Koni front shock replacement

[NorthernThrux]

So, after getting my car back after essentially 8 years of hibernation/restoration I started driving it and shaking down all the little details. The car had a pretty loud squeaking noise after the first few hours of enthusiastic driving from the front left, and this could easily be replicated by pushing down on the front driver's fender. Further examination showed oil leaking from the front shock. Enough to produce drips after a half hour drive.

The struts themselves looked original, had intact paint and were not touched during the restoration except for a thorough cleaning, although the rest of the front suspension was rebushed, repainted and replated.

Not sure how clear it is in this photo, but the shiny look comes from oil everywhere.



So I called Jason at Paragon, and ordered a set of Koni front strut inserts, 86-1638 and a set of rears as well. My rears are date stamped 3-73, and if I'm going to do the fronts, I should probably do the rears for a balanced ride.

So these showed up by UPS a few days later.



They come with Koni's hieroglyphic instructions, but fortunately the whole process is pretty straight forward and Paragon has a bit of a blurb on their website. However, there are a few tricks and things not mentioned, so I thought I would go through the procedure here for people. One thing to note is I built custom cafe racers and other bikes for many years, and so motorcycle forks are my specialty. That made things easier perhaps, but most importantly, I had the right tools.

To really make this an effortless job, you need a pin spanner wrench, like the one I have been using for years. Useful for many other things too.



I bought mine used (actually never used as far as I can tell) on Kijiji years ago, but I see Amazon still sells them for C$65 or so.

So the first step is to loosen the wheel studs and then jack up the car. I used my low slung Canadian Tire Motomaster pump/lever jack under the rear control arm point and jacked the car up until I could get a jack stand under the normal driver's side jack point. Remove the tire.

Then you undo the 22 mm bolt in the trunk and pry the big yellow washer off the rubber mounting piece. Note that that washer is keyed to a slot in the strut and that there is another smaller washer on top of it (that goes between the big washer and the nut) that is also keyed. The little tab on that points up (i.e. the nut goes over it). My hardware is all new, so removing was easy, but if the shaft starts rotating before you can loosen the 22 mm nut, just clamp the big washer in some vice grips and you'll be fine. It's keyed, so it stops the shaft from rotating.

Once you have that stuff out of the way, you can push the strut through the mounting bushing with a screwdriver or rod of some sort. These are hydraulic dampers, they only control rebound really and they don't pop back up, so when you push the shaft, it stays wherever you pushed it to. Once the shaft is clear of the mounting bushing, reach underneath the fender and push the shaft down until it is more or less flush with the shaft cover. this is the top orange sleeve that keeps your shaft protected. You can now remove that sleeve, even without tilting the shock out of the fender. Once you remove that, you'll see a black rubber bump stop that looks like the Michelin man. Note that the round part faces down. Remove that. There will also be a white washer with pie shaped embossed patterns. This is to prevent a bottomed out shock from sucking vacuum. The new Koni strut inserts come with this piece and a new rubber bump stop.

OK, so far so good. Now turn the steering all the way, as if you are making a left turn. Make sure your steering wheel is not locked as the force you use in the steps below could potentially break the steering lock. I found this angle was the easiest way to tilt the strut out of the fender later on.

So you should be looking at something like this if you have the original Koni shocks. Note that the gland nut (the thing with the 2 holes for the pin spanner) is chewed up with pipe wrench markings. This suggests I'm not the first person to go in here some time in the car's 47 year history.



This picture is what it will look like after you loosen the gland nut. But that comes in the next post.



Now go have a coffee, because you'll need your wits about you for the next steps. I'm going to get one before typing further.

[NorthernThrux]

Caffeinated? Let's continue.

Now pull the shaft back up into the fender mounting bushing. This will make sure the shaft is not waving around while you try to unscrew that gland nut. Insert your pin wrench and crank. Remember lefty loosey. This is why you turned the steering wheel to it's left stop. The spindle can't rotate further and you have a firm purchase to apply all your strength to rotate this nut. Mine wasn't bad at all, helped undoubtedly by the oil that has been coming out of the strut top.

