TRev's BRZ RTR Autocross Build

[qoncept]

Sweet, thanks guys. Sorry to hijack the thread but one (two) other question..

How important is the OBD-II data? Will it work with my Elm BT thing I got for Torque?

[TRev]

Originally Posted by qoncept

Sweet, thanks guys. Sorry to hijack the thread but one (two) other question..

How important is the OBD-II data? Will it work with my Elm BT thing I got for Torque?

No worries about hijacking this thread.

I like the data so I can see where it may make sense to shift to 1st/3rd. It also is good for showing how much speed is being carried through a sweeper, slalom, how long I am on the limiter, etc. The BT you have should work.

[TRev]

Here is a vid from the last Milwaukee event. I was getting towards the far end of firm in the rear on rebound and the car was easy to upset especially in the slaloms.

[ame]http://youtu.be/jo2WgunGYVs[/ame]

I lengthened the end links and backed off the rebound on the shocks at the most recent event (Winona) and had some interesting results which I commented on in the first page results.

Lance switched to STX with his FRS and offered me a good deal (thank you Lance!) on his Enkeis with Z2's so I will be trying out the Dunlops this coming weekend.

[cityhugo]

What does lengthened/shorten the end links do?

[TRev]

Originally Posted by cityhugo

What does lengthened/shorten the end links do?

Lengthening the end links softens the bar and shortening them stiffens the bar.

[xwd]

From most of what I have read over the years, the length of the end link has no real effect on the roll stiffness. Changing the angle of the bar has a negligible effect but without actually moving the connecting point of the endlink on the bar it's really not going to change the swaybar rate a noticeable amount.

It's not until you get the swaybar at an upward angle to the point where you are bending the bar straight up as opposed to twisting the bar. I used to have an old diagram someone did from another forum when discussing the topic and he calculated the angle (not on a BRZ mind you) to be like 45 degrees.

The exception is where your ride heights are different on both sides and you are pre-loading the bar. Technically you really only need an adjustable endlink on one side of the car to eliminate pre-load and lots of road racers just use one link.

[cityhugo]

thats what I though is the angle and not the length, TRev, did u feel the bar to be softer after the length change? pic of how it is mounted now? did it also change the timing of the bar of when it comes into affect?

[TRev]

Originally Posted by cityhugo

thats what I though is the angle and not the length, TRev, did u feel the bar to be softer after the length change? pic of how it is mounted now? did it also change the timing of the bar of when it comes into affect?

Sorry, my wording was not very good. My understanding is the angle has an effect on how stiff the bar "appears" to be. I didn't take pictures of before and after. It definitely seemed to remove some of the push I was experiencing in the sweepers mid corner. From what I have read, the angle of the bar relative to the mounts is most effective when level so wouldn't the end links being longer change the angle and make the bar less effective? I didn't notice a change in timing of the bar coming into affect but maybe that was the difference I was feeling? Relative to some other regulars that were at the last event, my times improved as well.

It did surprise me that the car was as fast at full soft rebound front and rear with some damp spots on the track as it was at 1 1/2 turns from full soft front and rear with a completely dry course. Has me thinking that I have been a bit too aggressive with the rebound settings I have been using.

[rx3]

Originally Posted by TRev

From what I have read, the angle of the bar relative to the mounts is most effective when level so wouldn't the end links being longer change the angle and make the bar less effective?

Yes, since the same Δ_distance would slightly lead to less Δ_angle (less swaybar torsion).
But I also think that this effect is negligible compared to moving the connection point of the endlink on the bar as dwx said.

Originally Posted by TRev

Whiteline 20mm Front sway bar w/adjustable end links - Soft setting w/end links @ shortest length possible

I'm confused by this sentence as the shortest length possible would lead to the hardest setting. Or what do you mean exactly?
http://www.whiteline.com.au/docs/bulletins/BL-281.pdf

[cityhugo]

if u r exp less push once the car is set, bar rate is softer...interested to see urs end link angles

[TRev]

Originally Posted by rx3

Yes, since the same Δ_distance would slightly lead to less Δ_angle (less swaybar torsion).
But I also think that this effect is negligible compared to moving the connection point of the endlink on the bar as dwx said.

I'm confused by this sentence as the shortest length possible would lead to the hardest setting. Or what do you mean exactly?
http://www.whiteline.com.au/docs/bulletins/BL-281.pdf

Agreed that there is less effect versus moving the endlink on the bar though my endlinks are already in the "soft" hole setting as depicted in the diagram you linked. The car only had a slight push on mid-corner on sweepers. The end links themselves were previously at their shortest length possible. I lengthened them about one inch.

Originally Posted by cityhugo

if u r exp less push once the car is set, bar rate is softer...interested to see urs end link angles

The car should be set by mid-corner. It was not a huge difference but it was noticeable and feels like it removed nearly all of the slight push I was experiencing.

[autoXracer]

TRev you're doing an excellent job of representing the twins at a National level. I have followed your thread from the start. Thank you for sharing your knowledge and experience.

I finally got to try out my Koni's. I started off at front : 1 1/2 turns from soft, rear : 1 turn from soft. What is a good starting point for adjustment? Also just to make sure, Koni's fronts have a total of 1 3/4 turns and the rears have 2 1/4 turns?

[TRev]

Originally Posted by autoXracer

TRev you're doing an excellent job of representing the twins at a National level. I have followed your thread from the start. Thank you for sharing your knowledge and experience.

I finally got to try out my Koni's. I started off at front : 1 1/2 turns from soft, rear : 1 turn from soft. What is a good starting point for adjustment? Also just to make sure, Koni's fronts have a total of 1 3/4 turns and the rears have 2 1/4 turns?

What tires, front bar, and alignment settings are you using? Also what type of surface and how rough?

I am finding even at events that have smooth, grippy surfaces the softer end of the rebound range seems faster. I would start out at full soft and dial in more rebound from there to get the car to feel the way you want. Once you find a setting that suits your driving style, try increasing rebound equally to see if your times improve.

My Konis have 1 7/8 turns adjustment range front and rear.

[autoXracer]

Originally Posted by TRev

What tires, front bar, and alignment settings are you using? Also what type of surface and how rough?

I am finding even at events that have smooth, grippy surfaces the softer end of the rebound range seems faster. I would start out at full soft and dial in more rebound from there to get the car to feel the way you want. Once you find a setting that suits your driving style, try increasing rebound equally to see if your times improve.

My Konis have 1 7/8 turns adjustment range front and rear.

That's strange... I checked again, my Koni's are front 1 7/8 adjustments, and rear 2 1/4 adjustment.

My setup:
Koni shocks
Strano front sway bar
225 Z1's (yes still have the old tires lol.. next are 225 Z2's)
OEM camber bolts
0 toe front, .24 total toe-in rear

I understand that depending on setup, course condition, and driver, the shock rebound should be adjusted. I'll take your advice and start off with full soft rebound and adjust from there.