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Pelican Technical Article:

Shock Replacement

Time:

3 hr

Tab:

up to $500

Talent:

**

Tools:

Drill/press for roll pin (Bilstein shocks only), Allen socket set

Applicable Models:

 
Porsche 911 (1965-89)
Porsche 912 (1965-69)
Porsche 914 (1970-76)
Porsche 930 Turbo (1976-89)

Parts Required:

Front and rear shock absorbers

Hot Tip:

Match front shock absorbers to the struts on your car

Performance Gain:

Better handling and performance

Complementary Modification:

Installation of a camber bar, replacement of ball joints, and tie rod ends
101 Projects for Your Porsche 911

This article is one in a series that have been released in conjunction with Wayne's book, 101 Projects for Your Porsche 911. The book contains 240 pages of full color projects detailing everything from performance mods to changing your brake pads. With more than 650+ full-color glossy photos accompanying extensive step-by-step procedures, this book is required reading in any Porsche 911 owner's collection. See The Official Book Website for more details.

One of the most popular projects to perform is the replacement of the front and rear shocks on the 911. It is usually recommended that you replace both the front and the rear at the same time, as they take roughly similar abuse over their lifetime, and the fronts or rears are not likely to be more or less worn than the other ones. As a rule, the shocks should always be replaced in pairs.

I recommend that you replace your shocks every 50,000 miles or so, or if they start to show signs of fading or wearing out. If you push down on a corner of the car, it should spring back with almost no oscillation up and down. If the car bounces up and down, then you probably need new shocks. Different driving patterns may also affect the life of shock absorbers. Cars that are raced or often driven on windy roads may need to have their shocks replaced more often than street cars.

The first step in replacing your shocks is to determine what type of front strut you have in your car. The front strut is the part of the front suspension that pivots on the ball joint that the brakes, wheels and tires are mounted to. Certain types of shocks will only fit certain types of 911 front struts. If your 911 car has Bilstein struts, then you must replace them with new Bilstein shocks. If you car has Koni struts, then likewise, you must use Koni shock inserts as replacements. You cannot use another shock, as it will not fit inside your 911's front strut.

The easiest and most basic method of determining which front strut you have is to take a look at the color of the strut. Green struts are almost always Bilstein struts, red is almost always Koni, black is Boge, and yellow struts can be either Bilstein or Koni. One sure method of checking for Bilstein struts is to look for the roll pin that is installed at the bottom of the shock (see photo). The Bilstein inserts are installed âup side down' as compared to the typical method of mounting the cylinder on the bottom. The shock extension therefore must be constrained in the bottom of the strut. The roll pin accomplishes this by securing the insert in the strut. If your strut has this roll pin installed in the bottom of the strut, then it is a Bilstein strut.

When you order your new front shocks, make sure that you order replacements that will match your strut type. If you wish to change to a different type or manufacturer of shocks, and you have Koni or Bilstein struts, then you will have to change out your inserts, which is not exactly a simple job. The Boge inserts can accept shock absorber inserts from a variety of manufacturers. When you order rear shocks, it doesn't matter which brand you order: they should all fit your 911.

Before you begin, jack up the front of the car and remove the road wheels from both sides. Now might be a good time to inspect your tie rod ends, brake discs, and pads.

The first step in removing your front shocks is to remove the large nut that holds the insert to the top of the car. If you have Bilstein struts, I recommend that you remove the small roll pin from the bottom of the strut prior to removing the large nut. This will keep the shock secured in place while you hammer or drill out the roll pin. Open the trunk and you will see the large nut located in the center of the shock tower mount. For pictures of this nut, see Pelican Technical Article: Installing a Camber Strut Brace, Installing a Camber Strut Brace. After you remove the nut off the top of the strut, you should be able to take the entire strut and pull it out from under the fender well. You will need to push down on the shock in order to gain enough clearance to do this. NOTE: The strut retainer nut on top of the Koni lower housing is a major issue. Very difficult to remove. Use penetrating catalyst and be patient with spanner or pipe wrench....upon replacement of strut insert, be careful to align retaining nut so threads are not stripped.

After the strut has cleared the fender, remove the dust shield from the top of the shock. The insert should now pull out of the strut. Check the rubber o-ring at the top of the insert for damage, and replace it if necessary. Make sure that you don't let the shock hang from the rubber brake line. Doing so will almost certainly damage your brake lines.

