Club Cobra Keith Craft Motorsports  

Go Back   Club Cobra > Manufacturers, Engine Builders, tools, and parts. > BackDraft Racing ---

MMG Superformance
Nevada Classics
MMG Superformance
Main Menu
Module Jump:
Nevada Classics
Nevada Classics
MMG Superformance
Keith Craft Racing
Advertise at CC
Banner Ad Rates
MMG Superformance
MMG Superformance
Keith Craft Racing
March 2024
S M T W T F S
          1 2
3 4 5 6 7 8 9
10 11 12 13 14 15 16
17 18 19 20 21 22 23
24 25 26 27 28 29 30
31            

Kirkham Motorsports

Like Tree1Likes
  • 1 Post By cycleguy55

Reply
 
LinkBack Thread Tools Rate Thread Display Modes
  #1 (permalink)  
Old 09-01-2007, 09:32 PM
Rwillia4's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Aug 2003
Location: San Diego, CA
Cobra Make, Engine: BDR #455, KC427W, TWM-FI
Posts: 727
Not Ranked     
Default Understeer

I have a ton of understeer, it just wants to dig. Front and rear tires are at 28psi. I could be going in the corners to hot but it just doesn't want to change direction. I'm going to lower the rear pressure to 24 psi and try again. Anyone else have this problem? Any suggestions?
Reply With Quote
  #2 (permalink)  
Old 09-01-2007, 09:35 PM
CC Member
Visit my Photo Gallery

 
Join Date: Mar 2006
Location: Mesa, AZ
Cobra Make, Engine: SPF136 427FE
Posts: 142
Not Ranked     
Default Front springs?

What lb front/rear springs are you running?

jeff
Reply With Quote
  #3 (permalink)  
Old 09-01-2007, 10:57 PM
Rwillia4's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Aug 2003
Location: San Diego, CA
Cobra Make, Engine: BDR #455, KC427W, TWM-FI
Posts: 727
Not Ranked     
Default

I have the M3 race setup , I'm not sure of the Lb rating
Reply With Quote
  #4 (permalink)  
Old 09-01-2007, 11:35 PM
lovehamr's Avatar
Stolen Avitar
Visit my Photo Gallery

 
Join Date: Oct 2004
Location: Brunswick, GA
Cobra Make, Engine: BDR 1311 428PI
Posts: 3,044
Not Ranked     
Default

What tires? Unless they are race slicks that pressure is way to low and may be allowing the tire to roll under onto the sidewall. Have you taken any tire temps?

Steve
Reply With Quote
  #5 (permalink)  
Old 09-02-2007, 12:14 AM
Rwillia4's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Aug 2003
Location: San Diego, CA
Cobra Make, Engine: BDR #455, KC427W, TWM-FI
Posts: 727
Not Ranked     
Default

They are the Nittos. And the car is only 2500# so tire load it not that great. Currently the walls are no where close to the edge of their traction area (as seen by the scuffs) in the fronts or backs. No roll of the sidewall has been noted. Just a push.

Steve- do you have a better way to get more neutral?
Reply With Quote
  #6 (permalink)  
Old 09-02-2007, 07:47 AM
dlampe's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: May 2004
Location: centralia, IL
Cobra Make, Engine: B&B cobra (sold), Hurricane HMS1002 (sold), Kirkham 289 FIA, (sold) RCR GT 40(sold) SPF GT40 2122(sold) Hurricane HMS2002, (sold) RCR SLC (sold) GTR on the way!
Posts: 1,288
Not Ranked     
Default

If they are 17 in, you really need to start at 30 -32 pounds and check them hot with a target of 36-37 pounds. If they are 15in then the target heat range is 30 pounds as a general rule. If that doesn't help, you will need more swaybar in the back or less in the front, heaveir springs in the back or less in the front. You might try more pressure in the rear but if it is severe, thats probably not going to get the job done.
__________________
High Maintenance Racing Team
Run & Gun 2003 - 2013
Reply With Quote
  #7 (permalink)  
Old 09-02-2007, 09:08 AM
Bailey's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Apr 2004
Location: Jupiter, fl
Cobra Make, Engine: Backdraft #985 Custom Pro/ Street Race Car, full cage, dry sump 427W and G Force T-56 Fully Street Legal!!
Posts: 402
Not Ranked     
Default

Hey Rob,
For perspective my street wheels and tires are at 24fr 26 rear, and the DOT track 17s are at 22fr and 24rear. Tire pressure and alignment play a big role with these cars, and also pressure differential between front and rear. BDR also offers a set of stiffer springs if you are interested. My car with the M3 bits still felt like a sponge. The springs really woke up the beast, no regrets.
Good luck and enjoy the ride,
Richard Bailey
__________________
Life is short, live like you mean it!!
Live every day like it's your last. One day you will be right!
Reply With Quote
  #8 (permalink)  
Old 09-02-2007, 11:11 AM
bobcowan's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Feb 2007
Location: Colorado Springs, CO
Cobra Make, Engine: Backdraft, supercharged Coyote
Posts: 2,430
Not Ranked     
Default

Bailey is on target.

I use 17 street and track tires. Cold air temps are 24-26 psi. Which allows the hot tire pressures to be around 32psi. Optimal pressure and camber can only be truly determined with a tire pyrometer. I bought one off e-bay for $40.

Carefull Alignment is the key to good handeling. All the right race parts won't perform well if alignment and ride height is off. Too much toe in will really cause an understeer.

Have you checked bump steer? If your springs are soft and you have a lot of bump steer, as soon as the nose dives your toe in will be significant.

