True coilover upper perch/mount
 

What about it? That seems like something simple enough and beneficial to everyone. A true upper mount that maintains the same shock and spring angle!

http://i158.photobucket.com/albums/t...ce/shock03.jpg
http://i158.photobucket.com/albums/t...ce/shock02.jpg
http://i158.photobucket.com/albums/t...ce/shock01.jpg
http://i158.photobucket.com/albums/t...ce/shock04.jpg

Yea that seems like a snap to do. I understand the need for it to move, but this just kind of jarred things in my head a bit. When you mount a strut tower bar, doesn't that further reduce the angularity that you can get with the shock? Seems like a strut tower bar would modify the effective spring constant. Though I'm not sure which is more prone to the deflection, the thin shock towers or the flimsy looking shock interfaces.

What is a reasonable price to pay for this? (I have to ask or I don't know what materials/ processes to start from, or if its worth it)

Market? How many people would by this?

Whats the performance increase? (maybe tied to what I was first talking about)

like the FM upper mounts with spherical bearing? same right?

ps move the shock shaft mounting point up like the NB mounts.

No. The FM mounts don't have the upper perch separate from the actually mount, so the spring is require to bend with the suspension arch. The OE upper perches/mounts actually achieve this to a degree - better than the FM pieces for sure since the OE pieces do flex. Technically what you see above is the proper way to do a coil over.

We used the above assembly with a custom built tube shock using bilstein pieces, that was shortened just over an inch. The results were phenomenal and bullet proof.

The arguments against this for cost would be that the Miata suspension has so little travel that the spring flex/bend is nominal and doesn't really effect performance. BUT if you were to combine what you see in the photos with some increase for travel using off the shelf shocks, you might have an argument for sale. But cost against competing product is your target.

Just throwing ideas out there because I know you're looking for something to do. :D

Basically I see one turned piece with a 2 piece aluminum housing ontop which traps the spherical joint of the turned part that sits around the shock extension, and is secured with a nut to the housing, which is further secured with another nut for paranoias sake. Is that what's going on here?

That sounds right. The top perch isn't technically secured by any nut, it's trapped between the spring top and the spacer/ring that sits between it's top and the bearing.

I seeeeee, I didn't look hard enough at the disassembled. Maybe you could make a post, and see who would want one.

Depending on the price, travel, and compatability I might be interested in a full package later in the year.

oh that's right, the FM perches bend the spring. as do the TEINs et al.

my issue with the separate perch is that you lose all that space for travel. and as you know from the "upgrade" from NA to NB top mounts, that top mounting space is valuable.

the picture shown above puts your bumpstop very low. that removes travel. you'd have to have very short shocks to maximize travel.

I would love to see something like that where the bumpstop was raised up from the spring perch so that the shock could compress further. problem is, there's not much space to do it. kind of like the the JIC FLT-TAR rears.

http://www.good-win-racing.com/miata...rs%20small.jpg

but of course with separate spring perches that move with the spring instead of hard mounted.

My issue with the seperate perch is that now ALL the (sprung) weight of the car is supported by the spherical bushing and the mount assembly.

I'm not sure what those bearings are rated for, and I'm sure they make sturdy ones, but just something to think about. In stock setup the sprung weight is transferred straight to the chassis, all compression. With this setup you are hanging all of that weight from the tops of the mounts, all tension forces. Where this mount usually only sees damping forces, you are now adding the mass of the vehicle, and the stored energy of the springs, as well as all of those vibrations.

Maybe it's really not a big deal...but I feel like you're adding a failure point for minimal gain.

The bearings aren't a problem, you can get 5000 pound rated thrust load spherical bearings without blinking. The big thing is how much additional travel would make it attractive, and how many people care about a true joint at the shock tower.

Ok, now that's a rating!

I was also alluding to the mount structure. Aluminum in this case. Anyone done fatigue life calculations on those for the added load?

EDIT: Again, probably not a big deal, but it is a dill until you've checked.

I'll use Mil-spec SN curves to check the number of fatigue cycles to failure for the maximum stress point. You don't have to worry about your part failing.

id be interested in something like this for the right price as well..

Well whats the right price? What is this worth? Spit it out I gotta know to start.

mounts that allow for a little more rear travel (as seen in JIC's above) would be super duper.

didnt danscreations make something for the rear a few months back?

Edit: Found it:
https://www.miataturbo.net/forum/t18502/

Looks like its only for tein users

Good catch, what happened to this guy?? Looks like the idea wasn't well received back then.

they were the expensive...

I know these are $40 each:

http://iscracing.net/images/01miataupperplate.jpg

and doesn't use a spherical bearing
and doesn't use a separate spring perch that moves with the shock

I'm gonna post a pic of the FM mounts just to keep the thread complete

http://flyinmiata.com/Store/images/13-57100.jpg

note the nice cavity for the bump stop. just slice off some of that phat bottom part and replace it with a shaft-mounted perch... tada.

Since no one wants to own up on a price. I was thinking probably a 100 a piece. These are more difficult to design, more expensive to manufacture, and use more proprietary parts the FM's unit. Probably the best I'm going to do. So who would buy a set of these for 200?

