Ohlins Road & Track setup discussion

[Mrfurious214]

So I finally got myself coilovers and I’m about to hit the track (NJMP Lightning) on Monday. Can’t wait! I’m in a 2015 F80 Manual with Ohlins R&T, Vorshalg Camber Plates, SPL Endlinks, Fall Line Monoballs, Hankook RS4’s. Not tuned.

I’m a little disappointed at how little info their is in the seatches I’ve done for good data/info on setting up the F8X with these coilovers. Everything I see is very basic stuff like “for track days I make it stiffer” lol.

I’m a big sim guy on iRacing and setup discussions are a hige part of that for me. i’ve spent countless hours making sets and tweaking things so I have a relatively good understanding of things from that perspective (of course I know IRL is different but the fundamentals are still there). So I was shocked to see such little discussion around track setups. Seems like most of the talk is around how to get an aesthetic fitment to eliminate wheel gap. I get it and I also want my car to look good…but if you’re buying coilovers imo there should at least be a half desire to actually help the car perform it best. My 2 cents anyway.

So I’m hoping anyone with experience and actual facts/data/info can share what yoo’ve learned about this kit and how to best set it up for optimal traction. I understand that will be different track to track and depending on your car (tuned, other mods, etc) but I still think there can be some useful info that I can consider.

So lets hear it! And please try to provide more than just “I run 2 all around and that seems to work well” type responses. I’m looking for anyone that has compared multiple stiffness settings and what they felt change on the car dynamics AND whether that impacted laptimes/tire wear/etc.

[Theruleslawyer]

Most of the people who would be that thorough buy more hardcore suspensions.

With a near identical setup I ran 6 clicks all around. Typically 34/35 hot pressures. I started at 4 and softened it a bit. I could feel the car skip a bit on rougher surfaces. 4 is where id start on really smooth track 6 for rougher ones. I didn’t feel the need to balance f/r with 275 square. In autocross i have 275/295 and i might play with softening the front a click or two.

[FaRKle!]

Originally Posted by Mrfurious214

So I finally got myself coilovers and I’m about to hit the track (NJMP Lightning) on Monday. Can’t wait! I’m in a 2015 F80 Manual with Ohlins R&T, Vorshalg Camber Plates, SPL Endlinks, Fall Line Monoballs, Hankook RS4’s. Not tuned.

I’m a little disappointed at how little info their is in the seatches I’ve done for good data/info on setting up the F8X with these coilovers. Everything I see is very basic stuff like “for track days I make it stiffer” lol.

I’m a big sim guy on iRacing and setup discussions are a hige part of that for me. i’ve spent countless hours making sets and tweaking things so I have a relatively good understanding of things from that perspective (of course I know IRL is different but the fundamentals are still there). So I was shocked to see such little discussion around track setups. Seems like most of the talk is around how to get an aesthetic fitment to eliminate wheel gap. I get it and I also want my car to look good…but if you’re buying coilovers imo there should at least be a half desire to actually help the car perform it best. My 2 cents anyway.

So I’m hoping anyone with experience and actual facts/data/info can share what yoo’ve learned about this kit and how to best set it up for optimal traction. I understand that will be different track to track and depending on your car (tuned, other mods, etc) but I still think there can be some useful info that I can consider.

So lets hear it! And please try to provide more than just “I run 2 all around and that seems to work well” type responses. I’m looking for anyone that has compared multiple stiffness settings and what they felt change on the car dynamics AND whether that impacted laptimes/tire wear/etc.

Have you seen my videos on them? Which spring rates do you have?

Originally Posted by Theruleslawyer

Most of the people who would be that thorough buy more hardcore suspensions.

With a near identical setup I ran 6 clicks all around. Typically 34/35 hot pressures. I started at 4 and softened it a bit. I could feel the car skip a bit on rougher surfaces. 4 is where id start on really smooth track 6 for rougher ones. I didn’t feel the need to balance f/r with 275 square. In autocross i have 275/295 and i might play with softening the front a click or two.

6R is pretty overdamped and probably causing your skipping.

[Theruleslawyer]

Originally Posted by FaRKle!

6R is pretty overdamped and probably causing your skipping.

4 was skipping. 6 feels okay. Im at 10 now just for street use and it feels pretty loose. I can’t imagine going softer.

[FaRKle!]

Originally Posted by Theruleslawyer

4 was skipping. 6 feels okay. Im at 10 now just for street use and it feels pretty loose. I can’t imagine going softer.

If you take a look at the damper dyno I've taken of the R&T, and were to model the damping ratios, you'd see how overdamping happens around the 11 mark with the 190N/mm spring.

That said, you almost kind of have to run overdamped (to reduce rear grip) in the rear to help the R&T rotate... Or go to skinnier rear tires.

[Theruleslawyer]

Originally Posted by FaRKle!

If you take a look at the damper dyno I've taken of the R&T, and were to model the damping ratios, you'd see how overdamping happens around the 11 mark with the 190N/mm spring.

That said, you almost kind of have to run overdamped (to reduce rear grip) in the rear to help the R&T rotate... Or go to skinnier rear tires.

