Rattling noise from rear suspension

Mo. J · Aug 11, 2020

KMaletsky said: ↑

I've had the same rattle for quite a few miles, figured it was something bouncing around behind the seats or maybe the seat pivots. So I did nothing, until yesterday when I had some time to look at it. It was the top nut on the shock indeed.

As I'm well beyond the 36K warranty limit, I did the repair myself. Would really have been easier if 1) I could find some information online about how to do it and/or 2) the nut is located in a similar place as on the Gen 1, 2 or 3 Prius models. Alas, I was unsuccessful with #1 so I did the older Gen thing and ripped out all the plastic trim pieces in the trunk and behind the seat only to find out that the top nut for the shock is NOT accessed from inside the car at all, rather from the wheel well. Bummer.

It's not a particularly difficult repair if you have a reasonable kit of tools. Jack up the car, remove the wheel and sit the car on a jackstand far enough in that the suspension arm can still move up and down. Then put your floor jack under the suspension arm (block of wood in between the two) so that you can move it up and down a little. Remove the two bolts from the 'wings' of the upper shock absorber assembly and remove the bolt & washer at the bottom of the shock.

The full instructions say to remove the rear stabilizer link assembly and the bolt holding the upper control arm assembly. This will (presumably) allow the wheel structure to pivot forward and backwards (when viewed from the side of the car) and will make it very easy to get the bottom of the shock out. I didn't do that, it seemed like a PITA. Instead, I raised and/or lowered the suspension arm via the jack while holding down the shock with my other hand. If you gently tap the bottom of the shock with a mallet, you can find the magic spot where it will just slip off.

Once the shock is out, you can pry off the top rubber cap and see the offending nut. I don't have a socket wrench with a hole in the middle where you can put an allen wrench, but it didn't turn out to be a big deal. I was able to get it off and back on with an offset box wrench. Or you can use a 17mm socket and a pipe wrench, which I also did just to make sure that it was tight. I used red Loctite, which is the color of the thread lock that was on the assembly (and which failed). From what I read it could be a bit of a pain to replace the shock in the future, but this is the correct cross for the Three Bond 1324 which is specified in the TIS.

BTW, I did finally find documentation on the repair via the AutoMate database that our local library had online. Very handy and very complete. Let's hear it for libraries! Wish I had done that before ripping out the plastic trim!

The T-SB-0144-16 Rev1 TIS (also available in its entirety on AutoMate) clearly states that the shock is not to be replaced as part of the TIS itself. The TIS mentions only one replacement part - a new nut on both sides of the car - from what I see on the web it's just a metal nut not including a plastic piece. On some web pages I'd seen that the repair involved a second lock nut on top of the first, but I don't see that nor did I do it.
Click to expand...

I had the noise for more than a month now, steadily increasing. I checked the boot and the door, but there is nothing. Also if I shake the car while it is parked there is nothing! So definitely suspension problem. Took it to a mechanic yesterday, and said that the upper part of the shock is to be replaced.
I guess I gotta try tightening the nut like (KMaletsky) before ordering any parts.

Mendel Leisk · Aug 11, 2020

Pretty sure there's a technical service bulletin or similar for this. Check with dealership: could be free, and they know exactly what to do.

Mo. J · Aug 12, 2020

Mo. J said: ↑

I had the noise for more than a month now, steadily increasing. I checked the boot and the door, but there is nothing. Also if I shake the car while it is parked there is nothing! So definitely suspension problem. Took it to a mechanic yesterday, and said that the upper part of the shock is to be replaced.
I guess I gotta try tightening the nut like (KMaletsky) before ordering any parts.
Click to expand...

UPDATE
Yep, took it to the mechanic, turned out it's true, the nut in the upper side is loose. Good thing he had the tools to tighten it without removing the whole shock absorber. Because removing the lower part is a nightmare.
Now I drove +20km and no noise. I'm just afraid it will loosen again sometime.

doctorman · Dec 30, 2021

just bought a 2016 Prius III with only 34K miles on it and noticed the squeaky noise from both back tire wheels and reproduced by shaking the car up and down by putting my weight on the each of back tires...
the VIN in the TSB does not include my VIN, could it be the lose nut?
JTDKARFU4G300 is in tsb
mine is JTDKARFU4G302.....

it is embarrassing for 34K toyota having this issue..

would Toyota cover this for me considering the mileage ?

any better video or picture of the nut in question?

Rattling noise from rear suspension

Mo. J Junior Member

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Rattling noise from rear suspension

Mo. J Junior Member

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Mo. J Junior Member

doctorman Member