'97 Volvo 855 Wagon Rear Shock Absorber DIY tutorial

[jreed]

I replaced the rear shock absorbers and mounts on my '97 855 GLT at ~147K miles yesterday. I was replacing the shocks because they were good and worn out, with sagging rear suspension height (~ 1-2cm of sag), visible leaking oil on the outside of the shock tubes, and rubbing of one of the tires on the inner upper plastic wheel well liner when going over bumps. I took photos along the way to show how I did it in the hopes that it might help someone else out.

*Picture of original rear shock absorbers

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I benefited greatly from the nice write-up by cn90, who posted Volvo V70 Rear Shocks DIY Tutorial

I did the job a little differently (I did not jack up the car) and used different parts (Sachs instead of Bilstein) and used different tools, so I thought it might be worthwhile to write it up and contribute it to go along with the nice write up already done by cn90.

Tools / Materials used:
10mm, 12mm and possibly 13mm sockets (depending on the size of the replacement mount bolts) (3/8" drive)
18mm socket (1/2" drive)
Ratcheting wrenches (3/8" and 1/2" drive)
Breaker bar (1/2" drive) for cracking off the torque on the bottom shock nuts
Torque wrenches (I used a 3/8" drive for setting 18 ft-lbs on the upper mounting bolts and a 1/2" drive for setting 59 ft-lbs on the lower shock nut. It is helpful if the 1/2" torque wrench is long and ratcheting).
Long screwdriver or prybar for sliding the shocks off of the lower mounting studs.
Needle nose vise grip pliers (for initial holding of the shock piston rod during attachment to mount)
10" or larger Adjustable wrench (for holding the shock rod during final attachment to mount)
15mm open ended wrench (for shock rod attachment) or a 15mm offset wrench
Penetrating oil (I used PBlaster)
Wheel bearing grease
White lithium grease
Small steel wire brush

Parts used: I used Sachs shocks and Hutchinson mounts (the OEM manufacturers for these parts). The shocks also came with new top nut and washer, and new bottom nut (but not a new bottom washer -- you can clean this up and re-use it). The shocks were made in Germany (Sachs part number 105 828). The mounts were made in Poland (Hutchinson part number 538124, Volvo part number 9461524).

*Picture of shocks

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*Picture of shock assembly kit

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*Picture of mount

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Due to the rust you will likely find on the upper mounting bolt threads, I would also recommend buying four new upper mount bolts in advance. I did not buy these in advance but should have. These bolts are flanged M8 x 1.25 (coarse thread) x 30mm long. The tensile strength grade was 8.8 on the original nuts with a black oxide finish. I replaced the original bolts with M8 x 1.25 x 30mm grade 10.9 flanged stainless steel bolts, which were the closest I could find. Several car parts stores nearby (NAPA, Carquest) did not have anything close in stock, but I located the grade 10.9's at the nearby Ace Hardware, which was pretty well stocked. The bolts cost $1.20/each. Both the new and old bolts have an 8mm diameter thread, but the original bolts had a 12mm hexhead and the new bolts had a 13mm hexhead.

*Picture of original (left) and new (right) bolts

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Procedure used:
The first step in the job is to remove the back decking in the wagon. The front deck lifts up and out, and the side decks snap out of their holding clips, revealing four bolts that can be removed with a 10mm socket and ratchet. Once these are out, lift up and remove the back deck while turning slightly to avoid hitting the trim around the wagon gate.

*Picture of rear deck

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*Picture of rear deck bolts

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With the deck out of the way you can see the shock mounts. There are three bolts visible on each mount. The center bolt is attached to the shock rod, and if you are replacing the mounts as well as the shocks, you will never need to touch these. The two bolts at the corners of the mounts need to be removed, and they are tricky because the threaded bottom of these bolts are exposed in the wheel well and get very rusty over the years.

*Picture of wrench on rear mount bolt

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The method that cn90 described worked well for me: use repeated blasts of penetrating oil while turning slowly and occasionally tightening back up a turn and applying more penetrating oil when I felt building resistance. I am grateful to cn90 -- he helped me avoid shearing any bolts!

*Picture of squirting penetrating oil

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The bolt removal takes a while due to the rust and because the bolts are 30mm long, so there is a lot of thread to unwind. After you loosen the bolts, the shock mount will rise up off of the attachment point on the car body.

*Picture of mount lifted off of body, rusty bolts visible

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Now, you are ready to loosen the bottom mounting nuts. I applied penetrating oil to these nuts too, and then loosened them with an 18mm socket attached to a long breaker bar.

*Picture of breaker bar cracking off the torque on the bottom shock nut

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After you get the nuts loose, you can remove them with a ratcheting wrench

*Picture of nut removal with ratchet

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With the nuts off, I used a long screwdriver to pry the shock off of the stud.

