Boss 302 Advance Road Race Tire setup thread

[Zquez]

Re: Boss 302 Advance Road Race setup thread

Sub'd

 

[ArizonaBOSS]

Re: Boss 302 Advance Road Race setup thread

Right - we're on the same page.
Jimmy's photos showed that the race teams used the factory position -- they didn't use any of the holes on the relo bracket.
I'll see if I can dig up the thread and bring the photos here.

I recall he even inquired about this with one of the race mechanics, and they essentially looked at him quizzically stating something to the tune of "why would I want to reduce the available grip?"...which spurred a big discussion on our forums here.

EDIT: found the pic:

http://www.jimmypribble.com/blog/wp-content/uploads/2013/08/RLCA_bracket.jpg[/ig]

Taken from thread: https://trackmustangsonline.com/index.php?topic=5902.msg89794#msg89794

So given that info, it only leads me to assume that the race teams must be playing with anti squat via the UCA, and leaving the LCA location more for tuning roll steer rather than anti squat.
[/quote]

Interesting.

 

[VoodooBoss]

Re: Boss 302 Advance Road Race setup thread

I'm running the stock UCA and have my FR LCA's mounted in the middle hole as suggested by FR. I'll have to take a good look at this and maybe try the upper position and see if I get more grip on corner exit.

 

[blacksheep-1]

Re: Boss 302 Advance Road Race setup thread

I was looking at the pic of the setup sheet form Miller, the important part of that is the cold vs the hot pressures, they stayed even all the way up, starting around 22 psi and going up to 31- 33 hot (looking at both sessions) which are within 1 psi of each other, that's pretty darn good. Can someone tell me if counter clock wise at miller is more left or right turns? I've never been there.
Also note that the air temp is 45 degrees the track was 58..pretty cool temps.
One other item is that those Roush cars are notorious for carrying the inside front tire in corners, so they seem to be "squatting" a lot. I'm guessing that everybody is running the softest springs imaginable, and controlling them with shock settings. I'm thinking that they also run 18 mm rear bars (maybe even less or no bar).
Lastly, don't be too afraid of bump stops as long as the car doesn't "hammer" the bumpers, but (sort of ) gently sits on them, They shouldn't be a problem, there are plenty of oval track cars that are designed to run on their bump stops in the corners.
No matter what your suspension setup is, it will show up in the tire pressure/temps this is why they are so critical.

 

[steveespo]

Re: Boss 302 Advance Road Race setup thread

What I find interesting about the tire sheet info IS the hot pressures of 31-32 psi. A lot of us are thinking 39-42 hot even on slick type tires. I have been experimenting with lower cold and hot pressures and found that going down to 36 hot vs 40 hot the car felt like overall grip improved with better mid corner speed. IR tire temps seemed about the same for me after each session, but I have not been faithful in a consistent procedure or documentation as of yet to trend it. I'm glad I started this thread as there is just the kind of info and dialogue I was hoping for here.
Steve

 

[Jimmy Pribble]

Re: Boss 302 Advance Road Race setup thread

Hey fellas, one thing I want to make clear is that not all race teams go without (or don't take advantage/disadvantage of) the relocation brackets. I have seen plenty of cars that use them as expected, including the Kenny Brown (Justin Bell) car for which I posted the setup sheet. Specifically, both Capaldi-prepped WC cars I saw this year had the LCA brackets set in the manner seen in the photo. This fits with what wwilde001 says about his experience with Craig Capaldi setting-up his car. So maybe it is only Capaldi doing this. Maybe that is part of their "secret sauce." We know from his videos that Kenny Brown doesn't like to use rear swaybars and sure enough, the Justin Bell car did not have one. Different teams and engineers have different philosophies about suspension tuning. That is one of the reasons that I expect this thread to be so interesting.

That being said, I like what blacksheep is saying about tire pressures and temps. THAT is where the...rubber meets the road. (D'oh, sorry about that one.) In fact, keep in mind this philosophy - a race car is nothing more than a machine designed to control four rubber tires. I think we can get lost in nerdy discussions about suspension details, geometry, weight, and aerodynamics, when really, we need to start and finish with the same questions - what are the tires doing?

