Koni strut insert

Fritz Peyerl · 12-11-2007, 06:44 AM

I am in need of new struts, front and back.
I managed to remove the front strut inset s, now the question is what kind of oil do I use to replace the bad smelling oil which was in it and also how much do I put in. The inserts are the one where the Bogi strut it self is the housing and I only replace the inner guts.

Fritz

richde · 12-11-2007, 06:54 AM

Call Koni, are you sure they're user serviceable?

ulrichd · 12-11-2007, 07:07 AM

Fritz,
When I replaced the front struts on my 78 (Boge struts with Bilstein inserts) I syphoned the oil out of the housing. If you are replacing Boge with Boge someone else will have to chime in.

Ulrich

chrisf · 12-11-2007, 07:23 AM

just replaced my koni "inards" for koni inserts. What a mess those original parts were in. What you will recieve will be a self contained catridge (strut insert). Remove as much oil for the strut as possible, try to clean out your struts entirely. Replace with the specified amount of antifreeze (that's what my Koni instructions specified).

I've heard that this is to help with heat dissipation, but I suspect it could be to prevent possible freezing & cracking of the compoents as a result of any water being in there; it is a tight fit & any liquid present is helping to form the seal down at the bottom. That's my take on it anway.

if you have Boge oem struts, you will need to specify this to koni in order to get the right part.

it really is all straight forward once you recieve your new parts:

new front inserts on the right.

~chris

richde · 12-11-2007, 07:25 AM

oh, now I understand what you mean.

The inserts are already serviced, did you search the Koni site for instructions?

On a different model of car, you drilled out the bottom, cut off the top, pressed the insert in, and put a bolt through the hole on the bottom. Reassemble and drive.

cgarr · cgarr's Garage

antifreeze is what you use, if you use oil and water get in there it will not mix with the oil and cause rust.

Fritz Peyerl · 09:42 AM

I used the enclosed insert as show in above reply, in my 912 front suspension and I tried the old used 912 insert in my 911 strut and it will not fit.
The part I am thinking is the Part which Pelican offerer's Part # 86-1647. Called Koni insert for Boge strut.
The insert has the check valve on the bottom and the strut housing it self is the reservoir.

By the way, it's a 911T 1972

Jim_Brown · 12-11-2007, 11:20 AM

Fritz-

I cleaned out the internals of some 1973 vintage open twin tube Koni inserts and used Amsoil medium weight shock oil on the refill (10 weight). I filled the internal cylinder completely and went up to half way in the outer housing level. You'll need less than a quart for two inserts. The outer housing level I used was a guess based on a graphic from the Koni website that showed how their twin-tube hydraulic shocks work.

One was leaking so I replaced both with red Koni special inserts rather than attempting to replace O rings, shaft packing etc. The ride was much better with the open inserts than with the KYB junk I replaced.

Good Luck,
Jim

bob deluke · bob deluke's Garage

I took my rear Koni's apart to rebuild. Called Koni direct and the rebuilder told me to put 20W motorcycle shock oil in the tube. Put in same amount as you drained out, no more, no less. These were the REAR'S, not fronts.....

Tom '74 911 · 12-12-2007, 09:03 AM

Quote:

Originally Posted by chrisf

just replaced my koni "inards" for koni inserts. What a mess those original parts were in. What you will recieve will be a self contained catridge (strut insert). Remove as much oil for the strut as possible, try to clean out your struts entirely. Replace with the specified amount of antifreeze (that's what my Koni instructions specified).

I've heard that this is to help with heat dissipation, but I suspect it could be to prevent possible freezing & cracking of the compoents as a result of any water being in there; it is a tight fit & any liquid present is helping to form the seal down at the bottom. That's my take on it anway.

~chris

I want to be clear on this as I just replaced my Koni front strut inserts as well. When I opened them up, one had some oil/antifreeze? inside the housing and one did not. The oil I'm talking about was free inside the housing, not the sealed strut cartridge - basically filling the void between the inside of the strut housing and the cartridge - is this the oil you reference? When I put everything back together, I did NOT fill the housing w/anything. I went back to look at the (very limited) instructions that came w/the new inserts and there was no mention of filling the housing w/anything.

Should I open them back up and pour some antifreeze in there? I can see the possibility of aiding heat dissipation, but to help freezing and cracking. . . not so sure about that.

I'd like to hear more on this if people care to share.

Thanks,
Tom

chrisf · 10:05 AM

it's very tight fit, any liquid present is going to make it seal that much tighter. I test fitted an insert before I had removed all the old oil, and it was very very difficult to remove it. A lot of suction going on there. Tight enough to crack something if enough water were to freeze and not be able to expand? I don't know, maybe.

