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Just curious if you just measured the OE part or measured a the actual engine mount bracket height on a stock Rx8 to see what the true loaded position is with the entire engine/trans/PPF/driveshaft/rear diff/axle drivetrain sitting on the soft OE engine mounts and soft rear diff bushings?
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Hey, sorry I just saw this question. We measured it off the car. I don' think the OEM ones would squish enough to justify removing that spacer. I included a picture for reference.
Also, on the tire discussion of 315s. Yes you can fit them, very carefully, with many restrictions in alignment settings and also incredibly aggressive steering limiters (you'll need custom ones), along with flares/cutting. We kept the the yellow corner marker since the rules were grey, and heated them to bend them to the fender's new shape.
We cannot run at certain locals that tend to have tighter turns now because we don't have a tight enough turning radius, but knock on wood, have not found a nationals course where we hit the steering limit (although we've been very close and have only done one season on the larger tires). So, consider yourself warned. Also, the tires did not magically make us significantly faster. On certain sweeper intensive courses they are faster, but I suspect they might actually be slower at pros or courses with more acceleration bias due to how much they hurt our acceleration from all of the added weight. We are running very light CCW 18x11 wheels so we added as little weight as possible to fit them. I love the way they feel, and also loved our 275s on 17x10 949s. The 295 on the 17 was a little mushy. I always wanted to try the 295 on an 18 but haven't yet. I really dislike the 285 on the 18 - I think it's not enough sidewall and has an incredibly sharp breakaway characteristic that makes the car less forgiving.
Sorry, it was an ongoing discussion over in the Feal 441” coilover thread regarding Feals recommendation for 16kg/10kg springs for competition. Rear rate is a bit light imo, but might be more appropriate for certain track conditions and no rear wing/spoiler.
Thank you Tamra. I know that the mounts were supposed to be designed to mimic the ‘loaded’ height and I know the OE mounts do squish down. The entire engine/trans/driveshaft/PPF/diff are supported entirely by those two mounts in the front and the two diff bushings in the rear. That’s a lot of weight being carried on those four smallish mounting points. It was kind of you to call it out though. I’ll do the same once I can get some measurements/pics of some installed OE mounts.
You don't even need that extension piece on the side of the body; the OE mounts move around that much that it limits them along with the rubber slats on the OE mounts so they're not rattling, plus the OE mount can even break apart/loose and then at least something is supporting the engine. These aren't likely to break, at least not unless the main structure does, which seems unlikely. Especially since those look like the stainless steel version. I don't see the aluminum ones listed anymore, must of dropped them.
Originally Posted by Tamra
Hey, sorry I just saw this question. We measured it off the car. I don' think the OEM ones would squish enough to justify removing that spacer. I included a picture for reference.
Dropped off the rotor rings and hats at a machine shop that wasn't far from where I live. Think I may have lucked out finding this place for some future stuff ...
Should have some solid answers for weight & fitment next week.
Sounds like S2 LCA, S2 Upright, S2 offset bushing for the lower upright, and NC rotors/calipers are a pretty sweet combination. Unless I am misreading some things?
Sounds like S2 LCA, S2 Upright, S2 offset bushing for the lower upright, and NC rotors/calipers are a pretty sweet combination. Unless I am misreading some things?
Are the NC brake stuff outside of the SP rules?
Yes, they do not meet the SP rules. I think JV was saying to use them for SM.
I do have a set of S2 upper control arms with the bushings already removed if someone is interested in buying them. i bought them on accident, installed the offset bushings, then realized they were the wrong ball joint taper and didn't fit the S1 uprights. They're ready to drop in the Mazda offset control arm bushings and install.
I'm not sure going through the effort of an S2 front suspension conversion would be worth it, but let me know if you notice a difference if you decide to do that
Yes, they do not meet the SP rules. I think JV was saying to use them for SM.
I do have a set of S2 upper control arms with the bushings already removed if someone is interested in buying them. i bought them on accident, installed the offset bushings, then realized they were the wrong ball joint taper and didn't fit the S1 uprights. They're ready to drop in the Mazda offset control arm bushings and install.
I'm not sure going through the effort of an S2 front suspension conversion would be worth it, but let me know if you notice a difference if you decide to do that
Oh, so the S2 uprights and LCA's aren't going to work with an S1 UCA? *****. Lol
Final version of the full exhaust. Only 3 lbs lighter than what I had for STX, but the CG is more centered between the wheels toward the RR corner now. The big middle 4” OD x 30” long spiral resonator is contributing a good portion of the total weight, but hoping it makes sound easily. Free-flow potential is improved and total weight with all clamps, brackets, etc. is 37.5 lbs vs. 81 lbs factory. Fairly satisfied with how it turned out, have a pair of small resonators for the tailpipes if needed (+1.5 lbs).
It won’t be worth when the S1 offset camber bushing gets released for sure, though there is some claim of slightly improved geometry.
They always come out with these parts after I go through all the trouble of doing it on my own
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Will it help that much? And I'm curious if this bushing would be STX legal. I haven't had the lca/upright out of the car, so I don't know what it's actually modifying.
There’s a metal insert bushing in the bottom of the upright where the LCA ball joint attaches. The tapered hole in the bushing for the tapered ball joint stud is centered on the OE bushing. The new bushing offsets the hole to move the lower end of the upright outboard, which tilts the axle angle to effectively increase camber. If I had to guess, it probably adds about -1 degree. No adjustment, just a fixed, static increase. It’s the equivalent of the LCA being slightly longer. So technically it increases front track width slightly too.
