Replacing my 20+ year old suspension, and wheels questions.

euph0r1a · Postby **euph0r1a** » Tue Sep 10, 2013 5:41 pm

Hi all,

Proud new owner of a '90 Roadster, and have been pouring over the forum working out what the best upgrades are for the car.

Taking a look under the car, it's currently fitted with KYB "Buzz Spec" which are 8-way adjustable and are definitely lower than stock. And they're purple. That's about as much info as I can get out of them.

Having no real frame of reference to other MX5's, or sports cars for that matter, I'm having a hard time figuring out if they're horrible or not. I'm gonna go out on a limb and say they've never been replaced (car has 83,XXXkm's on it) and they're extremely stiff. It doesn't feel like they're soaking up anything at all - took it to a mechanic for a different issue and he commented that my shocks probably needed replacing.

So the past few days I've been obsessing over what to buy - I think I've settled on BC BR coilovers, for height adjustability and ease of installation. Looked at Koni/Kings, but the BC's seem to offer a similar ride with more control, for less money. YSR's are an option too, but it all seems much of a muchness.

JustJap have the BR's for $1200, which seems to be a pretty good price. Am I going to feel/see a noticeable improvement? I've got no problem with a bit of stiffness, but speedbumps and highway speeds are a nightmare right now.

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As for wheels - am I going to fly off the road and die a fiery death if I buy some Rota's? The 'knockoff' brands all seem to be pretty much identical. Ideally I love the look of the Chaparral's, but shipping costs from the States seem to make them prohibitively expensive. I'm looking to spend around the $1000 mark, plus another $500 for new tyres (probably KU31's).

Not going to do any track driving at this stage, purely street as a DD.

I like the Chaparrals over the Superlites/Konig Rewinds/Rota RB's (pics seem to make them out to be a much brighter shine in silver, plus the spokes are a little more 'edgy').
Also enjoying the Work Meister (I wish)/Rota Grid look, and the various mesh patterns.

I don't want to roll guards at this stage, so 15x7 would be the max I could go, yeah? I'm not going to slam the car by any stretch of the imagination and don't want any crazy aggressive offsets. Currently on NA6 daisies.

Postby **NitroDann** » Tue Sep 10, 2013 5:43 pm

There is a lot of setup in getting a nice riding set of coilovers.

Have you played with their adjustment at all?

Dann

euph0r1a · Postby **euph0r1a** » Tue Sep 10, 2013 6:02 pm

They're all set to 1, which seems to be the softest setting. The car definitely needs a wheel balance at least, I'm getting the "65mph shimmy" which isn't a lot of fun.

Something that could be completely unrelated, or extremely related - at carpark speeds, turning, especially turning right, causes the whole car to vibrate/shudder, like it's about to stall. Doesn't happen at speed, but it's consistent, and very annoying. Waiting on a low profile jack to lift the car up and replace the gearbox/diff oil and see if that makes any sort of difference, or it could be the power steering playing up?

Postby **NitroDann** » Tue Sep 10, 2013 6:06 pm

The softest setting is almost certainly the least comfortable setting possible, have you adjusted it yourself through the settings?

Dann

euph0r1a · Postby **euph0r1a** » Tue Sep 10, 2013 6:09 pm

When you say it like that, I feel like a bit of an idiot. I'll play around with it and see what happens. What's a reasonable time frame to be replacing shocks/springs? I'm pretty new to DIY mechanics.

Postby **NitroDann** » Tue Sep 10, 2013 6:12 pm

Its very hard to say.

But basically you have to remember that a coilover is in 2 parts, the spring and the damper.

The damper has to be stiff enough to stop the spring just bouncing up and down wildly, and also if its very soft minor bumps will bottom the suspension out giving a very hard BANG, which your back wont enjoy.

If you go too stiff with the damper you simply get a ride like a bmx bike with flat tyres but no shocks, its bumpy and you feel everything.

The shudder... I suggest you open a thread about it in the engine section

Dann

euph0r1a · Postby **euph0r1a** » Tue Sep 10, 2013 6:17 pm

NitroDann wrote:Its very hard to say.

If you go too stiff with the damper you simply get a ride like a bmx bike with flat tyres but no shocks, its bumpy and you feel everything.

Yep, this is what it feels most like, the shocks don't seem to actually absorb any of the impact.

I'll open another thread for the shudder, thanks!

hks_kansei · Postby **hks_kansei** » Tue Sep 10, 2013 6:27 pm

Before opening a thread, is the shudder accompanied by any noises? (grinding noise or anything?)

It may well be that the power steering fluid is low and the pump is running dry.

Also check it's not something as simple as the tyre rubbing something at full lock (unlikely on stock wheels, but it's 2 secs to check... just look for a clean rubbed patch in the guard)

Postby **NitroDann** » Tue Sep 10, 2013 6:31 pm

You have set the shocks to do as little as possible, you need to add in some damping to control the bumps and the springs

Dann

euph0r1a · Postby **euph0r1a** » Tue Sep 10, 2013 6:34 pm

hks_kansei wrote:Before opening a thread, is the shudder accompanied by any noises? (grinding noise or anything?)

It may well be that the power steering fluid is low and the pump is running dry.

Also check it's not something as simple as the tyre rubbing something at full lock (unlikely on stock wheels, but it's 2 secs to check... just look for a clean rubbed patch in the guard)

Could be this, too! I'll probably just replace all the fluids regardless and start keeping a regular service history. Previous owners barely drove it and as a result, there's a very average service record. All I know is that there seems to have been a replacement clutch at 70,000km's, but that was in 09!

emily_mx5 · Postby **emily_mx5** » Tue Sep 10, 2013 6:35 pm

dont bother with cheap coils, just grab some new koni shocks and new springs like king/eibach etc.
15x7 with around offset of 30 will fit nicely no issues there.
195/50 ku31's are also great bank for buck at $90 each.

Magpie · Postby **Magpie** » Tue Sep 10, 2013 6:54 pm

With respect to rims you want to get as light as possible to reduce I sprung weight. The MX5's was designed with a certain unsparing weight and changing this will affect the rest of the suspension.

Also make sure you set pre-load on your coilover a as well as take out any weight being transfered by the swaybars.

Don't forget a 4 wheel alignment!

euph0r1a · Postby **euph0r1a** » Tue Sep 10, 2013 6:55 pm

emily_mx5 wrote:dont bother with cheap coils, just grab some new koni shocks and new springs like king/eibach etc.
15x7 with around offset of 30 will fit nicely no issues there.
195/50 ku31's are also great bank for buck at $90 each.

Good to know I won't have any fitment issues.

Will the Koni's be much better performing than BC/YSR at the same price? I don't understand why someone would buy shocks/springs over much more adjustable coilovers.

Postby **NitroDann** » Tue Sep 10, 2013 6:58 pm

The money that doesnt go into double height and preload adjustment and anodising and advertising goes into better valving that makes the koni a better shock, which rides and performs better.

Dann

euph0r1a · Postby **euph0r1a** » Tue Sep 10, 2013 7:27 pm

Huh, so it appears. Learning so much, so fast!

I've heard a few people sourcing things from shox.com overseas, their Koni/Eibach combo is a great price but shipping packs a punch. I've emailed them seeing if they can ship for less than $700. Otherwise Mania would be the best choice? Anywhere cheaper?