Prius Prime Rear Suspension Noise

There was a recall (or service bulletin) for 4th Gen rear suspension, a bolt (or nut) at top of shock tower prone to come loose. Maybe same applies to Prime, same suspension?

 

I also have a similar noise but I can’t tell if it’s coming from inside or outside of the car. I try pushing down on the car and never hear the noise.

 

I just started hearing it as well... just shy of my 10K service so i'll have them look at it when I bring it in. i'll let you know what they find.

 

yeah, that would have me a bit worried. Like I said, mine had worn through sufficiently to damage and require replacement of the upper control arm. I've never heard of a suspension component being shipped loose and require tightening at 5K. That would seem like a surprisingly dangerous thing as not everyone uses Toyota for service.

 

The noise started at about 5K (just after the first service... of course). However I noticed a bit of an instability at high speeds when I first got the car. I was intending to have them check the alignment at the first service but as things happened I didn't have time that day so pushed it off.

Things got progressively worse quickly, however. By the time 10K came around there was a noticeable squeaking sound whenever the rear suspension either loaded or unloaded (stopping, acceleration). It sounded very much like a bad shock. When I brought it into have it serviced the tech could not reproduce (which was strange as it happened every time you moved the car). By 12K all you had to do was to push down on the rear of the car slightly to have the noise occur. I brought it back in and had their service manager come over and watch me push down on the back of the car when it was parked so that there wouldn't be any more "can't replicate" happening.

They fixed it under warranty (although they kept the car for 4 days while parts were brought in)... and without a loaner car either which ticked me off (although I had just moved states and this wasn't the dealer that I purchased from, but if there's a warranty repair on a car that needs to be kept for a few days, Toyota Corp. should pay for a loaner).

It all seems good for now (although I do have to go back again as they had to order a retaining clip for one of the rear sonar sensors that had fallen into the bumper as they left the clip off during manufacturing apparently).

Still, non-tightened suspension components is a recipe for disaster.

 

Only in our DREAMS.....

I'm not positive, but it sure seems that the new Prime has more bugs & rattles than the regular Gen4 Prius? Lots of posts on here say so. I still believe the Toyota build quality has declined in the past few years.

 

You mean a wheel lug nut stud? If they were the last people to have the tires off, it likely broke because their mechanics last installed the lug nuts with an impact wrench, and/or didn't start threaded them on by hand, finish with a hand tightening with a calibrated torque wrench.

 

Again... only in our DREAMS. I have NEVER seen a tire shop or a dealer that DID'NT use an impact wrench.
However, America's Tire store does use a torque wrench.... after grinding the lug nuts on with the air impact wrench.

 

To get a suspension noise diagnosed, find a location near the dealership where you can cause the noise to occur. Have that in advance so you can take the service writer or tech for a short ride, and they can hear it for themselves. Not much is more dissatisfying than "Could Not Find the problem" on the work order.

There are ways to use an impact wrench and not over tighten & stretch the lugs. There are torque sticks which look like skinny socket extensions. They are spring steel that absorb some of the impact wrench's twist--and can still overtighten the lugs. A good tech with the impact wrench can use a light trigger finger to snug the nut down without hammering it tight.

What you want to see is the torque wrench, set at 76 lbs-ft for the Prime, used so the nut rotates until the wrench clicks. I've seen the gorillas at a Les Schwab tire store hammer the nuts tight with the impact wrench, then put the torque wrench on the nuts and rapidly click it several times. I do not know what they thought they were accomplishing. Actually their business concern is more to be sure the nuts are at least tight enough so they don't come off, not whether they stretch or strip or break a stud.

The threads need to be clean and dry. No rust, no dirt, no lube. The torque (twisting) spec is for dry threads. Lube on the threads reduces the friction, and the studs could be over stretched by the time the twisting force (torque setting) is reached.

 

Have seen ( on priuschat)three or more cases of the shock strut upper bolt not torqued properly and causing noise.

 

Maybe they could install them with impact wrench with lower value torque stick, say 40 foot/pounds, then go to the torque wrench at 76 foot/pounds.