'll have crunchy shifts besides metal on metal which later will chew up your new nylon pads.
A shifter top and lever in good condition or new plus a good clutch and pilot bushing should make a smooth shifting tranny.
Inside the 308L bearing is only 7 ball, replace it with a 11 ball.
The input bearing end play is a touchy adjustment, too loose and you have a rattling box, too tight and you'll preload the thrust needle bearing when hot causing the box to drag making it hard to not shift clean.
Depending on where you live with how cold it gets thick oil can make it hard to shift in the mornings. I added a little motorcycle transmission oil to thin down the 75/90 gear oil a little, this is a high shear oil with additives Honda uses.
On the input bearing retainer if you can't get the proper clearance with the paper gaskets supplied make one out of a different thickness paper.
I used a "just detectable" end play for the input shaft, a feel I had for over 900K and many 435 rebuilds.
Check the mainshaft bearing track where it rides on rollers inside the input shaft they seem to pit and come apart with high mileage and horsepower use.
Don't forget to replace the seal inside the bearing retainer for the input shaft.
Replace the cluster shaft end thrust washers while your inside the box.

 

Hey I see you have a lot if experience with these transmissions and was hoping you can help me with mine. I have an np435 and last year I got it checked out and it was supposed to be fine for the age. This summer I took the engine out after driving it for a few weeks. While driving it it made a clunking sound in 3rd gear but disappeared after it warmed up. So like I said I took engine out and put it back in and now it just won't grab a gear and it seems like it wants to stay in neutral. It's not the fork assembly. It pushes on the clutch plate like it's supposed to. So when I try to put a gear in without pushing the clutch I can feel the gear grinding on the lever. When I push the clutch it shifts smoothly but then just acts like it's in neutral meaning I can let go of the clutch and the truck will just idle actin like it's in neutral even tho the lever says it's in 1st or 2nd or 3rd or 4th. Do you know what's going on?