Rear End Shifts on Accel/Decel - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

White64Goat · 05-06-2024, 01:50 PM

Been a long time since I posted here.......have a 2013 BRZ and recently I have noticed when driving the car and accelerating up through the gears that when I shift and let off the gas and then get back on the gas, the rear end is changing directions. Can also make it do the same thing by hitting and letting off the gas. Have visually looked at the rear bushings and don't see anything wrong by the eye. Wondering if anyone else has had this problem and what it was?
Thanks.

Ohio Enthusiast · 05-06-2024, 02:28 PM

I'd check all drivetrain bushings - rear subframe, diff mounts, transmission and shifter mounts and engine mounts. All of these contribute to the rear being squarely.
In addition, check your suspension links, especially toe arms. Make sure everything is tight, bushings are in good shape and toe isn't out of whack (slipping or loose toe adjuster, for example).

ZDan · 05-06-2024, 06:22 PM

What are your tire pressures? What you describe is how a Torsen diff behaves when you have rear tires of different diameter, or one is at lower pressure.

strat61caster · 05-07-2024, 07:38 PM

I’ve also seen this when cross weight is jacked, ignore if on non adjustable spring perches.

grippgoat · Yesterday, 05:21 PM

I'd check wheel bearings and axle nuts, too.

Muskoka800 · Today, 09:42 AM

Quote:

Originally Posted by ZDan

What are your tire pressures? What you describe is how a Torsen diff behaves when you have rear tires of different diameter, or one is at lower pressure.

I experienced this. My right rear tire was worn significantly more than the left. The rear of the car stepped right during hard accelleration. No effect noticed during braking however.

White64Goat · Today, 09:52 AM

Tire pressures were the first thing I checked and all were good. Wear is even on all tires as well. Car is also puling to the right as well and it has driven straight as an arrow since I've had it. As far as I know there has been no curb contact to knock alignment out of whack. Going to take it to the dealer next week probably as driving it out on the interstate it has a constant tug to the right which is annoying as hell.

05-06-2024, 01:50 PM	#1
White64Goat Senior Member Join Date: Jun 2012 Drives: 13 BRZ CBS LTD MT, 02 WRX Location: Fred. Co. Md. Posts: 2,348 Thanks: 65 Thanked 1,111 Times in 627 Posts Mentioned: 19 Post(s) Tagged: 1 Thread(s)	Rear End Shifts on Accel/Decel Been a long time since I posted here.......have a 2013 BRZ and recently I have noticed when driving the car and accelerating up through the gears that when I shift and let off the gas and then get back on the gas, the rear end is changing directions. Can also make it do the same thing by hitting and letting off the gas. Have visually looked at the rear bushings and don't see anything wrong by the eye. Wondering if anyone else has had this problem and what it was? Thanks.

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05-06-2024, 02:28 PM	#2
Ohio Enthusiast Senior Member Join Date: Apr 2020 Drives: 2018 BRZ Location: Dayton, OH Posts: 924 Thanks: 1,385 Thanked 782 Times in 444 Posts Mentioned: 12 Post(s) Tagged: 0 Thread(s)	I'd check all drivetrain bushings - rear subframe, diff mounts, transmission and shifter mounts and engine mounts. All of these contribute to the rear being squarely. In addition, check your suspension links, especially toe arms. Make sure everything is tight, bushings are in good shape and toe isn't out of whack (slipping or loose toe adjuster, for example).

05-06-2024, 06:22 PM	#3
ZDan Senior Member Join Date: May 2011 Drives: '23 BRZ Location: Providence, RI Posts: 4,587 Thanks: 1,378 Thanked 3,893 Times in 2,034 Posts Mentioned: 85 Post(s) Tagged: 0 Thread(s)	What are your tire pressures? What you describe is how a Torsen diff behaves when you have rear tires of different diameter, or one is at lower pressure.

Yesterday, 05:21 PM	#5
grippgoat Member Join Date: Mar 2023 Drives: 2023 BRZ, 2018 Golf R 6MT Location: WA Posts: 56 Thanks: 8 Thanked 29 Times in 19 Posts Mentioned: 2 Post(s) Tagged: 0 Thread(s)	I'd check wheel bearings and axle nuts, too.

Today, 09:52 AM	#7
White64Goat Senior Member Join Date: Jun 2012 Drives: 13 BRZ CBS LTD MT, 02 WRX Location: Fred. Co. Md. Posts: 2,348 Thanks: 65 Thanked 1,111 Times in 627 Posts Mentioned: 19 Post(s) Tagged: 1 Thread(s)	Tire pressures were the first thing I checked and all were good. Wear is even on all tires as well. Car is also puling to the right as well and it has driven straight as an arrow since I've had it. As far as I know there has been no curb contact to knock alignment out of whack. Going to take it to the dealer next week probably as driving it out on the interstate it has a constant tug to the right which is annoying as hell.

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