- 7 Min Read
- By: Tim Wong
How to Replace Strut Mounts, Bearings, and Boots on a Volvo 940
A few years ago I had all four dampers on my car replaced, including the rear dampers as well as the front strut inserts. The operation went rather smoothly with the help of a friendly mechanic. It would have been a good idea to have replaced everything in the strut assembly at the same time, but my knowledge of my own car was lacking at the time, and I simply didn’t think I needed to do more to the suspension. Down the road, my car reminded me I neglected something and proceeded to display the failure of its strut bellows. Torn strut boots can lead to premature failure of the seals inside your strut. With impending winter weather and associated road salt and grime, it was time to get to work.
This time round, I figured I’d tackle the job on my own by buying the right tools and taking each step cautiously and properly. As this job deals with spring compressors, its extremely important to not skip any steps. For this job, I changed the upper strut mount, upper strut mount bearing, as well as the strut bellows.
[Disclaimer: This how-to involves the use of spring compressors. Improper use can lead to an extremely dangerous situation and possibly injury. Follow the proper procedures and steps when using spring compressors as well as replacing other components in the strut assembly and the risk of injury will be reduced]
Step 1: Acquire the proper tools
This is one job where having the proper tools is a must. This is what you’ll need:
- Spring compressor - If you’re unsure of which style to buy, our own Dan Bullmore wrote a good post on picking a proper spring compressor. I chose to go with an external spring compressor. A key feature of the spring compressor I chose was the ability to use a ½" ratchet to tighten the spring compressors. FCP sells a set of quality CTA spring compressors as well.
- Impact wrench –The problem is removing the top strut nut. The strut tube will turn with the top nut if you try to simply unscrew it. An impact wrench removes the nut with little fuss. As the nut is inset, without an impact wrench, you’ll need to either fabricate or acquire a tool that will allow you to unscrew the top strut nut while holding the strut tube from above. You could potentially use a 24mm box wrench with an angled neck and hold the strut tube from above with a 10mm wrench. Additionally, if you’re willing, you can use a pipe wrench and hold the very top of your strut tube under the strut mount, where it will not enter the strut body, undoing the top nut with a socket. You will inevitably gouge the surface, but it’s up to you whether you’re willing to live with it. Functionally, there should be little issue with holding the top of the strut tube below the mount. With that said, I would never recommend this last method unless you have no other choice, or you’re getting rid of the strut insert anyways.
Step 2: Acquire the proper parts
In many cases, I will tend to buy aftermarket parts. Reference my wheel bearing tutorial for example where I went with an aftermarket brand, saving me about 50% off the OEM price. In this case, I bought aftermarket strut bellows, but VOLVO strut mounts and Volvo-supplier strut mount bearings. FCP sells a very good set of Lemfoerder strut mounts and bearings, but I preferred to go OEM VOLVO. FCP conveniently, sells both.
The reasoning behind the OEM strut mounts and bearings was simple: this is not a simple job and I wanted these critical parts to last. I’ve heard of horror stories where strut mounts would fail prematurely, sending the top of the strut tube through the top of the hood upon failure. The bearing, made by SKF, is essentially an OEM part and is no different quality-wise than a Volvo-branded part. Yes, they cost significantly more, but the knowledge of having quality parts in critical locations was important to me. Bearings made by INA are the exact OEM replacement part.
As the strut bellows was not a critical component, while undergoing a much lower level of stress, I was comfortable going with a lesser brand.
You can see below, these are the old strut mounts after 387,000KMs. There are some cracks showing, but still performed well after so many miles. I did not want to wait until failure to decide upon replacement.
Step 3: Remove parts attached to the strut assembly
The point of removing assorted parts attached to the strut assembly is to give yourself the needed room to maneuver the strut out of the wheel well. It will also make handling the strut a much easier affair, not dealing with more heavy parts attached to the strut You will want to remove the following parts:
- Brake caliper and rotor
To remove the braking assembly, refer to this video guide by FCP. Make sure you hang up the caliper on something solid, like your sway bar. You can use a coat hanger or zip ties. Just don’t hang them up to the coil spring like you’re normally used to, for obvious reasons.
- Front tie rod
You need to have this removed for the extra travel needed to pull the strut out from under the car. You shouldn’t need to worry about any alignment issues after re-installation
- Sway bar end link
The sway bar and link will keep your lower control arm from lowering. You don’t have to remove the entire link, just the upper or lower bolt.
- Strut rod
This would be a good time to inspect and possibly change your strut rod cone bushings. These are common wear items.
