Rear Spherical Bearings Conversion on Stock Arms

[Redd]

Originally Posted by amg6975

I like this solution a lot. I didn't realize it was an option but I think I'll be going with this.

I would also say, I would not hesitate to run spherical on the toe link, the one on the very back side of the knuckle. I think that will see the most benefit from the spherical, has not had any issues, and doesn't even have the factory taper.

Problem with PU has always been noise. They will dry up and squeak after a few months.

Our M3 stock toe links are already spherical on both ends. The weakness of the stock toe link is the eccentric bolt that is used to set the toe.

[Ghmpin]

Rogue has some similar to what SPL has. It’s a spherical insert, not a washer.

https://www.rogueengineering.com/Rog...-V20_p_92.html

[ENinetyLou]

Originally Posted by kolosy

So I got my missing groundcontrol washers, and ended up with a set of ones meant for the spherical conversion (bought them before changing my mind). it's an interesting comparison

Attachment 3369898

Attachment 3369899

Attachment 3369900

the GC ones are 1.5mm thicker, and have an odd lip on the flat side. i was going to say that it mates up with the spherical bushing inside the arm, but it doesn't -- the opening is smaller than the OD of the bushing. hopefully they aren't just wrong, but not sure what the purpose of that cut out is.

I just got a set of Ground Control Rear Arms and they came with 8 washers like this. After reading about the bolt shearing situations, I'm strongly considering returning these GC Arms and just postponing my control arm replacements.

Going to call GC tomorrow and ask them about this issue and if they've heard about it. Anybody already spoken with them?

[tsk94]

Originally Posted by MaximusB

Has anyone with GC arms managed to shear a bolt?

Originally Posted by Redd

Not to my knowledge but I don't keep track of those things.

I had no issues with mine for ~3 seasons on my previous car. Not saying that means they cannot fail though.
I just bought another set for my new build, so hopefully all is good this time around again...

[ENinetyLou]

Originally Posted by tsk94

I had no issues with mine for ~3 seasons on my previous car. Not saying that means they cannot fail though.
I just bought another set for my new build, so hopefully all is good this time around again...

What kind of bolts did you install with? Factory bolts or ARP? How many track days through those ~3 seasons?

[tsk94]

Originally Posted by ENinetyLou

What kind of bolts did you install with? Factory bolts or ARP? How many track days through those ~3 seasons?

I did new OEM bolts.
~45-50 days on them in that time.

[amg6975]

I got around to doing the Powerflex Black bushing install. I'm a lot happier with this solution. I can't imagine the difference between this and bearings will be noticeable, and these were way easier to install. I used new ARP bolts for this install, torqued to 98ft-lbs.

Again not really a professional opinion but I'll certainly sleep better at night.

[testdriver]

Originally Posted by MineralWhiteF80

after reading this thread three separate times, my current opinion is that leaving my two OEM upper arms alone and dealing with a little more deflection is better than any gains I might see by changing the two rubber outer bushings to bearings with the possibility of suspension failures that lead to crashing Especially if I do the trailing arm and lower spring/camber arms with all bearings.

I'll change the lower spring arm and trailing arm rubber bushings out, but only way I'd mess with the two upper arms is by going with SPL Parts arms (or equivalent). It's just not worth it for my simply HPDE track car.

I have the same feeling as well.

At first I was excited to see this low cost options which can make improvement on our car. But it looks like if you do any track driving/ HPDE, the added washer for putting up the bearing can be a point of risk uncertainly to the whole thing.

In the rear suspension, I already hv the solid bushing subframe. I was planning to change out some bushing to bearing, now after reading all this, I decide if I have to swap bushing to bearing, I only pick those which I do not need to add any spacer/ washer or alter to length of the whole pieces to replace.

I guess one of the example would be the Rear lower control (spring) arm Inner bushing. This can be upgrade to bearing with little worries.


At the end I would like to say THANK YOU to many who willing to share their "successful" and "unfortunate" experience on this topic.

[Redd]

Just finished a trackday Sat night. Drove 55 mins straight at Sepang International Circuit. Zero issues with the sphericals. That said I was only on AD08R tires and no aero, so not extreme amounts of grip. I did ride the kerbs pretty hard tho.

At this stage I'm comfortable with the strength/safety of the spherical conversion for anything up to trackdays. If you're a competitive driver or doing time attack or racing then probably race arms are better.

[bipp]

I've been reading about this approach of removing the rubber while retaining stock arms, but I've found some other "package" approaches to this that take the self-sourcing out of it.

As an example, there's the Laptorr kit (https://laptorr.com/collections/m/E92-M3) and the Schirmer kit (https://www.teamschirmerparts.com/pr...s-gt-rear-axle) that provide full sphericals and eccentric camber arm bearing. Would this be a similar but safer approach? It definitely appears that going spherical isn't the problem but rather the improper use of washers, so maybe a "kit" is likely to mitigate some of that risk? (edit: ignoring the somewhat absurd pricing from both of those vendors, I see that SPL has the bearings for far cheaper)