Installation of the new shocks is easy. Simply place the new insert into the strut and reattach it to the shock towers with the large nut. For Boge, Koni, and other shocks, simply insert the shock in the strut and reattach it. If you have Bilstein inserts, install the roll pin in the lower part of the strut. A very important part of the installation is assuring that the roll pin is installed correctly. The roll pin must be installed with the groove facing away from the center of the insert. If the roll pin is installed backwards, or at some angle in-between, then the vibration of the shock will cause the roll pin to break after repeated motions up and down. Make sure that you install the roll pin as shown in the photos that accompany this project.

The rear shocks are much simpler. They are basically a bolt-in replacement. You can install any type of shock (Boge, Bilstein, Koni, etc.) on the rear suspension without any consideration of what the car originally shipped with. Before you begin the replacement of the rear shocks, jack up the rear of the car. You don't need to remove the rear wheels.

To remove the rear shock, place a jack under the rear trailing arm and lift it up slightly. The shocks support the weight of the trailing arm when the car is suspended in air, so you need to remove this tension from the shock prior to removal. Inside the engine compartment, all the way towards the front is the mount for the rear shocks. Remove this large nut while keeping the top âtab' of the shock from turning. Underneath the car, simply remove the large bolt that mounts the rear shock to the trailing arm.

Install the new shock by inserting it up into the car, and then replacing the rear trailing arm bolt. Back inside the engine compartment, reinstall the retaining nut on the top of the shock.

The top set of shocks are Bilstein front shocks, original equipment on some 911s.
Figure 1

The top set of shocks are Bilstein front shocks, original equipment on some 911s. It is important to make sure that you match the front suspension struts to the type of shocks that you purchase. The lower two shocks are Boge rear shocks, and were also original equipment on the 911s. Unlike the front, the rear shocks do not have to be matched to the original shocks sold with the car.

The front strut pulls away after the top fastening nut is removed.
Figure 2

The front strut pulls away after the top fastening nut is removed. At this point, the dust shield can be removed, and the shock insert can be removed. For the Bilstein inserts, make sure that you remove the roll pin that is installed at the bottom of the strut. For all other shock types (Koni, Boge, etc.) the shock should simply lift out of the strut. These are Bilstein struts, most easily determined by their green color. Koni inserts are usually red, Boge inserts are typically black, and yellow inserts can be either Bilstein or Koni. All the struts should be appropriately labeled by their manufacturer as well. NOTE: The strut retainer nut on top of the Koni lower housing is a major issue. Very difficult to remove. Use penetrating catalyst and be patient with spanner or pipe wrench....upon replacement of strut insert, be careful to align retaining nut so threads are not stripped.

The roll pin that holds in the Bilstein shock must be installed properly, or it will break under normal driving conditions.
Figure 3

The roll pin that holds in the Bilstein shock must be installed properly, or it will break under normal driving conditions. The roll pin must be installed with the slit facing away from the center of the shock. If not, the shock will flex the roll pin, and over time this will cause the metal to yield and break.

The rear shocks are much easier to replace than the front one.
Figure 4

The rear shocks are much easier to replace than the front one. Support the rear trailing arm, and then unbolt the rear shock mount located in the back of the engine compartment, towards the front of the car (shown by arrow). Make sure that you keep the top of the shock from turning as you remove the retaining nut.

Down below, the shock is simply bolted into the rear trailing arm.
Figure 5

Down below, the shock is simply bolted into the rear trailing arm. With the trailing arm supported by a jack, unbolt and pull out the shock from the chassis. The installation of the new shock is quite a straightforward, bolt-in process.

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Comments and Suggestions:
Scubadog Comments: I have an '85 911 and am told that it's a transition year where the front shocks can either be internal or external thread. What do you know about the difference and how can I tell if the shocks you are selling are internal vs. external?
August 30, 2016
  Followup from the Pelican Staff: lack of the roll pin is a sign you have the later version.

I’m not the best with part numbers.

Give The Pelican Parts parts specialists a call at 1-888-280-7799. They can figure out what part or repair kit you need.
- Nick at Pelican Parts
 
Doug Comments: Thanks Nick, I did manager to put a 1"x3"x 12" block of wood on the through the strut shaft and lock it down with a washer and nut. Then a lot of tapping/pounding got the old ones out. Awesome site and support! The rear shocks will be next.
June 2, 2016
  Followup from the Pelican Staff: Thanks for the follow up. We appreciate it.
- Nick at Pelican Parts
 
