XIDA coil overs installed- I'd like to raise the car a bit
 

I'm assuming that I raise the lower perch to accomplish this. My question: is it 1:1? In other words would raising the perch 1" raise the car 1"? Seems like it would also just compress the spring 1" so I'm confused about how this works to raise the car but if it does, great.

Setting ride height on Xida
 

Motion ratio of the suspension is close to 1.5. It's actually a bit under or over depending on year, which end of car where in travel and wheel offset. I use 1.5 as a rough guide

Thread pitch is 1.5mm. One full turn makes 1.5mm difference in collar position.

So multiply preload collar distance by about 1.5.

Example:
4 turns = 6mm preload change
6mm preload change x 1.5 = 9mm. Multiply mm x .0393 to get inches

9mm x .0393" = .35"

It's not 1:1. In Fact...

"On a Miata, the front motion ratio is 0.69:1 and the rear is 0.75:1"

So for every 1" you move the front perch, the car will be raised 1/0.69 =1.45".

Similar for the rear. Read this whole article, it explains a lot about shocks in a miata.

http://www.motoiq.com/magazine_artic...a-hacksaw.aspx

edit: beaten!

Why not just use FM shock spacers if you don't want to adjust the perches?

Uhhh, what??? Why not go spend money on something else when you can just adjust what you have? Please.:jerkit:

Don't think of it as compressing the spring - the weight is the same so the spring isn't going to change in compressed length. What you're effectively doing when you raise the spring perch collar is lowering the shock in relation to the spring, which pushes down on the lower control arm and raises the car up.

As shorthand, I have always gone with 3 turns = 1/4". Remember that raising one corner of the car will shift weight onto that corner from the opposite side, so even if you were to figure out the exact motion ratio the adjustments are almost never exact or perfect the first time. 3 turns actually ends up at something like 7mm, but it's more than close enough for rough adjustments before you fine tune at the end.

If he doesn't want to pre-load the springs, or has some other reason to not want to adjust the collars up further, they would work. Or he could be in my shoes and have maxed out the collars, and still have ride height issues; thus FM spacers may be applicable. :ky:

If it was 1:1 yes. but it's not, the ratios have been posted, but it's closer to 1.5x.

the spring doesn't compress an extra 1", because the car moves back up 1". the spring will always be the exact same length under the car's body weight...so all you are doing is moving the point in where it rests in relation to the shock...the car sits on the springs so the position of the perches dictate the body height.

Got my Xidas on Saturday, installed on Sunday! :)

I ended up ordering the FM shock spacers yesterday and while I wait for those to come in tomorrow, I didn't install the 4 extra bushings on the shocks before I put them in the car, which I assume is there to raise the car. Right now, I'm running enough preload to compress the helpers half way just to not bottom out on my 1-2" drop off my driveway while I figure out how to get the car a little higher.

Where do these extra bushings go in the stack and what exactly is their purpose?

wtf why? shock spacers on adjustable xidas, are you serious?

just raise the god damn perches. what a waste of $70+ dollars.


what bushings are you speaking of? and why would you leave something off a world class suspension setup? why can't my fist go through my screen and into yours?

Hmmm, wouldn't adding the spacers allow me to back off the preload a bit -- allowing the helpers to expand back out and regain some droop while getting that sweet progressive spring effect by not running with helpers fully compressed all the time?

All I want is to clear my 2" drop off my driveway and not bottom out on speed bumps -- which it did until i cranked the perches up an inch as a band-aid solution. Is my logic wrong here?

Jesus, calm down. The shocks came fully assembled and I installed them that way because that's what Emilio instructed me to. I'm just curious what the extra bushings included are for and where they go. They come in a separate baggie along next to the bag of allen wrenches in the delivery box.

Brainy there are extra 1/2" bushings that go under the top hat. They are optional and I imagine are for people that want to have stock ride height (????)

Joe even if the shocks are fully assembled you still need to set ride height for your specific car.

you have a slight point here, but helpers are meant to be compressed all the time, only in droop should they extend and only to keep the spring planted. If you had fully compressed tenders then that would be a different story. the helper springs are like the shock spacers for your springs :) if the were longer you wouldn't have to dial up back in any more preload.


I don't see raising up perches as a band-aid whatsoever so long as you have not compromised more droop then the sways even allow.

I was also wondering what those bushings were for.

I did raise the car last night- needed to go 20 full turns in the rear to get 12.75" (from center of wheel to fender) and yes, the helper springs appear to be almost completely compressed (and now doing nothing) with the tire in the air.

May end up going 12" in front and 12.5" in the rear which would give me a *slight* amount of room left for the helpers to compress. I'll drive it 1st and see how it feels at the new height and if I get any rubbing.

If you did add the extensions the collar could be unwound quite a bit which would seem to allow for less spring compression... Guess I could just install the other set of bushings and have the same effect although removing again doen not sound all that appealing.

Where are you guys running the shocks- full stiff, soft or in the middle? I counted 12 clicks of adjustment.

My helpers are completely compressed even with the wheel in the air- required to obtain desired ride height.

