NP 231 Rebuild Project

tellicorick · Dec 18, 2003

Looking for some directions/schematics/specs on rebuilding an NP 231 case. Specifically, I'm going to replace chain and any needed internals and while I'm in there install a SYE. If anyone knows if there is a site or location to get the specifics like shaft end play, clearances as well as a good location to purchase the guts fairly reasonable, just give a post or e-mail me.

Gracious

willysnut · Dec 20, 2003

Just rebuilt mine this last spring, my chain was slopping the case when the front yoke was turned due to lack of oil (previous owner), got my parts from Driveline Service of Las Vegas. (702) 876-3100. Master overhaul kit/ bearing kit/pump/ chain/small parts kit all for $327 shipped to the house. Check your FSM for specs. It's really an easy rebuild, all bearings are caged.Need lockring/snapring pliers too. Just watch out to put the range hub in correctly.It will go in backwards and will cause hard shifting and pops out of low range( learned that the hard way) Search the web for NP231. Just clean the case real good and all parts. Sprockets are way beefy so I doubt you need those- I didn't. Check your shift forks for wear on the plastic tip covers.Install new seal on front output shaft so that won't leak from the yoke. No gaskets only RTV so use it sparingly to prevent the excess from clogging your new pump later. :wave:

tellicorick · Dec 22, 2003

willysnut said:
Just rebuilt mine this last spring, my chain was slopping the case when the front yoke was turned due to lack of oil (previous owner), got my parts from Driveline Service of Las Vegas. (702) 876-3100. Master overhaul kit/ bearing kit/pump/ chain/small parts kit all for $327 shipped to the house. Check your FSM for specs. It's really an easy rebuild, all bearings are caged.Need lockring/snapring pliers too. Just watch out to put the range hub in correctly.It will go in backwards and will cause hard shifting and pops out of low range( learned that the hard way) Search the web for NP231. Just clean the case real good and all parts. Sprockets are way beefy so I doubt you need those- I didn't. Check your shift forks for wear on the plastic tip covers.Install new seal on front output shaft so that won't leak from the yoke. No gaskets only RTV so use it sparingly to prevent the excess from clogging your new pump later. :wave:

Thanks, really appreciate your help. I've done a Dana 20 and 300 case before, but they were all gears and easy. Guess I'll dive into this one as soon as Novak has their SYE on the market.

Goatman · Dec 22, 2003

tellicorick said:
Thanks, really appreciate your help. I've done a Dana 20 and 300 case before, but they were all gears and easy. Guess I'll dive into this one as soon as Novak has their SYE on the market.

Really, it's a piece of cake. Pretty easy to see as it comes apart. A couple of things to watch for......get the range hub in the right direction like has been said, you'll see what we mean as you take it out. There is a slot to pry on to get the case to split, look for it. Don't bother with the rear bearing on the front output shaft unless it's worn out, if it looks good don't bother with it....it's a PIA. Mine has been apart too many times to count but that one bearing has never been changed. Watch the oil pump engagement as you're putting it back together.

Have fun,

NP 231 Rebuild Project

tellicorick

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willysnut

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tellicorick

NAXJA Forum User

Goatman

NAXJA Forum User

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