Rear Spherical Bearings Conversion on Stock Arms

My mech managed to remove the wishbone/guide rod subframe-side bushings without removing the entire subframe from the car. They lowered it slightly to get enough working room.

I didn't have to lower anything, maybe E82 is slightly different with enough clearance.

On e92 m3, the subframe didn't have to move. It can stay in place to remove the control arms.

The job was a little difficult because I fabricated my own press tool. I had purchased the BAV Autosports tool in the past, after I was done with the bushings on the trailing arm and camber arm I put it up for rent to forum members and it was never returned. (I did keep the deposit so no worries) but the tool is far better than what I fabricated. (See pictures)

I drove the car yesterday with the job completed. I felt a slight difference. Little more hooked up. But it's hard for me to notice a difference on the street. Tried a few hard launch and no wheel hop but usually I don't get wheel hop on street tires (Ps4s) I track with R-comp tires and that is how I get some wheel hop. My car is fully solid. This conversion was the last remaining bushing on the entire car. Every single control arm was previously converted to spherical bearing.
I didn't notice any more added NVH.
I did have a thump noise before the conversion which I thought it was the half-shafts but it turn out it was a failed bushing which I couldn't determine. Because the noise is gone.

So overall happy it's done.
I'll report again after a track day.

Good to know, looking to do this next weekend, waiting on SPL toe arms to do it all at once. I picked up the bav tool and hoping to be able to replace the bushings by unbolting outer bolts only and swinging the arms up a bit to gain clearance for the tool. Interested in feedback as to whether or not this would work.

tlrid3r wrote

On e92 m3, the subframe didn't have to move. It can stay in place to remove the control arms.

M43S7RO wrote

Good to know, looking to do this next weekend, waiting on SPL toe arms to do it all at once. I picked up the bav tool and hoping to be able to replace the bushings by unbolting outer bolts only and swinging the arms up a bit to gain clearance for the tool. Interested in feedback as to whether or not this would work.

Yes this will work. I used the BAV auto tool and did it this way with no issues.

Biginboca wrote

M43S7RO wrote

Good to know, looking to do this next weekend, waiting on SPL toe arms to do it all at once. I picked up the bav tool and hoping to be able to replace the bushings by unbolting outer bolts only and swinging the arms up a bit to gain clearance for the tool. Interested in feedback as to whether or not this would work.

Yes this will work. I used the BAV auto tool and did it this way with no issues.

https://i.postimg.cc/xdVF7pK2/B5560450-DF6-E-47-CD-953-D-F01-B82-FAA58-F.jpg

M43S7RO wrote

Good to know, looking to do this next weekend, waiting on SPL toe arms to do it all at once. I picked up the bav tool and hoping to be able to replace the bushings by unbolting outer bolts only and swinging the arms up a bit to gain clearance for the tool. Interested in feedback as to whether or not this would work.

tlrid3r wrote

On e92 m3, the subframe didn't have to move. It can stay in place to remove the control arms.

Biginboca wrote

M43S7RO wrote

Good to know, looking to do this next weekend, waiting on SPL toe arms to do it all at once. I picked up the bav tool and hoping to be able to replace the bushings by unbolting outer bolts only and swinging the arms up a bit to gain clearance for the tool. Interested in feedback as to whether or not this would work.

Yes this will work. I used the BAV auto tool and did it this way with no issues.

https://i.postimg.cc/xdVF7pK2/B5560450-DF6-E-47-CD-953-D-F01-B82-FAA58-F.jpg

As mentioned above it does work. With the BAV auto tool is much better. I was able to do 1 arm this way but my tool was not as strong so I removed the arms.

Having driven the car more, here are my impressions of this mod. As mentioned previously, car rides like it's on stiffer springs. There's also less suspension movement (compression) going over bumps. At the same time, there not much additional NVH. If you go over a big pothole or sharp bump, you will feel it more thru the chassis but I suspect that may be from my Powerflex rear strut mounts.

Damping was where I noticed another difference. I run Ohlins R/T at 11 clicks for street and previously it always felt slightly under damped. After this conversion, damping feels perfect at the same 11 clicks. You really can't discount the amount of undamped spring rate contributed by those small rubber bushings.

The nett result is that the rear wheels settle faster after a bump. This results in the rear end feeling more planted and is more confidence inspiring. The rear end also seems to follow the front end like it was on rails (cliche, sorry) with the front end, and there's less 'snapback' (thanks, was looking for a term to describe this) with sudden steering input.

Something I'm still getting used to is there is now a lot more sensation coming thru the seat. You can feel minute rear end movements which give you early warning of oversteer but may also make you more nervous driving at speed. I think this feeling will go away with more seat time. I also suspect my rear toe could be slightly off, will get that checked later.

tlrid3r & Biginboca , thx for the reassurance fellas, gives me a better sense of what to expect. Dunno about you guys but rarley does working on anything go as smoothly as I'd like.

tlrid3r wrote

Ask mentioned above it does work. With the BAV auto tool is
much better. I was able to do 1 arm this way but my tool was not as strong so I removed the arms.

