The Stovebolt Site Forums The Parking Lot Tons 'o Fun rear end questions

hey everybody, im at the point in my custom/restoration project on my 59 3800 9ft bed monster where im almost ready to start her up for the first time in 5 years. i have a leaking rear pinion seal that i need to fix before i can put the driveshaft in and then fill my auto tranny up with atf fluid. i marked everything took off the pinion nut and pulled the flange off, but no seal, my rear has a bolted on flange housing with 5 bolts that mount it to the pumpkin, i have never seen one like this, my question is do i have to pull the housing off, replace the housing gasket and then somehow the oil seal is inside the flange housing? all the 70--80 model chevys i have worked on never looked like this, also is there bearing preload on the pinion bearings on one of these old ton trucks? does anyone know any part numbers for the oil seal and the housing gasket? i would love to see an exploded view or shop manual info about how to replace the seal, also does anybody know any part numbers for the seal and the gasket? napa is the only local place to get old parts around here if i can get this fixed i should be able to start her up and see if she will move.... and stop

Hy panmanhd, if you remove the piece that the yoke went into you should find the seal and felt inside that, the p/ns for the seal and felt are
National 411330N for the seal $6.90 Can. at RockAuto
National 5M89 for the felt $7.47 Can. at RockAuto
sorry I couldn't find a FelPro p/n for the gasket, hope that helps.

Don't forget to check your shop manual for those questions about preload.

Grigg

Hey 3b thanks for the part numbers, picked them up today at KOI auto parts in Lexington KY just got to take it apart and figure out how to reinstall the new seal and figure out where the felt goes. Grigg I wish I could check my shop manual for the preload questions but I don't have one and can't seem to find one to download online I'm just gonna put it back the way it comes off. I need to find taller gears for it anyway, I will probably have to have them made 💰💰💰

Hy panmanhd, the preload on that particular differential is set by a spacer between the two tapered roller bearings, so all you can do is tighten up the pinion flange nut up to 160 - 280ft.lbs., use some kind of tool to hold the pinion flange, a large pipe wrench braced against the frame or ground, or whatever you can think of. Do not use an impact wrench using the ring gears and axles to hold the pinion, the impacting shocks can break or crack teeth, hope that helps.

I don't know why one would use a felt seal now days. There is a one piece steel and neoprene seal that goes in there.

Shop manual link
http://chevy.oldcarmanualproject.com/

There was discussion here about replacing Eaton w/ GM FF 14 bolt for higher ratio. If you have a Dana 60, easy to get higher gears, might have to replace carrier though.

The 14 bolt has just about as many ratios as the D60; 4.56, 4.11, 3.73, 3.42, and 3.21. The 4.11 is the most common, the 3.42 and 3.21 is super rare, but still available.

My 41 1 ton long bed has 3.73 gears which gives me 70 mph at 2,000rpm with a 700R4,small block 350 and 17 inch wheels.

With the original running gear 40 mph was a strain.