Prius Prime Suspension Wearing Out Quickly

why were they replaced? Shop recommendation or abnormal tire wear? If your struts are bad there should be abnormal tire wear (cupping, inside or outside tire wear) and you'd likely need a new set of tires to go with the strut replacement. Most suspension and wheel bearing issues happen on the right side of the car, from parallel parking, rubbing against the curb - placing inward pressure against the tire and curb , and jumping the curb.
I believe most of us has good luck with OEM struts, though you may be an unlucky outlier.

 

138,000 km is about 85,000 miles.
Post 2 asks great questions.

FWIW
In other street cars I notice suspension improvement when replacing shocks at 50K miles.
I've read on Mazda Miata MX5 forums some feel shock degradation at 20K miles.
With "racing shocks" monthly nitrogen recharges/ checks are prudent and oil changes at 5K miles always improve the suspension feel.
Again, for what it's worth.

 

Yeah, second this. You "might" be the the dealership's cash cow.

How are you with speed-bumps, say between slow-to-a-crawl and take-them-at-posted-speed-limit?

 

it sounds like something defective in the rest of the car is causing this. maybe have a good suspension shop look everything over.
i haven't read of many others having early problems, if any.
at least you got 100k out of the second rears and 140k out of the front.
maybe the first rear replacements were defective.

 

Here appears to be the problem. The car is not designed for off road driving with heavy loads. The weight limit is posted on the door jamb. Post #1 says:


I travel on pavement about 90% of the time, with 5% on graded gravel roads, and 5% on not very good gravel roads. I have used my car about 20-25 times for transporting 400-600lbs of materials from home depot, but otherwise the car is empty. That load, when added to the 200 LB driver and another 200 lb for the passenger is enough to destroy the shocks when driven on poorly paved roads.

I would suggest that there is no problem with the Prius Prime if loaded as it was designed to be driven.

 

I'm not even going to try an guess what or why the shocks needed to be replaced. Trying to second guess what a service dept., repair shop or owner wants done to a car is a game without a winner. If shocks are the only issue you've had with your 2018 Prius so far, I think that is pretty darned good.
Just for giggles add the 300 lbs / 136 kilos to your 400 lbs of Home Depot materials. They do sell heavy duty suspension parts for these cars. Take a look around this general Prius forum and you'll see how many others have already added suspension enhancements.

 

Does the Prime already have heavy duty rear suspension components? Since it is night day difference you did wear out the parts. I’ve never replaced any shocks on a Toyota but I have some new ones in a box for my truck somewhere. Good to stick with factory parts.

 

That's a good question. I tend to pay attention to the limitations when they are posted on the door jamb and (I think) within the user's manual. I assume that the last part is true since I saw it somewhere BEFORE I found the limits listed on the door frame.

You did not specify in the original post whether the 800 pound load was carried on the badly paved gravel roads that make up 10 percent of your normal driving. As a result of the fore-warning, I'd expect a shorter than normal life from the shocks of a car configured as a sport car that is being used as a pack mule (complete with gravel roads and overload).

 

I appreciate your bringing this to the attention of the Prius Chat members. At some point in the near future I'll be picking up some landscaping river rock in 0.5 cu ft bags. I did that successfully in my 2017 Prius Prime, but I was not watching the weight closely when I put a few bags per trip in the hatch.

I suspect that I was saved by my poor calculations that resulted in multiple trips back to the store for "yet another couple of bags".

 

I'm going to beg to differ with everyone blaming possible overloading. My 2017 Prime has 132K miles, original suspension/shocks, and no sign of suspension or tire-wear problems. In April 2024, I took a 7500 mile car-camping trip, part of which was a solar eclipse expedition to TX, part of which was doing work for a nomadic friend in AZ, and part of which was some rough offroading in NV. So, I was loaded down with a couple hundred pounds of astronomy and photography equipment, plus a couple hundred pounds of tools/supplies, plus a couple hundred pounds of car-camping gear, plus hiking gear, plus a good hundred pounds of food, water, and PowerAde in a 50-liter freezer. The gear included a 100Ah LiFePO4 battery, a 50Ah LiFePO4 battery, a 300Wh power station, an inverter, all sorts of chargers, etc. Cordless power tools and batteries. Heavy hand tools.

Even with all of that, I estimated that the car was about 300 pounds or more lighter than a similar trip I took in 2021. Yet in 2024, after a Kansas state trooper traffic stop on 4/20 (they were looking for drugs coming from CO) which happened to take place at a closed weigh station, I rolled out of the weigh station and saw the scale flash my car's weight, which was 65 pounds over GVWR. My tires are load index 99, vs the 89 stock, and I inflate them to 50psi. The car handles the weight just fine.

I also used to routinely carry home 2000 pounds of wood pellets in 3 trips, from 30 miles away. Likewise for 2000 pounds of wood bricks.

I think it all comes down to how rough the roads are, and how you drive on them. I do not drive in a way to bottom out the suspension, ESPECIALLY when heavily loaded. I'm pretty sure that OP's problem is from that 5% of his driving which is on terrible, rough, unpaved roads. That causes a lot more shock wear than being overloaded, or even creeping through tough offroad conditions at very low speed, while needing to get out and spot where I was going to place each tire. I also drove maybe 15mph on a really terrible unpaved road in Kofa NWR, but it wasn't that bad on the suspension, more along the lines of driving with one side's tires on the hump in the middle, and the other side slightly off the road, up the side of the tire rut, while scratching the body of the car on brush. Switching which side was on the hump, got interesting a few times.

Moral of the story, if you pound the shocks continuously, especially while driving at speed (whether 20mph, 30mph, or 50mph) they will wear out, overheat, or otherwise fail. By going as slowly as necessary to prevent that, you're really letting the springs do the work of keeping your tires planted on the road, with no rapid movement to make the shocks dissipate energy. Just driving along on washboard at a "normal speed" will destroy shocks in a hurry. If you have to do that, use tires with a taller sidewall, to let the tires absorb more of it. I have fit up to 205/70R15 on my Prime, without a lift kit, which can slightly scrape if you bottom the suspension, but just don't bottom it.

 

Speed bumps are bad. If they're running diagonally across the road I find I just about dislocated my neck, lol. Anyway, they're to "slow you down", but my take is to take them, especially the very abrupt ones, at a dead-crawl, walking pace or less. Treat them as a road-hazard.

And then there's pot holes, sunken manhole covers, and their ilk...

All of these reverberate shocks up into your suspension, can't be helpful to it's longevity. Raising tire pressures makes it worse I think.

 

For the most part, I agree, but...

High tire pressure can help or hurt, as it makes the tire sidewall taller. Especially if combined with using a taller tire, crossing a speed bump (or even a pothole) at high speed, the sidewall can absorb it all, without the wheel even needing to move up. The faster you are going across it, the more vertically stationary the wheel will stay, as it hasn't had as much time to be accelerated upward by the limited amount of force the tire can transmit. Limited compared to what the wheel can transmit, anyway.

High tire pressure certainly provides more impact protection before the pothole edge can reach and damage the wheel. If you manage to hit the wheel, then the forces can be much higher than a tire can transmit, and the rapid upward acceleration of the wheel will definitely hurt the shock. Low profile tires run at low pressure, will cause that the most.