Bilstein B16 too stiff ?

[Coyner]

Hi Folks,
I'm new here and sorry if I'm raising an issue covered in the past.

I just bout a 1M coupe which has Bilstein B16 suspension (currently all the damping adjustments are set to mid point), HR roll bars and all round Polybush and while I love the idea of the car I'm bitterly disappointed with the reality which is that it's almost unusable on regular Irish (bumpy and variable) roads because its so stiff!

I have never driven a stock car so can anyone tell me how far from stock in terms of driver comfort / daily usability my car is?

All comments appreciated..

[CarJunkie]

Stock suspension is pretty compliant even in rough roads. I am pretty sure Bilstein B16 is VERY stiff. Is that struts only, or is it a full setup with springs? Regardless of springs, it would be worth softening the dampers to see if it helps.

Are the sway bars adjustable?

[nachob]

Originally Posted by Coyner

Hi Folks,
I'm new here and sorry if I'm raising an issue covered in the past.

I just bout a 1M coupe which has Bilstein B16 suspension (currently all the damping adjustments are set to mid point), HR roll bars and all round Polybush and while I love the idea of the car I'm bitterly disappointed with the reality which is that it's almost unusable on regular Irish (bumpy and variable) roads because its so stiff!

I have never driven a stock car so can anyone tell me how far from stock in terms of driver comfort / daily usability my car is?

All comments appreciated..

After looking into it Bilstein sells the same suspension and for E90 M3 with different weight etc. E90 is much heavier. KW made a 1M specific valving job, but from what I can see Bilstein didn't. It would cost extra money to make bespoke springs and valving so they just sell the E90 M3 stuff to you.

The stock suspension is good but even it is a little stiff sometimes especially in the rear. I recall one of the M engineers saying years later that in retrospect they went too stiff. I would put it back to stock before all the plastic bits inside become a symphony of rattles.

[PRTSB1M]

I've been researching my suspension upgrades since reading this post and definitely agree with nachob, you can see in their spec sheet the ohlins 1M kit has softer rear springs than their E9x M3 kit.

If you don't want to go back to stock, I plan on using the following components:
Ohlins R&T (BMZ MN01)
Ground Control street camber plates
stock sway bars

You might be able to get away with just replacing the springs with something softer, but I've read that the valving will be off on the dampers if you change drastically from the current spring rate. Measure the spring perch, swift should have something that fits. https://www.swiftsprings.com/product...lover-springs/

I'm pretty sure this is a 7" spring.
https://www.m3post.com/forums/showpo...6&postcount=48

[CarJunkie]

Originally Posted by UN1CORM

I've been researching my suspension upgrades since reading this post and definitely agree with nachob, you can see in their spec sheet the ohlins 1M kit has softer rear springs than their E9x M3 kit.

If you don't want to go back to stock, I plan on using the following components:
Ohlins R&T (BMZ MN01)
Ground Control street camber plates
stock sway bars

You might be able to get away with just replacing the springs with something softer, but I've read that the valving will be off on the dampers if you change drastically from the current spring rate. Measure the spring perch, swift should have something that fits. https://www.swiftsprings.com/product...lover-springs/

I'm pretty sure this is a 7" spring.
https://www.m3post.com/forums/showpo...8;postcount=48

Not to go too far off topic, but why ground control? I believe Vorschlag is the only camber plate to use a 3/4" spherical ball mount, which is much more stout than anything else available. Just my 0.02.

[PRTSB1M]

Originally Posted by CarJunkie

Not to go too far off topic, but why ground control? I believe Vorschlag is the only camber plate to use a 3/4" spherical ball mount, which is much more stout than anything else available. Just my 0.02.

I've had good luck with GC in the past and my car will likely remain a street car that sees some track time. I'm sure the vorshlag plates are nice, or they wouldn't have stayed around this long, but I wouldn't call it a "street" plate.

