The Stovebolt Site Forums The Shop Area Engine Shop 1953 3600 3/4 Pinion bearings

I have the pumpkin (diff) out and need a little help on attacking the pinion bearings. I have a lot of up and down play in the pinion shaft along with rearend oil leakage. there are some bolts around the pinion assembly, if I take these out with the pinion assembly come out as a unit? And also what is the nut and adjustment bolt on the side of the differintial for?

And where to find bearings for the 3/4 pumpkin.

I do not see any listed in the usual catalogs. Classic Parts, LMC, Brothers.

Thanks, Tim in Kentucky

TRK -

Inland Truck (www.inlandtruck.com) helped me with my Eaton HO52/72 3/4-Ton rearend for my '49 Chevy model 3600.

Good Luck!
Dan M.

Welcome to the Bolt!

Pulling those bolts in front of the pinion gear will allow you to change the seal, but wont allow you to pull the pinion assembly. Youll have to pull the axles and unbolt the front section of the differential to get the pinion gear and its assembly apart. I suppose you could probably do it without taking it out, but itll be much easier with it removed from the housing.

That bolt on the side goes through the housing and runs against the back of the ring gear. It has a small thrust pad at the end that basically prevents the ring gear from distorting if your towing or pulling a very heavy load.

If you dont have a maintenence manual nows the time to buy one. Most of the bearings you should be able to get through Napa or your local parts store, although youll probably get a much better deal through a bearing supplier. I use Applied Industrial Technologies.

Jeff

I have the differential (pumpkin) completely out. Last night I did a complete parts wash on everything. Boy does that old rearend oil stink! I can see part #'s on the pinion bearings but will still need to remove the pinion assmbly tonight. I was worried about the thrust bolt on the side before I did anymore disassembly.

This is my first restoration and my very first attempt at a full floating rearend. Truck is going to be a flatbed delivery truck when I am finished. I have 4 years. That's when my son gets out of the Air Force, unless he makes a career out of it.

I read a lot of the post everyday and have been helped a great deal.

Thanks,
Tim

This is where the manual comes in handy!

I believe the thrust bolt is turned in until you hit the ring gear and then you back it out 1 1/2 turns or somewhere in that neighborhood, before locking the nut down to hold it in place.

Your also gonna need to know the backlash for the ring and pinion, plus youll need the correct thickness of shims for the pinion to engage the ring gear properly and get the correct tooth contact.

Theres also a specific way to turn the adjusters for the side bearings to get the proper tension before locking it all down.

Just an FYI. Got any pics of the truck?

Jeff

Well guys I got home and took a look at the pinion assembly, and after cleaning everything I noticed no cotter pin in the pinion nut. There was a stiff wire (fence wire) I guess.

Also the pinion shaft nut was very loose? Suppose to be 160 to 250 ft lbs! I removed what I could and looked at the pinion bearings and noticed what holds the pinion in straight, is the torque applied to the front pinion nut. After reassembly looks like once the Oil seal is replaced and the pinion nut tightened to torque. Everything should be OK.

I will post some pics soon. After seeing most of the trucks on the site I am a little embaressed of mine. But I keep reminding myself that it will look better and better as time goes on!