Rear end pulls (jerks) to one side, over bumps

[mogindo]

One more note, the car does not "jump" up, just jerks to the side and it happens at any speed. I can start to feel it even at 20mph, of course it gets worse with speed.

[grossgary]

Originally Posted by mogindo

Yeah I jacked the car and found nothing broken or alarming, but it I pull the lower control arm on the Inner side it does move a little, when I apply force.

that is for the front correct?

they sell complete control arms for $68 - $100 on rockauto.com if you wanted to avoid the mechanic and get it all done at once.

if you bought the arm, you can come close to those rock auto prices buying from Advance Auto Parts online and using a discount code (usually can get 20% off easily particularly around holidays like this). might even be able to choose one that comes with a ball joint since you will likely have to pay the mechanic labor and ball joint replacement as well. watch the lower priced units, they might not have bushings in them.

Originally Posted by mogindo

[COLOR=RoyalBlue]
I loaded 4 bags of cement into the trunk few months ago, while working on the house, but I made sure it was spread out evenly. [/COLOR

OBW of this same generation i worked on earlier this year exhibited this side ways jumping motion on bumps after a 400 mile road trip involving 4 friends and lots of heavy gear pushing over 1,000 pounds total (including people). turned out to be a rear spring. spring had no noticeable issues at all, i thought it would be cracked or notably weak, but it wasn't and replacing it fixed it. that side also sagged lowed than the other when loaded with all that weight and only exhibited symptoms above about 40 mph, so maybe slightly different symptoms than yours.

[mogindo]

Originally Posted by grossgary

that is for the front correct?

No it was for the rear. Front is fine.

OBW of this same generation i worked on earlier this year exhibited this side ways jumping motion on bumps after a 400 mile road trip involving 4 friends and lots of heavy gear pushing over 1,000 pounds total (including people). turned out to be a rear spring. spring had no noticeable issues at all, i thought it would be cracked or notably weak, but it wasn't and replacing it fixed it. that side also sagged lowed than the other when loaded with all that weight and only exhibited symptoms above about 40 mph, so maybe slightly different symptoms than yours.

Hmm, that might be it, since each bag of concrete was very heavy, I could hardly lift it. It must have been at least 500-600lb total. The car was sitting low, but it went to normal after that. I do remember however, that afterwards the car was saging more on one side when driving over bumps. But it went back to "normal" after few weeks.

I think I will replace the lower arm bushings at the shop and do the spring strut job my self. I doubt I can replace the bushings my self since it appears that they require to be pressed-into the arm.

[Saint J VT]

Over the years, I have had various vehicles that would have the rear go to the right on me whenever I hit washboard or a lot of bumps. Since these were not my vehicles but were work trucks and other such vehicles, I didn't care to have the problem fixed. I did, however, learn to steer into the swerve so as to not spin out of control, say, on wet or icy pavement!

[cardoc]

Just a few things.

The springs support the weight of the vehicle while the struts hold the wheel assembly planted to the road. Worn struts make the springs work harder.

Is your steering wheel "cocked" to the right? If it is, the rear of you OB is steering right already.

Hitting a bump or hole at the speeds over 20 mph will cause a wheel hop, however small, and when the tire regains its friction on the road surface, it will direct the car in the direction the wheel's steering angle is at. I would be inclined to believe the struts are worn and the alignment is out of spec. The right rear or left rear wheel has a steering angle set to the right and the extra force of the tire patch on the pavement on the rebound overtakes the force of the opposing tire and steers the rear of the car in that direction. If the struts are bad enough, the "hop" will continue until the wheel assembly settles, continuing the "pull".

This also falls in with Saint's trucks. The rear axles are never square with the frame and as the springs settle, the front wheel alignment is altered, changing the handling characteristics of the vehicle and combined with poor shocks, the rear, having the least amount of weight, pulls the truck to one side on bunps. New shocks and a thrust line alignment fixes the problem.

110k miles: Could use a set of struts. Springs are iffy, but a new set will help with weight support and alter the ride some. After replacing the struts, do an alignment. All the wheels need to have the toe in set at 0.0. Depending on your daily driving or whether the car carries a lot of weight in the rear regular, front camber works good at -0.5 with everyday driving, upto -1.0 set unloaded if you carry a lot of weight. (the wheel will camber out with weight in the rear)

[nipper]

Found this just to add to the conversation, how multilink works

Dissecting the Rear Multilink. - Subaru Legacy Forums

[mogindo]

Hi Cardoc,

This makes a lot of sense, my steering wheel is in fact already cooked to the right. Thanks!

I will do the struts, the bushings and alignment and report later on the results.

Has anyone replaced the lower control arm bushings by them selves? Looks like a difficult job. Struts I will do my self.

Thanks all for the contributions and help.

[cardoc]

If you are referring to the front bushings in the front arm it is easiest with a press. If its the rear bushing, gravy. There may be a shop in your area that does front end repair that will change the bushing out for you if you take them the part and arm for a small fee. Take it out, drop it off, go back to do the rest of the work on the car and pick up the arms after.

The upper bolt on the strut to spindle is an eccentric bolt for camber adjustment. Be sure it goes back in the upper hole so the tech won't have to swap it when you get the alignment. When you get the alignment, make sure the tech adjust the camber on the front properly, not just do toe-in.

[grossgary]

Originally Posted by mogindo

Has anyone replaced the lower control arm bushings by them selves? Looks like a difficult job.

if you're like me and don't take your car to a shop (or don't want to), you have a few options:

1. remove the part and have a shop do the pressing.

2. buy a used part to swap with yours. then you can install the bushing with no down time. hardly anyone buys used control arms so you could easily get one with good bushings for like $25. that's worth no down time to me and saving the time of running/finding/waiting for a shop to do the pressing, i can throw the stuff in the trunk and do it when it's convenient rather than make a special trip.

the used parts forum on here or USMB are great resources or find the lowest price junk yard here: Car-Part.com--Used Auto Parts Market. i order via phone so i can have it shipped - part arrives on door step, install, done. saves so much time - i can order on the phone while i'm busy doing something else, not wait in auto parts store lines, not worry about finding a shop...

[cardoc]

Originally Posted by nipper

Found this just to add to the conversation, how multilink works

Dissecting the Rear Multilink. - Subaru Legacy Forums

I was referring to the front camber angle change with a load in the rear. Rear down, Front up, front camber goes positive. That's why I suggest more negative camber in the front if you tow a boat, haul a lot of weight or have that roof rack mounted tent and supplies up top and all the gear in the rear.

The multilink on these cars are great. Hands down.