Shock Woes :/ Advice aprreciated!
 

After a lot of research and work and buying stuff and making adjustments, I feel kinda stumped here...

So I bought TEIN S.TECH springs and had them installed about a year ago. All was well. However, I noticed that when I would bump over speed-bumps at even just 5-7 MPH (alone in the car, and I only weigh about 155lbs) my shocks would "bottom out" and hit the bump-stops in the rear (the front has never been an issue). If I had someone in the back seat the shocks would hit the bump-stops very easily and teeth-jarringly hard, and with TWO people in the back seat it felt like they were literally riding about two millimeters above the bump stops, and would hit them hard at the SLIGHTEST provocation - even just mild dips in streets or on the freeway, or during turns.

So, after reading that the stock Mazda shocks often start to go flat around 30-40,000 miles (I'm at almost 50k now), I purchased a set of Koni Yellow Sport shocks for the rear and had them installed. This did very little to fix the problem, and I was still hitting the bump-stops very easily. I read on here and elsewhere that installing aftermarket springs, especially the S.TECH's, requires one to cut an inch or so off of the yellow rubber bump-stops to avoid this phenomenon. So, I watched some YouTube videos and bought some tools, and basically taught myself how to remove my suspension. Upon doing so, I was very surprised to find that my car HAS NO BUMP STOPS. Apparently the dudes at Pep Boys just didn't put them back on when they installed the Koni Yellows. Maybe they realized I didn't need them because of the ride height, or maybe the bump-stops were already annihilated by all the hard bumps. So for the last 2 months at the very least, now I know my car has been hitting... Metal-to-metal I guess..?

While I had the suspension disassembled I adjusted the Koni's from fairly soft to very hard, and this helped slightly, but not much.

So... Does everyone who drops their car (only a 0.7" drop in the rear with the S.TECH's) just have to live with this happening constantly? Is there no fix? Will bottoming out the shocks without even having bump-stops to dampen the impact start to break the upper mounts in the trunk loose or damage the car? What can I do at this point? I'm thinking... MUCH stiffer springs maybe..? Any recommendations?

Anyone with any experienced advice is appreciated :sad:

While I don't have S-techs, none of this is normal. You should never even hit the bumpstops, never mind bottom out a sock without any.

See if the springs are installed how the manufacturer says to install them. PepBoys could have easily goofed up the installation. And I will guess that they didn't tighten the link arm bushings with the car on the ground, so that might not be helping.

Take some white-out and paint it between each coil of the spring, then go for a drive. It will show you where the spring is coiling completely and where not, so you can assess how it's behaving,

Correct me if I am wrong but you only have Koni yellows on the rear?
That could be the problem right there.
I have Koni yellows with s-techs and never hit the bump stops.

And you should go get bump stops for the rears if they are missing, they are there for a reason.

That's just wrong. MANY stock cars cornering hard will be onto the bump stops. They exist to smooth out the bump when you run out of suspension travel and can be a way to adjust handling without making the car too stiff in normal driving. Load the car up and it might be on the bump stops already. They're like a second spring, so you might not even realize what's happening.

It sounds like the springs are simply too low and too soft for you. Maybe if you got shorter shocks (as in custom) it'd allow more bump travel and you could get away with it, but I'd be looking for some higher, stiffer springs.

Also, get some bump stops on there ASAP. While you're in there, maybe try assembling one side without springs and compress the suspension to make sure there's nothing else hitting.

Yeah I looked at the instructions when I put them back on, and there doesn't seem to be it's pretty straightforward; not much way to put them on wrong.

Wait so if you have the same setup as me, then what are you saying the problem is..? O.o Also, should I trim down the bump-stops beforehand? And if so, should I trim the top part or bottom part (I read that the top section is harder than the bottom section for increasing stiffness as the shock moves upward)?


My drop is only 0.7" in the rear, that doesn't seem very low; and I mean I don't want to sit as high as stock. When you say "custom shocks" do you mean like custom-made one-of-a-kind? Or can I simply buy shorter shocks somewhere?

Also, if I installed trimmed half-height bump-stops, how hard would the "bump" be, since they would be bumping so much more often due to the reduced shock travel they lend? Will it hurt anything if the car is basically riding on the bump stops? Or literally riding on them if I have anyone in the back seat?

Sure, fine, but we're not talking about cornering force here, he gets this on speed bumps at walking speed. A suspension that bottoms out in this condition (or actually any regular street-driven condition) would be a hazard if it ever did experience hard cornering.

I'm at a loss as to the actual problem. Is the ride height at least correct? Is the car actually 0.7 lower or too high/too low? It sounds like a spring that's too weak to manage the weight of the car.