Man, this forum is awesome. I'm glad we hang-out.

 

[Jimmy Pribble]

Re: Boss 302 Advance Road Race setup thread

One other item is that those Roush cars are notorious for carrying the inside front tire in corners, so they seem to be "squatting" a lot. I'm guessing that everybody is running the softest springs imaginable, and controlling them with shock settings. I'm thinking that they also run 18 mm rear bars (maybe even less or no bar).

As you can see, the Roush rear swaybar is smaller in diameter than the end-links. It appears to be no bigger then the thickness of a coil spring.

 

[blacksheep-1]

Re: Boss 302 Advance Road Race setup thread

What I find interesting about the tire sheet info IS the hot pressures of 31-32 psi. A lot of us are thinking 39-42 hot even on slick type tires. I have been experimenting with lower cold and hot pressures and found that going down to 36 hot vs 40 hot the car felt like overall grip improved with better mid corner speed. IR tire temps seemed about the same for me after each session, but I have not been faithful in a consistent procedure or documentation as of yet to trend it. I'm glad I started this thread as there is just the kind of info and dialogue I was hoping for here.
Steve

I think I can answer that ...air temp 45 track temp 58 and the setup sheet shows an "average" of the tire temps, I would wager they are the same pressures as you are seeing at a hotter air/track temp...just sayin'

nudge..nudge

PS: I know one thing, I'm going to make sure you guys with the cameras stay the hell away from our car

 

[ArizonaBOSS]

Re: Boss 302 Advance Road Race setup thread

I dunno where the heck the post I put together went, BUT, I find that R6s and P-Zero slicks are a lot better at 31-32 PSI hot vs. the manufacturer recommended 37-39 PSI hot. If I run them 37-39 hot, they start to go away at the end of a session.

Also the 31-32 PSI gets better tire wear, at least visually.

Blacksheep, your thoughts? You know a lot more about this bit than we do.

 

[ArizonaBOSS]

Re: Boss 302 Advance Road Race setup thread

http://www.jimmypribble.com/blog/wp-content/uploads/2013/09/roush_rearsway.jpg[/im]

As you can see, the Roush rear swaybar is smaller in diameter than the end-links. It appears to be no bigger then the thickness of a coil spring.
[/quote]

Yeah I saw the 61 a few years back at Laguna and I swear that rear bar was like piano wire! :D

 

[blacksheep-1]

Re: Boss 302 Advance Road Race setup thread

I dunno where the heck the post I put together went, BUT, I find that R6s and P-Zero slicks are a lot better at 31-32 PSI hot vs. the manufacturer recommended 37-39 PSI hot. If I run them 37-39 hot, they start to go away at the end of a session.

Also the 31-32 PSI gets better tire wear, at least visually.

Blacksheep, your thoughts? You know a lot more about this bit than we do.

If I were you guys I would take a cold tire, air it up, then put it in the sun and measure the pressure every 15 minutes and graph it up until say 80-90 degrees. air temp. your 31 psi might actually be 37 psi.
Of course it would be more accurate with nitrogen.

 

[ArizonaBOSS]

Re: Boss 302 Advance Road Race setup thread

I bought that (I'm assuming) good Moroso tire pressure gauge btw, not some janky one from a gas station impulse-buy zone

What are you getting at with the sun test? I understand the tire will get hotter and base pressure will rise. What is the takeaway? Not being combative, I just think I'm missing your point.

I make sure each tire is starting at my known "good" cold pressure (typically around 24-26 psi) by bleeding out air before each session.

 

[boro92]

Re: Boss 302 Advance Road Race setup thread

I'm running the stock UCA and have my FR LCA's mounted in the lower hole as suggested by FR. I'll have to take a good look at this and maybe try the middle position and see if I get more grip on corner exit.

I'd becareful with that. Not only would you get more rear steer (via roll steer), but an increase in anti squate means also an increase in rear-end rise under braking. So the back end will get light/squirrely more easily under braking. Apparently though, people are finding more grip when going to spherical LCA's. Has anyone tried that?

