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Ok i see alt of threads talking about the rear diffs in the srt-8. it seems like evry one says they are open diffs, infact i know mine is but i can always lay 2 equally black tracks when i smoke em... i have video shwing both spinning at the same time and everything... how can this be? i need to know because i am looking to put in a taller gear and while im doing it if it makes sense ima put in an lsd. please help thanks
 

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yeah when ever i smoke em, i almost always lay down 2 tracks of black. i think the limited slip just guarantees both spin where as the open diff is kinda hit or miss. just my take on it though. heh not very technical huh?
 

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Ok i see alt of threads talking about the rear diffs in the srt-8. it seems like evry one says they are open diffs, infact i know mine is but i can always lay 2 equally black tracks when i smoke em... i have video shwing both spinning at the same time and everything... how can this be? i need to know because i am looking to put in a taller gear and while im doing it if it makes sense ima put in an lsd. please help thanks
The power does not go to one wheel with an open differential. Power is torque during a given time. An open differential can send no more than 50% of the available torque to either wheel. The power delivered drops off at both wheels when one of them spins up.

It really comes down to the Torque Bias Ratio or TBR. This is the ratio of the maximum split of torque between the axle shafts. Torsen is a really good example of a differential with LSD or what Chrysler usto call Sure-Grip. The TBR of the Torsen is about 2.5.

This is independent of the amount of torque and axle speed. If one wheel is supporting say 100 ft-lbs, then the other can support up to 250 ft-lbs. If that 100 ft-lb wheel is sitting on gravel and it hits a patch of ice and drops to 10 ft-lbs, the other wheel will also drop to 25 ft-lbs max. If 25 ft-lbs of torque on the high traction wheel is not enough to move the car, the Torsen will allow the ice wheel to spin up just like an open differential. Same with a Chrysler Limited Slip Differential.

A regular open differential has a TBR of about 1:1. If one wheel is supporting 150 ft-lbs, the other can support no more than 150 ft-lbs. This is why it is easy for the ice wheel to spin up on an open diff. 10 ft-lbs on the ice wheel means only 10 ft-lbs on the traction wheel. Of course, 10 ft-lbs won't move anything, so the low traction wheel spins up.

This is a complicated subject but at least we can understand basics here.:bigthumb:

Thanks
Brian
BND Automotive LLC:driving:
440-821-9040
 

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^^^great info...thanks!
 

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also the esp applies brake to the wheel that starts to spin and keeps them both at the same rate.
 

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That doesnt apply to a burnout. The key here is the independent rear suspension our cars have. See, in a solid axle car, when you hammer it, one side lifts due to torque, and that side spins. Our cars, they dont lift like that. If you keep from being turned, and have equal traction on both sides, you can spin both tires.
 

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That doesnt apply to a burnout. The key here is the independent rear suspension our cars have. See, in a solid axle car, when you hammer it, one side lifts due to torque, and that side spins. Our cars, they dont lift like that. If you keep from being turned, and have equal traction on both sides, you can spin both tires.
wrong!
if a tire spins on a solid axle car then the other wheel will spin because it is a LOCKED REAR END. meaning that both rear wheels turn at the exact same speed no matter what happens. the suspension is not the cause of this. it doesnt matter if it has independent suspension or if the car uses a rearend housing similar to ford 9 inch.
 

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370 hemi did a good job of explaining it.
 

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wrong!
if a tire spins on a solid axle car then the other wheel will spin because it is a LOCKED REAR END. meaning that both rear wheels turn at the exact same speed no matter what happens. the suspension is not the cause of this. it doesnt matter if it has independent suspension or if the car uses a rearend housing similar to ford 9 inch.

Damn, you could be a little more polite with your disagreement. I am using the term solid axle as I learned it, not like a lot of truck guys do, where its synonomous with a locker. In car terms, it usually which just mean the axle housing is one piece from side to side. Like you would find any car from the 60s. Like this.