Yah I’ve watched the video. You say the dampening is too much but never really get to the why. Or I missed it.

If I'm doing the math right doubling of spring rate needs about 41% more damping force for the same damping ratio. In the low speed regime 2 looks too much, 10 not enough. Even then what you are trying to achieve varies what damping ratio you want. Id venture that we want a higher damping ratio than bmw did from the factory for competitive driving.

If someone wants to follow along with the math, this is the best source I found.
https://www.chassissim.com/wp-conten...ork_book-1.pdf

[FaRKle!]

Originally Posted by Theruleslawyer

Yah I’ve watched the video. You say the dampening is too much but never really get to the why. Or I missed it.

If I'm doing the math right doubling of spring rate needs about 41% more damping force for the same damping ratio. In the low speed regime 2 looks too much, 10 not enough. Even then what you are trying to achieve varies what damping ratio you want. Id venture that we want a higher damping ratio than bmw did from the factory for competitive driving.

If someone wants to follow along with the math, this is the best source I found.
https://www.chassissim.com/wp-conten...ork_book-1.pdf

You're right I don't say "why," in that video because the definition of over/critically/under damped are standards. Overdamped is overconstraining the movement rate such that it returns to normal slower than it could. Underdamped is allowing fast suspension movement, but also over and undershoot leading to a long settling time, and critically damped is allowing the fastest return to normal/steady state without gross over/undershoot. Generally critical damping is in the 0.6-0.7 damping factor range.

I agree with you that you also don't necessarily want the same damping ratio in the various damper velocity regimes, but for the low and mid-speed regions I generally want to see in the critical damping range (high speed I want to see lower, like in the 0.25-0.4 range).

Most dampers are too rebound biased too IMO. R&T fall into this category.

[Mrfurious214]

Originally Posted by FaRKle!

6R is pretty overdamped and probably causing your skipping.

Just watched it! Don’t how I didn’t find that initially but thank you!!!

I have 90/190Nm springs. 275/295 tires. I left the ride heights at Ohlins recommended spec and I have my track alignment being done tomorrow.

Any recommendation on where I shoukd start my damper settings for Mondays track day? I’ll be at NJMP Lightning.

I see you posted 6F, 13R a couple months ago on your YT vid but I’m not sure which springs rates you have.

Thanks again!

[FaRKle!]

Originally Posted by Mrfurious214

Just watched it! Don’t how I didn’t find that initially but thank you!!!

I have 90/190Nm springs. 275/295 tires. I left the ride heights at Ohlins recommended spec and I have my track alignment being done tomorrow.

Any recommendation on where I shoukd start my damper settings for Mondays track day? I’ll be at NJMP Lightning.

I see you posted 6F, 13R a couple months ago on your YT vid but I’m not sure which springs rates you have.

Thanks again!

With a staggered tire setup and at critically damped settings for 90/190 springs, the Ohlins will have pretty bad understeer. The rear axle has too much grip relative to the front and you need to try and balance that out (narrower tire, bigger sway bar, or overdamp the dampers).

I've settled on 5F/13R for critically damped settings with 90/190 springs (6F/15R allows some pitching), so you'll probably want to run your rear in the 6-9 range.

[Mrfurious214]

Originally Posted by FaRKle!

With a staggered tire setup and at critically damped settings for 90/190 springs, the Ohlins will have pretty bad understeer. The rear axle has too much grip relative to the front and you need to try and balance that out (narrower tire, bigger sway bar, or overdamp the dampers).

I've settled on 5F/13R for critically damped settings with 90/190 springs (6F/15R allows some pitching), so you'll probably want to run your rear in the 6-9 range.

Good to know. So the front is ok to start at 5?

I’ll mess with rear throughout the day to see if its better to overdamp the rear and accept less grip or to keep it critically damped all around and try to trailbrake more to overcome the understeer.

Also, to deal with the understeer could I just increase rake by changing ride heights on the Ohlins? I won’t have time to change heights at this point so this would have to be for next season.

[Theruleslawyer]

Originally Posted by Mrfurious214

Good to know. So the front is ok to start at 5?

I’ll mess with rear throughout the day to see if its better to overdamp the rear and accept less grip or to keep it critically damped all around and try to trailbrake more to overcome the understeer.

Also, to deal with the understeer could I just increase rake by changing ride heights on the Ohlins? I won’t have time to change heights at this point so this would have to be for next season.

Lots of ways to address it. Tire pressures, rear bar, alignment. If bars wouldn’t change my class id probably do macro adjustment there.

[FaRKle!]

Originally Posted by Mrfurious214

Good to know. So the front is ok to start at 5?

I’ll mess with rear throughout the day to see if its better to overdamp the rear and accept less grip or to keep it critically damped all around and try to trailbrake more to overcome the understeer.

Also, to deal with the understeer could I just increase rake by changing ride heights on the Ohlins? I won’t have time to change heights at this point so this would have to be for next season.

Yes 5 is totally fine to run in front and isn't way overdamped like the "click number" might seem.