Now that I think about it, heat is transferred from the insert to the strut, hot to cold. Any liquid between the two will aid or impede this transfer. I guess antifreeze would be about the best to transfer this heat?

Fritz Peyerl · 12-13-2007, 07:19 AM

How could you have any dampening action without any liquid in it. I still say it should be oil. How do you get water into it? you have a seal / O ring below the top nut and the shaft strut shaft moving up and down has a tight seal around.
If you study the open strut you will see a small piston ring on bottom end and a a check valve in the insert housing and a check valve on top of the moving part. The oil it self is the dampening fluid and also is used to transfer the heat to the outside.
Antifreeze has NO lubrication factor and can imagine how much friction there is when that little piston ring goes up and down to dampen your ride. It can't be anything else than oil. even if you should get a drop of water into it, it will not burst the housing or do any damage.
My original question was how much oil and what type. It looks like no body has a real answer.

cgarr · cgarr's Garage

Quote:

Originally Posted by Fritz Peyerl

How could you have any dampening action without any liquid in it. I still say it should be oil. How do you get water into it? you have a seal / O ring below the top nut and the shaft strut shaft moving up and down has a tight seal around.
If you study the open strut you will see a small piston ring on bottom end and a a check valve in the insert housing and a check valve on top of the moving part. The oil it self is the dampening fluid and also is used to transfer the heat to the outside.
Antifreeze has NO lubrication factor and can imagine how much friction there is when that little piston ring goes up and down to dampen your ride. It can't be anything else than oil. even if you should get a drop of water into it, it will not burst the housing or do any damage.
My original question was how much oil and what type. It looks like no body has a real answer.

I think we are talking two different things here, one is just replacing the strut cartridge the other is actually taking the strut its self apart. I am not sure which one they are talking about

chrisf · 07:55 AM

you are missing a very important detail here. When you order new inserts, you are going to recieve a fully assembled, self-contained unit. SELF CONTAINED. The new insert is the shock itself. The strut (assembly) serves merely as a housing for this new insert. You will toss that mess you pulled out of the strut housing away. No need for it. (wait till your car is back on the road again.)

LOOK AGAIN AT MY PICTURE ABOVE. it's fully self contained. YOU ARE NO LONGER USING THE STRUT ASSEMBLY AS THE OUTER HOUSING FOR THE SHOCK.

This is, off course, if you are infact going to order new, replacement inserts. Now, if you are going to have your old original shock inards rebuilt, that's another story and I really don't have any knowledge on that.

Look at my picture above, again. FULLY SELF CONTAINED. No oil/fluid needed for any damping action.

Hey Fritz, take a look at your picture from above. The upper part is what I call the strut or strut assembly. The lower part is what I'm referring to as the "inards". It looks original. There is relative motion between these two parts, originally. If you order new inserts, there will be no relative motion between your strut assembly, and what you will drop down inside. The new insert will simpley drop in (I actually had to push and use the new top gland nut to fully seat the new insert).

I hope this helps.

~Chris

Tom '74 911 · 12-13-2007, 07:56 AM

Quote:

Originally Posted by chrisf

you are missing a very important detail here. When you order new inserts, you are going to recieve a fully assembled, self-contained unit. SELF CONTAINED. The new insert is the shock itself. The strut (assembly) serves merely as a housing for this new insert. You will toss that mess you pulled out of the strut housing away. No need for it. (wait till your car is back on the road again.)

LOOK AGAIN AT MY PICTURE ABOVE. it's fully self contained. YOU ARE NO LONGER USING THE STRUT ASSEMBLY AS THE OUTER HOUSING FOR THE SHOCK.

This is, off course, if you are infact going to order new, replacement inserts. Now, if you are going to have your old original shock inards rebuilt, that's another story and I really don't have any knowledge on that.

Look at my picture above, again. FULLY SELF CONTAINED. No oil/fluid needed for any damping action.

Yes, I think Fritz is not talking about the same situation w/new self-contained, sealed units.

Chrisf - I guess that's my point (and question too). Why is there a need to fill the void between the new, self-contained, sealed insert and the inside of the strut housing w/antifreeze? It's not really doing anything except taking up space is it?

Tom

chrisf · 12-13-2007, 08:09 AM

yeah, Tom, I think that's it. Put that small amount of liquid in there, and damn, it's a very tight fit.

again, that small amount of liquid will either aid or impede heat transfer (even though its a small amount). Putting anitifreeze in there helps to absorb heat from the insert and pass it on to the strut me thinks.