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About 2 years ago i had an embarrassing situation where i broke down in a remote town with a failed rear wheel bearing. More embarrassing was the fact
that the local mechanic ordered the wrong parts and said he did not have a proper press. I would be eager to hear from anyone who has done this fix
in their garage / shed as i believe the mechanic i came across poorly represents those in the trade.
I've done this job without the proper tools before. The tool of choice for getting the axle out is a slide hammer, but you can also use a cinder block (or something heavy) and a piece of chain. Once the axle is out there is a bearing puller tool that is used to force the bearing off the axle, but an alternate way can be to grind/cut the outer race to get it off, then grind/cut (carefully) the inner race until it's very thin. Before you break through and start grinding on the axle, take a hammer & sharp chisel and whack the thin spot (where you've been grinding). If you've ground it down correctly the inner race should crack and slide right off. When installing the new bearing, keep in mind the ID of the inner race is about .001 smaller than the OD of the axle (this makes it an interference fit). A press with the correct accessories to support is best, but if you're careful you can use heat instead. If you gently heat the bearing you can put it on by hand & it will slide right into place (a pair of heat resistant gloves can be very helpful). As it cools it will clamp onto the axle, then you can pound/tap the axle back into the housing, re-assemble brake parts, bleed as required, put your rim/tire back on and you're golden. Tim
Excellent,
Thanks for the advice Tim. I am a little tentative about the heating process of the new bearing and getting it on the shaft..apparently you heat it in oil? Either way my worry is you only get one shot at it :no:
Oil is safe (for the bearing), but also messy and dangerous to you. It can be heated in a regular oven & that's safe for the bearing and safer for you. I've also heated using a torch, but you need to be very careful not to overheat. It can also help to put the axle in the freezer for a couple hrs (if you have one big enough). If you have access to liquid nitrogen, spraying it down with that can help. Liquid nitrogen can be dangerous though (frostbite), so if using that, think about what you're doing and take precautions.
Even if it gets stuck before seating, there are other ways to drive it home. A piece of pipe that fits on the inner race can be used to drive it, or you could always take it to a place with a press and simply pay them to bail you out. Most places would likely do it for a smile and/or a small fee. Tim
I learned the same process for removal, cut/chisel the retainer and the bearing.
The very first one I did, I asked about the heating the bearing in oil as per manual and was told not to worry about it, "thats why we have a 20T press".
I have done hundreds of bearings and never heated one yet, never had a failure either (touch wood).
If I didn't have access to a good press, I would find a shop willing to press it all together.
If I was stuck, I would probably take the time to make a puller-style "press", out of threaded rod and hardwood blocks.
In that case, I would definitely heat the parts in the oven.
BB
I just replaced my rear wheel bearings a couple of weeks ago. I heated the new bearing retainers in a tin of 80-90 gear oil to 300 degrees in a toaster oven with a thermometer in it while I did the other work. Pulling the axle with an adapter and slide hammer is easy after removing the 4 bolts from the cover. You can leave the brake drum assy. on the van. Replace the axle oil seals and the gaskets while you are in there. Grind a cut into the old bearing retainer and use a sledge and chisel to finish splitting the old retainer. Make sure the axle is supported underneath while you are swinging away so that you dont bend the axle during removal of the retainer.Then press off the old bearing. I recommend heating the retainer before installation as heating the metal causes it to expand, thereby increasing the inside diameter of the retainer. Yes, you can slam it on there with a 20 ton press, but because this is an interference fit you are actually removing material from the axle shaft when you press it on cold. The reason you heat it in oil is so that it is heated evenly and therefore expands evenly. It isn't for lubrication as one might think. You want to remove the oil with a rag quickly after removal from the oven and before installation. I would heat it to at least 350 as even at 300 it still took a press to get it on there. (The heat transfers to the axle extremely quickly) Remember to not swap sides with the axles as they are wear mated and will most likely cause problems and extra noise and wear if you do. Use a torque wrench to evenly torque the four nuts when you go back together. Don't forget to oil the lips of the oil seals before you slide the axles in. Easy peasy.