[PRTSB1M]

Looking at another E82 factory setup, the 135i with M-sport has 26.5mm front and 12mm rear sway bars. Which indicates the 1M could be over-sprung in the rear using the much larger 22.5mm rear bar from the E9x M3. UUC also offers a kit for the 135i with a 19mm rear bar. Does anyone know if non-M rear sway will fit the 1M?

[Coyner]

Thanks guys for your feedback which supports my thinking that the |Bilstein B16 setup is just too much for daily driving , especially where I live. It's great on track or smooth roads where the car feels ultra sharp but for my needs I'm thinking stock setup would be best. I don't have the stock suspension anymore but if someone wants to sell a set please PM me.

PS... I've backed the damper clickers right out front and back and its still ultra bumpy. I'm guessing too the short and wide stance makes the car very sensitive to suspension setup.

[drwillb]

Originally Posted by UN1CORM

Looking at another E82 factory setup, the 135i with M-sport has 26.5mm front and 12mm rear sway bars. Which indicates the 1M could be over-sprung in the rear using the much larger 22.5mm rear bar from the E9x M3. UUC also offers a kit for the 135i with a 19mm rear bar. Does anyone know if non-M rear sway will fit the 1M?

I've got a 135i that had M-sport suspension but now I've converted to full front and rear 1M suspension (actual stock 1m shocks and springs), M3 sway bars front and rear, LSD, subframe, etc. I can tell you that you do not want to go to 135 spec. It's just too soft with excessive understeer. For street driving it's actually quite nice but a little bouncy. Also, the suspension bits were tuned with rock-hard run flat tires in mind.

My 1M spec 135 is fantastic!!

Sounds like the classic "grass is always greener" case but the 1M is still considered one of the best things to come out of Munich in a very long time.

[PRTSB1M]

Originally Posted by drwillb

I've got a 135i that had M-sport suspension but now I've converted to full front and rear 1M suspension (actual stock 1m shocks and springs), M3 sway bars front and rear, LSD, subframe, etc. I can tell you that you do not want to go to 135 spec. It's just too soft with excessive understeer. For street driving it's actually quite nice but a little bouncy. Also, the suspension bits were tuned with rock-hard run flat tires in mind.

My 1M spec 135 is fantastic!!

Sounds like the classic "grass is always greener" case but the 1M is still considered one of the best things to come out of Munich in a very long time.

I've previously owned a 135i w/m-sport, I wasn't saying that using 135i spec bars was something to do on a 1M; just using it for comparison as another suspension setup on the same chassis from BMW engineers. Looking at aftermarket offerings for the non-M e82, the max rear bar is 20mm. Unfortunately, most of these are built for E9x chassis and sold to E8x owners.

Looking at CarJunkie post on geometry and some other reading, I think 1M owners should "upgrade" to the E93 M3 front sway bar and leave rear bar alone. Logic being that the rear is slightly over-sprung from the factory, but increasing front roll stiffness offsets and shifts some grip to the rear. I will try to test while my suspension is still original.

[CarJunkie]

The stiffer front bar adds grip to the rear, so if it is the only change, the car's inherent understeer from the factory would be worse. I run significantly more camber up front, and square tire setup on track, and it is neutral at the limit mid corner with the M3 'vert front bar and stock rear bar.

Also if you like to DIY, keep in mind that changing the rear bar requires dripping the subframe. The front bar is easy to swap.

[PRTSB1M]

Originally Posted by CarJunkie

The stiffer front bar adds grip to the rear, so if it is the only change, the car's inherent understeer from the factory would be worse. I run significantly more camber up front, and square tire setup on track, and it is neutral at the limit mid corner with the M3 'vert front bar and stock rear bar.

Also if you like to DIY, keep in mind that changing the rear bar requires dripping the subframe. The front bar is easy to swap.

I would not be surprised if the E93 M3 bar alone increased understeer; and is likely best paired with square tires to make the car more "neutral". I just think, from my research, that there isn't any better option for the rear bar than stock. My opinion is that adjusting roll stiffness at the rear should be done via means other than the sway bar.

[e82speed]

Bump!
Considering an upgraded autocross or track setup, this helps.