Step 4: Support the strut and remove the top nuts
Support the bottom of your strut with your floor jack. place it directly underneath your lower control arm, or your ball joint. I chose to place it under the lower ball joint as it was the lowest point. Once your strut is sufficiently supported, remove the two nuts on top of the strut tower.
Step 5: Lower the strut out of the wheel well.
Slowly lower the strut out of the wheel well, letting the floor jack take all of the weight. Make sure you’re not snagging on anything (brake lines or ABS sensor wires). It should lower out with little effort.
Support the strut by holding the spring. As it lowers enough to clear the bottom of your wheel arch, hold the top of the strut as it falls towards you. You may want to tape up your wheel arch to prevent accidental damage to your car. Once it’s out, find something to support the lower control arm as you remove the jack from under it. I used a floor jack on its side and supported the strut by the wheel bearing.
Step 6: Compress and remove the spring
This is where you need to pay attention. PAY ATTENTION!
Grab your spring compressors and place them opposite each other on the spring, spreading them as far apart as you can. You will want to contain as many coils between your spring compressor arms as possible Optimally, you’ll want your spring compressor to be as near the top of your coil spring as possible. On these springs, only one spring compressor could be close to the top. The second spring compressor was placed directly opposite.
Once you’re happy with the placement, start tightening the compressors, not tightening one significantly more than the other. Although you’ll be tempted to use an impact wrench to tighten the spring compressors to save time, don’t! Take your time, and make sure you’re not tilting the spring in any direction. Also make sure the compressors don’t move from their original location.
You will need to tighten them just enough so that there is no more force on the upper strut mount. You can tell by looking underneath the strut mount, and the spring should be loose enough so that you can slide it around in its seat.
Step 7: Remove the top nut and spring
Needless to say, make sure your spring compressors are tight enough before proceeding to this step. Take your impact wrench and a 24mm socket to remove the top nut. Never stand above the strut while removing this nut in case you didn’t properly tighten the spring compressor and there’s a bit of energy still allowed to be released by the spring. Stand to the side, and remove the nut, followed by the strut mount. As the mount is removed, place the spring compressor safely to the side, never pointing towards you, or any doorway. You don’t want poor Mr. Fluffy to be surprised by a couple pounds of spring steel travelling towards him at a rather high speed. For you eagle eyes, yes, this picture was taken during installation.
Step 8: Remove the old components and replace with new ones
Take off your old components and replace them with the new ones. This includes the strut boot, strut bearing, and strut mount When replacing the upper strut bearing, the coloured side will be facing up. Also ensure to clean the strut bearing seating surface. When replacing the upper strut mount, make sure there is a washer located between the rubber and strut tube. It’s not a bad idea to lubricate the strut rod with appropriate grease. After all, you want your parts to last don’t you?
Step 9: Place spring back into strut assembly and tighten top nut
Place your spring back into the strut assembly, making sure the spring is properly oriented in its lower seat. The direction of the strut mount at this point doesn’t matter as you can always rotate it.
Tighten your top nut. You’ll need to use your impact wrench to tighten it. As long as it’s tight and your impact wrench isn’t spinning anymore, you’re good to go. I found it nearly impossible to get an exact torque number on the nut as the strut tube would spin.
Step 10: Remove spring compressors
If you’re comfortable with the top nut being secured, remove your spring compressors. Counterclockwise to loosen. Again, take your time and don’t resort to impact wrenches to speed it up.
Step 11: Refit strut assembly
You’re almost there! Lift your strut into place, using your floor jack once again to help you lift the strut assembly into place. Make sure your strut mount is oriented properly. The strut mount should be directed forward, with the forward bolt being the bolt with the greater distance between it and the top nut.
Tighten the upper nuts and remove your floor jack.
Step 12: Re-attach components to strut assembly
Reattach your braking components, tie rod end, strut rod, and sway bar link. Lower your car onto the ground, and check the torque of your upper strut mount nuts as your struts car might have settled after having the entire weight of the car on the ground. Use the following table for the appropriate torque values.
|Upper strut mount top nut (large)||90-100|
|Upper strut mount top nuts (small)||15-25|
|Sway bar link||66|
|Brake Caliper bracket bolt||77|
|Tie rod end||44|
|Strut Rod (control arm)||74|
|Strut rod (body)||79|
There you have it, a refurbished strut. All in all, it took me about 2 hours per side. The first side took me about twice that as I was still figuring out how exactly to tackle the job. I found the above method to be the most straightforward and more importantly, the safest method. Keep it rolling.
Tim is a Canadian from Windsor, with a knack for taking things apart, and sometimes putting them back together. He is a mechanical engineer by day and backyard mechanic by night. His mantra in life is to never break another bolt.