[Watsey]

Originally Posted by FaRKle!

It's coming from the subframe bushings. The diff is mounted to the subframe, so even if more vibration were coming from that, it'd still have to go through the subframe bushings into the unibody.

You can see my video below I experienced a significant degradation in ride quality after installing Powerflex subframe bushing inserts (I ended up taking them out because of it). Jump to 6:14 for driving impressions.

Hi FaRKle! I haven't watched your video yet (but will do later), but the shop that does all my suspension and geo work gave me one recommendation when I mentioned rear sub-frame inserts : "don't do it".

I'd expect them to make a difference in terms of body control and more consistent handling, but their experience (and yours) is that the NVH is too high a price to pay in that application.

[DasF30]

Originally Posted by johnung

You can't install M3/M4 upper control arms if you have an xDrive because it will break your front right driveshaft. If you install them on your F30 be aware that the arms are different lengths than F30 so alignment is critical.

I researched the same things recently. Poly or any bushing more solid than stock will introduce NVH- Noise, Vibration, Harshness.

Monoball is the way to go. I installed VAC Motorsports monoball thrust arms. Remember that this enhances STEERING under acceleration and braking. (For handing, upgrade your sway bars to get rid of body roll) Steering with the VAC monoball thrust arms is very precise without NVH. There is more road feel transmitted through the steering wheel but I wouldn't call it NVH.

VAC installs there monoballs into brand new Lemforder thrust arms so you also get new arms and ball joints. Last time I checked BAC didn't have all the info on their website so order them by calling with the correct BMW/Lemforder part numbers. See my diagrams for xDrive and RWD cars.

Hope this helps!

Mine is a RWD so that is good. After going through the thread, I think the monoballs is a very good upgrade for those who think the steering on the F30 feels lifeless (which I do).

Are you also planning to do monoballs on your LCA/wishbone as well or is the current setup with the UCA/thrust arm monoballs good enough? Thanks in advance

Originally Posted by brigade24

In front, I prefer the term crisp instead of harsh...There's more steering feel but I did not get the impressions it was harsh in the front.

Going delrin in the rear is harsh...period. I mean i love it because the car feels more instant. there is barely any delay in transitions, on-power or off-power transfers. I will say this, despite the harshness...going delrin in the rear has made my car come alive.

Thanks you! I was having a hard time finding reviews on rear solid subframe bushings but seeing now that it works, I might consider it after doing the control arm bushings. How long have you had them on and did you get used to the extra vibration?

[BMW DIY Guy]

Well done man.. I have a full suspension thread going too using these same inserts. I also did the differential as well.

[exE36M3]

CAUTION: You REALLY want to drive a car with the Monoball FIRST if you can.
The harshness IS THERE. I mean you WILL love how incredibly crisp turn-in is and the overall feeling when the car corners. But it is a noticeably different ride quality.

For instance...
STOCK CONTROL ARMS: Hit a pothole. Thump.
MONOBALL: Hit a pothole. BANG!!!

If you daily drive really bad roads the monoball solution is about the only time I wouldn't recommend it.

I come from Miatas, E36 M3 and the BRZ... so harsh road transitions aren't that shocking to me. But every person has a different preference and tolerance level.
I'm running the Turner Monoball. And yes, I love it.

[Jvac]

Originally Posted by DasF30

Mine is a RWD so that is good. After going through the thread, I think the monoballs is a very good upgrade for those who think the steering on the F30 feels lifeless (which I do).

Are you also planning to do monoballs on your LCA/wishbone as well or is the current setup with the UCA/thrust arm monoballs good enough? Thanks in advance

Thanks you! I was having a hard time finding reviews on rear solid subframe bushings but seeing now that it works, I might consider it after doing the control arm bushings. How long have you had them on and did you get used to the extra vibration?

Interesting to hear one man's opinion vs others. I came across some talk about solid rear subframe mounts or inserts in the f30 track/race/autox subforum (and the f80 series forum) and those guys generally noted an improvement in rear end stiffness and control with minimal nvh increase. I even talked to a couple of guys via PM about their mods and they didn't regret upgrading their rear subframe mounts. One guy said the biggest change in nvh of all his mods came from the monoball on the front tension strut, not the solid rear subframe mounts. I think one thing to remember here is that the opinions given in the forums are somewhat subjective. Road conditions vary around the country and so do the drivers' backgrounds. One guy's idea of comfy might seem harsh to the next guy and vice versa.

[FaRKle!]

Originally Posted by Watsey

Hi FaRKle! I haven't watched your video yet (but will do later), but the shop that does all my suspension and geo work gave me one recommendation when I mentioned rear sub-frame inserts : "don't do it".

I'd expect them to make a difference in terms of body control and more consistent handling, but their experience (and yours) is that the NVH is too high a price to pay in that application.

I agree with your shop. I ran these inserts with the whole thing installed and with just the tops installed. The ride was noticeably worse in all conditions with the full thing installed. With just the tops it was pretty tolerable, and only really more harsh with higher velocity bumps, but with either configuration with the inserts, I didn't feel the chassis was any more composed than without them, and without the inserts all together the chassis is more composed and smooth IMO.

