Hi! New member here!

I recently upgraded my '12 Boss suspension: Ford Racing springs, yellow Koni's, rear upper/lower control arms, relocation brackets and adjustable panhard bar.
The lower control arms are non-adjustable and are fitted with urethane bushings.
Everything fits well and seems to work as expected - no more wheel hop. ;-)
But now I have a whine from the rear end at freeway speeds under a load.
Was that noise there before and now I'm hearing it because the stiff bushings transfer the sound better?
Anyone else notice this after upgrading these components?

Looking forward to input and advise.
Thanks!
Dwain

 

My '13 had a whine that I thought was coming from the rear but it ended up being my Pirelli's. New tires and no whine.

 

And while tires is one thing, that upper control arm is the cause. Source: didn't put mine in at first. Left the old one in there, but upgraded the lowers. No noise to speak of. After I fully exhausted the rubber of the old upper ('cause I really didn't wanna change it out, it's a pain to do) I went ahead and swapped it out with the new BMR poly-poly upper. I didn't put the mount in, 'cause the tank, and I'm not THAT racecar... yet... But when that upper went in? Whine city. Not bad, lil' disconcerting at first, but 2+2="oh, yeah, that sorta makes sense, duh." The upper being *directly* on top of the gears, and gears are *gonna* whine, that sound goes right in the body.

When you upgrade from the OEM rubber, you're eliminating the protection Ford built in for Noise, Vibration, and Harshness, aka NVH. The OEM rubber absorbs a *lot* of road/gear/mechanical noise in the suspension, especially from the rear axle. The axle whine, the tires and road noise, all of it can vibrate its way through the axle, through those bushings, through the arms, and into the body, and you hear all that. Small price to pay for no more wheel hop and/or better handling, I say.

/Be glad you don't have heim jointed arms. You want NVH? That's how you get NVH. And also fun clunky noises to boot. Wheee...*clonk*..

If you're really concerned about it, you can get it up in the air and have someone listen to the axle, wheel bearings as the car's in gear. Just to verify there's not a problem.

 

yep it's probably the hard bushings transmitting more whine into the cabin

but just checking: do you have a one-piece driveshaft? if so, the pinion angle is more critical, might need to be adjusted due to the lowering . . . but if you don't have an adjustable upper control arm, then it is not adjustable so don't worry about it

 

I have brand new Mich's.
Definitely a mechanical sounds.
Goes away when I back off the gas.
Thanks for the reply!

 

Hmm, interesting thought.
The upper I used uses the stock Ford bushing at the diff end.
Is the stiff bushing on the body end enough to transmit all that noise?
Thanks for the reply!

 

No one-piece. Yet. ;-)

Thanks for the reply!

 

Yes. All harder bushings will have increased NVH, no matter what end they're on.

 

Thanks, houtex!

 

Just enjoy the noise! Because racecar! It'll let you know if something's wrong... 'cause it'll break. Which is the racer's motto: Fix, race, break, repeat!

 

I'm with ya there! ;-)