*Picture of screwdriver being used as a prybar popping off the shock

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Then, you go back inside the wagon and lift the shock and mount up and out of the car.

Old shock and mount being lifted out of car.

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The next step is to clean up the mounting stud. I used a wire brush to remove residual paint flakes, dirt and corrosion from the stud.

Mounting stud (pre cleaning)

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Then I applied a thin layer of white lithium grease to the trailing arm that the stud is attached to, and some wheel bearing grease to the stud itself.

Stud after cleaning and greasing

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The stud is now ready to receive the new shock absorber.
To get the new shock absorbers ready for installation, you need to attach the shock rod to the mount. It's easiest to do this ahead of time and doesn't need to be done on the car. To attach the shock rod to the mount, put on the washer and then the nut and tighten the nut by hand at first.

New mount with washer, nut and rod just starting to be engaged by the nut

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When the nut becomes a little tight, you will be able to hold the flats on the piston rod with needle nose vise grip pliers or something similar so you can continue to tighten.

Vise grip locking pliers holding piston rod while tightening the nut

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With further tightening, more of the flat will be exposed and you can replace the vise grips with a large adjustable wrench. The torque specification for this fastener is 29 ft-lbs. I tightened it up until it felt "really tight" because I don't have a torque wrench that fits.

Adjustable wrench and 15mm open end wrench applying tightening torque to shock nut and piston rod

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This job would be easier with an offset 15mm wrench to tighten the top nut, but it can also be done with a more common open end 15mm wrench (which is what I had in house). When you're done, the mount and center nut on the shock piston rod should look similar to this:

Mount and center nut, ready to install

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Now the new mounts and shocks can be installed in the car. Insert the shock and mount in the hole from inside the wagon. Then, go underneath the car and lift the shock slightly and slide it onto the stud.

New shock on stud

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Attach the washer and the new nut on the stud. Leave it a little loose and don't tighten it to final torque for now.

Nut on stud (loosely tightened only)

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Back inside the wagon, the new mount will be "floating" a few inches above the attachment point.

New shock and mount as seen from inside the wagon, before attaching the mount to car body

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Insert the new mounting bolts in the mount, compress the shock downwards by applying and holding a little force to the top of the mount. Start the mounting bolts until they catch in the threads. Then you can tighten down the bolts with a ratchet.

Mount being attached to car with new mounting bolts.

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Use a torque wrench to tighten up the mounting bolts to 18 ft-lbs. I did this in stages because I found that the rubber on the mounts compressed a little each time I tightened up a bolt.

Torquing the upper mounting nuts to 18 ft-lbs.

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Then, underneath the car you use a torque wrench to tighten the 18mm bottom nut to 59 ft-lbs.

Torquing the lower nut to 59 ft-lbs.

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Torquing the lower nut was somewhat difficult because of the force required and the amount of clearance under the car is limited. It's very helpful to have a long ratcheting torque wrench for this step.

At the end, the upper mount should look like the picture below. It might be a good idea to bounce the car a couple of times and then recheck the torque on the mounting bolts.

Completed upper mount

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You then reinstall the rear decking, tighten up the four bolts, and put the rest of the decking back in the wagon. Job done!

The job took about three hours and I did it in the driveway. As far as raising up the car to do this job, It might be a little easier to get access to the bottom shock nuts and studs with the car up on jackstands, but on the other hand it was easier to reach in and work on the mounts and nuts in the back of the wagon with the car on the ground.

[erikv11]

This is a fantastic writeup, great addition to the existing collection!

[matthew1]

Agreed. JReed, this is a Mona Lisa of forum posts. Going in the 850 Repair Database today.

[LamboSE5]

JReed - Amazing job on the write up (and the job)!

Matthew said it, this is such a well done writeup. I have absolutely no worries about doing this when the time comes now. From this and cn90's it should go smoothly.

The only question I'd ask is about this part:

There are three bolts visible on each mount. The center bolt is attached to the shock rod, and if you are replacing the mounts as well as the shocks, you will never need to touch these. The two bolts at the corners of the mounts need to be removed, and they are tricky because the threaded bottom of these bolts are exposed in the wheel well and get very rusty over the years.

Question: Do these just thread into the body, or is there a nut on the underside -- if there is a nut is it welded to the body on the underside. You say the bottoms of the bolts are in the wheel well. But I guess you (personally) didn't need to touch them because you didn't jack the car up, or remove a wheel, or the plastic wheel well splash guard (can't remember if there is even any on the rears )

I have a 98 S70. Should be the exact same to do hey..

Again, freakin' great write-up! Thank you so much.

