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Replacing Shocks & Springs
 
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Pelican Technical Article:

Replacing Shocks & Springs

Time:

8

Tab:

$1200

Talent:

****

Tools:

Spring compressor, floor jack, jack stands

Applicable Models:

Porsche 986 Boxster (1997-04)
Porsche 986 Boxster S (2000-04)
Porsche 987 Boxster (2005-08)
Porsche 987 Boxster S (2005-08)

Parts Required:

Shocks, springs and hardware

Hot Tip:

Purchase an electric or air impact wrench for this task

Performance Gain:

Smoother, crisper handling

Complementary Modification:

Install performance springs and lower your suspension
101 Performance Projects for Your Porsche Boxster

This article is one in a series that have been released in conjunction with Wayne's new book, 101 Performance Projects for Your Porsche Boxster. The book contains 312 pages of full color projects detailing everything from performance mods to changing your brake pads. With more than 950+ full-color glossy photos accompanying extensive step-by-step procedures, this book is required reading in any Boxster owner's collection. The book is currently available and in stock now. See The Official Book Website for more details.

One of the most popular projects to perform on the Boxster is the replacement of the front and rear shocks. I usually recommend 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 (left and right together). The replacement procedures for the front and rear shocks are very similar.

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. It is also important to remember to have the car realigned if you install performance springs into your car that lower it from its stock level. Changing the height of the suspension changes the values of the alignment / suspension settings.

With the car elevated in the air and the wheels removed, start with one strut, and remove the brake caliper (see Pelican Technical Article: Replacing Shocks & Springs). Unplug any brake sensors that may be connected to the caliper and disconnect them from the strut (see Figure 1). Use some rope or wire to tie the brake caliper aside so that it doesn't hang by its rubber hose. Now, disconnect the sway bar drop link from the wheel bearing carrier (see Figure 2). In the front trunk compartment, mark the location of the three nuts that hold the shock to the tower and then remove them (Figure 3). Finally, loosen but do not remove the bolt that attaches the wishbone to the chassis (see Figure 4). This will allow us to drop the strut downwards to its lowest point, so that we may pull it out from the car after we remove the shock insert and spring.

With the strut assembly and wheel bearing carrier loose, you should be able to push down on the wishbone and maneuver the shock down over the top of the fender. If your car has been lowered or has had some other suspension changes made from the stock configuration, you may need some extra wiggle room. In this case, use your spring compressors to compress the spring and remove it while the strut is still under the fender. Then you should be able to compress the shock further, and remove it from the bottom of the fender. When working close to the fender here, be careful that you don't scratch your paint: lay a moving blanket or something similarly soft out to protect the paint finish.

With your strut assembly off and on your workbench, install your spring compressor onto the spring and compress it until it no longer is tight in the strut assembly. While compressing the spring, be sure that you wear safety goggles: these springs are under a lot of pressure, and it is possible that the spring compressor may slip off suddenly. Place the two halves of the compressor on exactly opposite sides of the spring. I have found it very useful to use two ratcheting wrenches (I prefer the ones manufactured by GearWrench and available at PelicanParts.com) on each side of the compressor to assure that I achieve even and equal compression on both sides. Failure to maintain even compression when compressing the springs can make the compressor slip off.

With the spring compression removed from the strut assembly, and the springs loose on their perches remove the center nut that is attached to the top of the shock (see Figure 6). The reassembly process on the Boxster doesn't necessarily require an impact wrench, but it can sometimes make the job easier. So if you don't have one, now is a great time to buy one. I recommend an electric one: no air compressor is required (see Tools of the Trade in the front of this book).

With the upper strut mount removed, you should simply be able to lift the old spring off of the bottom spring perch. If you are reusing your old springs, then simply place them back onto the top of the lower spring perches. If you are replacing your springs with new ones, then move the spring to your workbench and slowly release the spring compressor on your old springs. Compress the new springs in a similar manner. You can use stiffer springs like Eibach Performance Springs, which serve to create a stiffer suspension and lower the car a little more than an inch in both the front and the rear.