Same, except i'm not running the perches as high as to fully compress them, because i'm still on my lame 14" wheels that tuck into the fender and dont' rub. If I had my 6UL's on I would have to roll and raise the perches some more. (6UL's get on this weekend when I borrow my friends hammer)

I bought the xidas knowing the shock body is not height adjustable, and I do think cranking up the perch is a bandaid to a degree which is why I went with the FM spacers.

if Soviet is correct and the extra 1/2in bushings add height by installing them with the other bushing under the top hat, what's the real compromise?

my helpers are completely uncompressed with wheel in air. I have poly bushings and 12.5/12.75" ride height

lol, no you don't. Run more camber and borrow your friend's mallet.

The only place I rub is inside the shock tower and maybe the sway bar at full lock. 15x9 + NT-01

they were made this way on purpose, as they were sized specifically for a miata. Adjustable length shock bodies are a horrible compromise and bandaid in order to make shocks fit cross-platform while giving up bump travel.

what spring rate/length did you end up with? something doesnt sound right if you need that much preload in order to only have a 12.75" rear and a fully compressed helper in droop.

Uncompressed length and spring rate of main springs?

Oh that wasn't me, that was carnut169 who has his fully compressed. My helpers are half compressed with 550/350 springs. I sit at about 4" front and 4.25" rear pinch weld heights right now. When I just installed the xidas without adding preload, i was at 3.75" front and rear... I don't understand why people measure hub to fender.

The rates are 550 and 350. Not sure what the uncompressed length is as they are currently compressed and installed.

My car is a 91 and I have the NB hats. Not sure why we'd have such different results to obtain the same ride height... I don't have the poly bushings (yet- they are on order), but can't see that changing anything. Maybe tire/ wheel/ I have Panasports 15x8 with 205/50/15s...

your suspension will droop as low as it can go with poly bushings....

the NB hats do lower an NA miata quite a bit. I've always had to run a bit longer springs in the rear with them than most guys. But so long as your droop travel is still maxed by sway, you've only gained bump travel but adding the preload without any adverse effects. Hopefully emilio chimes in.

XIDA CS only comes with NB mounts.

yeah and all things being equal, the NA chasis that gets the same spring rates as the NB chasis should have to raise the perches a bit more then the NB to achieve the same ride height in that case.

so long as coil bind isn't coming into play and the droop travel hasn't been compromised, there's nothing inherently wrong with adding preload.

I have the same setup on a heavy MSM and had to use FM spacers in the rear to get to 4,25" ride height without preloading the helper all the way down. (YES! With the car in the air...)

This is with a 6" 350lbs spring in the rear.

The extra bushing goes under the topmount to allow some extra droop and basically just positions the shock lower in the topmount. It also does help get some extra ride height even if it doesn`t really make sence...

I tried with 7" springs, but this just landed the spring perch a bit to close to the driveshaft. I have my own design delrin topmount spring locator which also uses the original spring isolator rubber and also gives a bit more height than how they originally shipped out.

anyone got a pic of the bushing -- just curious to see what you are all talking about.

the little black round things, upper left corner of picture.

https://www.miataturbo.net/attachmen...ine=1337714054

put them between the mount and lower washer?

yah i think that's how it was intended.
XIDAs don't come with instructions but if you think about it's not rocket surgery.

this is the normal bushing. the spacer would go between washer and shock.
https://www.miataturbo.net/attachmen...ine=1337716114

okay, makes sense. carry on.

Last Saturday, I took one of the rear shocks apart before I installed them and look at them like a confused ape for a while, and I did test fit that bushing under the tophat like lassi suggested because I thought I remembered a thread on CR where someone mentioned doing that.

IIRC, I didn't install them because with the two bushings under the tophat and then the bushing/washer on top of the tophat there were only a few threads left on the shock shaft for the nut to grab onto. I figured I was doing it wrong so I just installed the shocks the way 949 gave them to me, without the bushings installed.

I guess with the FM spacers and the bushings installed, I'd be able to remove a lot of preload and get my helpers more functional again which might improve ride quality?

I kind of understand that the additional bushing is moving the entire shock lower in the car, but what are the drawbacks? Loss of rear suspension travel? Seems like it's doing the opposite of the xida billet mounts or the FM rear shock mounts and limiting bump. I feel like such a noob with all these questions :facepalm:

If the dampers were originally designed for quite low track-orientated ride heights, which is what I can gather, then isn't screwing the springs to 'significantly' (1 inch? .5 inches?) raise the ride height taking the dampers out of their designed operating range? As in, they'll work, but the damping sweep will be a bit off. This is the logic I'm working with that's lead me to want to space my car up with the equivalent of FM's top mount spacers, instead of just winding the springs up beyond the 4.75" front/5" rear measurement that Emilio provided me with.
So in short, I'd like to defend the people that are getting slated for using top mount spacers 'unnecessarily' :P Unless, of course, I'm wrong. Thoughts/facts please people.

Edit: also, wouldn't spacers allow you to fine tune the compression of the helper spring at a given ride height? I.e., Set your preload, and therefore your helper spring squashedness, then set the ride height with spacers.

