Originally Posted by sixshooter
(Post 353083)
+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... . I've searched so much on fixing wheel hop with an IRS suspension. What I said is what I found. Don't let the front of the diff move and put long arms to support the A-arms. A few V8 guys did the long arms on the A-arms and reported success. Another Just triangulated them from the A-arms back to the subframe. Not as optimal, but it didn't affect ground clearance doing it that way. |
Originally Posted by AbeFM
(Post 353052)
You think the PPF does enough to hold it in the Z dimension (er, the y axis as we were talking earlier)?
oh and for the record, YAW, PITCH, and ROLL are the words you want. yaw is left to right like you steer pitch is up and down like pat's signature pic roll is side to side like when you have wimpy sway bars. |
Originally Posted by patsmx5
(Post 353092)
Love your avatar. :bowrofl:
I've searched so much on fixing wheel hop with an IRS suspension. What I said is what I found. Don't let the front of the diff move and put long arms to support the A-arms. A few V8 guys did the long arms on the A-arms and reported success. Another Just triangulated them from the A-arms back to the subframe. Not as optimal, but it didn't affect ground clearance doing it that way. Since my last post I have searched and only found the diff movement idea (which is not a problem for ours because of the torque arm between the diff and the trans/engine) and the need for less compliant A-arm bushings to disallow wind up. As you know, once there is wind up there is often a dramatic release. The long arm helps to compensate (take the brunt of the force) for the softer stock bushings and I assume that is why it helps. Thoughts? Edit: We have people who have noticed at least an inch of movement front to rear (I guess that is FORE and AFT :)) at the wheels. |
fore and art, I love it. My car pulled hard to starboard till I evened out the tire pressure. But you're right, the terms are better than an arbitrary XYZ.
Anyway, how about a small shock absorber? Tie it to the front with a shock - so it pulls forward, fine, but then it won't HOP back. I'd love to see a pic (pat or anyone) of this tieing the a-arm thing. I would guess something like solid bushings would help, at least getting the travel low enough... BTW - FM's frame rail kit certainly helps a bit. :-) I took my butterfly off (left the rails) recently and the car feels noodley. |
Originally Posted by y8s
(Post 353095)
I doubt the diff pivots much at all. it's rigidly attached to the motor.
I suspect the PPF does alot of twisting and bending. Interesting idea for a video shot. |
Originally Posted by AbeFM
(Post 353362)
fore and art, I love it. My car pulled hard to starboard till I evened out the tire pressure. But you're right, the terms are better than an arbitrary XYZ.
Anyway, how about a small shock absorber? Tie it to the front with a shock - so it pulls forward, fine, but then it won't HOP back. I'd love to see a pic (pat or anyone) of this tieing the a-arm thing. I would guess something like solid bushings would help, at least getting the travel low enough... BTW - FM's frame rail kit certainly helps a bit. :-) I took my butterfly off (left the rails) recently and the car feels noodley. Edit: found a link here -->http://www.foxthundercats.com/tctechhighlights.htm |
Originally Posted by BenR
(Post 353366)
I suspect the PPF does alot of twisting and bending.
Interesting idea for a video shot. Mazda Performance Parts: Miata PPF Power Kit |
Originally Posted by sixshooter
(Post 353101)
The only downside to the long arm is the front mounting point. As I discovered when installing Stein's framerail kit, the stock framerail is thin and soft. Maybe at the very back where it is reinforced.
Since my last post I have searched and only found the diff movement idea (which is not a problem for ours because of the torque arm between the diff and the trans/engine) and the need for less compliant A-arm bushings to disallow wind up. As you know, once there is wind up there is often a dramatic release. The long arm helps to compensate (take the brunt of the force) for the softer stock bushings and I assume that is why it helps. Thoughts? Edit: We have people who have noticed at least an inch of movement front to rear (I guess that is FORE and AFT :)) at the wheels. Of course the problem is that now the A-arms want to move in an arc. However, I don't 'think' this is gonna be too significant. IE- how much suspension travel does a stock miata have from say normal ride height to the bump stops? Or as someone suggested, a badass shock instead of an arm might would work. It would not limit the movement, just damp it to prevent an oscillation (wheel hop). |
Yeah - the shock (awesome find) on the t-bird isn't really doing what we're talking about, though I suspect it helps anyway - it's keeping the whole axel/diff from rotating. Certainly that's what I was thinking with a shock - I don't care where the wheel is, I just don't want it to hop, and it's plenty compliant.