Install the compressed spring assembly back onto the lower spring perch and reassemble the assembly as per Figure 8. Reinstall the dust boot / rubber bumper assembly over the shock to protect it from road debris and grime. Reinstall the upper spring plate and spring pad, taking care to verify that the plate is nestled correctly against the top of the spring. Inspect your upper strut mount and bearing carefully prior to assembly. The mount is manufactured out of rubber: both the rubber mount and the bearing will wear over time. I recommend replacing both of them if they look old, or if they haven't been replaced previously. Reinstall the upper strut mount on top of the spring plate, and tighten up the retaining nut. Always use new hardware when replacing your shocks: all of the nuts are self-locking and will loose some of that self-securing ability if they are reused.

Reinstall the shock assembly into the wheel carrier, and attach the lower sway bar drop link (which also functions as the pinch bolt for squeezing the shock assembly). Install the assembly back into the top of the shock tower. The upper strut mount may have to be rotated a couple of times in order for you to properly line up the studs integrated into the mount with the holes in the chassis tower. Attach the three nuts at the top of the tower, lining them up with the marks you made when you removed them. Reinstall the brake caliper (Pelican Technical Article: Replacing Shocks & Springs) and any other components you may have disconnected. Plug in the sensor connectors that you may have disconnected, and route the wires and hoses back through the tabs in the strut.

With the cable disconnected from its holder, make sure the wheel speed sensor and brake pad sensors are unplugged from their connector (green arrow).
Figure 1

With the cable disconnected from its holder, make sure the wheel speed sensor and brake pad sensors are unplugged from their connector (green arrow). Then remove the bracket entirely by unbolting it (yellow arrow).

The shock (yellow arrow) is held onto the wheel carrier (blue arrow) by a long bolt that is integrated into the sway bar drop link (green arrow).
Figure 2

The shock (yellow arrow) is held onto the wheel carrier (blue arrow) by a long bolt that is integrated into the sway bar drop link (green arrow). Remove the bolt / sway bar link, and then the shock should be free to be pulled out of the wheel carrier.

An electric impact wrench is a very handy tool for both removing and installing new shocks.
Figure 3

An electric impact wrench is a very handy tool for both removing and installing new shocks. The tool allows you to tighten nuts without having the shock shaft rotate. The three nuts that hold the front shock to the tower are shown by the yellow arrows. The three nuts that secure the rear shock mount to the chassis are hidden from view: two are located near the rear of the engine compartment, and the third is accessible only through an access hole in the sheet metal in-between the trunk and the engine compartment (inset photo). Mark the position of these nuts prior to removal: you want them to be in the same spot when you put them back on.

The yellow arrows in the photo show the bolt that needs to be loosened in order to gain enough clearance to lower the shock and clear the edge of the fender.
Figure 4

The yellow arrows in the photo show the bolt that needs to be loosened in order to gain enough clearance to lower the shock and clear the edge of the fender. You don't need to remove the bolt: simply loosen it so that the arm can rotate a bit more than is possible through the deflection of the rubber bushing. Don't retighten this bolt until the car's tires are back on level ground and the suspension is fully loaded. In the lower right is shown a new bearing installed in a new front strut mount.

With the wheel carrier supported by your jack, lower it down so that you have enough clearance to rotate the assembly out from under the fender.
Figure 5

With the wheel carrier supported by your jack, lower it down so that you have enough clearance to rotate the assembly out from under the fender. Then, pull on the shock to remove it from the wheel carrier (green arrow). Watch out that you don't accidentally scratch your paint.

Use a hex socket to hold the shaft of the shock as you tighten the nut and clamp down the entire assembly.
Figure 6

Use a hex socket to hold the shaft of the shock as you tighten the nut and clamp down the entire assembly. In order to get the springs compressed enough to be placed on the shock, you will need a spring compressor like the one shown in the upper left. When the assembly is clamped down with the locking nut, then carefully release tension on the spring compressors and remove them.

When replacing shocks, I recommend installing new parts.
Figure 7

When replacing shocks, I recommend installing new parts. Shown here are a new front shock (A), a new strut bearing (B), a new lock-nut (C), and a new front strut mount (D). Your Bilstein shocks should come with a beveled washer on the shaft (green arrow).

This diagram shows the installation of a new front shock and how all the bits and pieces fit together.
Figure 8

This diagram shows the installation of a new front shock and how all the bits and pieces fit together. These new Bilstein shocks came with a tapered washer that needs to be fit to the shaft prior to assembly (see Figure 7). Shock Bellows Spring Bumper stop Cup washer Foam insulator Upper strut bearing Upper strut mount Cup Washer Nut

When removing or installing the shock, be sure to remove and replace the wire harness for the brake pad and wheel speed sensors.
Figure 9

When removing or installing the shock, be sure to remove and replace the wire harness for the brake pad and wheel speed sensors. Don't forget the beveled washer when installing the new shocks (inset).

