Go Back  RX7Club.com - Mazda RX7 Forum > Tech and Performance > Race Car Tech
Reload this Page >

Brake Questions - Cooling related to Rotor Edge to Wheel Clearance

Race Car Tech Discuss anything related to road racing and auto X.

Brake Questions - Cooling related to Rotor Edge to Wheel Clearance

Old 08-30-04, 03:51 PM
  #1  
Rotary Enthusiast
10 Year Member
Thread Starter
 
John Magnuson's Avatar
 
Join Date: Dec 2002
Location: San Diego, CA
Posts: 1,147
Likes: 0
Received 0 Likes on 0 Posts
Brake Questions - Cooling related to Rotor Edge to Wheel Clearance

Just got back from an All Mazda track day at Laguna Seca. Tons of fun and lots of RX7s and Miatas.

I have 13" rotors with Wilwood SL-6 front Calipers (with thermolock pistions) and N-tech brake ducts plumbed into the R1 lip brake ducting. This combination can take a lot more heat than my stock brakes did but still doesn't perform quite as well as I like. I still can manage to boil the brake fluid (Motul).

I use the stock 16" rims which BARELY fit over my brakes. There is about 2/3rds on an inch of clearance between the inside of the rim and the edge of the rotor. Do you think this may be causing poor airflow out of the rotor vents? I don't want to blow $$$ on 17" rims but do you think an extra inch of space would help cooling?

Also, I have the RZ rear brakes but feel that the brake balance is still a little off. Anyone have an advise on brake proportioning valves?

-John Magnuson

Last edited by John Magnuson; 08-30-04 at 03:53 PM.
John Magnuson is offline  
Old 08-31-04, 08:40 AM
  #2  
Rotary Enthusiast
iTrader: (1)
 
Join Date: Jul 2004
Location: Rocket City, Alabama
Posts: 1,035
Likes: 0
Received 1 Like on 1 Post
I am not familiar with the brake ducts you mention. What is the diameter of the duct going from the nose of the car to the rotor. Exactly how do the ducts end at the rotor? do they just kind of point at the rotor, or are they directly connected to a shroud that forces all the air to feed the center of the rotor?

If I assume you have a 3" diameter duct going to the center of the rotor, it has a cross sectional flow area of about 7 square inches.
In the 2/3" annulus around the outside of your 13" rotors, you have a flow area of about 28 square inches.
Also, we have the centrifugal pumping action of the spinning vanes in the rotor to push the air out of the rotors.
Therefore, I doubt your problem is not enough air leaving the rotor; I suspect you do not have enough cold air forced into the center of the rotor. If you had a good clear photo of the duct where it attaches to the center of the rotor then I could see for sure.
speedturn is offline  
Old 08-31-04, 02:39 PM
  #3  
Rotary Enthusiast
10 Year Member
Thread Starter
 
John Magnuson's Avatar
 
Join Date: Dec 2002
Location: San Diego, CA
Posts: 1,147
Likes: 0
Received 0 Likes on 0 Posts
Yeah, a good 3 inch duct doing into a well built custom backing plate that directs the air into the eye of the rotor is what I have. I'll take some pics later today and post them.
John Magnuson is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
trickster
2nd Generation Specific (1986-1992)
20
03-29-18 02:05 PM
Marty RE
New Member RX-7 Technical
0
08-17-15 09:36 AM
Marty RE
New Member RX-7 Technical
0
08-13-15 11:19 AM


Thread Tools
Search this Thread
Quick Reply: Brake Questions - Cooling related to Rotor Edge to Wheel Clearance


Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: