47-55.1 Gear swap Axle troubles

[bootman49]

Project is a 1949 3800 long bed 1 ton. Truck is equipped with a HO72 axle with a 5:14 gear. We bought a HO52 rear axle so we could swap the 4:10 gear from it into the HO72 housing.

Problem is we are having a hard time installing the left axle (HO72 oem) into the 4:10 center section. Splines engage just fine but axle wont install fully. Right axle installs just fine. What am I missing?

[whitedog76]

Are you sure you have the correct axle shaft for that side? They are different lengths on either side.

If that isn’t the problem, take the rear cover off and take a look.

[mr48chev]

Good thing I went back and read Whitedog76's post or I would have duplicated it.
I'd be pulling the axle out of of the other side and comparing them as that is a five minute deal that may solve the issue.

[bootman49]

Originally Posted by whitedog76

Are you sure you have the correct axle shaft for that side? They are different lengths on either side.

If that isn’t the problem, take the rear cover off and take a look.

Yep, short axle is right side. I even pulled axles out of the HO52 housing to make sure I didn't get axles mixed up. No Chance, 69" to 71" hub face to face. Then I recalled I stamped R&L on HO72 axle flange's and hubs before disassembly for restoration.

If it is a direct swap for center section there must be something going on with the spline in the spider gear such as dried up muddy gear oil?

[weim55]

Rust (?) curious if your new 4.10 center sat around for years and years and has a bit of rust in the spline area of the side gear on the side that's giving you problems? With the trouble axle in place if you lightly tap it in with a hammer does it get stuck and you have to pry it back out to get it loose again? If so I'll bet it's A light film of rust. Spraying A bit of WD-40 on the splines of the axle then working the splines in and out of spider gear you may be able to carefully remove that rust film and finally slide the axle in freely.

Steve weim55 Colorado

[mongocanfly]

""(If it is a direct swap for center section there must be something going on with the spline in the spider gear such as dried up muddy gear oil?)""

Axle won't be in the spider gear....itd be in the side gear....

Try the other axle in that side and see how far it goes in ...mark/measure it and compare engagement depth of the 2 axles...if they're the same then I'd be looking at the side gear in the diff...but you can pull the cover and maybe see it as well...
Are the axle splines clean?...I've seen gunk/rust buildup in splines before as well.....

[bootman49]

Originally Posted by weim55

Rust (?) curious if your new 4.10 center sat around for years and years and has a bit of rust in the spline area of the side gear on the side that's giving you problems? With the trouble axle in place if you lightly tap it in with a hammer does it get stuck and you have to pry it back out to get it loose again? If so I'll bet it's A light film of rust. Spraying A bit of WD-40 on the splines of the axle then working the splines in and out of spider gear you may be able to carefully remove that rust film and finally slide the axle in freely.

Steve weim55 Colorado

We bought a complete HO52 (pic) axle from a 2500 series pickup sitting in field for years. We used small wire brush on side gear splines and gave 4:10 carrier interior a good wash with new seals and installed. Axle does get stuck to the point I need to pry it out. Never sounds like axle is bottoming against cross pin. Will try some Blaster on axle and repeat then take a look at axle end to see if I am getting some dirt on end.

[mr48chev]

I'd think that it is either a bur/bad spot on the end of the spline of the axle or on the side gear. It could be from a previous time when someone had the donor axle apart and forced the axle back into the side gear. Or rust in the side gear from sitting for years even though the housing was closed up.

[bootman49]

So, your gonna find this funny. Sorry for lack of timely update but because i'm the guy that needs help lots more than I can offer I don't spend too much time posting.

So here's the fix to the rear axle problem. PUT THE GEAR INTO THE FRONT! The bolt pattern is the same for the gear and cover so one can install it into HO72 housing wrong.

Thank you all for the help.

[1project2many]

I'm sure you're embarrassed about this. Don't worry, there have been worse mistakes made. At least you were good enough to post the real ending to the story.

Thanks.

[mr48chev]

That is one that I would never have thought of but you can bet it saved a lot of tooling at the factory the axles were made at.

I was just thinking that most of us had thought you were doing the third member swap under the truck and didn't consider that you might have put the third member in backwards.

[1project2many]

I was just thinking that most of us had thought you were doing the third member swap under the truck and didn't consider that you might have put the third member in backwards.

Very true!