Traction Bars
01-08-2009, 01:00 PM
#26
yeah - that's what I was thinking, a nice rear subframe brace, but it would work just as well on a front drive car. :-)
As to the beatrush... It's like trying to carry your luggage on the end of a 10 foot pole - you're pulling on it over a huge lever arm.
I would think even just a strap across the front of the dif would help, anything better would be huge. It would nearly be a flat bar across...
Er, something like this. You probably don't need the other bars. I wanted to make one "horizontal" across, but this does seem easier.
edit: I weld as well as I photoshop
As to the beatrush... It's like trying to carry your luggage on the end of a 10 foot pole - you're pulling on it over a huge lever arm.
I would think even just a strap across the front of the dif would help, anything better would be huge. It would nearly be a flat bar across...
Er, something like this. You probably don't need the other bars. I wanted to make one "horizontal" across, but this does seem easier.
edit: I weld as well as I photoshop
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01-13-2009, 02:18 PM
#28
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Here is what id do for a no wheel hop car.
1) solid diff mounts
2) mazdaspeed motor mounts
3) poly suspension bushings on all the rear arms
4) a good shock/spring combo with somewhat stiff dampening
5) some sort of brace, like a beatrush/autoex hybrid
1) solid diff mounts
2) mazdaspeed motor mounts
3) poly suspension bushings on all the rear arms
4) a good shock/spring combo with somewhat stiff dampening
5) some sort of brace, like a beatrush/autoex hybrid
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01-13-2009, 02:48 PM
#30
My opinion is that brace your drew won't do anything to help with wheel hop.
The differential can move on 3 axis as well as rotate about any of these axis. Rotating about any of these axis is a problem (there could (are) be other things that cause it to hop, but we'll get to that). It "winds up" like a spring when it does.
Here's a pic with 3 axis and moments(torques) about these axis labeled. Green is the axis that goes across the width of the car. Teal is the one that goes front to back. And Blue is the one that goes up and down the height of the car.
Now if we were to brace the differential, our goal would be to prevent movement along and about these axis. So what movements does the brace in the picture prevent? Looks like it's trying to prevent any moments about Y and Z axis. However, it's a very poor design if they were trying to restrict moments about the X axis. The brace is hanging out way away from where it's fastened to the diff. If you think about it, it's like a weight hanging on the end of a pole. If you're the one holding the pole, and I add some weight to the end of it, you will have a very hard time holding the pole steady. Leverage working against you.
The brace does help to prevent moments about the Y and Z axis. However, movement about those axis isn't the "problem" IMO. When you load the differential, the front end (attached to the PPF) doesn't try to rotate about the Y or Z axis. It wants to go up, rotating about the X axis. That's why they put the PPF attached to that end.
A better brace would offer as much support as possible at the PPF to prevent these moments about the X axis.
Of course, that's only considering the differentials aspect to wheel hop. The actual hub that the wheel bolts to could (does) move as well when it hops. When you take off in 1st gear, you're putting around 1K ft*lbs of torque to the ground. Well, the hub tries to move forward.
Meh, more later.
The differential can move on 3 axis as well as rotate about any of these axis. Rotating about any of these axis is a problem (there could (are) be other things that cause it to hop, but we'll get to that). It "winds up" like a spring when it does.
Here's a pic with 3 axis and moments(torques) about these axis labeled. Green is the axis that goes across the width of the car. Teal is the one that goes front to back. And Blue is the one that goes up and down the height of the car.
Now if we were to brace the differential, our goal would be to prevent movement along and about these axis. So what movements does the brace in the picture prevent? Looks like it's trying to prevent any moments about Y and Z axis. However, it's a very poor design if they were trying to restrict moments about the X axis. The brace is hanging out way away from where it's fastened to the diff. If you think about it, it's like a weight hanging on the end of a pole. If you're the one holding the pole, and I add some weight to the end of it, you will have a very hard time holding the pole steady. Leverage working against you.
The brace does help to prevent moments about the Y and Z axis. However, movement about those axis isn't the "problem" IMO. When you load the differential, the front end (attached to the PPF) doesn't try to rotate about the Y or Z axis. It wants to go up, rotating about the X axis. That's why they put the PPF attached to that end.
A better brace would offer as much support as possible at the PPF to prevent these moments about the X axis.
Of course, that's only considering the differentials aspect to wheel hop. The actual hub that the wheel bolts to could (does) move as well when it hops. When you take off in 1st gear, you're putting around 1K ft*lbs of torque to the ground. Well, the hub tries to move forward.
Meh, more later.
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01-13-2009, 03:51 PM
#31
Huh. I mean, you have the same logic as me, but you discussed the brace I called useless. The brace I "drew" just ties the front of the diff about your Y axis. Or tries to... And it has an extra "stick" I didn't erase, but I'm not sure it does much for you.
Matt: Vibrato-what? I was thinking you'd mount it similarly to the other diff mounts - a little play won't hurt, rubber mounting won't mean much - if the end of the diff moved 1/4" who cares - or are you saying with solid diff mounts, rubber mounting the end would cause MORE vibration than solid?
Matt: Vibrato-what? I was thinking you'd mount it similarly to the other diff mounts - a little play won't hurt, rubber mounting won't mean much - if the end of the diff moved 1/4" who cares - or are you saying with solid diff mounts, rubber mounting the end would cause MORE vibration than solid?
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01-13-2009, 04:10 PM
#32
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i meant that solid mounting the diff would suck for vibration and negate having rubber mounts in the first place. if you put that brace in, make some delrin or aluminum mounts for the diff ears.
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01-13-2009, 05:37 PM
#34
Already have delrin mounts for the diff. I would probably make the same for the brace if I made it.
The question, I thought, was simple - is that a light weight way to significantly improve the performance of the vehicle (comments on detraction from the comfort are also appreciated).
Certainly poly bushings is a good suggestion, one I've yet to take.
The question, I thought, was simple - is that a light weight way to significantly improve the performance of the vehicle (comments on detraction from the comfort are also appreciated).
Certainly poly bushings is a good suggestion, one I've yet to take.
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01-13-2009, 09:40 PM
#40
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+1
Long arm to framerail to stop front to rear motion sounds promising.
BTW - This isn't the only independent rear car in the world. There must be an answer already.
I sure wish someone would Google that for me...
.
Long arm to framerail to stop front to rear motion sounds promising.
BTW - This isn't the only independent rear car in the world. There must be an answer already.
I sure wish someone would Google that for me...
.
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