400ex axle bearing change

[maeziesdad]

The bearings went out on me just yesterday. Never done this before is this a hard project to do. And any tips would be appreciated.

[dariusld]

Ton of tips out there, do a search. Best tip is putting them in the oven, they fall right out. Make sure you clean them well first and I wrapped mine in foil to keep the smell down(burning grease).

[oldracer]

or if you have an old hot plate. then you can do it outside.

turn hot plate on med/high
place bearing carrier on hot plate(standing it up)
when it gets good and hot. if the bearing hasn't
all ready fallen out. grab the carrier(use a oven mit)
and tap it on a piece of wood.

then repeat for the other side.

the whole time you are doing this.have your new
bearings in the freezer.

then they just slip right in. and they fit tighter as the carrier cools.

[guinness77]

Carrier bearing change out.

Remember the other advice on using the oven and the freezer.

Elevate the quad so the rear tires are off the ground. Remove the chain. However way you want to do it is fine. Just be certain to loosen the 4 pinch bolts on the rear of the swing arm. Gently and carefully pry the pinched area open. A millimeter will do fine.
Remove the right rear wheel and hub. You can do this by removing the cotter pin from the hub bolt and removing the hub bolt. (The wheel should slide off).
Remove the skid plate.

Unscrew to rear brake caliper and rest it on the swing arm. There are 2 big nuts on the axel to the right of the break rotor. They look like just 1 nut. but they are 2. Spray a liberal amount of WD40 into the nuts. Take a rubber mallet and strike the nuts with about 5 lbs of force. Not much, just enough to force a little movement of the nuts on their threads.

Now you can unscrew the inside nut. Try wiggling it both ways to help get it loose. You'll probably find it needs lots more WD40 and it's reverse threaded (I think). Loosen it up by about 1/4 inch. If it won't turn, use a butane torch to heat the nuts. Since WD40 is flammable, be sure to wipe the nuts with a shop rag. You will probably need a cheater bar to get those nuts loose. As they loosen, they will move inward towards the brake rotor. Eventually, you'll expose a round clip that wraps around the axel. Use needle nose pliers to open that clip up and off the axel. You can now return the nuts back out to release the break rotor and mount off the axle.

On the inside of the break rotor/mount is a flat piece. I think it's called the carrier/break stay. It's bolted to the swing arm. Remove it.

The axle should now slide leftward and out. It will probably take a pounding with the rubber mallet to get it out.
Once out, get the grime off of it completely. I find a wire brush does the job very well. An air powered wire brush will save you an hour of work here.

Back to the swing arm now..
The carrier should slide out towards the left. Some gentle tapping with the mallet on the right side will help. On the carrier are 2 rubber gaskets. Carefully inspect them. If they are broken or damaged, replace them.

Be certain not to damage the carrier in any way during any of the total process.

Now that the carrier is out you can look into the center and see there are 2 rubber dust covers on the outside, then the 2 bearings, and in the very middle is a cylindrical spacer. The dust covers are easy to pry out. One on either side. Remove them and toss them. Then you have to remove the bearings. Once again, there is one on either side. Inserting a screwdriver into the one end of the carrier and tapping out the bearing on the other end of the carrier is the most common way to get them out. They are a very tight fit indeed. If you have to ruin them, no prob. But do not damage the carrier or spacer in the process. Once you get one bearing out, the spacer will fall out and the last bearing will be a breeze to tap out. Toss the bearings.

I cannot over emphasize this next bit....
Thoroughly clean the carrier, the spacer, and all other parts. Clean the inside of the carrier housing. Leave no residual oil or grease in there.

The bearing kit will tell you which side of the new bearings to face out. Place the bearing onto the carrier and make sure the carrier is flatly supported onto a very solid surface. Find a socket that patches the bearing size to tap in the bearing WITHOUT hitting the surrounding carrier. I think it's 1.25". But I might be wrong. Place the socket on the bearing and then begin tapping on the socket making sure the bearing goes in flat and completely. Turn over the carrier and drop in the spacer. Then insert the next bearing and tap it in the same way you did the other side.
Now go back to the original bearing and use the socket/mallet to gently tap it back flush into the base of its housing. You'll notice the bearings are inset into the housing. The 1/4 inch recess is to conform to the dust covers. Spring side in, insert the dust covers in the same manner as the bearings. The dust covers are the hard part of all this. They are a major pain in the rear end.
Once all that is done, liberally grease the inside of the carrier with the proper grease. ( I forgot what kind). Also grease the middle of the axle on the contact surfaces. DO NOT GREASE the inside if the swing arm.

Put the 2 outside carrier gaskets onto the outside of the carrier.

Insert the carrier back into the swing arm. Should be no problem here.

Put everything back together in reverse order except for the chain and wheel hub.

Lift the axle at one end. There should be no up-and-down free play. At least, there sure wasn't any when I did it. If there is free play, then either the wrong bearings were purchased, or the axle is trashed.

If everything is ok, then put everything back together. Remember, there is lots of grease in there. So the axle will have some very slight resistance to spinning. But that'll go away.

This next point is by far the most important. You know those 2 big nuts on the axle? Well... they're going to come loose. So check them (and re-tighten them if need be) after the 1st 30 minutes of riding, the 1st hour of riding, and then after every 6 hrs for next several rides. Be sure to bring the right tools to get those nuts tightened.

[TravEX]

^^^Excellent post! That should be a sticky in the "How to" forum.

Thanks

[guinness77]

There are a couple refinements I should make.

1. The break stay is not bolted to the swing arm. It has a circle clip that needs to be removed.

2. When tapping in the bearings with a socket, make sure the socket rests on the outer ring of the bearings; NOT the inner ring or center band(s).

3. When tightening the axle nuts you only need the center threaded cylindrical part to press against the brake rotor mount with 40 ponds or so. Be careful when cranking down the force on those 2 outer nuts. You can wind-up with hundreds of pounds pushing into the side of those bearings. This will lead to premature bearing failure. Crank those 2 bolts against each other, not against the brake rotor mount.