Volvo Forum member polskamafia mjl shows us what tools and parts we need for this rear shocks replacement, plus what to do, how to do it, and even torque numbers for related bolts.
850 Rear Shocks Replacement Tutorial w/Photos
This is a write up for the replacement of rear shock absorbers on an 850 sedan. Before doing this repair I would suggest you let the car sit for at least a night with PB Blaster or WD-40 sprayed on the shock mount bolts and the lower shock to trailing arm bolt. I broke one of the shock mount bolts and I spent the entire weekend trying to get it out. I eventually had to drive it to a mechanic with only one shock mount bolt in place on the passenger side!
In addition, take a look at these other links:
- CN90’s great write up for Volvo V70 Rear Shocks DIY Tutorial
- JReed’s outstanding Volvo 850 Wagon Rear Shocks DIY Tutorial
- My thread with a lot of 850 shocks questions
Note: I used OEM Sachs & Boge Shocks. If you use Koni or Bilstein some parts may be different.
- Crow Bar
- Cheater Pipe
- Pipe Wrench
- T-30 Driver
- Flat head Driver
- Crescent Wrench
- Torque Wrench
- Socket Wrench
- Regular Socket Set
- Deep Socket Set
- Offset Wrench Set
- PB BlasterAnti Seize
1. Remove 3 plastic floor fasteners 2. Remove the seat bolt; a pipe wrench is handy to get it started while a T-30 will help finish un screwing it. 
3. Remove the 2 flat head plastic fasteners with a flat head screwdriver. [1 and 3]
4. Remove the plastic 10mm fastener. 
5. Remove the pop out fastener.  6. Pull back the carpeting. Spray some more PB Blaster on top of the shock mount bolts and from below. Also, apply gobs of anti seize to the bottom of these bolts so it will be sucked up into the nut as you spin the bolts.
8. Slowly and carefully remove the 2 shock mount bolts with a 12mm socket. For the 3 bolts that I didn’t break, I used cn90’s technique. It works perfectly. Loosen it 2 turns tighten 1, loosen 2 tighten 1, etc… Periodically, if you feel a lot of resistance, stop, spray PB Blaster and let it set for a while then go after the bolts again.
Take my advice, DO NOT BREAK THESE BOLTS AT ALL COSTS! This is an easy job unless you break them.
9. Jack up the side of the suspension you are working on to relieve pressure on the shock absorber. Now, use the 18mm deep socket and cheater pipe to remove the 18mm bolt at the bottom of the shock. Be careful with this bolt as well because if you break the stud off you will have to buy a new delt link arm.
10. Use the crow bar to slide the shock off of the mount. 11. Lift the shock through the top.
1. Order of parts from top to bottom: Nut, Shock Mount, Shock. 2. Hold the bottom of the shock in between your feet. With one hand take an offset wrench [for OEM shocks, it is a 15mm wrench] and with the other hand use a crescent wrench. Tighten the nut as tight as you can. Don’t worry about the torque value for now, it is much easier to tighten once it is in the car.
Install the shock through the top. Dip the shock mount bolts in anti seize so the next time you need to remove them, they won’t break. Do not install these 2 bolts yet. 4. With the suspension jacked up a bit, maneuver the bottom of the shock onto the stud on the delta link arm and loosely tighten the 18mm nut with a deep socket. I also sprayed this with PB Blaster for future endeavors. 5. Now go back up top and tighten the center bolt to 29ft/lbs, then the shock mount bolts to 18ft/lbs, and finally, underneath, the 18mm bolt to 59ft/lbs. 6. Now, clean any excess oil or PB Blaster off, replace the plastic fasteners and button everything back up.
Remember to let the PB Blaster set over night and to apply grease from the bottom onto the bolts. Take it slow. They are a real PITA to get out. I spent all weekend trying to remove just one bolt and I still couldn’t do it.