I don't see how you can have both. The fixed mount is what allows for the increased travel of the long shock. That's really an ass-backwards approach - you're supposed to use a shock length to fit your suspension. I'm actually running the ISC pieces on the rear because they work and they're cheap. I'd choose the bushing over the bearing for a street car any day in this circumstance.

My guess is IF somebody saw the need for these proper mounts/perches, they'd also want to build a shock to suit their needs. It's really a difference between perfect and close enough.

That is always the question, is close close enough? Personally, from a mechanical engineering standpoint. Not close enough increases your spring constant at the points around maximum shock travel, and very little around usual travel. Further this is just spring constant. I couldn't imagine it being anymore then 50 lb/in variance. That is a long torque arm. I might be able to make a cheaper FM version, but isn't that what ISC is?

Yes- ISC has filled that void. IMO this design would be on the other extreme.

My intent was to throw out a product idea, not request a product. I thought this seemed more feasible, marketable and attainable for more owners. But I'm not an engineer.

When we were doing a suspension for the race car, the engineer flat out said that what he did was the correct way to do the coil over, anything else was less than correct and anything less than correct was a waste of time. Those might not have been the exact words, but that's a good summary and delivers the point. :D

and i guess that's where keith at FM was going when he worked out the optimum shock length for a miata. you dont need adjustable length shocks, you just need enough droop travel that you dont lift a wheel but not so much that you hurt driveline angles or bind and you need to set bump travel so that you almost but dont quite rub the wheel in the fender well with the bumpstop removed. if that length allows enough room for the suspension setup with the floating perch, the work is done.

however....

even though rob's suspension guru says it's not worth it to do it any other way, how much does the spring REALLY bend? and what load does that put on the components? and how do those loads affect handling?

I'd be all for a set that has the normal spring setup, just taller for more travel. I don't plan on going out and winning Le Mans, I just want something I can use with a basic shock (Illumina's for example) to improve on track ability for a better price (the bearings are nice too).

100 a piece? never mind

I think his point behind what he built was that going with a known proper application means you don't have to go to all the trouble of figuring out all the "what ifs". It's a very similar scenario to building a miata turbo setup.

if we give two identical cars (EXCEPT for these perches) to the stig and have him do a double blind set of laps in each, would the lap times be different?

It is the proper way to do coilovers, as long as a doesn't compromise travel. One other thing to look at would be the springs twist as it is compressed.

in theory yes :giggle: - I believe the approach in racing is to control the things you can to reduce lap times so you can compensate for the driver's mistakes.

I would HIGHLY recommend you grab the ISC mounts.

I had them on agx's and cheap sleeve coilovers and the entire package was very competitive, especially for the price.

For anything other than a hardcore track car I would say they are your best bet for price/performance.

I never discourage product suggestion thats for sure. I wasn't being condesending either I just wanted to make sure I was understanding everything correctly. We had alot of information flowing in, and I had to put in words what I was thinking so I could be corrected if I was wrong.

Clean sheet of paper, there is no reason not to do floating perches. There is a significant bending moment on the springs that has an effect on wheel rate and damper stiction. As you mentioned, if the damper is designed from the outset to give enough stroke with the floating perch, you have the best of both worlds. That's how I configured the double adjustables I'm developing.

I'm not good enough with the math but there is some data floating on the interweb and on Hyperco's site re: bending loads, before and after results with floating & fixed perches.

A dynamic lb/in spring factor yes, some trivial dynamic factor added. Damper static friction force... It adds side load to dampener, increasing the normal force, increasing the friction force and induces dampening characteristics based on theta of axis which is not intended? I could see that. The side load would be tremendous while the vertical load would not. I would bet the shocks life is significantly compromised without a full floating end.

Separate from the side loads that are geometry induced, a flat wound coil spring twists and generates side load when compressed. Additional reasons to isolate those spring forces from the damper shaft with floating perches. That's where hydraulic perches come in and where I stopped. The hydraulic perches take up too much room, require maintenenace and aren't cheap.

The Miata geometry isn't too bad, not as bad as some. What steered me towards floating perches was uncovering how much side load the spring itself generates. Combine that with the geometry and there was enough load to raise a flag. I go through so much effort with urethane bushings, spherical bearing shock mounts and all to reduce friction, and the fixed spring mounts are still introducing friction right at the damper shaft. Argh

Hyperco's OBD ( Optimum Barrel Diameter) springs are designed to reduce the side loads while reducing overal spring mass. Our damper is designed around the Hyperco springs.

The OEM replacement floating perches M2 showed are a great idea but I don't think too many will be able to make use of them without custom damper bodies. Typical OEM replacement steel bodies like Koni, Bilstein and Tokico are far too long. Koni Race's would have to be built with custom long shafts and I don't know if the valve body is short enough to actualy increase stroke and they're already only 72mm in rear.

Maybe the guys with 28/30 series Koni's, Penske's et.al would use them but that's a really small market.

Sorry for the necro-post,

Could you not use a torrington (aka needle) bearing to allow the springs to spin? capturing it may be a little tricky though.

We could chrome treat the springs and mesmerize the competition. :giggle:

It is a good point, I'd be worried there there would be complications with doing this. I don't know what effect building up angular momentum in your spring has.