Once you have loosened it, unscrew it all the way and then recompress the shaft all the way down, tilt the strut so that the shaft points out of the fender well and remove the gland nut. You won't be reusing it. Then pull out the shaft. It will clear, but barely. I had my wife hold a folded towel around the fender lip while I did this step so I didn't scratch the fender. Be prepared for a mess, and have a plastic tray under this as the strut is full of oil (or half full in my case!!!). Put the strut aside. You won't reuse it either. This is what it looks like (although see discussion later on. Note that the rubber seal under the gland ring is chewed up and that is what had failed and was the source of the oil leak. You can probably find a replacement at McMaster-Carr and rebuild your shocks for a few bucks in hindsight. There are really no other wear components in the shock except for the shaft seal.



Now you have to get the oil out of the strut. I used a number of shop rags rubber banded to a wooden stick. You can see it in one of the pictures below.



Now comes the interesting part. None of the instructions tell you that there is a piece still in the bottom of the strut housing. This is the piece that keys into the bottom of the strut and makes the assembly adjustable. That's right, you can adjust the rebound damping even on these old shocks. Here's a pic of it in the bottom. I only found it because when I put the strut insert in, it was a few mm too high in the housing!



To get it out, you need a magnet on a string or some plumbers putty on the end of a stick (my approach). Once you have it out. Mop up the few mm of oil still in there and you are almost ready to insert the replacement cartridge. Before you do that, you need to add some antifreeze or hydraulic fluid to the strut. People say this is for cooling, but who knows. the instructions call for 50 cc, but I put in 60 cc of automatic transmission fluid. 60 cc is a 1/4 cup, so you are guaranteed to have a handy measure in your kitchen. Once you have that filled, insert the new cartridge into the strut body and push to seat it. You need to displace some of that fluid you just put in so that the top of the cartridge is flush with the top of the strut body.

BEFORE you go further, you want to adjust the shock for rebound damping. No (i.e. minimal) damping is fully CCW. You do this by taking the larger flat washer in the kit, or from your topside mounting plate and pushing down fully on the shaft till it is bottomed. You then turn it CCW until it stops. This is the minimum rebound damping. Based on recommendations I read, I then turned it 1 full turn CW. If you turn it fully CW, the front end becomes less compliant and the light front end skips over bumps. Maybe appropriate on a smooth track, but not on the roads around here. 1 turn seems like a good compromise. You can adjust this later on the car if you wish. You just need to undo the 25 mm nut and push the shaft back down. It has 2 turns of range, so basically I set it in the middle goldilocks setting.

Now put the new gland nut on and screw it in. I used blue loctite on the nut, as has been recommended on other threads I have read. Notice that it is smaller in diameter than the original and so a pipe wrench won't get a good purchase on it. A pin wrench really helps. Once it is in place, extend the shaft back up into the shock fender mount, turn the steering all the way to the right turn position and then crank on the gland nut with all your might. Push the shaft back down. It should look like this.



Now you are going to put the new white plastic washer on the shaft, the rubber bump stop (round part down), the orange sleeve, making sure that the shaft protrudes enough that you can pull it up. Now the rubber bump stop does not ride on top of the gland nut, it lives at the top of the shaft, so you only get a few inches of the shaft (famous complaint....) exposed. To get this into, and through the fender mounting you will have to raise the spindle assembly, which means gently lowering your hydraulic jack (remembering that you need to support the car somewhere else!!) and placing the jack under the control arm near the hub. Then raise it. You will find the shaft still doesn't completely protrude above the fender mount. But it is close enough that you can get a nose pliers in there and pull up. As soon as it is clear, put the 22 mm nut on and pull it all the way up, then remove the nut, put the big washer, the little washer (with lock tab pointing up) and the 22 mm nut back up and tighten. Put a dap of paint as a tell tale to make sure at some later date that nothing has backed off.

Now get some more coffee.

[NorthernThrux]

Your first side should look like this.



The right side is the same, just adjusting the steering to the full lock that allows you to crank on the gland nut while unscrewing it and screwing it back in.

Might right side appeared untouched. No marks on the original gland nut. But I had two different outer sleeves on the shock innards. I assume the one with the spring (right side) is original ? Not sure. Also, there was no bump stop on the right side. Geez.

