Re: Sure grip = 15% torque loss?
[Re: mark7171]
#375798
07/15/09 12:40 AM
07/15/09 12:40 AM
|
Joined: Dec 2003
Posts: 5,314 Carstairs, Alberta, Canada
dave571
master
|
master
Joined: Dec 2003
Posts: 5,314
Carstairs, Alberta, Canada
|
Sorry I don't buy it. All a limited slip unit is, is a set of spring loaded clutches, that try to hold the side gears to the carrier. I don't see how it could cost any torque at all(other than the added mass the driveline has to turn). For that matter, the sure grip unit actually does nothing, if the traction is the same on both wheels. Of course there is probably some wizzy scientific explanationa as to why it is true.
Last edited by dave571; 07/15/09 12:41 AM.
|
|
|
Re: Sure grip = 15% torque loss?
[Re: mark7171]
#375800
07/15/09 01:09 AM
07/15/09 01:09 AM
|
Joined: Jan 2005
Posts: 12,423 Kalispell Mt.
HotRodDave
I Live Here
|
I Live Here
Joined: Jan 2005
Posts: 12,423
Kalispell Mt.
|
No performance improvement from open diferential, unless your car is useing the wheel slipage as a way to multiply the tq because your tq converter is too tight. There is no tq multiplying though.
Back before my car had any musterd I swapped from a 2.94 open to a 2.94 sg both 7.25s and it felt slower with the SG but ets were quite a bit better and on the street I could finally get a jump on my wife in her maxima.
I am not causing global warming, I am just trying to hold off a impending Ice Age!
|
|
|
Re: Sure grip = 15% torque loss?
[Re: dave571]
#375801
07/15/09 01:29 AM
07/15/09 01:29 AM
|
Joined: Feb 2003
Posts: 10,232 Someplace you aren't
SomeCarGuy
I Live Here
|
I Live Here
Joined: Feb 2003
Posts: 10,232
Someplace you aren't
|
Quote:
Sorry I don't buy it.
All a limited slip unit is, is a set of spring loaded clutches, that try to hold the side gears to the carrier.
I don't see how it could cost any torque at all(other than the added mass the driveline has to turn).
For that matter, the sure grip unit actually does nothing, if the traction is the same on both wheels.
Of course there is probably some wizzy scientific explanationa as to why it is true.
|
|
|
Re: Sure grip = 15% torque loss?
[Re: mark7171]
#375802
07/15/09 02:09 AM
07/15/09 02:09 AM
|
Joined: Sep 2005
Posts: 6,516 Santa Cruz, California
Lefty
master
|
master
Joined: Sep 2005
Posts: 6,516
Santa Cruz, California
|
Quote:
the sure grips/or posi type can take up to 15% of the turning torque away.
That energy would have to go somewhere and probably make a huge amount of heat, so I say no way...
|
|
|
Re: Sure grip = 15% torque loss?
[Re: Lefty]
#375803
07/15/09 10:24 AM
07/15/09 10:24 AM
|
Joined: Jul 2003
Posts: 63 Silver Springs, Florida
Charrlie_S
member
|
member
Joined: Jul 2003
Posts: 63
Silver Springs, Florida
|
I don't know for sure, but I think in a straight line, with both wheels haveing traction, there would be no power/torque loss. While turning, the clutches would slip, to allow one wheel to turn faster. This would generate heat, resulting in a power/torque loss.
Come to think about it, if the clutches were doing their job as designed (to transfer power to the wheel with the most traction), there would be heat generated, and this would equate to a power loss.
Charrlie_S 66 Cuda 170 nitrous 66 Valiant 225 nitrous 65 Valiant 170 turbo 64 Valiant driver 64 Valiant roller
|
|
|
Re: Sure grip = 15% torque loss?
[Re: DaytonaTurbo]
#375806
07/15/09 08:23 PM
07/15/09 08:23 PM
|
Joined: Jan 2003
Posts: 9,982 Ansonia, CT
CJK440
master
|
master
Joined: Jan 2003
Posts: 9,982
Ansonia, CT
|
Seems to me, that there is a certain amount of drag in a limited slip when turning that is exacerbated when under power.
2017 Contusion Blue Challenger T/A 392 M6 "BLKNBLU"
|
|
|
Re: Sure grip = 15% torque loss?