Based on my interpretation of the STX rule, yes; it is allowed. The OE bushing is 100% metal as is the aftermarket bushing of identical size, it’s an offset bushing, it fits in the unmodified OE suspension part, the attachment angle is not changed, the bushing type is not changed:
14.8.B. Suspension bushings may be replaced with bushings of any materials (except metal) as long as they fit in the original location. Offset bushings may be used. In a replacement bushing, the amount of metal relative to the amount of non-metallic material may not be increased. This does not authorize a change in type of bushing (e.g., ball and socket replacing a cylindrical bushing) or use of a bushing with an angled hole whose direction differs from that of the original bushing. If the standard bushing accommodated multi-axis motion via compliance of the component material(s), the replacement bushing may not be changed to accommodate such motion via a change in bushing type, for example to a spherical bearing or similar component involving internal moving parts. Pins or keys may be used to prevent the rotation of alternate bushings but may serve no other purpose.
Also, not sure you can change the top hat in a way that would fix the weird geometry, at least not legally. I don't think we are allowed to change the motion ratio in SP..
in SP the rule allows any shock mount that attaches to the unmodified chassis mounting point. The rules do not permit changing “geometry” outside of the permitted modifications. Within those two parameters any change in motion ratio would be permitted.
There’s a metal insert bushing in the bottom of the upright where the LCA ball joint attaches. The tapered hole in the bushing for the tapered ball joint stud is centered on the OE bushing. The new bushing offsets the hole to move the lower end of the upright outboard, which tilts the axle angle to effectively increase camber. If I had to guess, it probably adds about -1 degree. No adjustment, just a fixed, static increase. It’s the equivalent of the LCA being slightly longer. So technically it increases front track width slightly too.
Based on my interpretation of the STX rule, yes; it is allowed. The OE bushing is 100% metal as is the aftermarket bushing of identical size, it’s an offset bushing, it fits in the unmodified OE suspension part, the attachment angle is not changed, the bushing type is not changed:
Thanks! I had no prior information on that connection. I assumed it'd be metal, but can't throw the car in the air today and look at that stuff.
You can’t really see much without tearing it apart. Pretty sure I have some pics somewhere and will try to post them
Good idea to buy a pair of new ball joint boots too because they can be difficult to separate without tearing the existing one. I put nickel anti-seize on the studs so they come apart easier down the road.
Hey, sorry I just saw this question. We measured it off the car. I don' think the OEM ones would squish enough to justify removing that spacer. I included a picture for reference.
Based on your rationale of the OE mounts not squishing much I’d put forth that jamming the spacer in and crushing the uethane bushing like that still wouldn’t legal wrt the engine position not changing.
Frankly this situation never even occurred to me and I never had any intent to go around checking anyone’s motor mount height but now that it’s out for public consumption it kind of forces addressing it properly. Without modifying either the engine bracket or motor mount it’s apparent to me that the spacer has to go between the subframe and motor mount.
That’s my recommendation fwiw. It would have been helpful to know what spacer thickness is needed since most people maybe aren’t going to have OE mounts laying around. Which I’m still investigating what the actual “engine position” is by measuring the bracket-subframe height on OE RX8s. Kind of a stupid rule to place such absolute on something that is essentially undefined in the sense of addressing it in a protest.
So my car has the appearance package, which was a standalone option in 2004 if I'm not mistaken. I don't like it and want to remove it. I have to remove all of it (front + sides + rears + spoiler) correct? I understand it leaves some holes visible, is that going to be illegal?
I bought some heavy vinyl “dots” of various diameters in approx. body color and covered the holes & slots with them
I see what you're saying, but that lower platform does not change the position of the engine. It's more like a bump stop of sorts. The point of motor mounts is to stop the engine from moving as much as with factory mounts, so I don't see how its position would be relevant. Adding the spacer at the top puts the motor in the same position before squish at least, but I imagine that is difficult to measure given that a new vs very used stock mount might put the engine at a different height. I would assume that these mounts, with the spacer in place, put the engine within the factory margin of acceptable. Maybe you could get away with a slightly slimmer spacer, but probably not "no" spacer.
Also, the spacer sits on a wider washer of sorts, so it is not "squishing" the urethane any more than the OE motor mount gets squished. That upper arm has to bolt through the motor mount, so there is a metal inner sleeve that it threads into.
1, the spacer pictured comes directly from the company that makes the motor mount, and the spacer is designed to be used if you want the motor to be at the stock height. If you don't use it, the motor position is lowered relative to stock.
2, everything coexists fine. The extension off the mount easily fits into the OEM slot without any modification.
I apologize again because it’s not my intention to bicker or harass you over it. After coming out to look at it again I was just coming to edit/delete my post.
Instead, my position is what I posted previously; the position off the car is irrelevant. What I suggest you do is take those OE mounts, determine what that dimension is from the top to the bottom, and then measure from the subframe to the surface of the installed mount where it meets the engine bracket. I think you’re going to find that you’re mounted bushing height is a protestable distance less than the OE height you think they’re set to.
The true height mounted was even much lower than the unmounted height picture showed. I just proved to myself that even these supposedly stiffer bushings are squishing down under the engine weight more than I realized. Maybe more than the OE bushings, but I can’t be sure yet. I don’t have those measurements because I don’t have any OE mounts or access to an RX8 with OE mounts yet.
This is the unmounted, spacerless bushing off the car, position is not really much different than what you posted for the installed mount with spacer. Concentrating the weight on the smaller spacer area is part of what’s causing more bushing deflection on your mount imo.
So I’m either going to space mine up from underneath or if it becomes too much aggravation just go drop the cash on the way too expensive Mazda Motorsport mounts.
05-23-2019, 07:02 AM
, too many folks screwing around with compromised street spring rates ...