Replacement of the rear shocks is quite a bit more difficult than the front because you need to disconnect quite a bit more parts on the suspension.
Figure 10

Replacement of the rear shocks is quite a bit more difficult than the front because you need to disconnect quite a bit more parts on the suspension. Replacement of the rear shocks require removal of the axle nut (hard) or disconnection of the CV joints from the transmission (easier). The green arrow shows the CV joint / axle disconnected from the transmission - with the axles disconnected, you can rotate the shocks out under the edge of the fender. The yellow arrow shows the track rod disconnected from the wheel carrier. The purple arrow shows the wishbone disconnected from the chassis mount. The orange arrow shows the control arm disconnected from the wish bone. The red arrow shows the rear chassis reinforcement bar disconnected. In this photo, the shock has been already removed from the wheel carrier (white arrow). See Project 41 for more information on the CV joints.

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Comments and Suggestions:
zblack Comments: I have a 97' boxster that has been lowered, but I have no idea what height or kit was used on it. The rear struts are now in need of replacement. Anyway I can know what I'll need to replace them?
October 18, 2016
  Followup from the Pelican Staff: Only way to be sure is to see if you can identify the brand and the locate a part number on the strut. - Nick at Pelican Parts  
Mark Comments: When replacing the shock absorber on to the wheel carrier, how do you set the height i.e. how far the shock absorber is put though the wheel carrier before tightening the anti roll bar link bolt?
May 12, 2016
  Followup from the Pelican Staff: There is a notch or collar on the shock. it will install until it. - Nick at Pelican Parts  
DJ Comments: Hi I have a broken front spring on my 987, is the procedure for changeing it the same as the 986 listed above ? or is there a difference.Regards Dave.
March 23, 2016
  Followup from the Pelican Staff: It will be a different. We don't currently have that tech article. If we get a chance to perform the procedure, we will be sure to document it.

I would grab a repair manual. It will have the procedure, special tools and torque specs.

Give our parts specialists a call at 1-888-280-7799. - Nick at Pelican Parts
 
Brian Comments: Hi where can I source inserts for 986 rear suspension struts
January 22, 2016
  Followup from the Pelican Staff: Give our parts specialists a call at 1-888-280-7799. They can figure out what part or repair kit you need.
- Nick at Pelican Parts
 
GC Comments: Thanks for the write up, helped me a lot, I've done this on many cars to fit lowering springs but your write up took me through the boxster set up very well. Things to note....although my car had a new mot on the rear coils were both snapped, also I really couldn't have done the job without my snap on 18v windy gun, made light work of some very awkward and tight bolts!!
November 7, 2015
  Followup from the Pelican Staff: Thanks for the additional info and feedback. We appreciate it.
- Nick at Pelican Parts
 
stike Comments: I have a lot of oil on the inside front passenger wheel and lower control arm and lower part of shock. Does this mean strut is leaking? Don't see any oil around steering rack.
August 27, 2015
  Followup from the Pelican Staff: What kind of vehicle? Could be the shock. - Nick at Pelican Parts  
Manny Comments: Hey, so I have a 98 986 and my front passenger suspension tends to squeak/creak. It does this whenever I press down on the fender or pull up on it. It seems to spring back completely fine though, and this noise also happens when I'm driving and the car shakes even a little, like as if I'm shifting gears or going over a bump. I'm prepared to perform any change myself, but I was wondering if you could help with identifying the exact problem. Thanks.
July 2, 2015
  Followup from the Pelican Staff: I would check if one of the ball joints is making the noise. That is likely the cause. - Nick at Pelican Parts  
AndyF987 Comments: Hello,

Firstly thank you for help on previous questions. All helped me get there in the end. One final question. The headlight level sensor was easy to take off of wishbone, but for some reason it doesnt seem to fit when going back on. I don't believe that I have dislodged the arm/setting as it seemed pretty immovable even if i wanted to adjust it. Anyhow, it doesnt seem to line up. Any thoughts or general comments about refitting this. It's not mentioned in the article.

