Rear end pulls left under heavy braking

[lsxjunkie]

Car is my daily, 2014 with 70k miles. When I stand on the brakes at speed, the rear pulls like it wants to come around on me, always to the left. If I let go of the wheel, the steering corrects to the left. If I hold the wheel straight, the whole car turns right, which is what makes me believe that it's steering from the rear.

This only happens when I brake hard enough to pitch the car forward.

I'm thinking suspension or maybe a stuck rear caliper. I really don't think it's the front. Anyone have any thoughts?

EDIT: Update in Post 4, a lot of the rear steer went away when I swapped off my snows, but now I'm looking into LCAs anyways.

 

[rdplain]

I had something similar happen. Steering had to be corrected to the right when braking with anything more than a light touch. Ended up being a blown out LCA bushing on the passenger side causing the rear end to move.

 

[JDos1]

Sounds like something in the suspension. A quick way to tell if you have a seized pin in the caliper is take measurements, both sides should be within 30* or so of each other after braking.

I'd guess as rdplain said, a busted bushing causing suspension to shift or your thrust angle is off.

 

[lsxjunkie]

So I put my summer wheels back on, Boss 302 wheels with 255/285 Pilot Sport AS3+ tires, and it seems to be much harder to recreate. I was on studded 245 Nokian snows all around when I first noticed it, and I think the much lower grip exacerbated the symptom.

That's not to say it's gone away, but I really feel it at the limit of traction, which is now braking at a point that is uncomfortable (these Michelins are grippier than anything that calls itself an all season has any right to be).

That having been said, I'm probably going to do rear LCAs anyways, as 70k miles and 4 NY winters means it's time, I'd say, to start replacing some of the rubber under the car.

I've started reading up on LCAs, but the only thing everyone says is "Brand X binds up and the bushings tear" and "my wheel hop is gone!" I have no wheel hop and I need a part that is going to last, as I intend to keep this car for another 70k miles and the accompanying NY winters. All I care about, as you can probably see in my mod list, is handling. No drag racing, I have no wheel hop issues, I just want my car to do the corners good. Anyone have any recommendations for my goals?

 

[evanjp]

You put your summer tires back on already? Where do you live? I'm contemplating it myself, my car feels so spongy during this warm weather. It got colder now but it doesn't look bad enough to keep them on for the foreseeable future.

 

[evanjp]

I'm actually having a problem with my rear calipers too, I have so much more brake dust on my passenger rear wheel than my front wheels even. The rotor is warped insanely, just put these rotors on not even a year ago so I'm thinking I have a bent axle. I get a vibration in the car over 65 mph that literally vibrates one side of the car to the next and then disappears for 5 seconds, vibrates for 5 seconds and keeps doing that. Bent axle I think or my DSS shaft is out of balance.

 

[evanjp]

Excuse me I meant drivers rear wheel

 

[JDos1]

Caliper mount bracket is warped or you have a seized pin...or park brake cable is hanging up.

Jack the rear. Apply the parking brake and release it. After releasing, take a look at the park brake cable bracket on the caliper and ensure it is seating fully against the stop. If it is, move on to the caliper pins.

Use a 13mm to pull the caliper-to-bracket bolts off. These are 13mm. 15mm are the bracket-to-axle tube bolts, shouldn't need to remove these. Once you have those off, slide the caliper up off of the rotor. Pull out on the pins (which are what the bolts thread into. If you can't get them to pull out easily, you have a seized pin. Either drive the pin out (partially thread bolt back into it and use a slide hammer or pair of pliers to pull it out) or replace the caliper. If you pull the pins out you'll want to lightly sand them and repack the area with grease before reassembly.

The intermittent vibration doesn't really make any sense. Perhaps it is the warped rotor that makes contact, pushes the piston back into the caliper and then hydraulic pressure pushes the piston back out, making contact with the pad/rotor and recreating the vibration. Wild shot in the dark but all I can really think of with the symptoms you describe.

BMR LCA's. Contact Kelly or Dylan at BMR and ask if they still have the black bushings available. IIRC they are supposed to be more durable.

 

[JDos1]

And good choice on tires. I run the Pilot Sport AS3+ and love them. Excellent warm traction, moderate cold traction, good wet traction, minimal hydroplaning. I get about 45k miles out of rears and 60k miles out of fronts.