Go Back   American Sedan Forum > Main American Sedan Categories > American Sedan Rules

Reply
 
Thread Tools Display Modes
  #1  
Old 07-14-2020, 10:18 AM
Browntw Browntw is offline
Member
 
Join Date: Mar 2009
Location: Horseheads NY
Posts: 7
Default Bigger rotors?

I see in Fasttrack there is a proposal for bigger rotors. Going from a 12.2 diameter to a 13.1 diameter. I am on the fence about this. What is the thoughts from the community?
Reply With Quote
  #2  
Old 07-14-2020, 03:39 PM
PbFoot PbFoot is offline
Senior Member
 
Join Date: Feb 2008
Posts: 215
Default

Why do this? The guys that use 16" wheels can't fit a 13.1" rotor.

A set of 16" tires is about $200 cheaper than a set of 17" tires.

Rule changes like this just make the top 10 AS cars in the country faster with no apparent benefit to the broader AS community.
Reply With Quote
  #3  
Old 07-15-2020, 10:29 AM
Rotaryracer Rotaryracer is offline
Member
 
Join Date: Oct 2016
Posts: 20
Default

I guess I'm not sure what this does for the class. It doesn't seem to reduce costs (both upfront or operating), and I can't imagine it's going to give a significant impact on braking performance given that the tire contact patch isn't changing. I'm legitimately curious what's driving the rulebook change.

Honestly, given all the pandemic crap going on right now, I'd probably be more in favor of freezing the rule book for X period of time (aside from new platform classing). It would help minimize expenditures replacing perfectly serviceable parts, potentially make it more interesting for new builders (no need to worry about parts being obsoleted for X years if you build to the current spec), and allow us to focus more on racing and less on optimizing to rules changes. [/end_rant]

Last edited by Rotaryracer; 07-15-2020 at 11:32 AM.
Reply With Quote
  #4  
Old 07-15-2020, 03:43 PM
kbsmith1 kbsmith1 is offline
Senior Member
 
Join Date: Jan 2006
Location: Hillsboro, OR
Posts: 767
Default

What the heck? This is listed as a recommended change. I agree that there is
no need for this, and just complicates, and raises costs. Where was the discussion on this?

I run 17" wheels, so could maybe do this, but would have to do redo
all the special brackets for mounting calipers. And on the rear, this would
pretty much necessitate a whole rear housing change since cailiper brackets
are welded to the housing.

I don't get SCCA and American Sedan comittee at all.
__________________
Kevin Smith
1993 Firebird AS #03 Oregon Region SCCA & ICSCC
Reply With Quote
  #5  
Old 07-15-2020, 04:50 PM
jackmartin jackmartin is offline
Senior Member
 
Join Date: Feb 2009
Location: Hutchinson, KS
Posts: 139
Default

Bad idea. As others have said, it just raises costs to go a second or two faster, maybe.
Reply With Quote
  #6  
Old 07-15-2020, 05:01 PM
jimwheeler jimwheeler is offline
Senior Member
 
Join Date: Oct 2004
Location: Kansas City
Posts: 5,246
Default

This is a bad idea. The 17" wheel folks will love this, but the rest of us who stayed with 16" wheels will not be able to do this without major changes, including going to 17" wheels. There is already an advantage to having the 17" wheels, this will just increase that advantage. If it passes and you run 17" wheels with bigger brakes, you should add 100# to your weight.
Please make your opinion known at www.crbscca.com Comment here are pissing in the wind.
Reply With Quote
  #7  
Old 07-15-2020, 05:40 PM
MLong MLong is offline
Senior Member
 
Join Date: Aug 2010
Location: Chicago, IL
Posts: 28
Default

I can get 13.1" rotors with calipers within my 16" wheels. GT-1 has for many years had the 13.1" rotor spec and 16" wheels. Now I know AS is nothing like GT-1, but that was stated as a point of reference.

The larger rotor will provide a very slight increase in brake torque, however the weakest link in the AS braking chain is the tire contact and traction. A team with a developed braking package to the current rules will see very little improvement as they are already spending top dollar for calipers, pads and rotors that take braking performance beyond the tire grip threshold. The biggest benefactors are the ones that do not want to spend top dollar or can make the effort to build a package that equates to the top contenders.

But I will argue against the 13.1" taking seconds off lap times, when in reality, at best we are looking a tenth or two when taking into account the increased rotating mass.

The upside to allowing the larger rotor is wider range of available brake kits and rotor options that are cheaper and readily available, but I don't believe it will be a mandatory upgrade to stay competitive, however it will help those that are new to the class or are considering coming to the class find a brake package that doesn't involve McGyvering a package together with an antiquated rotor spec. The AS class can use all the new participants it can get to stay relevant in SCCA, so I am all for updating the rules that make finding parts easier and cheaper for a competitor to come join us.
Reply With Quote
  #8  
Old 07-15-2020, 06:41 PM
jimwheeler jimwheeler is offline
Senior Member
 
Join Date: Oct 2004
Location: Kansas City
Posts: 5,246
Default

Mlong,

Well. the larger rotors will not fit under my wheels and the brake kit I use. Wilwood, is cheap and available. You made a lot of statements and, I wonder where your data came from, to state what you did in your second paragraph. Show me some data. Or the third para, or any of the stuff you state as fact. PS. Another half inch in diameter is not going to give you "increased rotating mass" when your are talking about our tires and wheels. I'm calling total B.S. on that.
Reply With Quote
  #9  
Old 07-15-2020, 07:41 PM
MLong MLong is offline
Senior Member
 
Join Date: Aug 2010
Location: Chicago, IL
Posts: 28
Default

Jim, the second paragraph is easy to prove and is usually shown on any given weekend as our current braking capability exceeds the tire grip available, as it does with many other competitors and if your system doesn't then you now have a cheaper route to get to that threshold rather than using $300 rotors or a $500 set of brake pads every other weekend or having to buy rotors and cut down the diameter to meet specification.

The rule doesn't state you must use a 13.1" rotor, if a 12.8" fits then you have an option, same with 12.2".

And I agree, letters shall be written to the CRB for any rule change recommended or to request a rule change. The past few years has seen a decline in participation and the class needs an infusion of new competitors and we as a collective group need to find ways to achieve that.
Reply With Quote
  #10  
Old 07-15-2020, 11:16 PM
Tim White Tim White is offline
Senior Member
 
Join Date: Nov 2004
Posts: 356
Default

Sadly this class lost the plot about a year and a half ago. With rule changes like this the class is only going to get smaller.
Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 02:49 PM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2020, vBulletin Solutions, Inc.