How to Replace 3G Prius Front Struts

My 2015 Prius has logged 99.8K miles and the car has not needed repairs so far during my entire 10-year ownership period. This car has been far more reliable than my 2001, 2004 and 2007 Prius. For maintenance, I've changed the full synthetic engine oil and filter every 5K miles, changed the engine and cabin air filters and wiper blade refills when they needed replacement, bought a couple sets of tires, and changed the 12V battery preventively in 2023. The brake pads look great, and I'll need to change the radiator coolant soon.

Hence, I haven't had subject matter to post an original thread regarding 3G Prius repairs until now. I decided to replace the rear shocks and front struts, using KYB Excel-G components.

I'm listing tightening torque values for all of the fasteners in the following text, so even though the discussion is describing disassembly, note the torque values when you are reassembling.

There isn't much to say about the rear shocks as my Prius has access covers in the hatch trim, so it is just a question of removing the access covers, removing the top nut (18 ft. lb), removing the bottom nut and bolt (66 ft. lb after the wheels are on the ground) and replacing the shock. I bought new rubber upper suspension supports but the old parts were in great condition. The old shocks weren't great, when they were compressed they took very long to rise up. However there were no visible signs of oil leakage. The rear shocks cost $211 including AZ sales tax from TireRack.com while the upper supports cost $25 plus $17 shipping for $42 total.

The front strut repair was more complex since I decided to reuse the coil spring, bottom rubber insulator, and top rubber insulator. Total price was $446 including sales tax, from Summit Racing. The KYB part numbers:

339242
339243
SB112 Strut Boot, qty 2
SM5665 Strut Mount Plate, qty 2

I've provided a few photos and a description.

1. Remove the wiper arms (17 ft. lb), the black plastic cowl cover (two little black plastic fasteners, one at each end - to remove, depress the center slightly, then pull the fastener up), remove the end pieces from the cowl cover, then pull the cowl cover up from the sheet metal tray without damaging the windshield glass. Remove the wiper motor assembly (4 ft. lb), and the sheet metal tray (9 ft. lb) for access to the top nuts holding the struts to the body. This is not a difficult task, although there are many bolts to remove and it would be nice to use a power tool.

Removed parts described above.


Access to top strut bolts made available by removal of the sheet metal tray.


Although this is not part of replacing the struts, the following photo shows wire screen that I installed a few years ago to keep mice out.


2. Raise up the front of the car and place jack stands at the front jacking points. Remove the front tires (76 ft. lb).

3. At the strut top, remove the center rubber dust cover. Loosen the center nut 1/2 turn only to make it easier to remove the center nut once the strut is removed (35 ft. lb). You don't want to loosen that too much while the spring is exerting tension. Loosen the three nuts (37 ft. lb) holding the strut top to the body.

4. Remove the nut (55 ft. lb) holding the stabilizer bar link to the strut body. Fortunately my links were in good condition and I could remove the nut without having to use an Allen wrench to hold the threaded stud.

5. Remove the 14 mm bolt (14 ft. lb) that holds the brake fluid flexible line and the brake wear sensor wire to the strut body, and move those items away from the strut body.

6. Place a hydraulic floor jack below the steering knuckle, with a piece of wood to cushion the knuckle bottom. Remove the two large nuts and bolts (177 ft. lb) which secure the strut bottom to the steering knuckle. Loosen the nuts, not the bolts. I'm not exactly sure why that is, but the bolts are extremely hard to turn while installed, however the nuts are relaitvely easy to remove. I used a breaker bar and a 3 ft extension on the handle and was able to exert sufficient torque to remove and replace the nuts. I also have a Makita electric impact wrench and used that on the left front side since there was adequate space to fit the impact wrench in. Once the nuts are removed, you may need to use a hammer to pound the bolts out.

Right front corner, original strut with pleated cover falling apart.

7. I have a strut compressor which works really well, so I recommend something like this if you are interested in doing this sort of work. A hydraulic piston raises the lower strut support up to compress the coil spring so that you can remove the center nut holding the strut assembly together, without having a dramatic event occur.


8. I reused the original top strut rubber insulator which separates the top of the coil spring from the top strut mount, by removing the pleated cover which had mostly disintegrated. I was able to attach the new KYB pleated cover to the bottom of the rubber insulator after removing the original pleated cover pieces.

Right front new strut installed.


Detail of brake hydraulic hose and brake pad wear sensor wire attached to strut body.


Left front new strut installed.


The old struts were still operational although they were easier to compress, and slow to rise up compared to the new struts. They probably could have been used another 25K miles before they were replaced. I think the 3G original equipment shocks and struts are much better compared to the Classic and 2G Prius, where you would be lucky to get 60K miles out of those parts.

I was not thrilled with the design of the KYB strut boots since I had to reuse the old upper rubber insulator. Instead, I recommend that you buy from a Toyota dealer parts department, the upper rubber insulator which includes the pleated boot.

My steering wheel is exactly at center when driving on a straight road so I may defer getting a front wheel alignment. I actually have not ever had a wheel alignment on this Prius after 10 years of ownership. Thinking back to the Classic and 2G Prius, when I replaced the front struts there was considerable play in the front camber (you could move the strut in and out a reasonable amount before the bottom bolts/nuts were tightened. With 3G, the bolts fit so tightly into the holes, that there is no play to speak of.