Im not suprised I am getting hard nose dive, I know its normal, but I want to reduce it. So the reason I started the thread is to discuss a possible solution/reduction of the issue.
I'm getting alot of nose dive on my X. With Hoosiers it's so severe I feel the car "dance" while threshold braking. The same w with RE71s but the dance isn't as pronounced.
I have tried tightening the rebound on the rear shocks. I'm about 2-3 clicks stiffer in the rear than the front. I run the same brake pad material front and rear. I'm running 100lb stiffer springs up front.

I know if I can stop 50% of the diving I can brake later and have better control of the car threshold braking. I believe there may be more spring rate needed in the front, and possibly getting larger rear calipers and rotors.

there is one wild card. I have rebound only adjustment. The shocks are MCS one ways. Could having stiffer compression be a large part of the fix? The suspension feels amazing in every aspect through a turn. Spring rates are 700lb front 600lb rear. I am considering going to 800f 700r. The car is very compliant. It also has all OEM bushings.

 

Attached is a picture of the ride height and the car mid turn after threshold braking

 

Remove and compress the front brake calipers see if one of them is hard to collapse

 

What will that mean either scenario?

 

That a piston or pistons is seizing

 

That would cause me to have premature wear on some of the pads. Which isn't the case. Front are also rebuilt

 

Anyone else read the title and go "Duh" ?

Haha

It doesn't sound out of the ordinary to me.

Do you still have the spare tire in the trunk?

 

Well, im not suprised I am getting hard nose dive, I want to reduce it. So the reason I started the thread is to discuss a possible solution/reduction of the issue.

I will add this to the first post.

I do not have the spare tire.

 

Weight off nose, stiffer springs, anti dive kit if such a thing exists for EvoX, lower CG, etc al

 

we had out fuel cell in the trunk and every now and then it would dance like you're describing. moved fuel cell into rear seat and it hasn't happened again. so moving any weight behind the rear axle to the rear seat area would be good IMO.

the problem with stiffer springs (IMO) is you loose compliance and could potentially make the car less predictable.

 

Any toe out, front or rear? That could contribute, especially rear.

 

weight off the front is expensive LOL. But definitely key to this issue.
I am considering stiffer spring on all 4 corners.
Not sure if there are anti dive bushings, i will look it up
with my current suspension travel I am am at the minimun height. I may be working on custom LCA to lower the car more and retain current shock travel.

So you moved the fuel cell foward and it reduced the "dance". I would think the opposite. Thats interesting.
My car with 700-600 is still very compliant even at Sebring which is harsh. I can still go stiffer and will get positive results. I used to run 550-600 and went to 700 front and the car felt waaaayyy better.

Thats what I had in mind that day at the track. That my toe must be off. I usually run 0 toe square. But i believe some of the dance is partly do to alignment being off after 6 events and strapping to the trailer and dyno.

 

So i believe I found the reason for the shimmy under hard braking. Seems like the tires are the reason for it. Driving the car straight it wants to pull left. Started doing that after the tire change. I bought the r7's used.

On another note seems like my car on the r7's almost 2 wheeled at one point. So with hoosiers i would need stiffer spring and less bar.

See attatched...

 

And maybe more camber. Those things are rolling over a lot.

 

I can add a ton of anti-dive with my billet arm setup though currently havent made anything long enough for the X. Carl (MeatHooker) has my arms and Im pretty sure he's running them in the anti-dive setting. That seems to work well for track and aero but in AutoX it causes some push at high steering angle. So I run mine neutral. Just another level of adjustability I add

And the PSRS (or other brands) offset bushings that allow you to add anti-anti-dive is actually mandatory if you are low enough. You cant get to the anti-dive side of things with the offset and being low because you'll hit the chassis (unless you clearance it) with the bushing bore and likely break the arm.