Replacing Struts on a Subaru Impreza WRX STI
If you are an STI owner, you're likely all too familiar with the 'clunk' from the factory struts. The rear struts on my 2005 STI began binding after only 20K miles or so. The dealership would not replace them under the new car warranty despite a Technical Bulletin, and so I've lived with the annoyance for another 60K miles now.
I figure I got my money outta them, so time to put an end to the racket. After researching several after-market alternatives, I decided to purchase OEM. The re-valved set from Feal have received positive reviews on the Subbie boards, and include a Zerk fitting to allow periodic greasing, which KYB forgot in their original design.
As of this writing - I am finally 'clunk-free'
So let's get you started..
A Word About Spring Compressors
Years ago I borrowed a typical abused set from AutoZ@ne to do my Camaro and subsequently stepped way out of my comfort zone using them. Rather than subjecting myself to unnecessary risk and possible loss of limb a second time, I've since purchased two styles of compressors, which both worked well for this strut swap:
- OTC Clamshell Strut Tool, Part #6494 (optional; used on rears)
- A good quality pair of 'rod' compressors (required; used on fronts)
The clamshell unit is a bit pricey, and frankly not a terrific return on investment if you never plan on doing another strut swap. If that's the case, consider the alternative of removing the old struts yourself and taking them to a shop to do the spring swap. Moving on..
In addition to the spring compressor, you'll need:
- Ratchet Set
- 6mm hex bit socket or wrench
- 12,17,18,19mm sockets (6-point preferred)
- 12mm deep socket
- 19mm box wrench
- Breaker bar
- Hammer
- Slotted screwdriver
- Multi-purpose suspension/gear grease
- Means to raise the car (jack & jack stands, lift)
- A second person to help with strut removal/install
And a few Optional Tools that will make the job easier:
- Pneumatic impact wrench
- GearWrench or similar with a pass-through socket design
- PB Blaster or similar penetrating oil
- Marker paint
- Medium-sized metal punch
- Thin plastic baking sheet or similar
- A set of replacement struts.
- Re-valved OEM Struts (with or without new springs; I chose to re-use the original springs and rubber boots)
- New OEM
- Aftermarket Struts
- Aftermarket Coil-Overs
In addition to the 'clunk' from binding struts, older struts may result in a soft, spongy ride experience and/or 'bottoming out'. A blown strut may be visibly leaking.
Remove the Rear Seat
The rear seat must be removed to gain access to the rear strut top hat. Begin by removing the two 12mm bolts securing the seat bottom. These are located at the base of the seat near the floor - essentially between your calves if you were sitting back there.
Next we'll remove the back cushion. This time there are three 12mm bolts, again along the bottom of the cushion. The passenger-side bolt is illustrated here at location {A}.
With the three bolts removed, raise the seat back up over the three top retaining hooks. Once free of them, pass the seat cushion through the seat belt harnesses laterally and remove.
The rear strut top hat should now be accessible. Remove the three 12mm nuts that secure the struts at location {A}. The two interior nuts are accessible with a deep socket, but not the fella under the seat belt spool. For that one use a Gear Ratchet socket (or similar) if available - otherwise a 12mm ratcheting or simple (but oh so slow) box wrench.
With the three bolts removed, lift off the top hat dust cover, noting the orientation. They are stamped "out" at location {B} indicating the outermost bolt hole. I took the additional step of annotating them Passenger and Driver side as well.
With the dust covers removed, replace the three 12mm bolts finger-tight on both of the struts. This will prevent the struts from falling to the ground or tearing through your brake line when you release the bottom retaining bolts.
Using a ratchet and deep socket, break loose (but do not remove) the single 17mm bolt on the top of the struts. (note: this step can be done later, but breaking the bolts loose now is easier with the struts still mounted).
Caution: This is the top retaining nut and is under spring tension - DO NOT REMOVE; just get them started.
With the prep work done it's time to get down to it. But before raising the car, now would be a good time to fetch the lug nut security key from the center console or glove box.
Raise the Car
Always use a safe means to raise the car:
- Never rely on a jack alone, use jack stands
- If using a lift, know the proper lift points for your car
- Follow manufacturers' instructions...
Remove the Wheels
If you're using a lift or four jack stands, remove all four wheels.
- A nice freebie is to take this opportunity to rotate your tires front-to-back. Once I remove the wheels I pre-position them so I don't forget to swap them later.
- For the strut swap you'll want to remove the two rear wheels - we'll start there.
- The lug nuts are 18mm
Let's get those clunky struts off! Replacing the rear struts:
Spray the two 19mm lower strut nuts and bolts at location {A} with penetrating oil, PB Blaster or similar. They're going to be fun to break loose - so spray them down as soon as possible to give them a good soaking.
Remove the brake line from its retaining bracket by using a slotted screwdriver or small punch and hammer to tap it free. The tension clip will slide out with just a couple light taps. Take caution not to damage the brake line. (since I already had the PB Blaster out for the bolts, I sprayed the retaining clip too). Note the clip orientation for re-installation
With the brake line free from the strut, it's time to tackle the two 19mm strut retaining bolts. Grab your breaker bar and a wrench for the opposite side and give it a go.