[ oh, P.S. could I use the center bolt/shock rod to ground an amplifier ;p ]

[erikv11]

The nut is welded to the underside of the shock mount hole. There are two common problems when removing those corroded bolts: (1) the bolt shears and (2, less common) the nut breaks loose from its weld. If the bolt shears, most people just drill it out then reach up from underneath to get another (loose) nut up in there.

There is really no approach in which you would touch/access the bottoms of those shock mount bolts. However, you should spray some PB'blaster up in there, which wasn't mentioned in the writeup. Only spraying from the top works but makes for slower going.

[Lady-do-it-herselfer]

Thanks for the write up and many helpful pics you added! And yes, even with yours and cn90's warnings, I sheared a top bolt. And then when I was hammering the bolt retractor in the pilot hole, the nut fell off the car! I fortunately did not have a rust issue on my 149K, 16 year old 850 GTL Wagon thanks to it's first 134K being in New Hampshire where they do not use salt on the roads like we do here in the Buffalo, New York area! It was almost a sin how easily I removed the lower bolts! I messed up by not evenly removing the bolts, which is the reason for this posting. My suggestion to the next repairer is not only to alternate between the two 12mm bolts on each mount, but to alternate between all 4 bolts (both the left & the right shock mount) evenly. Even with my small 120lb frame inside the car, it was still enough uneven stress to bend both bolts on the other side, ultimately shearing one. But if you do find yourself in the same sheared-bolt situation, put the other sides 2 bolts back on in an even position (first cleaning and spraying them with white lithium grease). This helped me get the fourth, un-sheared bolt off easily, even though it was bent.

I also included a picture of the rear, forward decking; I struggled a bit due to not knowing there were 3 retention brackets(pictured). After you remove the four bolts fastening it to the cars frame, slide the decking towards the rear of the wagon til all three brackets are released. Hope it eliminates the frustration like I had for 5 minutes wondering what the heck was going on?!

Picture of 3 retention brackets on rear decking; 3 shiny items in picture

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Thanks also for the tip of not jacking up the car, I also found no need to do this. Everyone follow jreeds suggestion and read cn90's posting as well, both were of great help. His link is found in the beginning of jreeds (this one).

[LamboSE5]

I'll be using this tutorial again shortly. It's great.

First time, I had one of the nuts on the underside break free of its weld - which was so rusted! But much easier to deal with than snapping the bolt off inside the thread.

This time I'll use PB again, and probably my new friend - Heat.

[cn90]

I am reading this DIY, it is such a great write-up.

People already noticed that with my DIY, I placed the Rear of the Volvo on jackstands with Rear wheels removed. In retrospect, this was not necessary at all. So hats off to "jreed" for this time-saving tip (i.e., no need to remove rear wheels).

However, I'd add a few little tips:

1. The lower nut 18-mm, some people broke the stud because over time, the nut maybe rusted and frozen in place.
So in the process of undoing the nut, people break the stud!
To prevent breaking the stud, use PB Blaster and some heat (propane torch) on the nut before removing it.
Once the nut is heated, it takes much less force to undo it.

2. If you do it "jreed's way" (wheels on the ground), I strongly recommend that you back the Volvo Rear wheels on some wood ramps to give you added clearance, it will be more pleasant this way.

I have a 3-layer wood ramps that I use for oil change, you can use wood ramps for the rear wheels as well.
Example of wood ramps used for oil change:

[theWIFES_S70]

Thanks for this post. It really helped me out this past weekend! I managed to only shear off one bolt! But I knew how to tackle it.

In case anyone is looking for steps to follow:
- Take wheel off.
- Stick your hand in there with a nut in hand, fish around for the bolt and thread it on.

- Then take a long flex-head ratchet and deep socket to it and tighten, while someone from the top holds it in place.

- Hold nut in place while someone torques the bolt from on top.

For any of those who are interested in buying the replacement bolts and nuts and washers beforehand, I went over to boltdepot.com and picked them up before tackling the job. I couldn't find any 10.9 zinc-plated hardware locally in Queens, NY. Also, if you're going to install <<cough, cough>>, super-cost effective Gabriel shocks, you're going to have to purchase some fender washers to go between the top of the shock and the bottom of the shock mount. Also, I would really double check to see if you even need new mounts. The Volvo mounts in my wife's S70 looked almost brand new... In case anyone is interested, the Gabriel shocks make the car 70% less bouncy (and less noisy) than the totally shot shocks we had in there. We're pleased!

[skloon]

Those rear mounts are weird, I had one that looked good, I couldn't wiggle it but it was making a noise- great write up though- I feel like sending it to the 'Volvo Specialist Shop' that did my car before I bought it- they broke the bottom stud off and welded a nut in its place- new subframe time !@@#