Car is stored away for the winter, so i can't take measurments, so trying my luck here:
Will 7" 400 lbs spring and helper springs fit on the rear koni race shocks with ground control perches? I know 6" would be better, but I have 7" laying around...

Thanks for the help!

Ben

 

I had 7" 350lb springs with out helper on my old advance design shocks and was able to get the ride height down to about 4-4.5 rear pinch weld heights. I now have ASN bilsteins in the back and adjusting the perches down till they almost hit the drive shaft and now the rear sits at about 5". Note I had FM rear mounts and now have stock NA rear mounts which move the top of the spring down about a 1/2 as I recall. So the 7" 400lb springs will fit but your ride height will likely be limited to some thing like 5-5.5" on the low side depending on the upper mounts and I'm not really considering the helper springs. Hopefully that is somewhat accurate and helpful.

 

Thanks for the input! I guess It all depends on shock length and top hat design, because right now I'm running 7" 350lbs in the back, with NA top hats, and I have to put a little bit of preload in order tu have 4,5" rear ride height, and I still have some room on the threaded sleeve for adjustment.
I did some research on the STS miata thread on m.net (I know...) and it seems like it could work... I guess I'll have to just try it out...lol. I would still really appreciate other inputs from here!

Thanks

Ben

 

It's been years since I ran those shocks, but I don't think a 7" spring will fit back there.

 

Thanks for the input mr. Savington, you were pretty much the one I wanted to here. I'll probably end up trying them on and see. I really don't want to lose any droop travel, so if i can run 0 preload or "negative" preload but with an helper spring, I'll run them. If not, I'll be looking for shorter ones!

Ben

 

Like you and others have mentioned, 6" will work with low ride height. You can't get the 7" as low without hitting the shaft.

We had 400lb 7" on Koni race without helpers on NA top hats. When we removed the RSB we went up to 450 and found we couldn't get the height we wanted to run so we went to 6". Like I said though, this is without helpers.

 

Thanks, and with the 400, did they remain seated in full droop or were they getting loose (helper required) ?

Great info for me!

Ben

 

At the ride height we were running they were just unseated. But since we were running a RSB, they were really never unseated. Unless the rear caught air of course.

No RSB now and 6" spring so you know the rest.

 

Thanks for the input, I'll try the 7in in the back with 0 preload, and if I need negative preload, I have some thin swift tender spring that might fit in there.
I'll right the results when I instal them, just for reference.

Ben

 

For the record, ended up with 6.7 in springs, 400lbs/in. Needed about 0,5 inch of preload, and fit perfectly on the coilover sleeve.

Ben