Good ol' 12-bolt.
I considered a similar solution. I look forward to seeing what you come up with.I agree that all of the available adjustable rear perches are a huge pain, so I'm looking to modify, as well. I've been going the opposite direction, though. Rather than cutting the upper perch and making it adjustable, I think I'm going to make the LCA spring seat flat (cut and weld in a flat piece) and run some adjustable perches with spherical bearings. The hexagonal adjuster just sticks through the bottom of the LCA a bit.
Thanks very interesting. I'm at a complete loss for why they would use a bearing there. The strut and spring do not rotate - in fact the fork that connects the strut to the LCA prevents any rotation.I'm looking at this picture of your bilsteins, and it looks like the speed6's had a torrington bearing sandwiched between two plates, whereas you guys do not. Is that the case, or am I just missing it? Here's a pic of what our top hats look like, without that same rubber spring seat. Here's the bearing that is sandwiched between those two stamped pieces.
From the Formula MR=(a/b)^2 * (c/d)^2How did you come up with the .73 MR for the front suspension? I'm coming up with slightly less (probably negligible, just curious), measuring the forward LCA, and estimating the spring angle (12.24" chassis mount to ball joint, and 9.05" chassis mount to shock mount centers, estimated 70° angle from LCA).
From what I've read in the past, and after talking to some of the spring manufacturers, they say the spring twists as it compresses. Without allowing one end to rotate, it supposedly binds the spring a little bit, which changes its rate. BUT, those same spring manufacturers (and the folks at rogue engineering, and probably one or two others) said that with short springs that don't have a lot of travel, it's pretty much a negligible amount. The stock MS6 springs are awfully long, maybe the mazda engineers saw it worthwhile. Since I have them available, and after seeing how well they hold up, I'm going to keep mine in. At worst, they don't help anything and I'll probably never be able to tell one way or another.Thanks very interesting. I'm at a complete loss for why they would use a bearing there. The strut and spring do not rotate - in fact the fork that connects the strut to the LCA prevents any rotation.
For comparison here is my strut mount assembled:
My goal here is to figure out what spring rates I really need. I was using the simpler formula of MR=(a/b)*sin(θ), where θ is the angle between the LCA and spring. [Which is looking at it like a force vector, using only the force perpendicular to the LCA.] Using this, we would have a rising MR, because θ is moving towards perpendicular through bump.From the Formula MR=(a/b)^2 * (c/d)^2
a = LCA inner pivot point to the point where the spring attaches to the LCA
b = Length of the LCA from the inner pivot point to the ball joint
c = LCA ball joint to the instant center
d = Center of the tire contact patch to the instant center
The instant center is the intersection of two imaginary lines: one formed by the angle of the UCA and the other formed by the angle of the LCA. This is where you can have some variability. Also, the instant center changes with ride height.
On my car I found
The angle between the UCA and LCA was about 7deg.
The dominant term is a/b. Being off a couple of degrees and even a couple of inches in the c/d measurements makes little difference, but a 1/4" error in the a/b measurements makes a big difference.
I look forward to your build thread.
Sorry, my bad- I omitted the SQRT function in the formula I gave above. It should be:
Yeah I was thinking the same thing. I ordered some poly bushing to go above and below the plate.Are you concerned at all about the torque that will be put on the new plate and/or shock rod and seals? You have removed the bushing in the stock mount that allows a bit of flex as the angle of the shock changes through its travel.
This is what I ordered.Yeah I was thinking the same thing. I ordered some poly bushing to go above and below the plate.
We're thinking the same thing. I've measured it up and ordered a bumpstop that will line up with the upper ball joint as it reaches the top of its travel. I don't want to rely on my modified strut mount as a bumpstop because if it fails I'll have a hole in my hood. Also the force at the ball joint will be less (by the factor of the MR) than the force on the strut mount. I'll post pic as I get it fab-ed up.I might be a little concerned about removing the frame stop from the UCA. There have been many cases on other cars where the control arm will dent, or even punch through, the shock tower. I was toying around with the idea of putting a normal type of bump stop out there, but haven't done any measuring of the UCA or the math to see what would happen where.
I recall from engineering school, whenever they gave us a new formula they would send us to lab to collect experimental data and prove the formula accurately predicted the behavior we expected. So here we go:I'm a little confused again about your motion ratio and shock/wheel travel ratios and shock travel calculations. The shock motion ratio is a direct relationship between the ball joint and strut mount, along with the angle of the shock. I come up with .73, meaning the shock/spring move .73" for every 1" of wheel travel (it's dynamic, but probably close enough for anything we're doing). I'm not sure why you're using the .5 figure, I guess.