Yes, I know people complain about this with lowering their cars, but I might have the opposite issue and needs someone who knows more about suspensions to confirm/deny.

Long story is my car has been on and off the road for the last two years at various stages of supercharged and turbocharged; compounded by the fact I've been deployed and moved 4 times in that time-frame; so the 8 hasn't gotten its share of TLC.

When I was driving it last summer it was sitting low and would make a horrible knock going over bumps. My front main seal was also throwing oil so we tore out the engine and chased the suspension knock. Turned out the bottom coil and a half of my rear springs both rusted and sheared off, the car was bottoming on the bumps. So I bought some Mazdaspeed shocks and struts to swap out while everything else was going on. We swapped the rear out by bolting the top of the strut into the trunk and jacking up the end till it fit into the hub (not recommended I know)

I moved (again) in the spring and just now got around to finish getting it running. It has been sitting the entire time normally, without much movement. This week I got it running and noticed a terrible rhythmic scrape sound every wheel rotation. After jacking it up and checking wheel spin I couldn't find the problem and everything seemed fine. Then after taking it for another spin same thing happened. Pulled over and found out the rear wheels were all the way into the wells, and my tire was rubbing. I think every time I jacked the car up it would by me about 2 miles of no rubbing.

Long story but is this a case of a kind of 'pre-load' where my car sat for so long with broken coils that this is its "normal" position? Should I try and "un-load" them by loosening all the arms while the wheel is in the air? It is a matched set of MS springs and struts from Mazdatrix so I don't think it is the usual cheap springs argument. Please help before I start tearing this stuff apart.

 

I'm not sure that this would be the only reason for the sagging rear, but here goes: the suspension link bushings are supposed to be tightened at ride height. If they're tightened at some other height, they'll inherit a sort of a preload as you say. But, all things considered, I don't think they would have the force to compress your springs more than usual.

Any chance you're using springs for a S2 on an S1? The rear suspension geometry was tweaked for S2, so I believe (could have this backwards), the S2 rear spring perch is higher up, and the spring shorter, so if you did have a S2 spring on an S1 shock, I feel like it would sit lower. I know you said they came as a matched set, but might be worth checking the part numbers just in case.

 

I'm not sure why you installed the rear suspension that way but it sounds like blown shocks to me. I have a thread on the subject here somewhere from years ago where all the "experts" were telling me that shocks have nothing to do with ride height when in fact they definitely do. My rear would tuck tire with just my 50lb daughter in the back seat. I had the springs tested by Tein, they tested fine, and then I installed new shocks and all was good. Over the years I have seen this issue several times with various brands of shocks and I have seen it happen on brand new Koni and Tokico (stock shocks manufacturer) D specs.

 

Loki- I don't think MS make SII specific shocks.

9k- Really? MS right out of the box?

 

It can happen, a guy I know had leaking Konis straight out of the box. It is very likely that the Mazdaspeed parts you purchased were sitting on a shelf somewhere for many years. I highly doubt they are still manufactured.

 

How do I test that theory?

 

Pull the shocks and look for an obvious failure. Mine were not leaking in an obvious way but a five year old could compress the shock by hand. I'm not sure who makes the Mazdaspeed shocks, but they are likely gas and oil filled so if just the gas leaked out you would see anything obvious like you would if the oil from the shock was leaking like on my friends Konis.

 

But really if you are tucking tire in the rear then you have either a spring failure or a shock failure, there isn't anything it could be unless something is completely broken.

 

Well the shocks are good and the springs are on the correct wheels....

 

Or it could be that. How long did you drive it like this?

 

You misunderstand me. They have always been on the correct wheels. The fronts are stiffer than the rears anyway, I would expect swapping them to have the opposite effect of a bottomed out rear.

 

I don't understand what you are saying. You are going to swap the springs front to rear?

 

Hahahah no! Just saying at first I thought that might be an issue since they aren't labeled. But after taking them off and looking at the spring rates and heights I did have them correct.

I am sure swapping them would fix the ride height in the back, but the fronts are 100 lbs heavier than the backs, I would just be moving my problem from the rear to the font. I am going to unload all the arms. As soon as the hub was off they returned to a way to high of a "nuetral" load. I am not sure if the bushing have enough tension to compress the shocks and struts the way I was experiencing, but it is the only explanation at this point.

 

My guess is that your rear shocks are goners.

 

They are fine, more resistance the the old stock ones.

 

They are not fine, you have a sagging rear for a reason and if the springs are in the right location then that means the problem is in the shocks.

 

Just got back home from another 8 month vacation....

Bought a set of stock shocks. No dice.

So looks like I am going to have to start cutting bolts on the link arms and test out my theory.

 

Did you pre load the suspension before tightening all the bolts? It can happen. And the rear suspension sag is mostly due to worn shocks. A few RX-8s I know replaced the shocks and fixed the issue. I know you'd think it's the springs, but nope. It's the shocks.

What shocks did you get? Stock? New or used?

 

Do you have a huge speaker box or a dead body in the trunk? And yeah, new shocks or used?

 

All new. I am going with the pre-load/load issue. But all the links/bars to frame bolts are damn near seized. This is going to take some work to loosen them...

 

Well, if the links are seized then there is your issue.

 

not the links, the bolts.

 

Well if the bolts are rusted to the sleeves in the bushings then that is a problem.