Here's what they look like side by side. The piston rods were the same, but the outer sleeves were not.



At any rate, 1.5 hours to do the first side and about 45 minutes to do the second side. You can easily do this in a morning. And I can tell you the ride is x20 improved. And the annoying jounce squeak is gone.

Ravi

[gled49]

The small washer on top is a lock tab. It is suppose to be bent up and hammered over the flat on the nut which were originally not lock nuts. The piece left behind in the bottom of the strut is the foot valve which should be attached to the shock insert. When you lower your 911, the shock rod knocks the valve out of the bottom and the shock quits working as designed. And I just saw your last pix and you put the wrong top washer on. That is the one that usually comes with the new insert, Intended only for SWB 911’s.

[NorthernThrux]

Thanks for the pointers Gordon. The small flat washer on top of the big washer looks like this. Both what was on my car and what came in the kit.



It is internally keyed, but does not have the external tab that one normally hammers to lock the nut. If I understand correctly, you are saying that is what should have been there originally. I have seen these washers just bent on the lip to lock the nut. Which, on my car anyways, is not a lock nut. So I'll source a couple of these.

Should look something like this? Colour ?



The big keyed washer was on my car, so that's what we reused. It's similar to what came in the Koni kit., Except Robert replated the ones on my car. The ones that came with the kit are silver zinc. I have read your posts previously about the incorrectness of this washer and it's on my list to replace. I'm guessing these must have been associated with some previous upgrade of the shocks on my car? Or some repair, given that both from fenders have been replaced.

The foot valve was attached to the right side shock innards, but was not on the left. So I had to fish it out on the left side, while it came out with the right one.Yet another reason for the uneven handling I'd guess. Subtle, but I could tell. The car had been lowered previously, so not surprised the this valve was displaced. I was wondering about that.

Any guess as to which (if any) of the shock innards I pulled out are original?

[NorthernThrux]

Just noticed that the 700 mile 911 has the keyed washer bent, as I was trying to describe above. Looks to be yellow? Not a discrete tab on the outer circumference.



The big washer is dished, which I assume is correct for '73 as well? Mine is flat, then stepped to a curve as one moves out in radius by comparison. Is the Stoddard one correct ? Hard to tell. It's upside down. https://www.stoddard.com/catalog/pro...s/90134162900/ or different one with same part number. https://www.stoddard.com/sic34162900...62900-sic.html

[gled49]

Stoddard one is correct for LWB. The one you used is for SWB and get installed on a regular basis on all cars because they don’t know what’s correct. It is not just cosmetic, the dished one conformed to the top mount rubber. The keyed lock tab were black phosphated originally, all the ones I bought from Porsche were black, been a while.

[71gold]

This subject is very timely....I am doing my fronts on 71 now.
Here is photo of parts.
Per gled49 these are the originals that were on the original Koni’s and those provided new are shown below.
Ravi ..looked at Stoddard part #s you posted, one is just rounded and the other Has a flattened center area ( this matches mine as shown).
So seems to not use either of the parts provided by Koni ?
Will look for a part# for the washer that folds to secure the nut .

[davep]

Did the instructions say anything about how to install the grooved white plastic washers? Grooves should be down towards the inserts; for venting.

[NorthernThrux]

Dave,

You can see from the picture on my carpet of the new parts that the washers are groved on both sides. So idiot proof for someone like me! Important thing is to mount the Michelin man bump stop with the round part facing down, also for venting (also in the same pic).

71gold,

Both Stoddard parts are flat under the small washer and then dished. The flat part makes sure the small tabbed lock washer sits flat. It's just a bit harder to see in their photos, but it is there in both. One is a Stoddard part and one is Porsche OEM. Only difference is price. I talked to them on the phone this morning to confirm.
The small keyed washer in the koni kit is correct and you bend it after tightening the 22 mm nut on the shaft when you are done. Well, almost correct. It could be black phosphate according to Gordon, or some other original pics I have seen of original cars are yellow cad. Might depend on year. The 700 mile Porsche is a '70. Stoddard or your dealer sell black ones now. Porsche part number 90003800201.