TRD shocks and springs

[NoHachi]

Uzelac Wrote:Whats wrong with my math? Look pic4.
Raise shock for 15mm (bigger spacer (35mm), smaller cut (25mm)) and leave perch at same position.
You will get 75mm of comprssion and 72,5mm of extension for HTS 102 damper which have 147,5mm of travel.
What is wrong with that?.

I'm not sure what you are doing?
Even in the pic there is just 60mm of compression damping with the sectioned struts. What are you calling compression travel? The correct distance is from the rest position of the spring under the weight of the car to the point of bottoming out on the strut/bumpstop or coil bind.
The rest position is the red dot. You need approx 75mm from the red dot down. Capisce?

@4000gt: life is a lot easier with 200mm springs. Plug in the numbers yourself. Shouldn't have a lot of trouble with uncaptive springs.

[NoHachi]

I just realised: the position of the red dot is only dependent on the springrate and the perch position. You're not changing those so the red dot stays exactly where it is. I would not recommend changing it since it is your rideheight.
Maybe thats where some of the confusion started?

[4000GT]

Yes perch will be staying where it is, there is not a lot of meat to cut the 40mm above the perch! Mint have to take it off the top and come up with a solution to thread it.

[Uzelac]

NoHachi Wrote:I just realised: the position of the red dot is only dependent on the springrate and the perch position. You're not changing those so the red dot stays exactly where it is. I would not recommend changing it since it is your rideheight.
Maybe thats where some of the confusion started?

It looks like this:



So, ride height, stays the same, only thing changed is position of damper.
It is 15mm higher so there is 70+ mm of travel both up and down (rebound/extension and bump/compression).

Comprende ?

[NoHachi]

Sorry, but your drawing just isn't correct..
I did a drawing of what will happen. Less short strut housing at the same rideheight ALWAYS translates to less compression or bump travel and more droop. The theoretical best approach would be to cut 15mm MORE from the strut casing while keeping the perch in the same location.

[img name=]http://www.aeu86.org/files/st/strut3_177.jpg[/img]

[4000GT]

So to conclude, take 40mm off the top of the strut, put in a 20-22mm spacer under the shock, and the springs will be captive, and gives a good range of compression and rebound with TRD 8kg springs and the AE92 TRD short strike shocks.

[NoHachi]

And bumpstops! Don't forget the bumpstop! :-) If you plan on doing serious driving you can count on using them. I would suggest finding some linear bumpstops. Example:
http://www.ground-control-store.com/prod...12.00ea%29

For racing you use the stiffest linear bumpstop you can find, that makes things more or less predictable. Measure your shock rod diameter and make a choice.
Make your choice wisely, these things will dominate the limit behaviour of the car. Good reading here:
http://virkki.com/jyri/miata/bumps.html

Someone with access to a spring tester really should measure the stock ae86 bumprubber rates.

[Uzelac]

NoHachi Wrote:Sorry, but your drawing just isn't correct..
I did a drawing of what will happen. Less short strut housing at the same rideheight ALWAYS translates to less compression or bump travel and more droop. The theoretical best approach would be to cut 15mm MORE from the strut casing while keeping the perch in the same location.

Sorry, ur right, i was thinking the wrong way, 15mm further down with shock is way to get "theoretical best" with stock perches.

Thanks

[NoHachi]

No probs Glad we're on the same page and drawing all those struts wasn't for nothing.

[4000GT]

So my car is riding a little with the TRD springs, what would be the impact taking the 40mm off below the perch? Or 20mm above and 20mm below for example?