[Re: DaytonaTurbo]
#375807
07/15/09 08:24 PM
07/15/09 08:24 PM
|
Joined: Oct 2003
Posts: 21,345 Marysville, O-H-I-O
70Cuda383
Too Many Posts
|
Too Many Posts
Joined: Oct 2003
Posts: 21,345
Marysville, O-H-I-O
|
only 1 way to prove it! if anyone is planning on putting an LSD into their axle, go to the dyno first, get a baseline.
then swap in the LSD and go re-dyno to see if there's a loss.
this would only work if the ONLY thing you changed was the diff, and did not do a gear change at the same time.
**Photobucket sucks**
|
|
|
Re: Sure grip = 15% torque loss?
[Re: CJK440]
#375808
07/15/09 08:33 PM
07/15/09 08:33 PM
|
Joined: Nov 2007
Posts: 21,844 Kirkland, Washington
Pacnorthcuda
Too Many Posts
|
Too Many Posts
Joined: Nov 2007
Posts: 21,844
Kirkland, Washington
|
Ever driven a live axle go-kart? Those things are dogs at low speed with the wheel cranked. Everyone guickly learns to accelerate in the straightest line possible. Reason is simple, in a turn, the engine has to not only accelerate the mass, but over come the friction of the two rear tires having to turn different speeds. Now in a limited slip, the axle can differentiate, which GREATLY helps, but there is friction present in the cones/clutches, generating heat, all made possible from consuming torque from the motor. So yes there is some truth to it....IF (big IF) the differnetial is being forced to differentiate (its in a turn). Straight line? I wouldn't think there would be a difference, and of course if the peg-leg set begins to spin......
...and as far as a 15% torque loss? I don't believe it.
|
|
|
Re: Sure grip = 15% torque loss?
[Re: mark7171]
#375810
07/15/09 10:38 PM
07/15/09 10:38 PM
|
Joined: Apr 2005
Posts: 93 Jacksonville, FL
burnt_o_matic
member
|
member
Joined: Apr 2005
Posts: 93
Jacksonville, FL
|
Quote:
up to 15% of the turning torque away
Was that a circle track racer telling you this? There may be some truth to it in that situation.
|
|
|
Re: Sure grip = 15% torque loss?
[Re: burnt_o_matic]
#375811
07/15/09 11:11 PM
07/15/09 11:11 PM
|
Joined: Oct 2003
Posts: 21,345 Marysville, O-H-I-O
70Cuda383
Too Many Posts
|
Too Many Posts
Joined: Oct 2003
Posts: 21,345
Marysville, O-H-I-O
|
Quote:
Quote:
up to 15% of the turning torque away
Was that a circle track racer telling you this? There may be some truth to it in that situation.
Good catch! TURNING TORQUE! yes, I'd believe it if you had full traction on both tires, in a turn, when you're now forced to slip the clutches in the LSD.
maybe this is where a detroit true trac would be beneficial? no clutches, all gear LSD...acts like an open around a turn, until you gas it, then it acts like a locker, right?
I know if I have 1 wheel up in the air, the darn thing spins around and around like an open diff! scared me the first time I did that with it installed! I didn't fully understand how it worked yet!
**Photobucket sucks**
|
|
|
Re: Sure grip = 15% torque loss?
[Re: burnt_o_matic]
#375812
07/16/09 07:23 AM
07/16/09 07:23 AM
|
Joined: Jan 2003
Posts: 25,200 Upper Midwest
MoparforLife
Too Many Posts
|
Too Many Posts
Joined: Jan 2003
Posts: 25,200
Upper Midwest
|
Quote:
Quote:
up to 15% of the turning torque away
Was that a circle track racer telling you this? There may be some truth to it in that situation.
If it was he won't have to worry about it long using a SG on the circle track.
|
|
|
Re: Sure grip = 15% torque loss?
[Re: 70Cuda383]
#375815
07/16/09 11:54 AM
07/16/09 11:54 AM
|
Anonymous
Unregistered
|
Anonymous
Unregistered
|
IMO, having a LSD has much more benefits than it has negatives. They may take more power to make a turn but only if power is being applied and under normal cruise conditions, they are slipping pretty easily.
|
|
|
|
|