820' - Replacing needle bearings with bronze bushings.

Got a 820 Iv been building, going with a doc locker style locker, including the addition of a 1" keyed shaft. I'm going to be replacing the inner axle, needle bearings with bronze bushings, as the keyed shaft is not hardend, and the keyway will destroy the needle bearings (pictured). Curious if others have remedied this, and where they sourced brass bushings. Found some on ebay (found a part # through a stretch 44875 video)  but no shipping option to Canada is available. Thanks

I've heard this mod and think it may be a good one.  I still have my needle bearings still on my doc locker with no issue.  I have seen the carnage of loosing the needles and it's pretty bad.  Have you checked your local hardware stores?  Maybe Princess Auto up there?

@MightyRaze
Gonna try PrincessAuto after work tomorrow, also going to two local bearing and seal shops, in search of new outer axle bearings, aswell as a bronze bushings option. Was able to track some down through a local lawn tractor shop, however they would be 4-6 weeks away, or more.

Is the size (1.003 ID x 1.253 OD x 1.00 long) or basically 1x1.25x1 inch?  I like I mentioned.  I need to do the exact thing on mine.  Not sure if you know who Lawrence Deel is.  He was the most recent victim I know of the needle bearing failure with the gokart axle.

There's other options here guys, first and foremost would be to get unkeyed roundstock, cut it to length and have keyways milled on the ends to your specifications. Yes it's the most costly but makes your whole setup much stronger. If you're handy you could in fact fill the sections of the keyway the needles would roll on by welding, grinding then ALOT of filing and sanding to bring it into spec.

Alot of guys want to swap over to needle bearings for strength, I understand your concern with a keyed axle and would do the same as you if it was my only option so don't think I don't understand where you're coming from here!  Lol.

Hey @CRAFTSMAN MUDDER where do you hail from? I'm a couple hours north of Toronto.

Brianator wrote:

There's other options here guys, first and foremost would be to get unkeyed roundstock, cut it to length and have keyways milled on the ends to your specifications. Yes it's the most costly but makes your whole setup much stronger. If you're handy you could in fact fill the sections of the keyway the needles would roll on by welding, grinding then ALOT of filing and sanding to bring it into spec.

Alot of guys want to swap over to needle bearings for strength, I understand your concern with a keyed axle and would do the same as you if it was my only option so don't think I don't understand where you're coming from here!  Lol.

Hey @CRAFTSMAN MUDDER where do you hail from? I'm a couple hours north of Toronto.

I've tried the round stock and cutting in a keyway path once.  It was total failure.  Not because my keyway was pretty bad, but the first bump I hit bent the round stock pretty quick.  I was afraid my case would break.  Luckily It was at home and close to the garage.  I've thought about welding and grinding in, but was afraid of weakening the axle.  I have JB Weld in the keyway at the bearings to help keep the oil in.  The go-kart axle I have is pretty rigid.  Can't remember if I got the non-flex one.  I figured it would be safer on the case.  

In this case, it's a been pretty proven method in the mud mower community to go to the brass/bronze sleeves.  The keyway helps keep them oiled and they are good for lots of pressure and a good deal of heat.  I understand the desire for needle bearings, sometimes good ole bushing may be best.

MightyRaze wrote:

I've tried the round stock and cutting in a keyway path once.  It was total failure.  Not because my keyway was pretty bad, but the first bump I hit bent the round stock pretty quick.

Wow really? That's not good. Guess it depends on what type of material you used but I know 4340 chromoly is really tough, especially when heat treated but guess you can't really go wrong with a go kart axle that's for sure, it was designed to take the stress!

You're not wrong about bronze bushings, they really do take alot of abuse and hold up well!

Wait, doesn't the bearing have an inner race?

I'm still on an FNR, so no roller bearings to worry about as I upgrade to a solid, keyed axle, but I'm surprised that an oilite bearing would be better for any power transmission application. I've seen others fill the keyway near the ends with RTV or other to prevent lube from getting out or grime from getting in, but never considered the keyed shaft causing problems for the bearings.

What if one set about carefully filing down some softer metal (copper, bronze, aluminum) in a scrap from said axle to make a "filler key"? Of course there's always JB Weld, but I haven't tried that since the 1990's. It would probably be easier to fill and file with that, even if less durable than a metallic filler.

@Sarge no needle bearing do not have and actual inner race as seen here

Some, but not all FNRs have cutouts at the ends of the case for sealed bearings, I can't remember the exact specs right now but I'll be running them when I rebuild mine and run a strait axle locker.

A filler key is an excellent idea! JB weld it in place and it should be good to roll (pun intended)! Lol

@MightyRaze yes those dimensions seem to be correct headed to the city now to do some searching. @Brianator Good to see a fellow Canuck on here, I'm from Southern SK, near Regina, aka hill billy land lol

Update for you fellas.
I had good luck, and got some bronze, oil impregnated bushings ordered. 8$ a piece, through a local bearing supplier, Wajax. They are however about 4 thousands too big a round, so a bit of emery cloth, and she will be good to go. I will add a part number once I receive them sometime next week!

I think that close to the diff carrier/center point bronze bushings should be fine in a live axle deal. If you do want needle bearings- weld the jetway under the bearings closed, then take to a machine shop and have them ground down flush. Best of both worlds and shouldn’t cost too much for the work done. Just my .02

I thought I'd find machinists have solved this sort of issue with keyed shafts before, but I didn't find a solution other than filling with welding or epoxy and file/machine to dimension, or broach keyways only where you need them.

Got some PVC or PEX pipe laying around from a plumbing repair? Chances are it's thick enough, and it's easy enough to trim to dimension. If you can't stand the thought of recycling plastic to make them, McMaster-Carr has this plastic stock in several dimensions... https://www.mcmaster.com/8741K32/

The needle bearing personally work well, it's when they start wearing out and you do some pretty moderate off-roading causing the inner race to fail.  This is the carnage of one incident I know. (Not mine, this is a good fellow by the name of Lawrence Deel's rig this past fall)

PVC isn't all that great of a bushing material. Way too soft and not very wear resistant. Nylon or delrin would make a much better plastic bushing. Even UHMW would be better.

On my 820 I just filled the keyway with weld and turned it back down on a lathe. I realized later on that I almost definitely warped the axle to some degree from that. Probably not enough to damage anything, but it's definitely there.

Don't make those bushings too much of a press fit. Standard practice with heavy press fit bushings is to press them in and then machine them to final dimension in place. If the bushings get too loose from sanding then a big of loctite will keep them in place fine. The green loctite is ideal for that but I think red would be just fine.