 

[Grant 302]

Re: Boss 302 Advance Road Race setup thread

Steve, thanks for creating this thread...great idea. I've been following it from your first post. 8)

I'm running the stock UCA and have my FR LCA's mounted in the lower hole as suggested by FR. I'll have to take a good look at this and maybe try the middle position and see if I get more grip on corner exit.

I thought the middle hole was recommended by FR? More corner exit grip should come from the lower hole, but will be more roll steer loose as boro92 notes below.

I'd becareful with that. Not only would you get more rear steer (via roll steer), but an increase in anti squate means also an increase in rear-end rise under braking. So the back end will get light/squirrely more easily under braking. Apparently though, people are finding more grip when going to spherical LCA's. Has anyone tried that?

I think you have that backwards about rear rise under braking with increased anti squat.

 

[boro92]

Re: Boss 302 Advance Road Race setup thread

Steve, thanks for creating this thread...great idea. I've been following it from your first post. 8)
I thought the middle hole was recommended by FR? More corner exit grip should come from the lower hole, but will be more roll steer loose as boro92 notes below.
I think you have that backwards about rear rise under braking with increased anti squat.

d'oh! Thanks for the correction.

 

[blacksheep-1]

Re: Boss 302 Advance Road Race setup thread

I bought that (I'm assuming) good Moroso tire pressure gauge btw, not some janky one from a gas station impulse-buy zone

What are you getting at with the sun test? I understand the tire will get hotter and base pressure will rise. What is the takeaway? Not being combative, I just think I'm missing your point.

I make sure each tire is starting at my known "good" cold pressure (typically around 24-26 psi) by bleeding out air before each session.

You develop a baseline, as an example the tire has:
24 psi @ 50 degrees air temp
24.5 @ 55
25@ 60....etc

and so on so that no matter what track you go to you now have a starting pressure for that tire at whatever temp the track is at. By bleeding air out of a hot tire. you are making a mistake, when those tires go back to "normal cold" pressure a few hours after the race you will have far less air in the tires than when you started on the original "cold" pressures.

 

[ArizonaBOSS]

Re: Boss 302 Advance Road Race setup thread

You develop a baseline, as an example the tire has:
24 psi @ 50 degrees air temp
24.5 @ 55
25@ 60....etc

and so on so that no matter what track you go to you now have a starting pressure for that tire at whatever temp the track is at. By bleeding air out of a hot tire. you are making a mistake, when those tires go back to "normal cold" pressure a few hours after the race you will have far less air in the tires than when you started on the original "cold" pressures.

Well obviously the tires need to be aired up again the next morning.

OK now I get it w/ the temperature thing I will do that with one of my tires in a couple weeks.

 

[blacksheep-1]

Re: Boss 302 Advance Road Race setup thread

Well obviously the tires need to be aired up again the next morning.

OK now I get it w/ the temperature thing I will do that with one of my tires in a couple weeks.

the only time you bleed air out of a tire (or add to it) is to effect a tuning change. (not quite written in stone but close)

Well obviously the tires need to be aired up again the next morning.

why? if they started at proper cold pressures at ..say 70 degrees on saturday they should return to those same exact pressures at 70 degrees on sunday morning. Providing you didn't make a pressure change for tuning, or they had a leak.

 

[blacksheep-1]

Re: Boss 302 Advance Road Race setup thread

I'd becareful with that. Not only would you get more rear steer (via roll steer), but an increase in anti squate means also an increase in rear-end rise under braking. So the back end will get light/squirrely more easily under braking. Apparently though, people are finding more grip when going to spherical LCA's. Has anyone tried that?

adjust the decomp to a stiffer setting on the rear shocks and leave the compression alone (IMO) as far as the sphericals, any time you get bind out of the suspension, it's a good thing. It should be virtually "free" (no bind) at the normal ride height once adjusted. Once it comes off of NRH the panhard bar will introduce bind because it is trying to keep the diff centered. The spherical attempt to negate that bind and let the suspension work.

 

[blacksheep-1]

Re: Boss 302 Advance Road Race setup thread

Just to let you guys know I did some ninja edits to the above 2 posts, I guess it's an age thing but I find myself having more fractured thoughts than ever before, I attempted to explain and/or add to the above posts after the fact