BSP Suspension Baseline
03-10-2014, 08:31 PM
#31
Registered User
Originally Posted by rrthorne8' timestamp='1394488895' post='23055907
[quote name='sproutxj' timestamp='1391778600' post='23003576']
^ I do appreciate the sharing of knowledge for sure.
Do you think I will need to be concerned about bumpsteer in the rear going as low as suggested? Our big course venue doesn't have the smoothest tarmac.
Sent from my Transformer Prime TF201 using Tapatalk 4
^ I do appreciate the sharing of knowledge for sure.
Do you think I will need to be concerned about bumpsteer in the rear going as low as suggested? Our big course venue doesn't have the smoothest tarmac.
Sent from my Transformer Prime TF201 using Tapatalk 4
After a couple hours on the shock dyno, my recommendations are as follows.
From full stiff on each adjuster. I consider the first detent that engages to be position 0 (standing for 0 clicks from full stiff.)
front rebound -2, compression -5.
rear rebound -4, compression -6.
Front rebound adjustment is very course in this area. I dont think i would recommend moving from this position as the jump up and down one click is double or half the force.
Front compression, again not a ton of wiggle room, only adjusts very low speed compression rates. I would only recommend moving 1 click in either direction depending on how things are feeling, often a click stiffer will find you some mid corner front grip, but will cause a lack of compliance over anything bumpy (lincoln concrete
)Rear rebound, I would start with this adjustment if you want to play with a little transitional balance and on power rear grip (sounds backwards to some but hey its just one guys opinion and i cant control what works
). I wouldn't recommend more then 1 click stiffer or two clicks softer (1 click stiffer is an equal change to two clicks softer as the adjustment is not linear)Rear compression, If your going to venture somewhere, i wouldn't go more then two clicks softer and 1 stiffer
IMO, hope this helps
Rear rebound is one that I've just left alone for the most part.
[/quote]
speaking all strictly on rear rebound.
The settings i gave above contribute to the front shocks putting roughly 2.5 times the rebound force on the shock dyno in relationship to the rears.
Take note that these shocks have virtually the same valving for the front and rear shocks.
To give a basic example on transition. If the rear of the car was loose during transitions side to side, i would remove dampening, or go to a higher number of clicks away from stiff.
This may come as a trade off, as i would normally first go to add rear rebound for power down grip (again i am sure that second part sounds backwards) but generally to achieve transitional stability and pace the rear rebound needs to be very "open", thus throwing off the compression to rebound ratio that our rear end likes creating a general loss of inside tire grip under heavy load situations. So again, increase rear rebound for power-down corner exit, decrease for transition stability.
Rear rebound is one of the most powerful tuning knobs on my specific car, So these explanations are derived from real world experiences explained to me through data and my engineer Will Moody at 3R Automotive
On that note, Will will be my engineer this year on the Mclaren as he has been Randy Pobst's engineer for the past 5 years
03-11-2014, 05:50 AM
#32
Those responses were gold, thanks a ton Robert. 
.
I have also noticed that more front rebound than rear is good for transitional stability but can hurt power down on exit. Being in STR I'm on street tires but otherwise similar to a BSP setup. I don't suppose you plotted the shock dynos of those settings you're recommending on the KW? Curious what they look like.
.I have also noticed that more front rebound than rear is good for transitional stability but can hurt power down on exit. Being in STR I'm on street tires but otherwise similar to a BSP setup. I don't suppose you plotted the shock dynos of those settings you're recommending on the KW? Curious what they look like.
03-12-2014, 04:16 PM
#33
Registered User
Thread Starter
Join Date: Mar 2012
Posts: 63
Likes: 0
Received 0 Likes
on
0 Posts
Hey Robert, you went above and beyond with my request and I'd like to show my appreciation. PM me somewhere I can send you a nice bottle of scotch (or libation of choice) or if you're a skier I will gladly hook you up if you ever want to come to Whitefish, MT.
Brad
Sent from my Transformer Prime TF201 using Tapatalk
Brad
Sent from my Transformer Prime TF201 using Tapatalk
03-19-2014, 06:52 AM
#35
Registered User
I have edited my initial post on front rebound to the following after running the shocks on a customer car.
Front rebound adjustment is very course in this area. I dont think i would recommend moving from this position as the jump up and down one click is double or half the force. With the low front spring rate, you may have no choice but to drop the front rebound 1 click on rough surfaces. If you feel this is needed, i would consider softening the rear rebound 1-2 clicks as well. On street tires, i found that F_Rebound -3 and R_Rebound -5 felt very nice
Front rebound adjustment is very course in this area. I dont think i would recommend moving from this position as the jump up and down one click is double or half the force. With the low front spring rate, you may have no choice but to drop the front rebound 1 click on rough surfaces. If you feel this is needed, i would consider softening the rear rebound 1-2 clicks as well. On street tires, i found that F_Rebound -3 and R_Rebound -5 felt very nice
03-21-2014, 07:32 PM
#36
re: ride heights. The higher the car, the lower the spring rate has to be because the high roll center transfer's rate faster The roll center and CG are closer together. When you lower the car, you also lower the roll center, and more weight is transferred, but it takes longer to happen, so you have to use shocks/springs/bars to get the responsiveness back.
I think I will be raising my car slightly and running a slightly softer setup this season with all of this in mind.
I think I will be raising my car slightly and running a slightly softer setup this season with all of this in mind.
03-22-2014, 06:15 PM
#37
Registered User
Join Date: Jul 2006
Posts: 635
Likes: 0
Received 0 Likes
on
0 Posts
Let me clarify - the distance between the roll center and the cg has a big impact on roll. The farther apart they are, the bigger the impact unless you do something to increase roll stiffness.
I misspoke in my previous post. More weight isn't transferred, what I was trying to explain is that the car just rolls more because the length of the lever is longer with lowered roll centers, and it also takes longer for total roll to occur.
The roll center is determined geometrically, so lowering the cg doesn't really matter if the roll center moves farther away. A longer lever arm will create a bigger roll "force" aka more roll. This is an overly simplified explanation of the relationship between the two.
I misspoke in my previous post. More weight isn't transferred, what I was trying to explain is that the car just rolls more because the length of the lever is longer with lowered roll centers, and it also takes longer for total roll to occur.
The roll center is determined geometrically, so lowering the cg doesn't really matter if the roll center moves farther away. A longer lever arm will create a bigger roll "force" aka more roll. This is an overly simplified explanation of the relationship between the two.
03-27-2014, 02:23 PM
#40
Let me clarify - the distance between the roll center and the cg has a big impact on roll. The farther apart they are, the bigger the impact unless you do something to increase roll stiffness.
I misspoke in my previous post. More weight isn't transferred, what I was trying to explain is that the car just rolls more because the length of the lever is longer with lowered roll centers, and it also takes longer for total roll to occur.
The roll center is determined geometrically, so lowering the cg doesn't really matter if the roll center moves farther away. A longer lever arm will create a bigger roll "force" aka more roll. This is an overly simplified explanation of the relationship between the two.
I misspoke in my previous post. More weight isn't transferred, what I was trying to explain is that the car just rolls more because the length of the lever is longer with lowered roll centers, and it also takes longer for total roll to occur.
The roll center is determined geometrically, so lowering the cg doesn't really matter if the roll center moves farther away. A longer lever arm will create a bigger roll "force" aka more roll. This is an overly simplified explanation of the relationship between the two.
At the moment, we appear to have Robert staying 13/12.5" is good while Marc is saying lower than stock was bad. I know nothing, I just know when I like the car or not. FWIW, my car is 13/12.9" I believe.