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Old 02-03-2012, 08:12 AM   #1
frankie591
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front strut bearing wobble

Hey all,

I started putting my struts back together last night, got all the components back on and in the correct order. Everything seems tight (ie. the drop hat is rock solid and doesn't wobble or move), but the strut bearing feels kind of wobbly. Is this a bad bearing, or is it normal for there to be some play?

The bearing doesn't move up and down like if I were to push and pull in the same axis as the strut, but it can rotate maybe 5-10 degrees in each direction. I think the inner race of the bearing is being held tightly, but the outer race is loose around it.

Please let me know if it's normal or if I'm gonna have to pick up some new bearings! Thanks
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Old 02-03-2012, 09:20 AM   #2
Bullet Ride
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Iím going to start off by saying, Iím not sure how itís supposed to be because when I replaced my suspension I put in ground control bits which have the spherical dish to give the required compliance and I never really looked at the stock parts too closely. That being said Iíve attached two images from a simple mock up I did of a macpherson strut assembly. As you can see, as the shock travels up and down the angle of the strut axis relative to a fixed vertical plane changes. The upper strut mount needs to be able to comply with this otherwise the system would be over constrained.
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File Type: jpg s2.jpg (66.1 KB, 42 views)
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Old 02-03-2012, 09:32 AM   #3
frankie591
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I figured this might be the case. The bearing inside the rubber mount has 1 ball bearing less than a typical skf bearing, so I think it may be designed that way so that the outer bearing race can have some play around the inner race.

I guess worst case I can just go with it for now, and if I'm getting some odd behavior from the front end once the car is driving again, I can just swap out the strut mounts and see if that fixes it.
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Old 02-03-2012, 09:40 AM   #4
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Quote:
Originally Posted by frankie591 View Post
Hey all,

I started putting my struts back together last night, got all the components back on and in the correct order. Everything seems tight (ie. the drop hat is rock solid and doesn't wobble or move), but the strut bearing feels kind of wobbly. Is this a bad bearing, or is it normal for there to be some play?

The bearing doesn't move up and down like if I were to push and pull in the same axis as the strut, but it can rotate maybe 5-10 degrees in each direction. I think the inner race of the bearing is being held tightly, but the outer race is loose around it.

Please let me know if it's normal or if I'm gonna have to pick up some new bearings! Thanks
I would replace them for added measure. You are changing the geometry on the front end so you will get different stress on the bearing. I lowered mine and whether it needed new (which it didn't) I changed the strut bearing anyway. I don't feel like doing to job twice.
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Old 02-03-2012, 09:47 AM   #5
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Originally Posted by frankie591 View Post
I figured this might be the case. The bearing inside the rubber mount has 1 ball bearing less than a typical skf bearing, so I think it may be designed that way so that the outer bearing race can have some play around the inner race.

I guess worst case I can just go with it for now, and if I'm getting some odd behavior from the front end once the car is driving again, I can just swap out the strut mounts and see if that fixes it.
I think I still have the old stuff I ripped out of my car kicking around somewhere. I'll look for it tonight and take a closer look. Since the amount of compliance required is very small, it might just come from the rubber in the mount itself rather than the actual bearing. 5-10 degrees sounds like a lot seeing as only a few degrees is actually needed.
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Old 02-03-2012, 10:08 AM   #6
frankie591
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I think I still have the old stuff I ripped out of my car kicking around somewhere. I'll look for it tonight and take a closer look. Since the amount of compliance required is very small, it might just come from the rubber in the mount itself rather than the actual bearing. 5-10 degrees sounds like a lot seeing as only a few degrees is actually needed.
I think i may have to bite the bullet and get new mounts. I remember one mount being more loose than the other, so they are probably both bad and one is just worse than the other.
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Old 02-03-2012, 10:17 AM   #7
InfiniteDice
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I wash out the old grease with cleaner, then a light spray of lube. Rotate it while you spray and wash out all the old crap.

Once the grease is cleared out, you should be able to see the balls/race better, look for anything obviously damaged.

I usually repack it with new grease, as long as the rubber and bearings look decent.
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Old 02-03-2012, 10:25 AM   #8
frankie591
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Originally Posted by InfiniteDice View Post
I wash out the old grease with cleaner, then a light spray of lube. Rotate it while you spray and wash out all the old crap.

Once the grease is cleared out, you should be able to see the balls/race better, look for anything obviously damaged.

I usually repack it with new grease, as long as the rubber and bearings look decent.
I did exactly this. Bearing spins great, and looks to be in good shape, but if I were to put my finger in the inner bearing race I can physically make the inner bearing race wobble with respect to the outer race. I think it happens because the bearings are full minus 1 ball bearing.
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Old 02-03-2012, 12:04 PM   #9
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As suspected I think they are all like this, there may be some additional play due to wear, or simply from lack of grease, pack the grease in there really good then fit the cup on the bottom. As long as they rotate freely without skips or jittering, no major up/down play and have good rubber, then I don't see any point replacing them yet.
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