Locally we have had two member with blown Koni Yellows within a month or two of install. One of the failures was obvious and just complete failure and the other was internal, you could compress the shock by hand easily. One had H techs, the other had S techs. And before the failures both cars sagged in the rear (common issue with failing shocks). I also saw a post in the RX8 FB page where a guy got a set of Koni's that were DOA with leaking fluid and there was not apparent damage of the package so my guess is that quality control is an issue at Koni. But he track guys on many platforms love the Koni stuff so i don't know what the deal is. One other guy I know (WTBrotary) had the Koni yellows with S techs and while he never complained of any issues, his car always sat lower in the year. This is also a somewhat common issue with Tokico D specs.

The only way to know for sure is to install a set of shocks springs that is know to be in proper working order. Both guys I know who had issues just went with coil overs, sadly one of them went with powertrix coilovers (didn't listen to me) and then had issues with those and failing bushings. The other guy is running a set of SARX coilovers that are based on Rx-8 spec Bilstein HD's.

My thoughts exactly :/

It's sure as hell not too high. I don't think it's sitting too low either though; I mean I have a relatively small 12" subwoofer box in the trunk with an amp, but I don't think it's enough weight to significantly weigh down the back at all. Keep in mind that although there's only a very small gap, these aren't short sidewalls - 255/45 tires on 18" rims.

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I don't know. In any case, anyone know where to buy rear bump-stops for our cars? I'm not seeing any online right now with the old Google search...

Holy tire batman. And yes a 12' sub box will make a difference in ride height on an RX-8. I don't think you are hitting the bumpstops either.

Also, what are the specs of those rims? They surely are not stock 18' RX-8 wheel specs.

Yeah... I gotta buy bump-stops I guess. And those are Konig Lace 18" x 9.5" rims, with a +45 offset, on 20mm spacers (which I think means they effectively have a +25 offset, I guess?). On the plus side, I have zero rubbing even with the spacers and wide rims and tall/wide tires. Just bump stop problems :(

You have no rubbing? I don't believe that for a second.

Haha no seriously, I swear. It took me like a week of tweaking it, but eventually I got it done.

After a feeble and horribly-misguided attempt about a year ago to roll my rear fenders ghetto-style with a rag wrapped around a small baseball bat (I know, don't even start) in order to fit 245/40's in the rear with 25mm spacers, I recently upgraded the rear tires to the beefy 255/45's.

Those fat bastards did not want to fit, but I was bent on making them. I ended up largely gutting the liners out of the fenders, buying a professional fender-flaring tool (the kind with the roller on the adjustable arm that you mount on your wheel hub) from Ebay and rolling the fenders as much as possible with that, and then using the trusty ole' phone-book flaring method to get those extra few millimeters of clearance, and eventually had to drop down to 20mm spacers... But finally I triumphed and they fit now without any rubbing whatsoever! So much for resale value.... But then again, my 8 is already a salvage title, so screw it right?

Measure from the hub to the fender lip and compare that number to other people's posted numbers to get an idea if they area actually lowering the car 0.7". Also, I'd check to make sure it's actually the shock bottoming out and not something else hitting, as that wheel and tire setup would be high on my list of suspects. Maybe try removing the spacers and see if it's still happening.

One side effect of spacers is to effectively lower the spring rate, as you're moving the tire, which is where the forces come from, further away from the spring, sort of like putting a cheater bar on a wrench. This will make any bottoming problems that much worse. Now 20mm may not sound like much, but in the context of the suspension arm lengths, it far from negligible.

I'd suspect that with the extra weight in the trunk and spacers, you're actually lowered more than 0.7". Plus, are you sure they're genuine springs? I seem to recall there being a problem with counterfeit Tein springs.

I have them on all 4 corners and you didn't answer my question do you only have them on the rears or did you replace all 4

yes cut the bumpstops from the bottom (smaller end) up about an inch.
the photo shows the front but you get the idea
https://cimg0.ibsrv.net/gimg/www.rx8...31d29f0626.jpg





try removing the spacers like black said and see if the noise is still there

Only on the rear. As I said, the front is plenty low enough and has zero rubbing problems and zero bottoming-out problems, so I elected to simply not screw with it. One variable at a time... Especially when spending an extra $300+ would bring no significant benefit while bringing a risk of causing more issues.


I will order some bump-stops and do this. Thanks for the pic, that clears up a lot.


I'll try this first and see if it changes anything. Given the extreme ease at which they bump, I suspect they will still bump, although maybe a bit less; hence I'm betting I will want some bump-stops either way.

I'm pretty sure my TEIN springs are genuine; I mean they came in a legit box with instructions and such, and I bought them from TurboXS right here on the RX8Club Vendor Forums, so if they're fake then there might be a bigger problem going on... TurboXS is reliable, right?

