View Single Post
  #105  
Old 11-07-2017, 08:17 PM
andrewwynn's Avatar
andrewwynn andrewwynn is online now
Member
 
Join Date: Jun 2015
Location: Racine, WI
Posts: 10,817
andrewwynn will become famous soon enough
Front Wheel Bearing R&R

The gun sound I'm very familiar. I preloaded about 33,000# and nothing was happening. (other than slowly stripping the push rod). I then heated up the carrier knuckle up to about 240F and B A N G! Scared the shit out of me. Worse it was about 9pm working outside. I figured out it had to be the bearing finally slipping about 0.001". Just like an earthquake. Stress builds then releases. While hot I started to turn the bolt with a ratchet with about 30" handle and most of my body weight. Every 1-2" down on the handle another BANG BANG BANG. Knuckle cooled off and then it could hold my entire body weight (180) at 2.5' (450 ft·lb) way more than a 3/4-16 can handle (as evidenced by the smooth appearance after I rounded off all the threads).

Another round of heating back to 240F and I could turn the bolt again (i had to add some spacers to find a non smooth part of the bolt). The second round of heating the bearing was maybe 5/16 " out and taking less and less effort and the bangs happened every 1/2" or so of travel (30" away). A few minutes of bangbangbangbangbangbang and off it came.

The rod was TOAST. I had to buy a new rod to install. Fortunately with freezing the bearing and a touch of oil It goes in with half the force.

I was very glad even with self destructing the prime mover I was able to learn more than had it been too easy.

I did my wife's car first and it previously had cv replaced so not factory axle nuts and my baby torque took them off. My car with 16 yr old factory axle nuts: different story 4# hammer end of a breaker bar wasn't happening at all. I bought a decent hardened rod but 3/4-16 grade 8 is good for about 33,000# just about exactly what the math worked out to and I stripped yet another.

With 8 bearings between our two x5 and having 9 brothers and sisters I figured I'll beef up the thing and never have that problem again.

Now even with my 700 ft·lb impact wrench I can't over torque the 1" bolt designed for 750 ft·lb (at which 62,000). Means I can apply about 56,000# hundreds of times without wear as I'm operating well within design limits. After pushing out and in the last bearing the drive bolt looks new. Operates a little smoother even (nut will soon down the bolt by hand).

I've seen people make up a redneck bearing puller with stock cast plumbing parts (steel nipple, flanges) and if you could get enough layers of iron between the outside pipe and the bolt, you could make a puller for $20. If you have access to a lathe, copy upallnight with the beautiful aluminum slugs but use a 1" hole so you can get fierce pushing force. Even by hand I think 40,000# would be easy. Fine threads theoretically make it easier to turn but they add friction so you might do better with coarse.

7/8-14 grade 8 lubricated is 500 ft·lb and 46,000 # force. Numbers a little easier to achieve than the 1" bolt 765 ft·lb max torque. I just wanted something stronger than my impact wrench so I'd stop braking it twice per bearing.

Now if I was still having problems and if I could find one, a left thread 1-3/16 bolt I could turn to 1100 ft·lb (my impact wrench can hit harder lefter) I could achieve 74,000#.

I was suitably impressed how hard the tool had to work at 700 ft·lb to push off the last bearing. Chewed through most of a battery and I had to go get ear muffs it was too long too loud but other than having to hold the nut back from turning with seriously 8x the most I've ever had to do, I just watched and it did. A minute or two of 110-120 dB banging of the Impact and bearing dropped in my hand.

Going on was a cake walk. I didn't even freeze the bearing nor heat the knuckle. It might have taken 20-25T but it just eased right in. Maybe a minute. Pressing the hub in was very fast. Took longer to set up the machine (to make sure only pressing on the inner race) than actually push the hub into the bearing.

Anybody within a reasonable drive of SE Wis i would come visit with the press and the monster impact. I like to see it get some action.

I'm trying to invent a way to use it to push the hub off so i dont have to blow apart the dust shield every time. Maybe I can engineer a bracket that clamps around the inside of the knuckle once the axle is removed. That bracket has a fixed nut and I can push one of my smaller plates on the hub from the inside. That probably only takes 4-6000# I can probably use the 3/4" pusher and just a ratchet.

Hmm. My next bearing is a rear. Brain is spinning. I'll share if I figure out a clean solution wo having to rent a slide hammer.
__________________
2011 E70 • N55 (me)
2012 E70 • N63 (wife)

Last edited by andrewwynn; 11-07-2017 at 08:43 PM.
Reply With Quote

Sponsored Links