I was not referring to the differential, which in the case of a locked one, or a limited slip one, will, when locked, indeed turn both tires equally. Now, about the thought that the independant rear isnt the cause, I believe your wrong. since we have open diffs, explain why we can do two legged burnouts, which, in any non-lsd leaf spring car, WILL result in a one wheel burn.
 

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Good thread...lotsa interesting tech info :bigthumb: (something CF kinda lags on these days)

FWIW: I would be inclined to think GLHS knows more about our cars than most anyone :beerchug:
 

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Damn, you could be a little more polite with your disagreement. I am using the term solid axle as I learned it, not like a lot of truck guys do, where its synonomous with a locker. In car terms, it usually which just mean the axle housing is one piece from side to side. Like you would find any car from the 60s. Like this.



I was not referring to the differential, which in the case of a locked one, or a limited slip one, will, when locked, indeed turn both tires equally. Now, about the thought that the independant rear isnt the cause, I believe your wrong. since we have open diffs, explain why we can do two legged burnouts, which, in any non-lsd leaf spring car, WILL result in a one wheel burn.
i didnt mean to come across like that. i was in a bad mood. gf was being a b*tch.

the only reason why we can do a burnout with both rear wheels is because of the esp. it senses that one of the rear wheels is spinning and applies just enough brake to get the other one to spin. the car thinks that it is on a low traction surface such as ice where in some cases you have to spin the tires just enough to get the heat up to melt the ice so that you can get traction. the abs module keeps applying the brakes at one wheel or the other to keep the spinning at the same rate. this all happens so fast that you cant feel it or hear it. especially when your more worried about making a big cloud of smoke.
trust me. i work for chrysler.
the other manufacturers thought that chrysler was crazy for coming out with an all new rear wheel drive vehicle. because a fwd is actually better as far as chassis dynamics go. all the weight is on the driven tires on a fwd vehicle where as the driven tires on a rwd are at the lightest part of the car which is the rear. chrysler took the 300c to an ice skating rink to prove that this design will rival the fwd. when the driver stepped on the gas tires spun for a little bit while the abs system applied the brakes to each wheel to get traction and when the torque to both wheels got close enough to being the same it got a bite and drove off the ice as if it was on a paved road.
 

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i didnt mean to come across like that. i was in a bad mood. gf was being a b*tch.

the only reason why we can do a burnout with both rear wheels is because of the esp. it senses that one of the rear wheels is spinning and applies just enough brake to get the other one to spin. the car thinks that it is on a low traction surface such as ice where in some cases you have to spin the tires just enough to get the heat up to melt the ice so that you can get traction. the abs module keeps applying the brakes at one wheel or the other to keep the spinning at the same rate. this all happens so fast that you cant feel it or hear it. especially when your more worried about making a big cloud of smoke.
trust me. i work for chrysler.
the other manufacturers thought that chrysler was crazy for coming out with an all new rear wheel drive vehicle. because a fwd is actually better as far as chassis dynamics go. all the weight is on the driven tires on a fwd vehicle where as the driven tires on a rwd are at the lightest part of the car which is the rear. chrysler took the 300c to an ice skating rink to prove that this design will rival the fwd. when the driver stepped on the gas tires spun for a little bit while the abs system applied the brakes to each wheel to get traction and when the torque to both wheels got close enough to being the same it got a bite and drove off the ice as if it was on a paved road.
That doesnt explain why SRTs in full ESP off mode can do it, nor why cars with the ESP mod can do it. To be technical, its sub-branches of ESP that you are talking about, TCS and BLD. The TCS compares rear wheel speeds to front wheel speeds, and BLD does rear wheels compared to each other. It would be the BLD your talking about, but that would stop a burnout, not enable one to keep going. Now, if you keep both rear wheels spinning equally, as in a burnout, then BLD wont intervene, unless one wheel changes speed relative to the other.

Thats the turning part I spoke of. Take a turn, that lessens the weight on one, and it spins faster, kicking in BLD.

I've spent three years studying this system, and nagging the crap out of the SRT engineers every web chat we have, grilling them on the system and how it works.
 

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At least they came to their senses on the 09 SRT's and put a LSD in:beerchug:
 
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