Does anyone know the motion ratio for the front and rear suspensions on the Evo? I can measure it, but if someone already has this would be great.

 

I believe they are .65F and .615R. I have them written down at home. I'll double-check this evening.

Joe

 

Strut suspension is ordinarily pretty close to 1:1. I would expect the Evo front to follow that convention. I have no idea of the rear though.

.6* is quite high (or low, depending :-) Even the 2G's SLA front suspension doesn't get into the 6s.

Charles

 

Just double-checked my notes. .650 front, .615 rear. These measurements were taken from my '03 by Chris ***.

Joe

 

I would question the front number. Mine measured very close to 1 as expected with a near vertical strut. The rear sounds right - depends on which point in the travel range.

Eric

 

Eric,

Thanks for chiming in. Now that you mention it, the front # does sound low. I'll look at the calculations in my notes. I know its possible he miscalculated, but Chris knows his stuff. More likely a mistake I've made.

Also, we pulled the springs out of the car when we took the measurements so IIRC we had the suspension in about the middle of its travel.

Joe

 

A typical strut still won't get into the 6s, anywhere in its travel. It's going to hover around 1:1 for the full travel.

Charles

 

The distance from the center of the contact patch to the point where the strut is attached will also change the ratio. AKA if it was at the inboard pivot point the motion ratio would be 0.

Could what Chris calculated be the wheel rate which is the motion ratio squared.

That would make the motion ratio .806 front and .784 rear?

Joe, do you have the initial measurements (tire and spring)?

 

Bringing this one back from the dead. Does anyone know for sure what the motion ratios are for the stock suspension on an 8? How does wheels with a 33 offset effect the motion ratios?

 

not entirely correct. if the strut is at an angle relative the vertical motion of the wheel, the ratios change. even so, the motion ratio should still be 1:1 (or just 1), not 0. a motion ratio of zero would imply that something doesn't move.

 

Yea if I understand the front suspension correctly on and Evo, they do not have an upper a-arm, therefore the strut is going to be very close to vertical. You should have a MR less than 1:1, but just slightly.

I use the attached method for MacPhearson struts.

 

That makes sense. Has anyone taken any measurements on the rears?

 

I recently bought a set of Ohlins DFV and contacted the company to make sure that the spring go in the order of 8/10 as i read in the forum. However their response was much differentthan what i expected.
So my question is, what is the motion ratio front and rear. Do most users install it in the "wrong" way? Is the company (Ohlins) ignorant in regards to the product it sells? Is it something different?. I am really confused.

 

Front is around 0.91 and rear is around 0.73 though both change a bit with ride height (both) and camber settings (front). Their description of course shows the resellers dont really know the Evo and that we arent MacStrut front/rear like most the subies.

When doing the math, you use MR^2 which puts the multiplier at .83 and .53 F/R which has a massive effect on the actual wheel rate. 8k front, 10k rear is the proper way to go. Ohlin just cant seem to accept they made up rates back in 2002 on wrong information but it doesnt seem to matter cause in my mind they got lucky that it works out well in valving to just flip the springs.

 

Ohlins developed their kit for the evo on the evo x platform and then just adapted the springs a bit for the earlier models. I had some fights with their representatives allready on another forum and indeed they do not accept their mistake... Ideally on a road car I would run 8/9 but 8/10 will work, even with stock ARB in the rear.. You need to add a bit of preload on the front springs when you go 8/10 or you will have too much sag on the front..