DIY Network

Racing-Suspension Upgrade: Adjustable Front-Struts From "Tricked Out" episode DTRK-204

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In this episode of Tricked Out, host Andrew Totolos installs a coil-over suspension system into a Ford Focus SVT for a quicker steering, better handling. The project involves removing the factory front strut, transferring upper strut mount to the new assembly and installing the new performance strut. Andrew also discusses the proper use of spring compressors.

Materials used in this episode:

In addition to standard auto-mechanic's tools (wrenches, ratchets, extenders, screwdrivers, nut-drivers, etc.), tools and materials used in this episode include:

Suspension kit
Floor jack
Jack stands
Wheel chocks
Rubber mallet
Torque wrench
18mm open socket
Measuring tape
Vise
Spring compressors
Safety glasses

DIY Difficulty Rating for This Project: We gave this a difficulty rating of 4 on a 5-point intermediate-level scale.

Safety Alert: Never get under a vehicle supported only by a jack. A jack is designed for lifting, not for supporting, and vehicles can fall off a jack! Make certain that your vehicle is properly supported by jack stands before do any work underneath it.

Front-End Struts: Standard vs. Performance

The factory struts on the front end of a modern sport compact are comprised of a spring that supports the weight of the car and a damper that works with the spring to smooth out the movement and eliminate bounce (figure A).

In most factory setups, the springs are normally wound so that the coils are evenly spaced. That means that, for the full range of movement, you have basically the same amount of resistance. A performance spring like the one we install in this project utilizes a progressive wind. The coils are wound closer at the top of the spring (figure B). In that configuration, for normal driving you get a nice, soft ride but, as the spring is compressed more during aggressive driving, the resistance increases. Increased resistance means better control of body-roll and stability.

Figure A

Figure B

The performance damper we selected offers adjustable resistance so that you can set the car specifically for the kind of driving you do (figure C). Another important feature is the adjustable spring perch (figure D) which allows you to raise and lower the car to the height you want .

Figure C

Figure D

Removing the Front Struts

Begin by removing the factory strut, which is attached at the top to the strut tower under the hood (figure E) and to the control arm at the bottom. First, however, the brake line bracket and a couple of other components will need to be released.

• Remove the ABS sensor cable from the bracket (figure F).

• With a wrench, hold the 15mm securing bolt in place and loosen it using an Allen wrench.

• Remove the bolt and slide the bracket off.

  Figure E

  Figure F

  
  

  Figure G

• Push the steering control arm out of the strut bracket and carefully release the brake line (figure G).
  

  
  

• Remove the lower strut support bolt (figure H), then hammer the control arm down with a soft mallet until the lower mount is released (figure I).

  Figure H

  Figure I

  
  

• Next, reach in under the hood and loosen the three retaining bolts from the upper mount. As the bolts are removed, keep a hand on the strut to keep it from falling out once it's released (figure J).

• Carefully remove the strut (figure K).

  Figure J

  Figure K

  
  

  	Figure L
  	Figure M

With the old strut removed, the next step is to transfer the top mount onto the new strut. All that holds the strut assembly together is a top nut. Because of the spring pressure, you can’t simply back the nut off. Simply removing that nut could cause the stop piece and the spring to shoot off with force and could cause injury. You have a couple of options. You could take the struts to a suspension shop where they have a professional spring press to take the pressure off safely (figure L). The cost for this will be around $15 per strut. Or you could do it yourself using manual spring compressors You can rent spring compressors from your local auto parts store.

• If you decide to do it yourself, you’ll still need a vise to hold the strut steady while you compress the spring. Hook the jaws of the spring compressors onto the spring directly opposite of each other and tighten each side evenly (figure M). A socket extender may come in handy for this procedure.
  

• With the spring compressors securely attached, once the top cap is loose you can use one wrench to hold the damper cylinder while you back off the top nut with a second wrench (figure N).

• Pull off the top cap and loosen the spring compressors slowly one side at a time (figure O).

• As you loosen, the cap will pop off. Just remove it and continue to loosen until the compressors release.

  Figure N

  Figure O

  
  

  Figure P

• The new lock nut fits tight so, before you assemble the parts, hold the shaft in place and tighten the nut. It’s nylon insert adheres to the threading of the shaft, providing a grip that will not vibrate loose. Then back it off completely to assemble the strut.

• Once you have the old strut cap removed from the factory strut you can build the new unit. Place the new spring on top of the thrust washer, set the spring seat on top of the spring, and the old strut cap on top.

• Tighten down the locking nut finger-tight (figure P).

• Important: You'll want to use a new locking nut whenever you disassemble a strut.

• Torque it to about 40 foot-pounds. The new strut is ready to install.
  

• Align the lower bracket on the damper with the split in the lower strut support mount and twist and push the damper down into place. You can tap it gently with a soft mallet until it sets against the flange (figure Q).

• Next, replace the lower strut support bolt and torque it to 68-foot pounds.

• Set you floor jack underneath the lower control arm and slowly lift the assembly as you guide the damper into the upper mount (figure R).

  Figure Q

  Figure R

  
  

• Once it’s in place, install the three securing nuts up top snugly, but not too tight. Leave them loose enough to allow for some room for play below.

• Push the steering control arm into the damper bracket, and reinstall the anti-lock braking bracket with the original nut (figure S).

• With the bracket installed, go back to the top and torque the securing nuts to 19-foot pounds each (figure T). Also tighten the locking nut at the top of the strut.

• Slip the ABS sensor wire and the flexible brake line into the bracket and check for enough slack by turning the steering wheel lock to lock.

  Figure S

  Figure T

  
  

• After the struts are installed, you can make adjustments to the ride height on the car.

  Important: When adjusting the height, it’s best to start with them all adjusted to the factory settings and go up or down from there.

• To make adjustments, measure the area from the flange on the damper body to the lower spring lock (figure U) and spin the lock until the measurement is at 20mm. Then spin the lower spring seat down and jam lock it into place with the two spanner wrenches supplied with the kit (figure V).

• After the two pieces meet, continue rotating the top ring to the left to seat the lock.

  Figure U

  Figure V

  
  

Important: Included in this summary are the steps in this automotive procedure as shown in the episode. These steps are general guidelines that are applicable to most vehicles. With any particular vehicle, there may be procedures, specifications, settings, tolerances, components, etc. that are specific to that vehicle. There are also variations according to the type and brand of upgrade-kit you select. Always consult your vehicle's service manual when undertaking significant automotive repairs, and read and follow the manufacturer's directions and precautions that come with your kit or replacement parts.

RESOURCES :

Tires, Suspension and Handling
ISBN: 1560918314
Author: John C. Dixon
(Society of Automotive Engineers

Sport Compact Bolt-On Performance Guide: Import Cars (Sport Compact Bolt-On Performance Guides)
Author: Joe Pettitt
Order this book from Amazon.com.
Voyageur Press (October 2000)
ISBN: 1884089526

TEIN USA, Inc.
Website: www.tein.com