Got a track related question? I'll try to answer.

[lutfy]

Originally Posted by finch1750

Figure here is the most likely place anyone has done it.

Looking to refresh my brakes and want to replace the guide pins and bolts. Already have seals. Has anyone found any solid OEM alternatives for the slide pins? Or do I just bite the bullet from Subaru?

Autozone/Duralast has reman front calipers for $127 a pop. Part no: D7085

Comes complete with everthing refreshed/new bits. There is a core charge (refundable).

Lutfy

[Turbo]

Hi Mike-

For mainly track-driven cars, do you have a recommended ride-height? And how do you recommend measuring it?

I was measuring from the fender lip to pavement, but then thought about it and realized the fender lips might not be equally placed with respect to suspension mounting points. Would they be the more relevant reference point?


Also, do you recommend running a "flat" setup? My ride height was set to preserve the 1/4" back-to-front rake the cars come with stock. Thinking this through, though, it likely isn't ideal for a track car and likely increases rear-to-front weight transfer.


In fact, I wondered if this might be one factor relating to your comment earlier in this thread that I'm using my front tires too much.

[redlined600]

^will, at least in part, depend on spring rates

[CSG Mike]

Originally Posted by Turbo

Hi Mike-

For mainly track-driven cars, do you have a recommended ride-height? And how do you recommend measuring it?

I was measuring from the fender lip to pavement, but then thought about it and realized the fender lips might not be equally placed with respect to suspension mounting points. Would they be the more relevant reference point?


Also, do you recommend running a "flat" setup? My ride height was set to preserve the 1/4" back-to-front rake the cars come with stock. Thinking this through, though, it likely isn't ideal for a track car and likely increases rear-to-front weight transfer.


In fact, I wondered if this might be one factor relating to your comment earlier in this thread that I'm using my front tires too much.

It's dependent on your suspension setup, and handling preference.

[Turbo]

Originally Posted by CSG Mike

It's dependent on your suspension setup, and handling preference.

Thanks, Mike.


Suspension setup right now is HKS Hipermax IV SP (track) coilovers - 8K springs front & rear.

Hotchkis sway bars front & rear. Since I installed the bars, I've backed the dampers off 2 clicks front & rear (from 25/23 out of 30 clicks to 23/21).


As for handling preference I'm looking for neutral balance. Something I can steer with my right foot, but not something that requires corrective lock. After softening the dampers I have noticed when the rear end slides or gets loose it seems more progressive/controllable. Before, it felt like it was on more of a knife edge.

Does that help?


I also have installed a pretty aggressive brake system up front - 13" x 1.25" 2pc rotors with 6 piston calipers and new HP+ pads. Brake bias calculates about 1% further forward then stock. This also made me think the 1/4" back-to-front rake I'm running isn't ideal, as it will transfer weight forward quicker, won't it? And the natural question on this is if I am eliminating it, am I raising the front or dropping the rear.

[CSG Mike]

Originally Posted by Turbo

Thanks, Mike.


Suspension setup right now is HKS Hipermax IV SP (track) coilovers - 8K springs front & rear.

Hotchkis sway bars front & rear. Since I installed the bars, I've backed the dampers off 2 clicks front & rear (from 25/23 out of 30 clicks to 23/21).


As for handling preference I'm looking for neutral balance. Something I can steer with my right foot, but not something that requires corrective lock. After softening the dampers I have noticed when the rear end slides or gets loose it seems more progressive/controllable. Before, it felt like it was on more of a knife edge.

Does that help?


I also have installed a pretty aggressive brake system up front - 13" x 1.25" 2pc rotors with 6 piston calipers and new HP+ pads. Brake bias calculates about 1% further forward then stock. This also made me think the 1/4" back-to-front rake I'm running isn't ideal, as it will transfer weight forward quicker, won't it? And the natural question on this is if I am eliminating it, am I raising the front or dropping the rear.

The two in bold are mutually exclusive. If you can throttle steer, you will need to give the car corrective steering at some point.

Softening the dampers to break the rear loose means you're just getting unwanted rotation from a pendulum motion from a underdamped rear.

Try using the front oem sway with the rear hotchkis bar.

Rake will make the car more stable at speed, at the cost of braking stability (which is good in many cases).

[Turbo]

Originally Posted by CSG Mike

The two in bold are mutually exclusive. If you can throttle steer, you will need to give the car corrective steering at some point.

