2013FSport

iTrader: (2)

Yes

10 char

ELexis

Thank you for the follow up 2013FSport, and confirming the rear OEM IS F stabilizer bar will fit the IS 350 without issue. I appreciate it!

ELexis

Didn't think to bring it up previously however, is the F-Sport PTR02-53080 19 mm blue rear sway bar confirmed to be stiffer than either the OEM 48811-53070 28.6 mm IS F front and OEM 4881230400 17mm rear sway bars (does the larger diameter determine the stiffness or other values such as material and being solid / hollow etc.)?

2013FSport

iTrader: (2)

Go buy one and try it!
Think about the front and rear differences. The front has more leverage applied as the contact points are closer to the wheels than the rear. In short, this is not apples to apples comparison.

Unfortunately there is no data that Im aware of that specifies the actual spring rate of the bars. Only a percentage and non of those used >2011 fsport cars. Even actual spring rate for the coils holding the cars is black hole for F-Sport cars.

That said, material, tempering, hollow and solid are factors.

ELexis

Understood, ahanks again for the follow up 2013FSport. Will remove the F-Sport PTR02-53080 19 mm blue rear sway bar removed and install OEM 17mm rear sway bar to compare the effect on oversteer.

ELexis

Cam across the following provided by Quickor Engineering / Garage;

Adjustment Made / Increase Understeer / Increase Oversteer
Front Tire Pressure / Lower / Higher
Rear Tire Pressure / Higher / Lower
Front Tire Section / Smaller / Larger
Rear Tire Section / Larger / Smaller
Front Wheel Camber / More positive / More Negative
Rear Wheel Camber / More negative / More positive
Front Springs / Stiffer / Softer
Rear Springs / Softer / Stiffer
Weight distribution / More forward / More rearward
Front anti-sway bar / Thicker / Thinner
Rear Anti-sway bar / Thinner / Thicker

Perhaps installing the "in between" 17" rear diameter stabilizer bar along with tire pressure adjustments will assist with correcting the oversteer being experienced

Additional information:
Weight distribution 54/46 front to rear (IS 350/IS 250 RWD 52/48 / 53/47 with driver and full tank of fuel) (IS 250 AWD 54/46
Wheelbase (inches) 107.5 (IS 350)
Curb Weight 3,527 lb (1,599 kg) (IS 350) (IS F Base Curb Weight 3780 lb)
3,455 lb (1,567 kg) (IS 250 RWD M/T & A/T)
3,651 lb (1,656 kg) (IS 250 AWD)
IS 350 Steering Ratio (:1) 13.4 (IS F Steering Ratio 13.6)
IS 350 Turns, lock to lock 2.91
IS 350 Turning Diameter / Radius, curb to curb (feet) 33.5

ELexis

Follow up: began hearing noise from front end, as if something was loose. Have not checked however, would it possible be due to the IS F front sway bar bushings (part # 4881553060), that were installed, and colder weather causing them to make noise? I had Energy Suspension polyurethane bushings installed on previous vehicle, and they did become noisy (when going over speed bumps, uneven pavement etc.)when the weather became extremely cold (single digits), but the sounded more like a rubbing / squeak, compared to what's being heard now. I don't recall when I began hearing the noise, but do believe it began when temperature dropped. Will monitor and see if it goes away pending temperature change. material if not mistaken, believe I read that the ISF / F-Sport bushings, are a composite material or a high-durometer rubber (.75?) and thought this may be causing the noise.

ELexis

Noise heard has since dissipated with warmer temps being experienced.I'm assuming the noise most likely was caused by the IS F front sway bar bushings (part # 4881553060), or perhaps the RC F front lower control arm bushings; part 48076-24010 (Driver side) & 48075-24010 (Passenger side).