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Discussion Starter #1
...getting ready to do my front brakes and wondering if I will need to
press the bearings into the rotor/hub..or will they just fall in...
 

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For the inners, you can use the old bearing to press the new one in. With the outer bearing, you place it in the hub and then it gets tightened down when you torque down the nut that holds it all on.
 

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but... in all the years I've been working on my Benzes, I've never replaced an outer bearing race. If you take off the front hub, repack the bearings with the green MB grease, put on a new seal (on the back of the hub), and set the bearing run out with a dial indicator.

Markus - what's the run out requirement?
 

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This should help.
 

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Discussion Starter #5
For the inners, you can use the old bearing to press the new one in. With the outer bearing, you place it in the hub and then it gets tightened down when you torque down the nut that holds it all on.
..thanks for the reply. Reason I asked, the old bearing race on the hub is extremy tight and I dont want to damge the hub trying to remove it...can I use a small amount of heat to help get it free or is there a quicker way...
 

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On the inner bearings, there's 3 parts - a race, the bearing, and the seal.

On the outer bearings, there's the race and the bearing itself.

Like Mike said, if the races are in good shape, not scarred, pitted or discolored, you can simply leave them there and just doing the bearings themselves and the seals.
 

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Discussion Starter #7
On the inner bearings, there's 3 parts - a race, the bearing, and the seal.

On the outer bearings, there's the race and the bearing itself.

Like Mike said, if the races are in good shape, not scarred, pitted or discolored, you can simply leave them there and just doing the bearings themselves and the seals.

good stuff Markus, tks

Simon
 

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For those who don't have a press on hand, but happen to have an arc welder or MIG welder handy:

You can remove a bearing race with nearly zero effort by running a bead of weld around the face of the tapered race. Run a bead, doesn't really matter the composition of the electrode, as long as it's still steel. E7014 or E6013 is all I have; they're pretty generic and work well on anything.

After welding, simply let the hub/race assembly cool for 30 minutes in air, after which the race should just fall out or be easily pulled out.

Linear play for re-assembly is 0.020"
 

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If you're going to replace the bearings, you should also replace the races. Not doing so is a bit like putting a new timing chain on old cam gears: do-able, yes; ideal, no. The old races are not too difficult to extract if you don't have the welding equipment mentioned above. You simply need a sturdy punch with a well-defined edge and the patience to work them out gradually. Keep your new races in the freezer until you're ready for them, then use the old races as perfect-sized drivers for the new ones.

Setting the preload has been discussed many times. To seat the bearings in the races, I over-tighten the collar washer with channel-lock pliers, release, and repeat several times. For final preload, the collar washer is tightened as far as I can get it with my fingers - no more. Excessive preload will kill your bearings in no time. When the wheel is mounted, it should splin freely with no play when rocked at the 12 and six o'clock positions.

And watch that little socket-head screw used to tighten the collar washer in place. If you over-tighten it, it will break. Use an allen key and you should be fine. (Am I the only person who's found that the torque specified by M-B, which I think is 14Nm, is unattainable?) And bear in mind that the pressure you exert when tightening that little screw could easily move the collar washer just enough to mess up your carefully-set preload!
 

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Discussion Starter #10
If you're going to replace the bearings, you should also replace the races. Not doing so is a bit like putting a new timing chain on old cam gears: do-able, yes; ideal, no. The old races are not too difficult to extract if you don't have the welding equipment mentioned above. You simply need a sturdy punch with a well-defined edge and the patience to work them out gradually. Keep your new races in the freezer until you're ready for them, then use the old races as perfect-sized drivers for the new ones.

Setting the preload has been discussed many times. To seat the bearings in the races, I over-tighten the collar washer with channel-lock pliers, release, and repeat several times. For final preload, the collar washer is tightened as far as I can get it with my fingers - no more. Excessive preload will kill your bearings in no time. When the wheel is mounted, it should splin freely with no play when rocked at the 12 and six o'clock positions.

And watch that little socket-head screw used to tighten the collar washer in place. If you over-tighten it, it will break. Use an allen key and you should be fine. (Am I the only person who's found that the torque specified by M-B, which I think is 14Nm, is unattainable?) And bear in mind that the pressure you exert when tightening that little screw could easily move the collar washer just enough to mess up your carefully-set preload!
so I shoud replace the race...they do look fine, but so far it seems they are stubborn to come out. Can I use some mild heat from a small torch to free it..tks
 

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What kind of tool are you using in your attempt to remove them? The exposed edge of the race is, admittedly, a small target; it puts a premium on the quality of the edge of the tool. A large screwdriver, for example, just won't cut it (and would risk damaging the hub, too).
 

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I just use a decent set of punches..they always come out. If they are RELUCTANT a bit of heat, be it propane or map gas Always gets them to come free.

+1000 on replacing the races! bearings and races are made as a matched set, to leave the old race in is a sure fire way to wear out your new bearing prematurely!

Jonathan
 

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Discussion Starter #15
What kind of tool are you using in your attempt to remove them? The exposed edge of the race is, admittedly, a small target; it puts a premium on the quality of the edge of the tool. A large screwdriver, for example, just won't cut it (and would risk damaging the hub, too).
..this was going to be my first choice...
 

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Discussion Starter #16
I just use a decent set of punches..they always come out. If they are RELUCTANT a bit of heat, be it propane or map gas Always gets them to come free.

+1000 on replacing the races! bearings and races are made as a matched set, to leave the old race in is a sure fire way to wear out your new bearing prematurely!

Jonathan
...it makes sense, I mean you buy the bearings and the race is included. Im going to use a small propane torch to see if that works. Then use the old race to set the new ones.
 
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