Do you have sway bars? Less front bar or more rear bar will help improve understeer.
Reply With Quote
  #9 (permalink)  
Old 09-02-2007, 03:04 PM
Rwillia4's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Aug 2003
Location: San Diego, CA
Cobra Make, Engine: BDR #455, KC427W, TWM-FI
Posts: 727
Not Ranked     
Default

I have the 17's, race springs and, sway bars front and rear. I play with the tire pressure some more to see what. The alignment is in specs along with getting the ride height as low as possible with respect to the camber spec. I think the toe is 1.5-2 degrees.

Bob- Bump steer? what is that and how can I check it?

Steve- Are the race springs ABOVE the $4500 race package?

thanks for all the help
Reply With Quote
  #10 (permalink)  
Old 09-03-2007, 12:06 PM
CC Member
Visit my Photo Gallery

 
Join Date: Aug 2003
Location: Gilbert, AZ
Cobra Make, Engine: Backdraft #90, 351w,Tremec 3550, SB100 SOLD
Posts: 577
Not Ranked     
Default

Rwillia4

Introduce right foot to gas pedal and eliminate all your understeer very quickly. But, get ready to catch the rear end coming around behind you.

SkipB
Reply With Quote
  #11 (permalink)  
Old 09-03-2007, 09:39 PM
Rwillia4's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Aug 2003
Location: San Diego, CA
Cobra Make, Engine: BDR #455, KC427W, TWM-FI
Posts: 727
Not Ranked     
Default

Skip,
I am fully aware of the right foot modulation , even then it is still a pig and wants to snap right back to understeer. I'm still trying to decrease my overall radius thru turns.
Reply With Quote
  #12 (permalink)  
Old 11-15-2020, 03:21 PM
cycleguy55's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Feb 2014
Location: White City, SK
Cobra Make, Engine: West Coast, 460 CID
Posts: 2,844
Not Ranked     
Default

Quote:
Originally Posted by Rwillia4 View Post
I have the M3 race setup , I'm not sure of the Lb rating
What's the F/R weight of your car vs the target F/R weight that setup is designed for? Between the springs and sway bar you may have too much roll stiffness in the front. If so, you'll need to reduce it in the front, increase it in the rear, or both.
t walgamuth likes this.
__________________
Brian
Reply With Quote
  #13 (permalink)  
Old 11-16-2020, 06:50 AM
CC Member
Visit my Photo Gallery

 
Join Date: Sep 2017
Location: Frederick, CO
Cobra Make, Engine: ERA FIA 2158, ERA 427SC 649 sold
Posts: 169
Not Ranked     
Default

If you want the front to bite on sharp turn ins, you need negative camber on the front, -1* or more. More rear roll stiffness will help too.
Reply With Quote
  #14 (permalink)  
Old 11-16-2020, 02:42 PM
MKS427's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Jan 2017
Location: Glendale, AZ
Cobra Make, Engine: FFR MkIV 427
Posts: 629
Not Ranked     
Default

Factory Five recommends 22psi cold for 17" tires. It really helped just for street driving. On the Nitto NT-01s you will see triangles on the sidewall close to the tread. When you are scuffing close to the tip of the triangle, you are close to optimal pressure.

Last edited by MKS427; 11-16-2020 at 02:46 PM..
Reply With Quote
  #15 (permalink)  
Old 11-18-2020, 10:36 AM
t walgamuth's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Jan 2018
Location: Lafayette, IN
Cobra Make, Engine: Looking to buy
Posts: 1,295
Not Ranked     
Default

I tend to agree with the fellow who recommended 24 front and 26 rear as a start point.
__________________
Cobra loving, autocrossing Grandpa Architect.
Reply With Quote
  #16 (permalink)  
Old 11-18-2020, 11:33 AM
CC Member
Visit my Photo Gallery

 
Join Date: Dec 2015
Posts: 1,442
Not Ranked     
Default

Btw guys you're replying to a 13 year old thread. Bob Cowan started another thread this week in the BDR forums with the same title though.
Reply With Quote
  #17 (permalink)  
Old 11-18-2020, 12:33 PM
t walgamuth's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Jan 2018
Location: Lafayette, IN
Cobra Make, Engine: Looking to buy
Posts: 1,295
Not Ranked     
Default

What a dirty trick!

__________________
Cobra loving, autocrossing Grandpa Architect.
Reply With Quote
Reply

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

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
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -7. The time now is 10:51 AM.


Powered by vBulletin® Version 3.8.0
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Search Engine Friendly URLs by vBSEO 3.6.0
The representations expressed are the representations and opinions of the clubcobra.com forum members and do not necessarily reflect the opinions and viewpoints of the site owners, moderators, Shelby American, any other replica manufacturer, Ford Motor Company. This website has been planned and developed by clubcobra.com and its forum members and should not be construed as being endorsed by Ford Motor Company, or Shelby American or any other manufacturer unless expressly noted by that entity. "Cobra" and the Cobra logo are registered trademarks for Ford Motor Co., Inc. clubcobra.com forum members agree not to post any copyrighted material unless the copyrighted material is owned by you. Although we do not and cannot review the messages posted and are not responsible for the content of any of these messages, we reserve the right to delete any message for any reason whatsoever. You remain solely responsible for the content of your messages, and you agree to indemnify and hold us harmless with respect to any claim based upon transmission of your message(s). Thank you for visiting clubcobra.com. For full policy documentation refer to the following link: CC Policy
Links monetized by VigLink