Club Cobra Gas-N Exhaust  

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

MMG Superformance
Nevada Classics
Keith Craft Racing
Main Menu
Module Jump:
Nevada Classics
Nevada Classics
Keith Craft Racing
Advertise at CC
Banner Ad Rates
MMG Superformance
Keith Craft Racing
December 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 Tree4Likes
  • 2 Post By bobcowan
  • 1 Post By SBSerpent
  • 1 Post By bobcowan

Reply
 
LinkBack Thread Tools Rate Thread Display Modes
  #1 (permalink)  
Old 01-10-2021, 06:40 PM
SBSerpent's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Jun 2020
Location: SoCal, CA
Cobra Make, Engine: BDR build #983, FRM 392
Posts: 380
Not Ranked     
Default Open or LS Differential...

...on the BMW M3 E36 that comes standard with our cars?
Reply With Quote
  #2 (permalink)  
Old 01-10-2021, 06:51 PM
CC Member
Visit my Photo Gallery

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

It can be either depending on what was optioned when the Backdraft was spec'd out.
To tell what you have there should be a metal tag attached to your rear diff cover.
having an "S" in front of the ratio is the LSD Id. Pics here.

https://differentials.myshopify.com/...p-differential
Reply With Quote
  #3 (permalink)  
Old 01-31-2021, 01:13 PM
SBSerpent's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Jun 2020
Location: SoCal, CA
Cobra Make, Engine: BDR build #983, FRM 392
Posts: 380
Not Ranked     
Default

Quote:
Originally Posted by spdbrake View Post
It can be either depending on what was optioned when the Backdraft was spec'd out.
To tell what you have there should be a metal tag attached to your rear diff cover.
having an "S" in front of the ratio is the LSD Id. Pics here.

https://differentials.myshopify.com/...p-differential
I can't see any tag.

When both wheels are off the ground and the tranny is in neutral, spinning one wheel does not effect the opposite wheel (i.e. the opposite wheel does not spin). However, spinning either wheel in a forward direction results in the drive shaft rotating in the same direction. Is that an indication of a LSD?
Reply With Quote
  #4 (permalink)  
Old 01-31-2021, 04:26 PM
bobcowan's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Feb 2007
Location: Colorado Springs, CO
Cobra Make, Engine: Backdraft, supercharged Coyote
Posts: 2,445
Not Ranked     
Default

Put it in neutral, and get both tires in the air. Spin one tire.

If the other tire spins in the same direction, it's LSD.

If the other tire spins in the opposite direction, it's open.

https://itstillruns.com/identify-lim...l-7805308.html
eschaider and SGwick like this.
__________________
.boB "Iron Man"
NASA Rocky Mountain TTU #42
www.RacingtheExocet.com
BDR #1642 - Supercharged Coyote, 6 speed Auto
Reply With Quote
  #5 (permalink)  
Old 01-31-2021, 06:33 PM
SBSerpent's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Jun 2020
Location: SoCal, CA
Cobra Make, Engine: BDR build #983, FRM 392
Posts: 380
Not Ranked     
Default

Quote:
Originally Posted by bobcowan View Post
Put it in neutral, and get both tires in the air. Spin one tire.

If the other tire spins in the same direction, it's LSD.

If the other tire spins in the opposite direction, it's open.

https://itstillruns.com/identify-lim...l-7805308.html
As I noted in my post, the other tire did NOT spin at all.

That being said, I went out and did the true test - a burnout in the street. Only the passenger side left a mark. That's disappointing, especially on a car like this.
joyridin' likes this.
Reply With Quote
  #6 (permalink)  
Old 01-31-2021, 07:02 PM
Gaz64's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: May 2008
Location: Brisbane, QLD
Cobra Make, Engine:
Posts: 2,797
Not Ranked     
Default

The easier way is to jack up one side, select neutral.
If the wheel turns easily, you have an open diff.
An LSD takes a lot more effort to turn, the "breakaway torque" can be about 70 ft/lbs.
Gary
__________________
Gary

Gold Certified Holden Technician
Reply With Quote
  #7 (permalink)  
Old 01-31-2021, 07:07 PM
patrickt's Avatar
Half-Ass Member
Visit my Photo Gallery

 
Join Date: Jun 2005
Cobra Make, Engine: ERA #732, 428FE (447 CID), TKO600, Solid Flat Tappet Cam, Tons of Aluminum
Posts: 22,004
Not Ranked     
Default

Quote:
Originally Posted by SBSerpent View Post
As I noted in my post, the other tire did NOT spin at all.