Also as a follow up to my experience of changing my front springs:

I finally got there! Both springs replaced and everything back together. If it helps others in removing the top nut, I used a 12 inch vice/mole grip with crescent jaw clamped as tight as i could get it microfibre cloth on first near the top of the piston rod. I then used a long screw driver to stop the top mount from turning, held against the bolts that stick out...finally a 1/2 drive electric impact wrench on the top nut. Using this method is was dead easy!
April 30, 2015
  Followup from the Pelican Staff: I think you may have a broken part. The piece you need is part number 996 341 371 03. There is an expanding rivet which holds it in place and it is very common that they are broken.

http://www.pelicanparts.com/cgi-bin/ksearch/PEL_search_2014.cgi ?command=show_part_page&please_wait=N&make=POR&model=1058§ion=ELSENS&page=3&bookmark=14&part_number=996-341-371-03-M100 - Casey at Pelican Parts
 
AndyF987 Comments: Thanks for Comments, still can't get nut off even with a huge channel lock wrench 20"! Taking the strut assembly to a mechanic tomorrow. Also in figure 4 it says about not tightening the nut on the chassis end of the wishbone until the tyres are back on the ground and loaded... It was hard enough getting access to this bolt/nut when the car was jacked with the tyre and caliper etc off, can it really be reached to be tightened sufficiently with the car on the ground? How exactly should this be done?

Many thanks for your help
April 12, 2015
  Followup from the Pelican Staff: Using wheel stands. The suspension is loaded down onto stands and the fasteners are tightened. You can use ramps if you have them. - Nick at Pelican Parts  
AndyF987 Comments: I haven't been holding the shaft, just trying to use a pin wrench in the grooves of the stop plate under the M14 hexagon top nut. however the pin wrench doesn't have enough leverage to hold the plate still. How should I hold the shaft without damaging it, it's going to clamping pretty tight i think to stop it spinning. It seems to perfectly straight. Many thanks for your help.
April 8, 2015
  Followup from the Pelican Staff: Oh WOW, that bugger is pretty rusty!! What you most likely will need to do is hold the shaft by folding a stack of 5-6 shop rags or about 3 wash cloths. Fold the stack in half, then wrap the rags around the shaft of the shock as high up toward the mount as you can. Then take a BIG pair of channel lock pliers and clamp down on the shaft around the rag, as tightly as possible. Use that impact to try and pulse the nut from the top. Make sure that your hands are clear of the spring when doing this. Make sure that you check to make sure that you are not damaging the shaft of the shock every couple of tries. IF that fails and it might, you may have to cut the nut from the shaft, or purchase a new pair of front struts. Let me know how it goes!! That is a tough one. - Casey at Pelican Parts  
AndyF987 Comments: Ps: it's a pasm strut
April 7, 2015
  Followup from the Pelican Staff: It should just come off when you hold the strut shaft, and hit the nut with the impact gun or a suitable breaker bar. What I have seen is the shaft can bend making the nut impossible to remove. Spin the strut shaft and make absolutely sure that the shaft is not bent. What tools are you using to hold the shaft and loosen the nut? - Casey at Pelican Parts  
AndyF987 Comments: Having purchased the book and followed the article I now have the strut assembly on my work bench but cannot for the life of me remove the top nut. I've tried heating it, penetrating oil over a week, a pin wrench to hold the top washer still although could do with some more leverage as its not that long. Any ideas as its sunny in England for once and the car is still up on jacks!

Many thanks

Ps: tried an impact wrench but not sure if it's providing enough torque maybe faulty and in any event the strut spins still.
April 7, 2015
  Followup from the Pelican Staff: See reply to your next question... - Casey at Pelican Parts  
Rick Comments: I recently changed the right rear axle and CV joint on a 1999 Boxster. Now I need to change out the strut, I did not have any problem getting the nut off the axle so would it be easier for me to get the strut out that way or take it loose from the transmission to drop it down?
August 2, 2014
  Followup from the Pelican Staff: I would pull it out of the whee bearing carrier as shown in the article. - Nick at Pelican Parts  
Andy Comments: Hi, I just need to replace a front spring on my 986 Boxster, will using an electric impact wrench cause any possible damage to damper ?
Thanks
Andy
April 7, 2014
  Followup from the Pelican Staff: Damage to the strut? where are you planning on using the impact? Just be sure to torque the fasteners by hand when assembling it. - Nick at Pelican Parts  
Greg Comments: I'm about to replace all 4 shocks on a 986 1999. Can I use the sport version or does that need some other lowering work to be done?
January 29, 2013
  Followup from the Pelican Staff: It depends what you mean by sport version. Bilstein makes a view different versions of these shock absorbers. In general unless you're replacing it with the PSS9 system then you should be perfectly okay swapping out your shocks for the heavy duty ones or the sport shocks. - Wayne at Pelican Parts  
Bruno Comments: Hello Wayne,

When my 986 S is lifted off the ground, I can shake the front struts from side to side a bit, so a mechanic told me to replace the strut mounts. So I ordered new strut mounts, bump stops, and the associated nuts from Pelican Parts, but was wondering, would I also need new Shock Bearing Plates?

