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Discussion Starter · #1 ·
Ok. I'll start by saying that I was stuck in a shallow pond a few weeks ago. It just hit me that I probanly could have gotten out by giving resistance to my spinning left tires. Out of curiosity, how much more torque could a parking break allow the tires to receive? I havent tightened the cables or anything so this is a stock tj e-brake. (You know, very loose and not really engaging until the last 3-4 clicks )

I may be asking a silly question but I'm just curious. Thanks!
 

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Well that's the same traction aid my dad uses on his old pickup. He took the lock mechanism out so he can use it and release it without pulling the handle thing.
 

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An engine can only put out the amount of torque it takes to start a tire spinning. Once a tire starts to spin, that immediately limits the engine to that level of torque... the amount it takes to get a tire spinning.

Stepping on the brakes or pulling the parking brake up increases the amount of torque the engine can put out by making it more difficult to spin a tire. This is exactly how a LSD (limited slip differential) works but instead of making you engage the brakes, a LSD connects the spinning tire to the non-spinning tire which makes it harder to spin the tire with the least amount of traction... which increases the amount of torque the engine can develop.

Whatever torque the engine can develop is always (!) split exactly 50:50 to the left and right sides. Contrary to what the ads for limited slip differentials say which are worded this way to make it easier to understand, torque is never "sent" from one side to the other. They increase the overall torque the engine can develop which is then split 50:50 by the differential... which increases the amount of torque made available the side with more traction. :)
 

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Discussion Starter · #7 ·
Thanks Jerry! I appreciate that! So, if one tire is off the ground, the other side (Same axle) Is on the ground. Obviously one spins, one doesn't... so the torque increase would only be as much as is required to overpower the brakes on the tire with the least traction. right?
 

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If the e-brake hits both tires I don't see how it would help. Maybe if you set it up like a tractor, an individual petal for each wheel, it would help. Could be wrong though.
 

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I don't see how it would help if the e-brake hits both wheels. Maybe if you set it up like a tractor, where you can break only the right or left side using two peddles but not with the e-brake.
 

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With open diff the tire that has the least traction is going to spin so when using the e brake with make the diff think its getting traction sending more power to the other wheel, never thought of trying that
 

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So if one tire is in the air with an open diff it takes 0 torque from the engine to spin that tire. So the tire on the ground gets 0 torque. The diff splits the torque 50/50. Half of 0 is 0. Now in theory if you set the brake and the engine produces torque to get it spinning it should split that to the other side causing it to turn. Then your unstuck. But like stated above that sounds like it would only work if you could set the break to only the tire that is in the air.
 

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Discussion Starter · #12 ·
Oddly, it never crossed my mind that it's applying brakes to both tires. It still requires torque to spin a tire, but it's so little (like 25~lbs) that the other does nothing. Ok so now the question is if the brakes apply to both tires, will it reduce the torque that actually gets to the tire, essentially still only giving enough to spin one and leave the vehicle stationary. Also, wouldn't this method eat the clutch like a biscuit for breakfast?
 

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It would be about like taping the brakes
 

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We have a vehicle over here manufactured in the 80s with two seperate handbrakes, one for each wheel. Works great offroad.
 

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Discussion Starter · #16 ·
That would be cool! So is cutting the breaks the same thing. Making two brake lines, left and right?
 

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I was kind of hoping someone knew how much of a difference the handbrake could make in an optimum situation.

In other words, if the brake is nice and tight, how much torque would it take to spin the wheel?
 

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BirminghamTJ said:
That would be cool! So is cutting the breaks the same thing. Making two brake lines, left and right?
Well it is just the had brake so you only need two cables.
 

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The e-brake cables actually Y from a double at each wheel to a single only a few feet from the actual handle.. it wouldn't take a whole lot to get them direct.
I was looking into it a while ago and had considered getting a fabrication buddy of mine to make a single/dual style pull for mine.

This thread may have re-spiked that interest...
 

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To me it'd be a lot easier to just install some type of locker in the front or rear depending on what rear axle is installed. :)
 
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