That being said, I went out and did the true test - a burnout in the street. Only the passenger side left a mark. That's disappointing, especially on a car like this.
Just replace it with a LSD. That's actually kind of a fun project.
Reply With Quote
  #8 (permalink)  
Old 01-31-2021, 10:06 PM
SBSerpent's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Jun 2020
Location: SoCal, CA
Cobra Make, Engine: BDR build #983, FRM 392
Posts: 380
Not Ranked     
Default

I'm just scratching my head as to why there was no spinning of the other wheel when I turned the opposite wheel.
Reply With Quote
  #9 (permalink)  
Old 02-01-2021, 06:57 AM
patrickt's Avatar
Half-Ass Member
Visit my Photo Gallery

 
Join Date: Jun 2005
Cobra Make, Engine: ERA #732, 428FE (447 CID), TKO600, Solid Flat Tappet Cam, Tons of Aluminum
Posts: 22,004
Not Ranked     
Default

Quote:
Originally Posted by SBSerpent View Post
I'm just scratching my head as to why there was no spinning of the other wheel when I turned the opposite wheel.
Well, that's a good question. The only time I can ever remember that occurring with a car of mine was when a gear was broken. But just putting it up on a lift and popping the cover off will tell you. Maybe it was just having a bad day.
Reply With Quote
  #10 (permalink)  
Old 02-01-2021, 08:28 AM
joyridin''s Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Feb 2009
Posts: 1,695
Not Ranked     
Default

Quote:
Originally Posted by SBSerpent View Post
I'm just scratching my head as to why there was no spinning of the other wheel when I turned the opposite wheel.
Are you sure it doesn't have a helical style LSD instead of a clutch type? I am not sure if you bought the car new, but if not, maybe somebody had one installed?

Doing a burnout is not a good way of checking. If the clutch plates or the cones are worn in the LSD, both wheels may not spin anyhow.
Reply With Quote
  #11 (permalink)  
Old 02-01-2021, 09:05 AM
patrickt's Avatar
Half-Ass Member
Visit my Photo Gallery

 
Join Date: Jun 2005
Cobra Make, Engine: ERA #732, 428FE (447 CID), TKO600, Solid Flat Tappet Cam, Tons of Aluminum
Posts: 22,004
Not Ranked     
Default

Quote:
Originally Posted by joyridin' View Post
Are you sure it doesn't have a helical style LSD instead of a clutch type?
Dang, I don't even know what a helical style limited slip is, but I did post this thread on checking the breakaway torque on my Powr-Lok, for what that's worth. Breakaway Torque on ERA's Powr-Lok
Reply With Quote
  #12 (permalink)  
Old 02-01-2021, 09:10 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

The opposite side caliper might be sticking enough to keep it from turning easily.
__________________
Cobra loving, autocrossing Grandpa Architect.
Reply With Quote
  #13 (permalink)  
Old 02-01-2021, 05:16 PM
mln385's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Dec 2001
Cobra Make, Engine: BDR
Posts: 536
Not Ranked     
Default

BDR's come standard with an open diff unless otherwise ordered and paid for.
Reply With Quote
  #14 (permalink)  
Old 02-01-2021, 06:48 PM
FredG's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Sep 2018
Location: Howell, NJ
Cobra Make, Engine: Backdraft Car #1209 Roush 427R
Posts: 607
Not Ranked     
Default

Do the modern limited slips have the same annoying ratcheting effect when making a slow sharp radius turn that my 66 vette had?

Fred
Reply With Quote
  #15 (permalink)  
Old 02-01-2021, 09:17 PM
SBSerpent's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Jun 2020
Location: SoCal, CA
Cobra Make, Engine: BDR build #983, FRM 392
Posts: 380
Not Ranked     
Default

Did some research on a helical style LSD. The proper way to test the wheel rotation is to have both drive wheels off the ground and the transmission in gear. Spinning one wheel will result in the other wheel spinning in the opposite direction.
Reply With Quote
  #16 (permalink)  
Old 02-01-2021, 09:18 PM
bobcowan's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Feb 2007
Location: Colorado Springs, CO
Cobra Make, Engine: Backdraft, supercharged Coyote
Posts: 2,445
Not Ranked     
Default

No. Your old 'Vette had a locking gear. They're famous for that ratcheting action in the corners. A limited Slip is a lot different.
FredG likes this.
__________________
.boB "Iron Man"
NASA Rocky Mountain TTU #42
www.RacingtheExocet.com
BDR #1642 - Supercharged Coyote, 6 speed Auto
Reply With Quote
  #17 (permalink)  
Old 02-07-2021, 06:08 PM
SBSerpent's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Jun 2020
Location: SoCal, CA
Cobra Make, Engine: BDR build #983, FRM 392
Posts: 380
Not Ranked     
Default

So this is what I did. Lifted the rear end so that both wheels were off the ground.
1) with the transmission in gear, I spun one wheel in one direction and the other wheel spun in the opposite direction
2) with the tranny out of gear, I spun one wheel and it did not affect the motion of the other wheel
3) with the tranny still out of gear, I spun the driveshaft by hand and both wheels spun in the same (forward) direction simultaneously

Took the car out for a drive today and I did feel both tires let loose a couple of times on hard acceleration.

Last edited by SBSerpent; 02-07-2021 at 09:53 PM..
Reply With Quote
Reply


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 07:05 PM.


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