Part of me wonders if the differences in opinions is due to the extra bracing the F31/33/34/36 has over the F30/32. In addition to the bracing going from the center stiffening plate to the forward rear subframe mounts, they also have a brace going from the sides (just under the rear passenger seat) to a central point below the trunk.

[johnung]

Originally Posted by Jvac

Interesting to hear one man's opinion vs others. I came across some talk about solid rear subframe mounts or inserts in the f30 track/race/autox subforum (and the f80 series forum) and those guys generally noted an improvement in rear end stiffness and control with minimal nvh increase. I even talked to a couple of guys via PM about their mods and they didn't regret upgrading their rear subframe mounts. One guy said the biggest change in nvh of all his mods came from the monoball on the front tension strut, not the solid rear subframe mounts. I think one thing to remember here is that the opinions given in the forums are somewhat subjective. Road conditions vary around the country and so do the drivers' backgrounds. One guy's idea of comfy might seem harsh to the next guy and vice versa.

FYI- I based my opinion on conversations that I had with the BMW tech who did most of my suspension work. I've got a F30 335ix. He told me flat out that if I changed out the rear rubber bushings that I would add harshness to the rear suspension. Now at the time I was talking about materials like poly bushings. Maybe rear monoballs may be a different story. They may not have been available at that time. I'm not tracking the car so that isn't something that I'm considering. Hope this helps!

[johnung]

Originally Posted by DasF30

Mine is a RWD so that is good. After going through the thread, I think the monoballs is a very good upgrade for those who think the steering on the F30 feels lifeless (which I do).

Are you also planning to do monoballs on your LCA/wishbone as well or is the current setup with the UCA/thrust arm monoballs good enough? Thanks in advance

Thanks you! I was having a hard time finding reviews on rear solid subframe bushings but seeing now that it works, I might consider it after doing the control arm bushings. How long have you had them on and did you get used to the extra vibration?

To answer your question, I am not planning to do monoballs in my wishbone/lower control arms. My top goal was to improve steering which is primarily controlled by the thrust arms/upper control arms. I am very happy with the results.

I do know someone who replaced both sets of front control arms with VAC monoballs but I haven't had a chance to discuss with him in detail. I already spent $549 plus labor for the thrust arm monoballs. Right now I don't see a benefit in doubling that to also do the wishbones with monoballs.

I read the post about harshness with the Turner monoballs. Honestly my VAC monoballs aren't displaying any of that. I know that all monoballs are not the same. "Monoball" is a description of the generic design but each manufacturer implements that design in their own way. It doesn't surprise me that descriptions that guys post about how their front monoball thrust arms drive can sound a bit different. From the photos that I have seen that do not look the same.
Hope this helps!

[andino]

Originally Posted by DasF30

Are you also planning to do monoballs on your LCA/wishbone as well or is the current setup with the UCA/thrust arm monoballs good enough? Thanks in advance

I have monoballs in both my LCA and tension struts. I don't find it too harsh for daily driving. Tension strut bushing will give you the most bang for the buck but the LCA monoball will give you just that extra edge of crispness in steering.

I'm running KMAC adjustable caster monoballs in my tension strut and VAC monoballs in my LCA.

Farkie is running a similar setup but with the difference being he has KMAC adjustable camber poly bushings in his LCA. When driving our cars back to back, my car has just an edge in response over his but his car is very quick to respond as well. If you're looking to add camber, I'd recommend the KMAC LCA bushing but since I also run camber plates, I opted for VAC's LCA bushing to replace my powerflex poly bushing. Why is shown in the video that Farkie made on the LCA installation video.

[Polo08816]

Originally Posted by FaRKle!

It's coming from the subframe bushings. The diff is mounted to the subframe, so even if more vibration were coming from that, it'd still have to go through the subframe bushings into the unibody.

You can see my video below I experienced a significant degradation in ride quality after installing Powerflex subframe bushing inserts (I ended up taking them out because of it). Jump to 6:14 for driving impressions.

Originally Posted by Watsey

Hi FaRKle! I haven't watched your video yet (but will do later), but the shop that does all my suspension and geo work gave me one recommendation when I mentioned rear sub-frame inserts : "don't do it".

I'd expect them to make a difference in terms of body control and more consistent handling, but their experience (and yours) is that the NVH is too high a price to pay in that application.

I've never really liked the idea of "inserts". I've heard that a complete bushing replacement is the way to go:

https://www.bimmerworld.com/Suspensi...shing-Set.html

My understanding is that F8X M3/M4s basically have solid bushings or a solid connection between the chassis and rear subframe unlike the F3X series.

[brigade24]

Originally Posted by Polo08816

Is the harshness coming from diff bushings or rear subframe to chassis bushings?

it is coming from the rear subframe bushings. That's whats bolted to the frame...

[brigade24]

Originally Posted by DasF30

Thanks you! I was having a hard time finding reviews on rear solid subframe bushings but seeing now that it works, I might consider it after doing the control arm bushings. How long have you had them on and did you get used to the extra vibration?

I have been running delrin bushings in the rear for around a year now. Yes i did get extra vibration but its not substantial imo. I dial some of it out with the dampers but it is still there.