Unfortunately I've been unexpectedly sent to a tech-school all the way in Virginia for a few weeks, but I will do all of this as soon as I get back to San Diego and reply back for sure!

Well TurboXS doesn't show up on Tein's dealer list on their website. Anyway, read this, compare the pictures to what you've got and decide for yourself, it's something to consider at least: TEIN USA | COUNTERFEIT

Note: I have no opinion of TurboXS either good or bad, and I'm not saying that they tried to screw you or anything, it's just that counterfeit Tein springs are a problem that I'm aware of, so something to check on.

Hmmm... It seems like they are real, but I can't see the box label or the TEIN logos on the springs themselves very well in these lo-res pics I have on my laptop that I brought with me on this trip... I still have my stock springs in the TEIN box back at my place. As soon as I get back I will examine my springs and the box and labels and try to see if they are counterfeit :/

If you had Pep Boys install the Koni shocks then more than likely they didn't know any better and used power tools to install the top nut shaft like the usual non-adjustable shocks they normally install. Using a power tool to install the top shaft nut will cause the Koni shock to fail internally.

I wouldn't doubt it. When I removed them myself and used an allen-wrench to adjust them to varying degrees of softness/hardness, they responded appropriately and expanded much more slowly or quickly depending on how I set them; would they do that if they had failed?

In any case I have ordered a brand new set of bump-stops, so I'll go from there when I get back home to San Diego in 2 weeks.

Got my new bump-stops in the mail and cut them down today... I will install them soon - likely this weekend - and update :)

Since this seems to be stumping the group. I had a thought.

Knowing that Pepboys did original install and that you are a little new to suspension install and may not know when something is missing; Do you recall there being a washer on both sides of your top hats in the rear? I wondering if you are missing the lower washer and your strut is passing through the top hat and hitting the body of the car above the top hat.

That is a stretch, but this wouldn't be the first time I have seen someone do this.

Here is a freeze frame of us doing the fronts on an RX8. These are not Koni's, but the setup is essentially the same.

See the Big Washer on the shaft of the strut? There should be one like that on the rear as well. Then the bushings and black top hat (seen bottom left) go on follower by another large washer and then the top nut.


https://cimg9.ibsrv.net/gimg/www.rx8...9093b8b36b.png

what does hitting the bump stop sound like? Is it a soft thud, or a metallic bang. If soft, you are hitting the bump stop, it is soft. If a harsh bang, you bump stop left you for a better place and you need new ones. The front ones last, the rear ones do not. This is coming from the guy who installed coil overs to correct weak springs and did not find out the rear bump stops dissolved until he tore them down after the install. I like the coil overs, but that was a crap load of work and money when I needed $40 of rubber.

OK! Well, I disassembled my rear suspension today and made a few discoveries, and also got the new bump-stops installed!

First Discovery: My TEIN S.TECH springs appear to be legit, given the properly-aligned labels and the way they are applied to the springs via laser-heat or whatever instead of being cheap stickers like the counterfeit versions.

Second Discovery: Bump stops? What bump stops? I have no idea what those shredded, disintegrated red/pink things were, but apparently that was all that was left of my old stock bump stops after eight years of use in hot climates (Hawaii and SoCal).

Third Discovery: KONI shocks appear to not have been broken by Pep Boys' installation; they were still fully adjustable and seemed to respond normally. I had them set at about a quarter-turn away from the hardest setting before, so I reversed course and set them to about a quarter-turn from the softest setting.

Fourth Discovery: I might possibly be missing a big metal washer..? Not sure. The KONI shocks came with the built-in white plastic one in the pics, and there is a big metal washer on to of the black rubber top-hat inside the trunk on top of the shock sock, and there's a sort of bell-shaped silver metal thing that the bump-stop mounts sort of inside (it covers the first/largest tier of the bump stop), and then there's the other black rubber top-hat on the actual shock. Am I missing a washer? Everything seems to work alright... O.o

So I got the new bump-stops properly cut to size and installed with the shocks set to a much softer setting, and there is no more ugly bumping at all! Even doing 10mph over the stark brand-new speed bumps nearby, the ride was relatively smooth and completely clunk-free.

More pics... The shock sock inside the trunk, and the passenger-side shock/bump-stop setup. In the second pic (the pic of the KONI shock, not the first pic of the shock sock), I should note that there was no second metal washer that sits on top of the black rubber top-hat, but that the little narrow extruded ring part of the top of the rubber top-hat fits perfectly up into the hole at the top of the shock sock show in the first picture and seemed sized to fit that way... I'm assuming that's how it's supposed to be? If not, then I guess Pep Boys or someone else must have lost both of the secondary metal washers, because I never encountered one on either shock O.o