Axle Hop Help

[darreng505]

Gurus of racing,
I'm having an axle hop issue coming out of Oak Tree turn at VIR when I get on the power mid-corner. Here is my suspension setup.

Front Springs:
700lb
Front Dampers:
Compression: 3/10
Rebound: 5/10

Rear Springs:
400lb
Rear Dampers:
Compression: 2/10
Rebound: 5/10

Rear LCA's (adjustable):
Middle hole on relo brackets. There's an open bottom hole still

Any suggestions?

thank you,
D

 

[blacksheep-1]

what car is it?

 

[darreng505]

2012 Boss 302

I just put the 302s spherical end control bars on and stiffened the compression and rebound (8 compression/6 rebound) but won't be able to test it until superfest.

 

[blacksheep-1]

Call Andrew Aquilante at Phoenix Performance and do EXACTLY as he says. Ford builds all you need, tell him Rob sent you.

http://phoenixperformance.net/

 

[darreng505]

Will do. Thank you!!

 

[blacksheep-1]

You'll probably get punted over tot he owner Joe, AJ is buried in rebuilding race cars right this minute.

 

[darreng505]

Yeah. I sent Joe an email. I might have them finish prepping/caging my car for AIX too.

 

[Grant808]

Tighten your rear compression and/or use the lower LCA hole. What is your rear UCA setup? What angle is your LCA now?

 

[DocB]

You may have to call Aquilante a few times to get his attention.
I wanted to upgrade my full suspension and was referred to him.
It's been two years now since I spoke with him and I am still waiting for a call back.

 

[BMR Tech]

Gurus of racing,
I'm having an axle hop issue coming out of Oak Tree turn at VIR when I get on the power mid-corner. Here is my suspension setup.

Front Springs:
700lb
Front Dampers:
Compression: 3/10
Rebound: 5/10

Rear Springs:
400lb
Rear Dampers:
Compression: 2/10
Rebound: 5/10

Rear LCA's (adjustable):
Middle hole on relo brackets. There's an open bottom hole still

Any suggestions?

thank you,
D

Are you on R comps?

What are your fender arch heights on the car, F and R?

I think the LCA and the stiffer Compression will likely solve your issue.

 

[darreng505]

I'm on Hoosier R100's.

Fender apex's are 27"

 

[BMR Tech]

Okay.

Yeah, I would retain the middle position of the brackets (assuming they are BMR - which is 3" lower than OEM)

What UCA are you running? On your combo, I would suggest possibly raising up the LCA angle slightly. Not sure what others do with theirs, but, our 11+ UCA Mount will raise the UCA angle about 1/4" to help broaden the curve of the force applied to the tires, via IC/AS%. If you are running the OEM UCA, you can retain that and just use a Mount.

Again, I really think that the LCA and Stiffer C will help you out.

 

[blacksheep-1]

You may have to call Aquilante a few times to get his attention.
I wanted to upgrade my full suspension and was referred to him.
It's been two years now since I spoke with him and I am still waiting for a call back.

Don't feel too bad, he doesn't do well with phone calls, try e-mail I've received e-mails and texts from him at 5AM. When I talk to him about the race team he always tells me to text or e-mail him, the guy is going 200mph standing still.

 

[Grant808]

That's great, but it would also help to know your tire size. You're geometry is wildly different with those dimensions on a 25.6" tall tire vs. say 27.7". If you're using a short tire, you're probably okay to leave the LCA position. With a tall tire and that ride height, I'd go to the bottom LCA hole.

 

[darreng505]

Grant. Good point. My tires are 295/680/18
Diameter is 26.9

I'm in the second hole on the LCA brackets. You think I should soften the compression and try the lower hole?

 

[darreng505]

You may have to call Aquilante a few times to get his attention.
I wanted to upgrade my full suspension and was referred to him.
It's been two years now since I spoke with him and I am still waiting for a call back.

Yeah, I haven't gotten an email response from Joe yet. I know they're busy, but I'm willing to give them some business.

 

[Grant808]

Grant. Good point. My tires are 295/680/18
Diameter is 26.9

I'm in the second hole on the LCA brackets. You think I should soften the compression and try the lower hole?

That's what she said.

Stiffen the compression. I'd try that first by itself just because it's easy to do. If or when that doesn't work completely, try the lower hole or you may need to raise the car a bit in the rear to get the geometry you need.

Could also help everyone else visualize the problem if you post some pictures.

 

[BMR Tech]

I wouldn't use the bottom hole for any handling app, unless the fenders at at , < 26.5" in height, and you have a relocated UCA position. (higher than OEM)

I can usually plot suspension geometry pretty well, just from knowing fender heights. Not 100% precise, but close.

 

[darreng505]

That's what she said.

Stiffen the compression. I'd try that first by itself just because it's easy to do. If or when that doesn't work completely, try the lower hole or you may need to raise the car a bit in the rear to get the geometry you need.

Could also help everyone else visualize the problem if you post some pictures.

lol. I WISH that's what she said.

When coming out of this tight turn (Oak Tree Turn at VIR), followed by a long straight, I try to get on the power as soon as possible but am feeling axle/wheel hop[1] if I give it too much throttle (literally feel the rear bounce under throttle as tires gain/lose traction).

Now, I could just delay the throttle input some and it goes away, but the better answer is to address the mis-configuration. I've not had hop in that turn in the past, but that was on a much softer suspension.
My rear LCA bushings could be weakening finally so the spherical ones would solve that.

Guess I'll have to try a few things and see.

[1] http://www.mc2racing.com/tech/20061012a/

 

[darreng505]

I wouldn't use the bottom hole for any handling app, unless the fenders at at , < 26.5" in height, and you have a relocated UCA position. (higher than OEM)

I can usually plot suspension geometry pretty well, just from knowing fender heights. Not 100% precise, but close.

Once your watts link is ready, I'll be first in line. I know that device will also address this.