Doug Comments: I have Boge struts and can't get the insert out after removing the lock ring. Any ideas on how to get this out? 1983 911sc. The insert will actually turn inside the strut but won't lift out.
May 30, 2016
  Followup from the Pelican Staff: The inserts can be tough to get out. Try reinstalling the nut, then using it as a gripping point for leverage. - Nick at Pelican Parts  
Franks89-911 Comments: I just replaced rear shocks on my 89 911. To access the right rear shock top I removed the airbox and mass air flow metal box to its left. The mass air flow box and left half of the airbox are held together with four 10mm screws deep in the inside of the airbox. You will need a long socket and extension to reach them. Its pretty tight in there so be patient.
May 30, 2016
  Followup from the Pelican Staff: Thanks for sharing your installation process and experience. These type of comments add so much to the Pelican tech community.
- Nick at Pelican Parts
 
Rubytub Comments: Agree with Andrew above! This article & 101 projects book is incomplete! The strut retainer nut on top of the Koni lower housing is a major issue. Very difficult to remove. Use penetrating catalyst and be patient with spanner or pipe wrench....upon replacement of strut insert, be careful to align retaining nut so threads are not stripped.
March 31, 2016
  Followup from the Pelican Staff: Thanks for the additional info and feedback. We appreciate it. I'll see if I can have the article updated. - Nick at Pelican Parts  
bill Comments: i installed new Boge strut inserts this weekend on my 1987 -911. You say above to re-use the rubber o-ring inside the strut. Is this necessary? the new struts seem self contained and i am not sure what the o-ring would do. Also there is not a lot of room to re-install it.
March 7, 2016
  Followup from the Pelican Staff: I believe the o-ring seals the insert and helps to hold it in place. - Nick at Pelican Parts  
BigJim Comments: Thanks Nick, for your reply. Unfortunately I cannot duplicate the problem with the car on a single-post lift that leaves the wheels to turning by hand. It only occurs when the care is moving slowly backing out of the garage. I believe that it is suspension problem and to have to replace all the components to solve the problem seems like overkill. Oh well, unless somebody has a different idea that is how I will proceed.
December 23, 2015
  Followup from the Pelican Staff: You don;t have to replace them all, you have to pinpoint the area of the fault. Unfortunately, I can't do much via the web, without hearing and experiencing the issue. - Nick at Pelican Parts  
BigJim Comments: I have a 1987 911 coupe with a popping noise coming from the left front wheel area when turning right or left out of the garage. It does not pop when turning the wheel at a stand still. The best local Porsche mechanic can't find the problem. I am thinking of replacing the front shocks. Any body ever had a problem like this?
December 20, 2015
  Followup from the Pelican Staff: I would pull or push the wheel forward and back in the wheel well, with the front end off the ground. You should be able to duplicate the sound this way, and identify the problem. I would assume it is in the suspension. - Nick at Pelican Parts  
Thor 81 Comments: Hi
I have instaled new bilstein inserts in front, but If I put one hand on the insert and the other hand on the tube and aply some sideways force to it I can see that there is a small play betwheen the inserts and the tube.. maybe a couple of milimeters. Is this normal?? Can the tube become woarn by time?
Im afraid this will change the camber under driving..
Any ideas? 😕
Regards,Thor😊.
December 1, 2015
  Followup from the Pelican Staff: It could be worn. Compare it to the other side. It should slide in, be a fairly good fit. - Nick at Pelican Parts  
Lee Comments: picked up my 83 911 3 mos ago. Replaced rear shocks. Thank you pelican staff for this site. Really help me a lot. As well as members suggestion mrhaydndownes especially rt side shock. Didn't have to tie oil line hoses. I used craftsman elbow wrench and 4" bar magnet on top. Didn't loose the nut and washer in tight area while removing and installing. Great job guys.
July 1, 2015
  Followup from the Pelican Staff: Thanks for sharing your installation process and experience. These type of comments add so much to the Pelican tech community.
- Nick at Pelican Parts
 
Andrew Comments: Nick, my '72 car has factory fitted Koni's that take the standard strut inserts
June 4, 2015
  Followup from the Pelican Staff: Ah, OK. Funny I couldn't find anything showing the nut to release the cartridge. Which seems it should be covered.. - Nick at Pelican Parts  
rodneygt3 Comments: For the rear shocks the article shows the drivers side tower which is visible with eye and easy to get to. However, it does not mention the right side tower is not visible and from what I have seen you need to remove the air box to get to the tower on order to remove the engine mount bolt.
June 3, 2015
  Followup from the Pelican Staff: Thanks for the additional info and feedback. We appreciate it.
- Nick at Pelican Parts
 
SpawnyWhippet Comments: Thanks for the additional info. We appreciate it. I will have someone look into it and have the article updated if needed.

What is the year and model of your vehicle?
- Nick at Pelican Parts

This was for a 1972 911T
June 3, 2015
  Followup from the Pelican Staff:
Did you have the Bilstein style or was it a drop in cartridge?