The CV joint boot doesn't provide sufficient clearance to the lower bolt head to get a socket on there - so I improvised by working on the nut side, slipping a torque wrench into the box wrench to form a 'T-handle' for leverage
Once you have them started switch to a ratchet to finish them off.
Support the rotor assembly when removing the second 19mm retaining bolt to prevent the rotor from flopping forward. This will also relieve tension on the bolt and make removal easier. Back the bolt out using the ratchet if possible. A gentle tap with a punch may also be necessary, but be sure to relieve rotor weight when tapping to avoid stripping the bolt.
Note the orientation of the bolt and nut for re-installation. For the rears, the bolt goes in from the rear (opposite for the front struts)
This is good time to get your buddy off the couch to assist.
Have an assistant remove the 3 top hat bolts while you hold onto the strut assembly to prevent it from falling.
Tap/slide the strut assembly back off of the bolt perch and remove.
Also note the spring position on the top and bottom where it seats onto the strut assembly top and bottom hats. The springs will need to be in these same positions on the new struts. You can use the paint again to mark the spot on the hats if you want.
Remove the spring from the old struts
The rear springs are under relatively little tension, so this won't be tough. Still, error on the side of caution whenever you're doing spring removal:
Place the strut assembly horizontally on a bench or the ground. Don't stand them up on the ground or against a solid surface so as not to create a projectile on the off-chance the compressor should slip.
Position the spring compressor hooks squarely on the springs and close the retaining bolts, if equipped. Ideally you want as much spring as is available between the opposing compression hooks. In this case a single coil between them was sufficient.
Compress the spring until you can freely slide it away from the top/bottom hats of the strut assembly. When you can do that you know there is no remaining tension on the hats and it's safe to remove the top hat retaining bolt. A hex wrench is needed to keep the strut shaft from free-spinning while you loosen the 17mm retaining nut. I used an open-end Gear Ratchet wrench and 6mm hex bit socket.
Prep the new struts for install:
- Clean off the rubber boots and install
- Apply suspension grease to the outer valve
Re-assemble the top hat and new strut with the spring using the paint alignment marks you made earlier.
Replace and tighten the 17mm top hat nut down.
Slowly remove tension on the spring compressor, keeping the top and bottom spring ends aligned in the proper spot on the hat perches. Here I have the old strut assembly alongside the new to provide a visual check.
Fetch your buddy from the couch a second time to help reinstall the new struts. Work the new strut into place, manually aligning the rotor assembly position and strut, and being careful to avoid damage to the brake line or CV boots.
Once your buddy threads the three top bolts, slide the strut over the bottom bolt perch (I greased the surface areas ahead of time to make this a bit easier). A small chisel or screwdriver is useful to get the holes aligned for the bolts.
Replace the bolts and nuts being mindful of the orientation as previously mentioned.
Replace the brake line retaining clip.
Replace the top hat dust covers, noting the orientation.
Nice Job - Relax for a bit and take a break.
Replacing the front struts:
Replacing the front struts is similar, but not identical to the rears:
On the plus side:
- The top hats are readily accessible
Not so Fun:
- In addition to the brake line, there's an ABS signal line to get tangled up in
- The front struts are larger, heavier and under more tension than the rears
- Camber bolts require proper alignment
But enough of that, let's get started again.
Remove the brake line from the strut bracket. Unlike the retainer clip used on the rears, a 12mm bolts is used here.
The top 19mm bolt adjust the camber of the front wheels. There is a reference mark on the strut at location {A} and similar alignment marks on the top bolt head. Mark the camber bolt position on the bolt head so you can match it up again on re-assembly. Caution: Failing to do so may necessitate a front-end alignment (or new tires) later.
With the camber bolt position marked, brake line and ABS signal line out of the way (I taped the bolts in place to find them later), break loose the two 19mm strut retaining bolts. Access is a little tight - I found coming in from below to be effective on the bottom bolt.
As before, keep the rotor assembly supported and stable when removing the last bolt. Once the strut was out, I used a couple of bungy cords to hold it in place.
Disassemble the front struts
I used a pair of traditional rod spring compressors for the fronts. Note that the short spring didn't allow for a coil run in-between the opposing compressor hooks. Less than ideal and it took all of the rod length to loosen, but it worked.
For re-assembly of the new struts, the FEAL rebuilt struts have the shaft end welded up, preventing use of the stock hex wrench approach to prevent the shaft from spinning. They recommend using an impact wrench instead.
You'll need your swim buddy to assist with the installation again. Take caution with the brake lines, ABS signal line, and CV boot when aligning everything back up. The extra line and heavier strut makes this part not-so-fun. But hey, you're almost done now.
- Greasing the strut perch surface helps some
- I also placed a thin plastic cutting sheet from the kitchen over the CV boot to protect it from getting ripped as I was wrestling to get the strut assembly in place. It helped.
Once the strut is in place and your buddy has finger-tightened the three topside bolts, align the bottom for the 19mm bolts.
Remember to use your alignment mark as you tighten up the top camber bolt.
Re-install the brake line and ABS signal line.
Tighten the three top side bolts and replace the rubber dust caps
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Written by:RobT
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