Help! Koni install problems!

[Adam]

I'm pretty steamed right now. It's almost 10pm and I've been wrestling with the installation of my Koni (red) front struts (part # 86-1943) for a few hours now. I have the standard Boge struts, which were half-full of oil from my long-dead Boge strut inserts.

When the insert is in the strut, it seems to be 3-4mm too long. The Koni instructions (to my interpretation of their universal "no-words" heiroglyphics ) specifically say NOT to cut/trim the stump at the base of the strut insert, unless graduated to specific, ribbed measurements, which these are not.

Basically, I can't tighten the collet/ring thing at the top of the strut housing tight enough and there's a few mm of thread still showing. It's friggin' infuriating! The car is immobilized and there's tools and crap everywhere. I wanted to get this job sewn up and completed tonight, but it seems I'm stuck.

So, do you have to trim these damned things to suit your car or should they just fit out of the box (like you're lead to believe)??

Can anybody help? Please?

[Adam]

Whoops. I forgot to say that I stood the (dead) Boge up next to a new Koni, and there's that same 3-4mm difference in height (the main body of the strut, not the piston/shaft).

[dickster]

have you definitely got the right inserts?

Getting ready for Koni install - a couple questions

[Adam]

Hi Rich,

My front Konis look exactly the same as what Anthony has posted at the top of his thread. They're the same units. His rears are the same as the ones I've already fitted. According to the Koni website/pdfs, the 86-1943 is the correct front insert for Boge struts.

[dickster]

ok, just a thought as the pn's are different between his and yours.

[Wil Ferch]

At times such as this, Wayne and Pelican nothwithstanding....I'd go to an aknowledeged Koni expert like Jason Burkett of Paragon Products in Texas for advice. He has a lot of Koni/Porsche experience, and often offers advice freely and gladly over the phone......

--Wil

[Adam]

Rich - The close-up on Anthony's shock (showing the part number) is the rear shock, which I've just fitted to my car, too.



That's the bit I wanted to know if I should be trimming... The Koni instructions certainly don't say so.

Wil, I might try him if I can't get anywhere with my local Koni rep. Thanks!

[dickster]

i assumed it was the front.

Those fronts look like the correct ones for Boge. The ones for the Koni strut don't have the little narrow step down at the bottom. Koni for Koni won't fit in a Boge. Koni for Boge will fit in a Koni with a special collar nut. You can cut the snubbers down by one ring if you like. I preserve the taper part, cutting one the of big rings off.

maybe milt is referring to koni/boge when he says "you can cut the snubbers down"?

are you getting the cap nut started? how far?

you don't want to remove too much otherwise it will be a loose fit.

[Adam]

I think Milt's referring to the rubber bump-stops under the top sleeve. They're separated into 3 sections, which you can trim down to suit.

The cap nut at the top of the strut, where the insert slides in, I can tighten to around 3/4. I can't get the last few turns done and the threads are still exposed. It's just not right.

Does anyone know if the Boges have some kind of bush at the base of the strut insert? I certainly can't see anything down in there, but can anyone say for sure?

[911SCfanatic]

Are you absolutely sure you've soaked up all the oil out of the strut? It seems like the bottom of the Koni shock pictured above would accommodate a little oil with no problem though, unlike a replacement Boge shock. Just a thought...

[Wil Ferch]

Good point...you need to get all the old fish-oil out before inserting the new shock-insert.

Vaguely recalling my own install of koni's in a boge housing....don't clearly recall the small "teet" on the bottom of my insert as is shown here...

Once inserted you can still add a "small" amount of oil or antifreeze as a heat block and buffer for the insert. Only needs a few ounces.

---Wil

[anthony]

My fronts are actually model #8641 1039. Adam, did you figure any thing out?

[Adam]

I'm pretty sure I got it all out, but I might try stuffing more shop rags down there again tomorrow after work (it's 11:30pm here).

Thanks for all the suggestions, guys. I'll let you know how it goes.

It sounds like nobody has had to cut the strut insert to size. The problem must be something to do with my strut assembly.

[Wil Ferch]

Adam:
-- something to consider, too.
You may want to record the model / type number of the Boge strut housing that is stamped on the outside...may be a model year specific problem that doesn't match the model year of your car. Then...do the same with the Koni part numbers and compare/contrast to Porsche knowledge on this board and Koni knowledge elsewhere...

---Wil

[Tim L]

The cap isn't supposed to thread all the way down, there should always be a few threads showing. That’s what holds the shock tight in the housing.

Tim

[Adam]

It's morning now and I just got off the phone with Koni Australia.

They were surprised that the strut was slightly taller than my Boge insert, but told me that having a few mm of thread showing on that collet isn't a problem. They told me I could grind a few mm off the stump on the strut and that wouldn't affect performance or reliability.

I'll measure the current clearance of the collet to the leg and then grind exactly 1.5mm less than that to ensure a good tight fit.

Hopefully I'll get it all finished tonight!

[Zeke]

There's got to be something down inside the strut tube.

The 'stump' is not there on a Koni for Koni. So, you apparently have the right part.

I would be afraid to grind anything off the shock. First of all, that could void the warranty. 2nd, how can you be sure you won't enter the oil area of the shock and ruin it?

Yes, I was talking about the rubber snubbers. The shocks wre designed to stay in the working range, but on a lowered car, that woking range gets to be close to not much. You get another inch by removing on the the bigger rings. But, you're one inch beyond the 'normal' working travel of the shock on full compression. I think this is safer if you have bigger t-bars (I don't know why I say that, but I do).

Get in there with a flashlight and find out what's going on. Lastly, there will be some thread showing, but not a 1/4 inch on my car(s).

[Oldporsche]

okay, the assumption here is that everything is exactly right!

Not so all the time. As I remember there was a thread showing or at least half a thread showing when I have done these inserts before. If I recall, correctly, my Boge shocks left a little screw thread exposed. You might check that on yours by reassembling your boge inserts into the strut and see how much thread is exposed. You would like to be close to that amount. After all that's what the factory assembled specs were.

I have also chucked up a shock in a lathe and nibbled a little off that stump to get them to sit down a little more. The big thing here is not screw up your working length of this shock.

Get a light in that shock tube and look around. Get the oil out of there, you're not going to use it anymore. You can utilize used motor oil for this project. You own a Porsche, You got all the used motor oil in the world.

That stump on the end of the insert allows Koni the ability to use this insert in another istallation. All they have to do is manufacture this insert, stamp some other numbers on it, don't weld the stump on and it will fit another model car. They likewise change the top nut on the strut for the same reasons.

I think that the konis used in koni struts are necked down on the bottom to be used in the koni strut which is a smaller diameter on the bottom also.

This is a solvable problem mate! No sweat.

David Duffield

[Adam]

Thanks, David (and Milt, Wil, Tim, Anthony, Bill, Rich etc)

Koni tell me that the stump is solid and can be shaved/cut/ground to suit. I'll certainly double-check that the strut is empty before I do anything to the shock, but when I pointed my Surefire down there last night, it sure looked empty.

Measure twice, cut once...

[anthony]

Where is the extra few millimeters of length? Is the stump itself longer than on the Boge?