So i had a chance to take the stock shocks off last night in order to compare them to the yellows that i have been waiting to install. In comparison to the yellows and to a set of oe 04 shocks, there is only one slight difference in the shocks and that is that the perch height is about a 1/4" higher on the 09 shocks than it is on the previous models. I have the stock ones out and am gonna have a spacer made for the spring. I was originally gonna have the shocks sent to koni, however the difference is so small that im just gonna get a spacer. All other dimensions including shaft length and body length are identical. I should be able to get pictures later tonight of the two shocks side by side.

Sacha

 

Base 09' or R3?

 

Pics would be great. +1 on Jason's question.

 

R3?

 

Let's see some pics.
Would a spacer make it BS legal?

 

09 sport, pics shortly

 

If all else is cool, yes. Similar thing had to be done on the early R pkg Miata, shim the rear perch.

From what I hear the R3 is different.

 

Picture. We have ours at a machine shop to right now which is C&C pieces to raise the height and duplicate the differing perch.
We measure 1/2 inch diff in height.

 

WOW. Looking at the ramp on there now it almost looks like an MX-5 rear.

 

Here are the pics that i took. I measured 15mm on the flat side and 10mm on the ramp side.

 

a) it better be the perfect thickness, too much or too little is a DSQ violation

b) adding it to a helical perch isn't as easy as you think

c) the helical angle and spring contact surface length also have to be a dead match to OE

the Miata application mentioned had a loose perch and the shock body had grooves that a c-clip fit into to locate the perch, so adding a flat shim of proper thickness was easy in comparison to what's being proposed here ...

 

well im sill thinking about sending the oe shocks and the yellows for modification as an option

 

Anyone know about how much it's going to cost to get the perch moved up.
And this might be a dumb question, but has anyone tried to get the rears externally adjustable?

 

I will probably send the oe ones and the yellows to koni next week and i had the same question about making the rear externally adjustable. will keep you posted

 

Getting the koni sports converted to double adjustable ran ~ $350/ea. So yes, it can be done. I would assume just converting to external rebound would be less.
FWIW, Truechoice Koni Racing Service had a better lead-time than Koni NA a couple months ago.

 

It doesn't cost that much more to get DA vs external rebound only, they still have to disassemble the shock in entirety and replace all the seals etc.

my recommendation is to have the perch relocated, it's actually very easy to do it yourself on a twin tube shock if you have the metal working skills/tools, the tricky part is locating it properly

 

Have you sent them out yet?
I plan on sending mine in next week. I have an event this weekend and then nothing till July. But its my DD so I can't send in my stockers. Hoping someone else sends in a set before me so they have the specs.

 

I would assume that this means that all aftermarket shocks for 04-08 RX8's will have a similar difference when applied to the 09's?

 

Provided they were built like the 04-08 shocks in the first place, some never matched up.

 

They are actually being shipped to Koni today.

 

Do you mind pming me you name so I can tell them who I want mine like.
Did you get the externally adjustable? Price?

 

Call Phil Harris @ Truechoice Koni Racing Services 1-888-566-4722

http://www.truechoicekoniracingservices.com/


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It is true that it has turned out to be difficult to build a shim that match the Koni perch and moves a match of the 09 perch to the correct position. We have failed so far. So we got a 04-08 shock for comparison since the perch on the Koni appeared to be so different from the 09 perch. It turns out that the OEM perches from a 09 and 04-08 are identical except for position on the shock and differ from the Koni stock class legal design. See picture: Koni top, 04-08 OEM middle and 09 OEM bottom. The Koni perch is not an exact replica of the OEM perch for any year as the rate of rise is less in the Koni 180 degrees from these pictures. This results in a section of the Koni perch being > 1/8 lower than OEM from in the middle of the rise to top perch height. This was identical for 4 Koni rears.


So the question is: If the low point and high point of the perch is identical to OEM are we OK. This is true for the Koni’s used but the rate of rise in the perch between these 2 points differs on the Koni vs OEM. Where in the rule book is the requirement for perch dead match?

 

Mine are out at koni as we speak. More than likely i will have them converted to double/external since they have to be taken apart anyways. i will have an answer hopefully today. They have already sent the info and measurements they gathered from my stock 09 rears to holland to start producing an 09 specific rear fitment

 

I called them and they told me they could not convert them to external adjustabilty.