DIY: S65 M3 Rod Bearing

[MMMM3]

so why does a worn bearing continue to wear? the wear opens up the tolerances the gap fills with oil and all should be well.

And if the answer is that it just does, then I would like to know how it can be expected that a replacement bearing will not do the exact thing. And if the bearing surface is harder in the new ones, then camshaft wear has to be greater...

please explain...

[deansbimmer]

Originally Posted by MMMM3

so why does a worn bearing continue to wear? the wear opens up the tolerances the gap fills with oil and all should be well.

please explain...

Fluid dynamics. Journals survive on an oil wedge and a specifically engineered bore eccentricity. Alter the bore (abnormal wear) and you alter the qualities of the oil wedge and accelerate towards bearing failure. Nobody will be able condense the information required to understand the concept into a single post. Here are some good links that will help put together some understanding. These are just a couple of the top Google hits. Find qualified sources to learn from, not us forum warriors.

http://kingbearings.com/files/Engine..._They_Work.pdf

http://www.substech.com/dokuwiki/dok...ngine_bearings

http://www.enginebuildermag.com/2017...sel-dominator/

[///M Power-Belgium]

Originally Posted by MMMM3

so why does a worn bearing continue to wear? the wear opens up the tolerances the gap fills with oil and all should be well.

And if the answer is that it just does, then I would like to know how it can be expected that a replacement bearing will not do the exact thing. And if the bearing surface is harder in the new ones, then camshaft wear has to be greater...

please explain...

Here is more information about bearing wear ...

=> http://www.agkits.com/bearing-failure-analysis.aspx

=> https://www.knowyourparts.com/techni...earing-damage/

=> http://mechanicalinventions.blogspot...-analysis.html

[oldmanstyle]

Originally Posted by MMMM3

so why does a worn bearing continue to wear? the wear opens up the tolerances the gap fills with oil and all should be well.

The tolerances aren't opening up uniformly around the perimeter. The rod is growing an oval inside of a circle. Also, the bearing isn't a uniform material throughout.

[swhat]

Did you guys remove both steering rack bolt? I have removed the lower bolt, but curious if the upper bolt needs to be removed. It is a bit harder to reach. thanks.

[SYT_Shadow]

Originally Posted by swhat

Did you guys remove both steering rack bolt? I have removed the lower bolt, but curious if the upper bolt needs to be removed. It is a bit harder to reach. thanks.

Just one. If you remove it completely it will be tough to line up right

[swhat]

Originally Posted by SYT_Shadow

Just one. If you remove it completely it will be tough to line up right

Did you remove the lower one or the top one? Thanks

[SYT_Shadow]

Originally Posted by swhat

Did you remove the lower one or the top one? Thanks

I don't recall. The DIY should show it

[deansbimmer]

Remove the lower column shaft bolt. There is even a notch cut out in the frame to access it from the driver wheel well.

[Duk996]

Originally Posted by deansbimmer

Remove the lower column shaft bolt. There is even a notch cut out in the frame to access it from the driver wheel well.

Dean, is there a good way to know when the wheel is centered? After I disconnected the steering input from the rack the wheel might have spun around 360 degrees one way or another. Is looking at the clock spring the only way?

[bigjae1976]

Originally Posted by Duk996

Dean, is there a good way to know when the wheel is centered? After I disconnected the steering input from the rack the wheel might have spun around 360 degrees one way or another. Is looking at the clock spring the only way?

Shouldn't matter if the steering wheel spun.

[Duk996]

Originally Posted by bigjae1976

Shouldn't matter if the steering wheel spun.

Yeah? No clock spring to get overwound when maxing a left or right turn? I admittedly haven't taken it apart to see how it all works.

[///Mobbin]

Originally Posted by Duk996

Dean, is there a good way to know when the wheel is centered? After I disconnected the steering input from the rack the wheel might have spun around 360 degrees one way or another. Is looking at the clock spring the only way?

I'm sure how correct my methodology was but this is what I did, LINK.

Hope that helps!

[deansbimmer]

It's simple. When you lift the car just line up the steering wheel straight. Go to remove the bolt on the column; line it up with the access groove in the frame and remove it from the wheel well area with a torx on an extension. Use a bungee or similar to tie the wheel to keep it from rotating while the subframe is down. Once done just put things back, nothing should have moved. The column joint is keyed and will only go on the same way it came off.

[Duk996]

Originally Posted by deansbimmer

It's simple. When you lift the car just line up the steering wheel straight. Go to remove the bolt on the column; line it up with the access groove in the frame and remove it from the wheel well area with a torx on an extension. Use a bungee or similar to tie the wheel to keep it from rotating while the subframe is down. Once done just put things back, nothing should have moved. The column joint is keyed and will only go on the same way it came off.

I did that dean but sans the bungee or similar. Now I think the wheel turned 360 one way or another and am afraid I'll over rotate the clock spring....

[deansbimmer]

The clock spring itself rotates several turns past what the steering rack will allow. If it's not lined up close to center then your DSC light will come on since the steering angle sensor is built into that clock spring/switch assembly. You can view the steering angle through a software interface.

If you're still not sure, you can remove the clock spring and count the turns full left, then full right, then center it from there.

[Scharbag]

Originally Posted by deansbimmer

The clock spring itself rotates several turns past what the steering rack will allow. If it's not lined up close to center then your DSC light will come on since the steering angle sensor is built into that clock spring/switch assembly. You can view the steering angle through a software interface.

If you're still not sure, you can remove the clock spring and count the turns full left, then full right, then center it from there.

How is this clock spring accessed? And can you see its value using a Carly or do you need an AutoLogix?

Thanks,

[deansbimmer]

Originally Posted by Scharbag

How is this clock spring accessed? And can you see its value using a Carly or do you need an AutoLogix?

Thanks,

It's the SZL module in the module tree. I use ISTA in my shop. I know SnapOn scanners can see the value too. I don't know for sure about Carly or others.

[Scharbag]

Originally Posted by deansbimmer

It's the SZL module in the module tree. I use ISTA in my shop. I know SnapOn scanners can see the value too. I don't know for sure about Carly or others.

Thanks. And physically? What is the best way to re-center if needed?

[deansbimmer]

In most modern BMW's the SZL is part of the column switch cluster, aka clock spring, aka turn signal assembly. It's the assembly behind the steering wheel.

...you can remove the clock spring and count the turns full left, then full right, then center it from there.

[Scharbag]

Originally Posted by deansbimmer

In most modern BMW's the SZL is part of the column switch cluster, aka clock spring, aka turn signal assembly. It's the assembly behind the steering wheel.

Thanks. After asking the question, I did some looking. Found some information on it. I think mine is OK as it only moved slightly during the subframe re-install due to my own idiocy.

Given it is -33ºC here right now, I might as well figure out how to take the steering wheel off...

Cheers,

[Duk996]

Originally Posted by deansbimmer

The clock spring itself rotates several turns past what the steering rack will allow. If it's not lined up close to center then your DSC light will come on since the steering angle sensor is built into that clock spring/switch assembly. You can view the steering angle through a software interface.

If you're still not sure, you can remove the clock spring and count the turns full left, then full right, then center it from there.

Ok, no sense doing more work if it's right anyway. I'll reassemble and if the car lets me know I'll trying 360 one way or the other until it's good. It's not that hard to access with that factory notch cut in the chassis. Thanks!