Too much flex in IFS front end??

[geohil]

Long story short I’m wheeling down some steep hills and ONLY when I downshift going downhill do my front tires rub, and rub bad!
Specs are 3 inch Bilstein/Einbach lift with a 1 inch body lift. Upper and lower control arm bushings are only a year old. Inner and outer tie rod ends are OEM and only a year old. Running BFG KO2’s in a 295/75/16’s. I have trimmed and beaten down my pinch welds and can flex to the stops in a stationary position. But as soon I’m rolling downhill with engine braking the whole IFS shifts back far enough to run. I really don’t want to SAS and I’m happy with the height so my hopes are you gents can talk me through what could be the culprit and how I might solve the flex?
Thoughts – would uniball upper control arms help? Spindle gussets? Polly bushings?

 

[JayRolla]

Are your LCA cams maxed out to push the LCA forward all the way? Are you cam bolts slipping? What was the caster spec on your last alignment?

 

[geohil]

Are your LCA cams maxed out to push the LCA forward all the way? Are you cam bolts slipping? What was the caster spec on your last alignment?

I hadn't thought about the cam slipping??
This is an alignment right after replacing my UCA and LCA bushings.

 

[JayRolla]

I hadn't thought about the cam slipping??
This is an alignment right after replacing my UCA and LCA bushings.

Are you rubbing mainly on the front right? The front right should be around 1.6-2.0* and its a little under. That could be enough to cause that tire to push into the pinch weld.

Do you have OEM cam bolts or did you replace them?

 

[geohil]

Are you rubbing mainly on the front right? The front right should be around 1.6-2.0* and its a little under. That could be enough to cause that tire to push into the pinch weld.

Do you have OEM cam bolts or did you replace them?

Cam bolts are original to the vehicle. I don't have much underbody rust or corrosion out here in Oregon either. I will certainly replace the cam if you think that might help?
Rubbing is mostly driver-side from what I can tell.

 

[the great him]

what UCA are you using?

 

[geohil]

what UCA are you using?

Still stock OEM. I was thinking this may be an excuse to get some uniball - Light racing or something like that.

 

[PWD4R]

My rubbing is my driver also. No BL but 10mm thinner tires.

Sent from my SM-G935T using Tapatalk

 

[JayRolla]

Cam bolts are original to the vehicle. I don't have much underbody rust or corrosion out here in Oregon either. I will certainly replace the cam if you think that might help?
Rubbing is mostly driver-side from what I can tell.

OEM hold well. I was wondering because I had issues with my SPC cam bolts slipping till figured them out. I bet the cam bolts are fine.

Stock control arms usually give the most pinchweld/firewall clearance. You lose caster but gain some clearance at the pinchweld. If you go uni ball it corrects some of the caster angle but at a cost of pinchweld clearance. They actually make the tire rub a lot worse.

Not till I pushed my SPC arms back to stock arm location (full forward setting) I was able to eliminate all pinchweld rub on my 285s when wheeling downhill and turning, full flex or not.

 

[geohil]

OEM hold well. I was wondering because I had issues with my SPC cam bolts slipping till figured them out. I bet the cam bolts are fine.

Stock control arms usually give the most pinchweld/firewall clearance. You lose caster but gain some clearance at the pinchweld. If you go uni ball it corrects some of the caster angle but at a cost of pinchweld clearance. They actually make the tire rub a lot worse.

Not till I pushed my SPC arms back to stock arm location (full forward setting) I was able to eliminate all pinchweld rub on my 285s when wheeling downhill and turning, full flex or not.

I'll give that a roll - move the setting forward. Wishing I had an at-home alignment jig so I could see what else changes as I change the lower cam?

 

[JayRolla]

I'll give that a roll - move the setting forward. Wishing I had an at-home alignment jig so I could see what else changes as I change the lower cam?

You want to set the lower cam bolts to max but this will change alignment so you need an alignment shop to try and get max caster from the LCA cams.

When I say push the UCA forward I was talking about aftermarket SPC control arms.