M43S7RO wrote

tlrid3r & Biginboca , thx for the reassurance fellas, gives me a better sense of what to expect. Dunno about you guys but rarley does working on anything go as smoothly as I'd like.

tlrid3r wrote

Ask mentioned above it does work. With the BAV auto tool is
much better. I was able to do 1 arm this way but my tool was not as strong so I removed the arms.

Yes I hear yah. I struggled with my tool. Didnt feel like buying again.

Interesting, I'm the opposite and looking to go stiffer in the rear. It is harsher but softer imo.

First track day with these installed, with generally the same alignment I ran prior. On HC'd AD08R, there'd be way more wheel work involved. Sometimes this short video helps people understand the changes.
It also reduces the OE diff contribution/impact. I personally don't like it's a) slowness b) variable nature which often results in way too much lockup; at least with this wheelbase and tq.

gmx wrote

Interesting, I'm the opposite and looking to go stiffer in the rear. It is harsher but softer imo.

First track day with these installed, with generally the same alignment I ran prior. On HC'd AD08R, there'd be way more wheel work involved. Sometimes this short video helps people understand the changes.

It also reduces the OE diff contribution/impact. I personally don't like it's a) slowness b) variable nature which often results in way too much lockup; at least with this wheelbase and tq.

So you're seeing less overall grip from the rear spherical conversion?

But the M3 OE diff is slow and sudden lockup. It does nothing for quite a while as you start to go sideways. Then suddenly it wakes up and applies full lock which violently puts the tail back in line. Perhaps the sphericals just made this character seem more obvious?

That's exactly my point. With the sphericals I don't get as much abrupt lockup which is way more brutal in the E82/N54 combo. But the brutality is still there if I want it at the demand of my right foot.

I have way more response, precision culminating to confidence to exploit available grip. That video has a tyre set on their/beyond their last legs; HC'd = heatcycled. It'd be way more sideways, engaging way more lockup without the sphericals. It shows the control I have even with a garbage set of tyres in an oversteer situation. Basically on a low grip track, low grip tyre - I still have confidence. Does that make it any clearer for you?

It makes sense that switching from the rubber bushings to spherical bearings would reduce the effective spring rate a bit, since the rubber bushings require torque to twist from the neutral (at ride height) position, which increases with more deflection.

Bartledoo wrote

It makes sense that switching from the rubber bushings to spherical bearings would reduce the effective spring rate a bit, since the rubber bushings require torque to twist from the neutral (at ride height) position, which increases with more deflection.

Yes, in contrast to Redd it's definitely softer for me but I've foreseen this and compensated for now with a softer front spring till I figure out what height/perch etc spring I need to up the rear to 900~
The "stiffness" may just be NVH transmission perceived as wheel rate. Anyway I chose not to initially comment on this and here I am.

gmx wrote

The "stiffness" may just be NVH transmission perceived as wheel rate. Anyway I chose not to initially comment on this and here I am.

Yes that's certainly possible. But I do note less compression travel and that's not indicative of less spring rate.

Redd wrote

Yes that's certainly possible. But I do note less compression travel and that's not indicative of less spring rate.

Yea it's complicated by the fact that some radial deflection of the bushing is occuring as well.

tlrid3r wrote

I think it's mostly your subframe bushing. The insert are marginally better. Just install Delrin ones. Some much better. Help the car feel more planted over all. Plus you have a lot more torque than M3.

That's what I'm thinking too, it's a daily driver with everything being stiff in the back, I hope stiffer subframe bushings won't make it terrible driving around nyc.

thanks redd all the way from malay ren town msia =P

Recently went full spherical in the back along with monoball control arms for the front.

The back feels pretty quiet with no significant change in NVH.

Taking turns at speed the car feels like it has so much grip.

However the front sounds normal unless I hit a dip or bump head on then it's loud, if I take bumps or dips at an angle then I don't hear anything, but head on it's thump.

Does anyone else that did full spherical conversion front and back notice the same with the front?

Yes there's a bit more harshness up front if you go over a sharp bump or pothole. If you drive slowly over the bump you don't feel anything.

Redd wrote

Yes there's a bit more harshness up front if you go over a sharp bump or pothole. If you drive slowly over the bump you don't feel anything.

I figured that’s what it is, if it is I’m fine with it.

I’ll probably retorque things one of these weekends when I do my oil change and inspect the sway bar end links. I bet the sway bar links are probably worn since I have over 100,000 miles on the car and I can feel it more now with the new monoballs.

I need to get this out to the track one of these days to really appreciate the upgrades!!!

Does anyone have any concern with the Spherical not being seated in the center of the arm? I know I’m probably overthinking it but I know my car will hit 1.5+ lateral G’s pretty easily.... I wonder about the stress and how it hits the arm vs the stock bushing that may distribute the load more evenly since it’s housing goes all the way through?

Just a thought, curious if any bad stories out there or input?

Thanks!