tasty danish

iTrader: (5)

This is a question for some of you crazy engineer types that design goofy stuff a bunch (Jeff 20B comes to mind). This is NOT a discussion on how I should, "just go buy an REspeed kit cuz they roxx!!!" I know what I'm asking is kinda... mickey mouse, I just want to ask and see.

Anyway, I had/have a bad *** turbo miata that was wrecked and now I'm parting it out. The spring/shock setup was really baller with custom valved bilsteins and some other stuff.

To make a long story short, the shocks under my miata are nicer than ANYTHING you can possibly buy for the FB. Anything I fit that would compare with or do better than them would have to be custom anyhow, thus my question: Has anyone ever attempted to fit miata shocks on an FB? If bilsteins were still sold for FB's I'd consider it... But even then I already have these babies, and paid for!

I already have REspeed coilovers front and rear, but don't really want anything to do with koni's or tokicos. I don't have all the parts in front to me to compare how different the mounts are, or how impossible this actually will be, but if figured everything on this car is custom already, why not see if anyone has ever had the same idea.

Any input is appreciated.

orion84gsl

iTrader: (5)

Coilovers have been used in the rear, mostly on Ford rear-end swapped drag cars, or at least that's all I've seen for pictures. To be honest I've never seen any data or read about anyone actually TRYING it. Actually JUST read something to the contrary. Here ya go: https://www.rx7club.com/1st-generation-specific-1979-1985-18/front-rear-coilovers-possible-975939/. There was one guy that swapped the Miata rear subframe into an FB. He cut out the frame and welded in new steel where he needed it to mount the subframe and I think he built new inner fender/upper strut mounts. If you search a bit there's a thread lying around here somewhere.

The front would be a little more tricky. You would be converting from a Macpherson strut to a double wishbone. Swapping the lower subframe from the Miata would probably be a good starting point if it will fit. It's been done with the 2nd gen subframe but then you also have to make a mount for the upper A-arm in a space that was not designed to house an upper A-arm.

One last thing, the Miata gear would be ridiculously stiff compared to how they felt on your other car, since the different designs work with a different wheel ratio. If you have the fabrication ability, the tools, the space and the time I say to hell with sanity and go for it. However, if you don't, then just sell the Miata stuff and put the RE-Speed bits on. That will only take a few hours and you'll be able to drive the car the next day.

j9fd3s

iTrader: (3)

i know its tempting to use the nice stuff you have, but you should just buy the right parts.

i think the miata rear shock would actually fit, i know the Rx2 people use em, and the FB can't be too far. for the spring, the miata won't work as its got a very different motion ratio, and anyways you should just buy the right 5" diameter (or whatever it is) spring in the right rate. eibach and hypercoil both make springs in the right sizes for the FB rear

in the front you could use the spring, and the coil over hardware, but again the miata has a different motion ratio, so the spring rate is way off.

there is no way to use the miata front shock, without converting the whole suspension.

tasty danish

iTrader: (5)

Appreciate the response guys. As I said, i DO have REspeed coilovers front and rear (well, adjustable perches in the rear) and intend to use them, I'm just concerned about the shocks. I have 325 rates for the front, 200 rear.

I do not want to switch to a miata subframe or running gear or any of that. I don't need to keep the springs etc, I simply want the shocks themselves as nothing available for the FB gets close to what I'm running now.

I'm thinking I could fit the rear shocks and keep the REspeed coils and perches, as j9fd3s alluded to.

Also, I had intended to do the FC subframe swap, so if the fronts are just impossible, I suppose I could buy FC bilsteins and have them revalved and still get to have custom bilsteins all around?

bshusted

iTrader: (1)

I'm running Miata front struts on the rear of mine with stiffer coils in the stock location.

Kentetsu

I'm running Biltstein short stroke shocks on the rear, along with the adjustable perches. A tad stiff around town, but always ready to get down to business when needed. They're not adjustable, but for performance aplications, they just plain work.


(I didn't say the "R" word a single time! )
.

tasty danish

iTrader: (5)

right but you are running pieces made for the FB which are not longer available. That, and mine having been custom valved are a little nicer, so i'm just curious if I can make them work.

Kentetsu

The Bilsteins I'm running are still available, and are re-valveable as well.

j9fd3s

iTrader: (3)

FB rear = camaro and AE86 rear.

its the FB FRONT that is the hard part

Box_Man

What is the length difference between the Miata shocks and stock rx7 rear shocks?

RX-7 Chris

iTrader: (19)

I thought a number of people used the fox mustang rear shocks.

mattp

iTrader: (3)

The difference between Miata front and RX7 rear? I think about 3". I don't know the exact stock RX7 length, but Monroe's replacement (5881) is 21.125" extended. I've got the same number written down for Tokico Illuminas. Monroe shows 18.125" extended for the Miata front (71285) length.


See attached for some additional reference info on Miata strut length. These came from http://www.fatcatmotorsports.com/chassis.htm. I believe these are the measurements of the strut bodies only.



Monroe's catalog has a pretty comprehensive list of part numbers and their dimensions:
http://www.monroe.com/catalog/Misc-Information
Mounting and Length Sheets


I've attached a really rough copy and paste of this catalog. It's a ZIP of a TXT file because of the file size restrictions here. You can import it into Excel with no problems. You will need to reference the actual PDF of the catalog to see the mounting types and how things are measured.

Monroe's part lookup is a great resource to use as a starting point.
http://www.monroe.com/catalog/Part-Search



So to provide some input for the actual question, you may be able to swap the Miata front to the RX7 rear, but that's probably about it. The Miata rear is incredibly short for our application.



There's this other current thread that might be of interest to people reading this one.
https://www.rx7club.com/showthread.php?t=975939