Installing Front Strut Inserts

One of the most common jobs here in the shop in the rescue/restoration side of 924S944.com is replacing rear shocks and front strut inserts.  The rear shocks are pretty straightforward, with a bolt at the top and the bottom that are removed and replaced.  The front struts, however, are more involved as they are generally inserts that require the strut to be disassembled for replacement.

The 944 has two different strut designs – early and late.  The early insert starts with the ’76 924 and goes through into the Series II cars.  This early design is characterized by the screw cap on the top of the strut housing that is unscrewed to release the strut insert.  However, some Series II cars have a “sealed strut” would require replacing the entire strut – with a pretty steep price tag.  However, Koni has a fix for the sealed strut that, with a little cutting and fitting, can replace the strut mechanism with a new Koni unit without replacing the entire strut.  This alternative is priced at about the same level as a regular insert.  You will have to remove the sealed strut, though, to install this Koni unit.

This article, though, deals with the more common insert installation – without removing the strut.  Many cars with these kinds of struts do require removal from the car for disassembly and replacement of the strut insert, but here we detail how to do that without removing the strut from the car.  This has the advantage of not messing up the alignment settings on the car since you will not touch any of the bolts that adjust the caster, camber and toe of the front end.  It also has the advantage of taking a lot less time.

For this procedure, we detail the tools needed and the steps needed to complete the process of replacing strut inserts.  The brand of insert is not important here.  For daily driving, we like the KYB shocks and strut inserts; for track or autocross use, we like the Koni Sport Adjustables.  Either way, the process is exactly the same.

While we know that this process works for us, there are those out there who have a better/faster/easier way to do it – and that’s fine.  This article is to introduce a process that we use that works for us in our shop.

Tools and Equipment Needed

• Floor jack
• Two jack stands
• Air or electric impact
• 19mm socket (lug nuts)
• 21mm Socket (top nut on the strut)
• Vice Grips
• Pipe Wrench
• 13mm Socket, long extension and ratchet handle (for the sway bar bolts)
• Torque wrench (for torquing the lug nuts)

Step-by-Step

• Jack up the front of the car under the cross member. Support the cross member with the jack stands. Remove the jack.
• Remove the front wheels.
• Find the 13mm bolts that hold the inner sway bar mounts to the frame. There are two bolts in each one.  Remove all four bolts and pull the sway bar down.  Do not remove it, just pull it loose from the subframe.  This allows the control arms to extend farther down.
• Put the floor jack under the ball joint on the side that you are changing. Just lightly support the control arm.
• Put the 21mm socket on the top of the strut under the hood. Using an air or electric impact helps.  Put the vice grips on the shaft between the coils of the spring to prevent the shaft from turning, and remove the nut, washer, and metal cup from the top of the strut mount.
• Lower the jack and control the top of the strut as it drops out of the mount.
• With the strut down, pull it out so that the top of the strut is outside the fender.
• Remove the spring and other associated hardware.  Note the order in which you take the stuff off the strut.
• Use the pipe wrench to loosen the screw cap on the top of the strut housing.
• Remove the screw cap.
• Pull out the old strut insert. It will have oil on it as installation requires a little motor oil to cushion is against the housing.  Prepare for dripping oil onto the floor, try not to make a big mess of it.
• Install the new insert. If needed, put a little motor oil in the housing – should not be needed, though.  A little goes a long way.  The oil creates a fusion between the insert and the housing.
• Remember to put the spacer in the top of the strut insert. A new one comes with the insert.
• Replace the screw cap and tighten with the pipe wrench.
• Replace the spring and associated hardware – in the right order!
• Compress the insert shaft if needed and point the top of the strut back towards the strut tower. Jack up the control arm and guide the top of the insert into the hole in the strut mount in the strut tower.  When it is in place, keep the jack pressure on it so that it stays.  NOTE – it helps to have someone operate the floor jack while you line up the strut with the mount.  A light in the fender well helps you to better see when the strut is lined up.
• Install the metal cup, new washer and new nut. DO NOT allow the tightening process to spin the shaft – hold it with the vice grips if needed.  Spinning the shaft can damage the internals in the strut insert.
• Go to the other side and repeat the process for the other insert.
• Go back under the front end and reattach the sway bar with the four bolts.
• Reinstall the wheels and put the car back on the ground. Torque the wheels to 95 lb/ft.
• For Koni Adjustables, adjust the struts to about ½ strength with the included knob. Always make sure they are the same side to side.

Since you did not touch any of the alignment points on the front end, the alignment will not have been disturbed.

The first time always takes longer, but with practice this whole process takes about twenty minutes per side.  And no trip to the alignment shop!

Here is a good YouTube video on changing the strut inserts.