You can try to add significant rake to the car, but might need quite a bit. I'm running some forward rake, but it isn't curing the natural understeer.

I'm kind of torn whether I want to just toss the 230N/mm rear spring (already own) on next to put me into flat ride, or change both F/R springs to 350lbs/in F and 950lbs/in R for more comfort and flat ride (would need to buy both sets of springs).

[jbalabas]

I've got a full season of dual duy with 10 track days in the mix. I've settled on 5 clicks from full close on F & R. Works great at the track and I even tolerate it on street.

[Mrfurious214]

My first track day with these was “interesting” to say the least. I started with 5 front, 8 rear I think. I’m a heavy trailbraker and the rear was too unstable for me. So I kept increasing softness in the rear until I got to 15. I was still not thrilled but I felt better. It could’ve also been me getting used to the new coilovers though. I’ll have to wait until next year to test further. I was disappointed that I didn’t have an immediate great experience :-( but I also understand that changing the suspension takes some getting used to.

[Theruleslawyer]

Originally Posted by Mrfurious214

My first track day with these was “interesting” to say the least. I started with 5 front, 8 rear I think. I’m a heavy trailbraker and the rear was too unstable for me. So I kept increasing softness in the rear until I got to 15. I was still not thrilled but I felt better. It could’ve also been me getting used to the new coilovers though. I’ll have to wait until next year to test further. I was disappointed that I didn’t have an immediate great experience :-( but I also understand that changing the suspension takes some getting used to.

At Road America my rear end really wanted to dance. Most tracks were fine, but it is something i need to settle down. I was running 6/6

[Mrfurious214]

I def admit my issues could easily be me because it was only under trailbraking that i had issue. Mid corner and corner exit were not problems at all. As the day progressed I was getting better about releasing brake pressure earlier and thats when I started to feel more comfortable.

[jbalabas]

FaRKle! have you ever had the TTX on a dyno and compared to R&T??? Besides the obvious difference in external adjust on the 2 sets I'd be curious to see the difference in the damping curve.

[Mrfurious214]

What ride heights is recommended front/rear? For street purposes I have no wheel gap to give a flush look but my tires lift off the ground very easily when on uneven surfaces which is obviously not good for tracking. Is there a go to spec?

[Mrfurious214]

FaRKle! hoping you see this

[M3SQRD]

Originally Posted by Mrfurious214

What ride heights is recommended front/rear? For street purposes I have no wheel gap to give a flush look but my tires lift off the ground very easily when on uneven surfaces which is obviously not good for tracking. Is there a go to spec?

Do you have significant forward rake? Bimmerworld recommends 3/8-1/2” of rack measured at the center of the rectangular jack pads. This will get you close to a corner balanced car but cross weight adjustments are still needed.

Are you adjusting ride height per the R&T manual? Did you set the ride heights based on the manual? How much lower are you now vs. R&T recommended ride heights? If your tire is lifting off the ground then you’re exceeding droop travel at one or more corners which I find odd on a R&T damper. I’d recommend the max lowering to be ~1/2” F and 3/4” R relative to the R&T ride heights (or set the rear and then set the front using the 3/8” rake measured from the F and R jack pads).

[Mrfurious214]

Originally Posted by M3SQRD

Do you have significant forward rake? Bimmerworld recommends 3/8-1/2” of rack measured at the center of the rectangular jack pads. This will get you close to a corner balanced car but cross weight adjustments are still needed.

Are you adjusting ride height per the R&T manual? Did you set the ride heights based on the manual? How much lower are you now vs. R&T recommended ride heights? If your tire is lifting off the ground then you’re exceeding droop travel at one or more corners which I find odd on a R&T damper. I’d recommend the max lowering to be ~1/2” F and 3/4” R relative to the R&T ride heights (or set the rear and then set the front using the 3/8” rake measured from the F and R jack pads).

I’m not sure what my measurements are currently but there is zero wheel gap so I’m pretty low. Def lower than I assume I shoukd be for tracking. I guess going with the R&T recommended heights is the best solution unless someone has data to prove otherwise.

[M3SQRD]

Originally Posted by Mrfurious214

I’m not sure what my measurements are currently but there is zero wheel gap so I’m pretty low. Def lower than I assume I shoukd be for tracking. I guess going with the R&T recommended heights is the best solution unless someone has data to prove otherwise.

Yeah, zero wheel gap is definitely low. This ride height setup results in extreme forward rake which can impact steady-state handling (i.e., no damper piston rod-damper body relative velocity so no damping force). I’d recommend running Ohlins baseline ride height. You’re safe running ride heights that are an additional 10 mm lower than the Ohlins baseline. With more track time, you can fine tune the ride heights. However, as I stated previously, you could also try running the BimmerWorld forward rake based on the center of the front jack pad sitting 3/8-1/2” lower than the center of the rear jack pad. This results in a baseline that’s close to a corner balanced car (cross weights will be off a bit but it’s a good starting point). I used 3/8” on my car and the cross weight adjustments were 1/4 turn off.

What are your current damper settings for the 90/190 N/mm spring rates?