Why would you tie to the a-arm, and not the spindle/brake/etc? Something on the end of the travel, and even with the axel as much as possible? That is where the force is applied, restricting only one A-arm would help,but would potentially introduce a torque twisting the entire hub. Pat, why don't you sketch up this picture? |
Originally Posted by AbeFM
(Post 353450)
Yeah - the shock (awesome find) on the t-bird isn't really doing what we're talking about, though I suspect it helps anyway - it's keeping the whole axel/diff from rotating. Certainly that's what I was thinking with a shock - I don't care where the wheel is, I just don't want it to hop, and it's plenty compliant.
|
ideas.
I should point out that these below with the trailing link work because there are two bottom arms and they allow some amount of rotation as the wheel moves up and down. that means you replace the miata component with two arms with heim joints, not standard cylindrical bushings or you will bind. http://www.hyundai.co.in/tucson/imag...neering/25.jpg http://farm3.static.flickr.com/2143/...7ad48c2c8e.jpg http://www.gtfours.co.uk/pics/suspension/205/005.jpg http://www.gtfours.co.uk/pics/suspension/205/006.jpg |
Originally Posted by AbeFM
(Post 353450)
Yeah - the shock (awesome find) on the t-bird isn't really doing what we're talking about, though I suspect it helps anyway - it's keeping the whole axel/diff from rotating. Certainly that's what I was thinking with a shock - I don't care where the wheel is, I just don't want it to hop, and it's plenty compliant.
Why would you tie to the a-arm, and not the spindle/brake/etc? Something on the end of the travel, and even with the axel as much as possible? That is where the force is applied, restricting only one A-arm would help,but would potentially introduce a torque twisting the entire hub. Pat, why don't you sketch up this picture? I need a decent picture that shows the rear suspension and the frame rails to draw to. Searched and I don't have any pics like this, and haven't found any posted yet. |
That 2nd pic that y8s posted looks like the rear suspension of an STI. I own a 2006 and I can tell you that it still wheelhops pretty bad sometimes.
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Found some part numbers for those little dampers.
Monroe 32242 Koni Red 25-1215 $209.95/pair KYB KG 4521 $ 79.95/pair It was also stated in the Ford Mustang forums that the KYB's were much stiffer, and that cheap replacements were available for $25 from some discount parts places. |
It still seems that the cause of the hop would be good to get down - is the wheel moving back and forth, are we just feeling the tire grip and relax, etc? Some high speed video of the rear wheels on a launch would be awesome. I never should have quit my job working for the high speed video camera guys. :-)
Still, I think I have something here at work which might be able to get at least a few hundred FPS, it probably doens't have to be the highest resolution. I'd have to think about it... |
Originally Posted by y8s
(Post 353462)
ideas.
that means you replace the miata component with two arms with heim joints, not standard cylindrical bushings or you will bind. |
Originally Posted by AbeFM
(Post 353531)
It still seems that the cause of the hop would be good to get down - is the wheel moving back and forth, are we just feeling the tire grip and relax, etc? Some high speed video of the rear wheels on a launch would be awesome. I never should have quit my job working for the high speed video camera guys. :-)
Still, I think I have something here at work which might be able to get at least a few hundred FPS, it probably doens't have to be the highest resolution. I'd have to think about it... |
I wonder if you couldn't mount a camera to the car itself. I imagine a webcam would be too slow (though it's the lowest investment, and would follow the wheel). I should look around. And see if we still have the pco.1200
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Originally Posted by AbeFM
(Post 353532)
"The" two arms? You mean, these trailing arms we'd put in or?
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We will be making Miata Traction bars very soon. I just need to find some time when the Hoist is not busy with a Honda getting Traction bars fabbed up for our new models.
Traction Bars is what we do... Checkout Http://www.etdracing.com (Parent company of M-Tuned.com). Just need the hoist free and pull my miata out of storage. |
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