And secondly, the Bentley Manual mentions removing the tie rod and control arms from the wheel bearing carrier to remove the front struts, and says to use a ball joint press. I am NOT replacing shocks and springs, just strut mounts, nuts, and bump stop, so would I need the ball joint press?

Thank you,
July 31, 2012
  Followup from the Pelican Staff: If you remove the strut as shwon in our tech article you will not have to separate the ball joint.

It might be a good idea to refresh the bearing plates atthe same time, there won't be any additional labor.- Nick at Pelican Parts
 
WRGREENER Comments: RATHER THAN TAKING THE STRUT OUT AS A UNIT... CAN I RAISE THE ASSEMBLY, COMPRESS THE SPRING TAKE OFF THE SHOCK NUT, DECOMPRESS AND TAKE OUT IN MULTIPLE PIECES, THAN REVERSES PROCEDURE.
May 9, 2012
  Followup from the Pelican Staff: I'm pretty sure that if you do that, you will not have enough clearance to pull the shock out from under the fender. Perhaps if you used a spring compressor, but I don't think that will work well either (I think we tested that method when writing the book). - Wayne at Pelican Parts  
pedro Comments: the front shocks driver side of my 1997 boxster is leaking oil.is this a signal that i should replace my front shocks? when i push down on the front driver side it springs back up with no oscillation. traces of oil are evident on the shocks.i have purchased your book and am now ready for project 63 as soon as you say i have to replace the shocks.
September 13, 2011
  Followup from the Pelican Staff: Believe it or not, Bilstein states that some leakage of fluid from the shocks is a normal occurrence. I personally never felt super-comfy with this analysis from them. But, they will not take shocks back under warranty if they are leaking. Hard to believe huh? Back to your question - if it were my car, I would replace the shocks, probably on all four corners. If one is leaking, the the others are probably not too far behind. - Wayne at Pelican Parts  
Jeremy Comments: I would also like to know an answer to JT's question above. I think he is talking about the bumpstops. Can they be replaced without removing the shock?
September 12, 2011
  Followup from the Pelican Staff: Nope, they cannot be replaced without taking the shock off. They have a hole in the center and fit down the center of the shock. I suppose if you wanted to replace them without taking out the shock, you might be able to buy a new one, cut it in half, and then put it on the shock and fasten it with some type of tape or zip tie. But that approach is not ideal of course. I'm not sure how long they would last, or whether that would even work terribly well. - Wayne at Pelican Parts  
JT Comments: is it possible to change the foam insulator on 996 front suspension without taking of the shock? Regards John
June 14, 2011
  Followup from the Pelican Staff: I suppose that you could cut out the old one and the put a slit in the new one and slide it on, then wrap some type of zip tie around the new one. But, this would not be ideal. - Wayne at Pelican Parts  
Hal Comments: Hi Wayne, quick question. In Figure 8 above you clearly do not list 'Support Ring' brass cover over the top of the 'Shock Bearing Plate'. My question, is that brass cover over the bearing really just overkill, is there likely damage to the bearing if it isn't there? The bearing is pretty rugged and the 'Foam Insulator' provide cushion from the spring end. I know it's funny question, but like always there is a reason behind a question :.
December 27, 2010
  Followup from the Pelican Staff: Hmm, somehow the caption for this photo got cut off:
A- Shock
B- Bellows
C- Spring
D- Bumper Stop
E- Cup Washer
F- Foam Insulator
G- Upper Strut Bearing
H- Upper Strut Mount
I- Cup Washer
J- Nut

As for your specific question, there are no brass pieces on this assembly - you probably mean the two cup washers, which are yellow-plated steel. Both are very vital to the proper operation of the whole strut assembly. - Wayne at Pelican Parts
 

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