Without thinking this through I would assume you'd loose a little bit of bump travel, sound like you'd install it if you wanted to lower the bump stop a little more to stop the travel of the shock...maybe to prevent a tire from hitting the fender on very very low setups.

Correct.

Problem I had was that without the bushings it felt like I had to force the shock to droop fully to get my desired ride height.
I was more like forcing them to get to a height that it was not designed for and the remaining droop travel was becoming more like non-existant as I went higher.

The way I set it up now in the rear with the extra bushing and the topmount spacer and spring locator I have the ride height just the way I want it and preloaded the helper about half the way down at full droop in the rear. With a lighter NA you should have even less preload on the helpers.

The extra bushing we include in each kits makes the damper longer for a given preload. Stroke remains the same since they mount above the collar, not below it. For heavier cars with softer springs running taller ride heights, it's good idea to add it in make the helper more effective.

The helpers are designed to be fully compressed at static ride height.

FM shock spacers do the exact same thing for $68. Ours are free and come with the kit.

Are we talking about the 'spring locators' discussed on m.net? For the record, my rear tender springs are completely coil bound at full droop. The fronts are fine. I don't have the ride height measurements handy but it is pretty low. When comparing the track car (NB/MSM subframes, control arms, etc) to the now stock MSM, the OEM MSM rear suspension droops 3 or 4" farther than the Xida equipped car. If I unhook the shock and sway, the track car's control arms droop as far as the MSM. How does the droop travel for the xidas compare to the bilsteins according to the build specs?

We ship each kit with foue extra black urethane shock mount bushings. These can be stacked on top of the identical bushing that is already against the mount on the underside. This makes the effective shock length about 1/2" longer which reduces preload required by the same amount.

Some cars end up with bound rear helpers, some don't. It depends on the weight and ride height.

No, spring locators afaik are a dead issue. Regarding the rear "helper" springs, so are mine. My 95 hasnt had any weight reduction. In fact all ive done is add weight to a fully optioned car with a rollbar, hardtop, rail braces, and gaining 15lbs since the holidays that I need to lose before summer. (Oops!)

I think this thread is about making a purpose built race shock streetable with a fat miata. I added the said bushings mentioned above along with the FM shock spacers to get the height I need to clear speed bumps and my driveway without adding a lot of preload.

I freaking love my xidas and have no regrets so far in choosing them over ohlins. Weight reduction on myself and the car coming this summer!

Joe, are you saying that even with minimal preload on the rears, due to you spacing the car up instead of winding up the springs, you're still experiencing bound helpers?

When the car is static, yes. I assume the helpers are working though because when I jack up the rear they do expand about half way, so I assume when I go over a bump they do their job and shove the tire back into the ground to keep that contact patch.

The only video i've found of the rear suspension in action is this. Looks like he has an aftermarket sway bar in the rear (I don't) and 7" springs (I don't) and 300lb rear springs (I don't) and a heavier NB miata (I don't)... So I don't know how comparable this is. He's also running .5" higher so probably a bunch of preload. But his helpers look fully bound to me and he seems to be pretty happy with it.

Essentially, I don't know what my suspension is really doing and I think only a good video with my application will tell me.

"I assume the helpers are working though because when I jack up the rear they do expand about half way"
Sounds all good to me then! I thought you meant they remained bound in droop, like the ones in the video.

I'm seriously leaning towards using FM-type spacers not just to jack my car up so the bloody low sump clears speedbumps, but to ensure I use minimal preload to get the helpers working as they should. Could be tested by just jacking up the car and seeing if the helpers extend. If they don't, use less preload and more spacers.

Thats my video which I did to verify the movement, no spring bind and that the helper stayed bound during operation. So basically in the video the helpers are acting as springs spacers and expensive ones at that...
At the time I was running 7" 350lbs springs, the extra bushing, and preloaded the helper about 1\3 down at full droop. Swaybar is oem MSM.
I have since gone back to 6" 350lbs springs, extra bushing, FM spacers and made my own spring centering setup that effectively extends the springs by about 1\3 of an inch. I am very happy now. I have good height, preloaded the helpers about half way down at full droop and the perches are no longer close to the axles like with the 7" springs.

Car feels perfect now. I will make another video to check movement when I get the chance.

My take on the spring centering issue. They center on the washer on the shaft and are made so they do not contact the shock body at full compression. (If the bump stop should fail...)

https://www.miataturbo.net/attachmen...ine=1338275211

And fully loaded before it went back into the car. I had to give it slightly more preload to get my desired ride height.

https://www.miataturbo.net/attachmen...ine=1338275211

The MSM was the heaviest NA/NB made and mine had well over 100# of added braces. With the perches run all the way up to the very top, I had to be careful getting out of the parking garage at work and often times used my frame rails as skid plates. My Xidas are now on the track car which is 95% stripped. It should be under 2,100 dry but I haven't weighed it. In that configuration, I'm still coil bound in the rear but just barely on similar ride heights. Being that low is fine (preferable) for the track car.

I don't know if there are any geometrical differences but everything that can be bolted on the rear of the chassis is from an MSM.