I can't find anything different from what the article states. It's possible you have an aftermarket cartridge strut. Which would have a nut on top to allow removal of the cartridge.
- Nick at Pelican Parts
 
Andrew Comments: This article is very useful, but missed one key step that caused me to damage one of my struts. There is a top cover to the front strut housing that has to be unscrewed using a special tool or pipe wrench prior to pulling the strut insert out. My struts have not been touched in 45 years and were so covered in road dirt and rock chip paint that I couldn't see the cover and I tried to pry out what I thought was the insert, but turned out I was pulling the rim off the cover.
June 3, 2015
  Followup from the Pelican Staff: Thanks for the additional info. We appreciate it. I will have someone look into it and have the article updated if needed.

What is the year and model of your vehicle?
- Nick at Pelican Parts
 
Layno Comments: You say that the roll pin must be installed with the slit facing away from the center of the shock. Is this the "3 o'clock" position?
May 16, 2015
  Followup from the Pelican Staff: The slit needs to be on the spindle side of the shock. The o'clock position will be different depending on which side of the car you're working on- Casey at Pelican Parts  
gkwoodfin Comments: I have to replace my original Boge front shocks. I'm confused with what I've read and I'm not a DIY guy. Can my mechanic replace this shock only or is the whole assembly needed? Could I or my mechanic call for info?
Thanks
March 9, 2015
  Followup from the Pelican Staff: I believe they have to be rebuilt. I am sure we can answer his questions and supply high quality parts for your vehicle.

Give our parts specialists a call at 1-888-280-7799 and they can help figure out which part or repair kit you need.
- Nick at Pelican Parts
 
Bucko Comments: This an awesome site, as important as the correct tool.
Congrats to you and staff.
April 9, 2014
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 
mrhaydndownes Comments: Additions to the article, based on Jan '14 install on an SC, incorporating some posts from the tech forums.

Front Shocks:
Top - The tab washer may be bent up on one side,and should be hammered flat before attempting to undo the large nut.

Bottom - A roll pin punch is required to drive out the pin on the bottom.

Rear Shocks:
on Top: For removal/installation, either vice grips for an oval head, or an allen wrench for an allen socket in top should be used. You may want to tie up the oil hose to get it out of your way on the right side of the car, and reach to the right around the flexible fuel lines. Note that this was a 17mm wrench/socket.

The bottom bolt 22mm socket may require a large breaker bar to free the bolt.

January 17, 2014
  Followup from the Pelican Staff: Thanks for the additional info. We appreciate it.
- Nick at Pelican Parts
 
drbill 201 Comments: Both new Koniyellow rear shocks on my restored 1969 912 are showing interference and rubbing of the outer shock cover against the shock body. I believe the rear trailing arms are correct for this year so I cannot figure out what is causing this, car has never been hit or damaged. Anyone have this experience as well?
December 28, 2013
  Followup from the Pelican Staff: I opened a post in our forums. A Pelican community member may be able to answer your question.
- Nick at Pelican Parts
 
krisbrook9 Comments: It is time to replace the front and rear original Boge shocks on my 1982 911sc. I do not take this vehicle to the track, it is driven entirely on the city streets & highways. So the most important thing to me is a comfortable touring ride. Now the current ride seems to be "loose" but this may be because the current shocks are 30+ years old... So based on this would you recommend going back with the Sachs Boge originals or change to the Bilstein HD?
December 2, 2013
  Followup from the Pelican Staff: Save yourself some money and just go with the stock parts. - Nick at Pelican Parts  
Tidybuoy Comments: I wish you would include TORQUE SPECS on all "technical" articles. It's frustrating searching the net for the correct torque specs for any project.

In my opinion, the job is not done until the bolts are torqued - the article needs to be completed with correct torque specs.
September 22, 2013
  Followup from the Pelican Staff: Thanks for the suggestion. In general, I shy away from providing these, as they are sometimes updated and changed by the manufacturers. It's also very easy to get them incorrect, and even the factory manuals are sometimes incorrect. - Wayne at Pelican Parts  
TT Gasman Comments: Try an impact wrench. Also on the rears you can stabilize the tab with vice grips and loosen the nut.
April 22, 2012
  Followup from the Pelican Staff: Thanks for helping out. - Nick at Pelican Parts  
JordanSC Comments: Wayne, do you have any tips or recommended tools for keeping the top 'tab' of the shock from turning? I've been struggling for a little while now with that piece. Thanks, Jordan.
April 18, 2012
  Followup from the Pelican Staff: You can use vice grips but you do not want to mar the shaft. Use some rubber hose over the jaws to protect the shock shaft - Nick at Pelican Parts  

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