Front Shock Replacement (65-89)
Last Updated: 04/09/2013
The 911, 914 and some 944’s featured a rebuildable front McPherson Strut. Instead of having to replace the entire strut unit, you will be able to merely replace the strut insert that is on the inside of the strut housing. You will know that your strut is rebuildable by looking in the area where the shiny piston rod goes into the lower strut housing. On rebuildable struts, a screw on cap (gland nut) is used to hold the insert into the lower strut housing. You will know the gland nut is removable because you will likely see a few threads sticking up on the cap. 1965-83 cars used a male threaded gland nut, and 84-89 cars used a female threaded gland nut.
Jack the front of the car and secure with jack stands. Remove both front wheels. Remove the top-mounting nut (inside the front hood, 22mm) and lower the shock out of the tower housing. If the shock shaft begins to spin before the 22mm nut loosens, you can hold the big washer under the nut with a pair of channel locks. This nut has a “tooth” that fits inside a groove on the shock shaft. Once you are holding this washer, you will be able to loosen and remove the 22mm nut. Some shock shafts will have a 8mm allen head end which can also be utilized to prevent the shock shaft from spinning. Once the nut is removed, reach in the wheel well and grab the upper dust cover that protects the shock shaft from dirt and grime. Pull down, this will extract the piston from the upper strut bearing. Carefully tilt the strut out past the fender lip and slide the dust cover off the shock shaft being careful to not put your brake line in too much of a bind. If you are removing a gas insert, you may need to compress the shock shaft a bit to enable you to tilt it past the fender lip. Once the dust cover is removed, pivot the shock back and push the shock shaft back up into the upper strut bearing and finger tighten the top 19mm nut. This will hold the assembly in position while we loosen the gland nut. I usually like to use a big pipe wrench or a large pair of channel locks (cheater pipe optional ;-). As you try to unscrew the gland nut the strut will want to turn. Use a small piece of 2x4 to brace the spindle to the inner fender well to keep it from turning. Now loosen the gland nut…. remember lefty loosey, righty tighty. Once the gland nut is loose, reach up and remove the 19mm nut on the top of the shock shaft. Once again, tilt the strut out past the fender lip (watch the brake line) and remove the gland nut and insert.
You are now ready to install your new inserts. Remove any rust or corrosion that may be present on the threaded portion of the strut tube. Some strut housings may be full of hydraulic oil. You can either remove this oil by using paper towels to “wick” it up, or you can reuse it as a “coolant” for your insert. Another popular coolant is anti-freeze. Either will work, but remember, it won’t take much liquid because the insert will displace most of the area in the strut tube. Koni recommends 50ml of fluid, but I usually just use the dipstick method and try to get the coolant to ride about 2/3 up the side of the insert. Once your coolant level is set, slide your new insert into the strut housing. Koni supplies new male thread gland nuts for the 65-83 cars. Place some Blue Loctite on the gland nut threads and finger tighten it down. 84-89 cars utilize a female threaded gland nut. When using this type of nut, Koni has supplied a special washer that sits on top of the insert prior to installing the gland nut. This washer centers the insert in the strut housing, a job that had been performed by the male type gland nut. Position the shock rod back up into the body and once again, finger tighten the 19mm nut. You may need to place a floor jack under the A Arm to assist in moving the shock shaft up into the upper strut bearing. Use your piece of 2x4 to block the spindle and really tighten the gland nut with your pipe wrench or channel locks…. I mean REALLY tighten it. Gland nuts have been known to back off so your muscles and the Loctite will insure this doesn’t happen. Once the gland nut is tight, remove the top 22mm nut and retract the shock rod from the piston. You will need to install 2 items on the shock piston prior to installing the dust cover. First is a small plastic washer. This washer prevents the bump rubber from pulling a vacuum on the strut housing when the shock goes into full compression. Probably would never happen, but that’s what it’s for. After the plastic washer, install the bump rubber. Koni’s standard bump rubber looks kind of like a tootsie roll. The curved portion will face down. Koni’s competition bump rubber is made out of a more advanced material and is correctly installed with the angled portion facing down. If the car has been lowered you can shorten the bump rubber to regain some shock travel but you ALWAYS want to run a bump rubber. Failure to do so will destroy your shocks. Now, install the dust cover on the shock shaft and slide the piston up into the upper strut bearing. Install the new top washer and nut. Once again, the shock shaft may turn as you attempt to tighten the top nut so have your channel locks handy. Never use the adjusting tab on Koni insert as your “holding” mechanism, it WILL break off.
You are now ready to reinstall the wheel/tire assembly, do the other side, and enjoy your new added level of performance! - Jason Burkett
Application: 911 65-73, 911 74-89, 914 all
Parts: Koni 8641-1039 Sport
Tools: 22mm socket, 8mm hex, Pipe Wrench, Large Channel Locks, floor jack, cheater pipe, 50ml anti-freeze
Credits: Jason Burkett