Softening the dampers to break the rear loose means you're just getting unwanted rotation from a pendulum motion from a underdamped rear.

Try using the front oem sway with the rear hotchkis bar.

Rake will make the car more stable at speed, at the cost of braking stability (which is good in many cases).

What I meant was 'more controllable throttle steer'. Corrective steering input is fine, just not if it requires sudden opposite lock.


I wasn't softening the dampers to break the rear end loose - it actually ADDED traction back there. Now that it's softer, what I notice is when it breaks loose I find it more controllable and progressive- it actually allows me to throttle steer more as I'm more confident in controlling it. Before it was more of a knife edge - when it broke loose I frequently had to catch it -fast- with opposite lock.


My rear bar is set on the 2nd softest of 4 settings, and the front bar is set to it's softest setting.

[CSG Mike]

Originally Posted by Turbo

What I meant was 'more controllable throttle steer'. Corrective steering input is fine, just not if it requires sudden opposite lock.


I wasn't softening the dampers to break the rear end loose - it actually ADDED traction back there. Now that it's softer, what I notice is when it breaks loose I find it more controllable and progressive- it actually allows me to throttle steer more as I'm more confident in controlling it. Before it was more of a knife edge - when it broke loose I frequently had to catch it -fast- with opposite lock.


My rear bar is set on the 2nd softest of 4 settings, and the front bar is set to it's softest setting.

I can't help any further without data or video. We don't know why the improvement happened, only that it happened with the adjustment.

[Phantom_9192]

I did a quick search with no results so here's my question.
I'm considering setting the car up for endurance racing but I'm worried about mileage vs other cars in class with much bigger tanks.

What kind of mileage do you see on track in anger? If you can relate it to a specific track that'll help as well (for instance CoTA's very different from Hallett).
The motor would be stock with potentially a tune to bump the power a bit.
Let me know please.
Thanks!

[14stu]

Originally Posted by Phantom_9192

I did a quick search with no results so here's my question.
I'm considering setting the car up for endurance racing but I'm worried about mileage vs other cars in class with much bigger tanks.

What kind of mileage do you see on track in anger? If you can relate it to a specific track that'll help as well (for instance CoTA's very different from Hallett).
The motor would be stock with potentially a tune to bump the power a bit.
Let me know please.
Thanks!

6-8mpg at COTA, TWS, MSR-C, MSR-H, and ECR. The bigger issue is that if you don't have the velox fuel flapper valve long left handers will cause fuel starve as early as half tank (I still get fuel starve under a quarter tank on RS4's with no aero at MSR-C).

[CSG Mike]

Originally Posted by 14stu

6-8mpg at COTA, TWS, MSR-C, MSR-H, and ECR. The bigger issue is that if you don't have the velox fuel flapper valve long left handers will cause fuel starve as early as half tank (I still get fuel starve under a quarter tank on RS4's with no aero at MSR-C).

The flapper does not work. I've experienced starve with it as high as 7/8 of a tank (ethanol, FI).

[CSG Mike]

Originally Posted by Phantom_9192

I did a quick search with no results so here's my question.
I'm considering setting the car up for endurance racing but I'm worried about mileage vs other cars in class with much bigger tanks.

What kind of mileage do you see on track in anger? If you can relate it to a specific track that'll help as well (for instance CoTA's very different from Hallett).
The motor would be stock with potentially a tune to bump the power a bit.
Let me know please.
Thanks!

MPG can be significantly altered with an enduro racing tune, where you value economy and overall average pace over outright speed. It would really depend on your pit strategy and specific event, as to where this balance is, but I can get you set up with a tune that has on-the-fly changable maps that run different mixtures and outputs so the driver and/or crew chief can make the call on the go.

[kch]

Originally Posted by 14stu

6-8mpg at COTA, TWS, MSR-C, MSR-H, and ECR. The bigger issue is that if you don't have the velox fuel flapper valve long left handers will cause fuel starve as early as half tank (I still get fuel starve under a quarter tank on RS4's with no aero at MSR-C).

That back straight at TWS was the site of many failed PR attempts due to the post 5-6 fuel starve

[nico_rsx]

Originally Posted by CSG Mike

The flapper does not work. I've experienced starve with it as high as 7/8 of a tank (ethanol, FI).

OP is talking stock with a tune, not FI.