loose front strut cartridge - i need a cure.

[dickster]

hi,

i installed new front strut inserts some time ago and over a period the car developed a clunking noise at the front. this turned out to be a loose strut cartridge cap.

i tightened the cap but the clunking remains. i'm pretty sure its the strut because if i rock the wheel top/bottom it makes the noise.

so, do i need a new cap - is that what stops side to side movementof the insert inside the strut housing? or do i need to refill the strut with oil before the cap goes on?

i emptied out the old oil but never replaced - i wonder if this is required. bentley says to remove old oil but doesnt say anything about replacing it.

thanks.

[North Coast Cab]

The strut is probably loose in the housing. Remove the bolt in the trunk, pull the strut down and out and lift off the top. If it's loose crank it down with Bilstein tool or pipe wrench (ouch).

John

[2.7RACER]

Sounds as if you have some side to side play between your new strut and the housing. Tightening the top retainer nut may hold it for awhile but it does not solve the loose side to side fit issue.
Remove the strut and wrap the bottom with electic tape to build up diameter of the stut. Slide the strut back into the housing and check side to side play. Repeat until you have a nice snug side to side fit. Tighten the top retaiing nut and reinstall.
Had this problem six years ago when I installed Koni's. Been racing since with no problem.
Good luck!

[dickster]

mmm, interesting, thanks guys.

i have tightened the cap nut with no luck.

what about the oil? where does that come from?

[2.7RACER]

Oil comes from leaking old struts.

[dickster]

ok, that confirms that then!

i will try your tip then, thanks.

[Oldporsche]

The cartridge itself contains oil. The cartridge itself should be immersed in oil itself inside the strut housing. This is to help it dissapate heat.

I don't know about using the electrical tape. It probably would work if the inside of the strut is to remain dry.

Good luck,
David Duffield

[dickster]

david

so you're supposed to pour oil down there before replacingthe cap? what type of oil, engine?

[Zeke]

A thin oil is fine. All it does is gives the heat a direct conductive medium to the outside. There isn't much room between the shock tube and the strut tube, so it doesn't take but a couple of onces.

The tape won't stay on in oil, I would use that as a means to diagnose the problem. Most of us don't have this problem, so something is wrong. Wrong shock for the strut, or something. You are not supposed to have to shim your shock with tape or anything else.

Put the shock in and snug the cap nut. Extend the shock shaft, and brace the strut somehow. Now try to move the extended shaft. If you feel movement, then the problem is at the bottom inside the strut where there shock should be centered and tight.

Let us know, because if that's what it is, we need to find out more. Tape just is not the permanent solution. I have experience with Koni and Boge struts, but not Bilstein. I seem to remember that there is some kind of thru bolt at the bottom of a Bilstein strut. I'll leave that for the Bilstein guys to address.

[UK Carrera]

I once replaced some strut inserts in a car and was plagued by a rattle from the front end, felt through the steering wheel and sufficient to destroy the tie rod end joints and also fatigue some rack components.

In the end I cured the problem by doing nothing more than put some oil (I actually used gearbox oil) in the strut housing along with the insert. I reasoned that this would damp out any movement from the insert.

This worked a treat and completely cured the problem. I subsequently found out that it's a relatively common practice to put a small quantity of oil in a strut housing before fitting the new insert.

Hope this helps.

[Oldporsche]

I guess that I'm just whistling here in the dark but something doesn't add up. Which way is this movement? Side to side or up and down. From your description, it would seem that your insert's diameter is too small. What's the combination of insert/strut that you are putting together?

Enquiring minds need to know.

David Duffield

[dickster]

thanks again guys. i thought that maybe the oil would "damp" the movement.

it is side to side movement, so the insert is not as snug fit as it should be. i can't remember the combo i have, will check and let you know. will have to wait a week now........

a side note - for anyine chasing a rear end rattle/knock. mine actually sounds like the rear shock is loose, but its the front! it only seems to make the noise in corners - i guess thats the side to side movement.

[Oldporsche]

Try this small diagnostic.

A right hand turn will load the left front as the weight transfers and vise versa. As the weight transfers it may change the noise or clunking of loose components. This may help you in diagnosing this problem.

Good luck,
David Duffield

[Zeke]

I suppose the oil would damp the movement, but there shouldn't be enough movement for this to happen, IMO. Can you give us the make of strut and the PN on the shock? I guess that is what you mean by the combo. Yeah, let us know. It's got the be a mismatch.

[SteveStromberg]

Check the Spindle to Shock housing weld they can crack.

[Grady Clay]

Rich,

I agree with Milt. I think it is probably (not certainly) a mismatch of parts that didn’t initially show up as a problem. The other possibility is a shock that is damaged/broken internally.

The strut-to-shock match has always been an issue. The manufacturers that Porsche A.G. chose were initially Boge and Koni. Each chose to make their struts incompatible with the other’s spare parts. Add Bilstein and several other manufacturers and replacement shock insert compatibility can become a real problem.

There are two main potential problems.
First is the attachment at the top. There are different thread pitches and diameters. Additionally there are different attachments to the shock body, some shocks have the nut integral to the shock body and others have separate nuts. The separate nut must properly fit the shock. Of course it must screw into the strut body. It is not uncommon to find a mismatch between the shock body and a separate nut that allows the shock to move laterally under side load.
The other issue is the locating “pin” so to speak, at the bottom of the replacement shock insert. Most OE shocks were not inserts; they used the strut housing as the outer body (that is the shock fluid in the strut.) The replacement shock insert must properly fit where the original shock mechanism was located in the bottom of the strut. Unfortunately there are some combinations of strut and insert that will be able to be assembled but will not locate properly.

A good alignment tech will take a 20# soft hammer and tap the strut at the nut or on the wheel and see if the alignment settings change.

David and Milt are right on. You should have some oil in the strut to provide heat transfer from the shock insert to the outside. Two thirds full is OK. Full will make a big mess when everything heats up. Used engine oil is just fine (and free.)

I agree, don’t use tape.

Steve is on a good path – inspect the spindle to strut tube welds.
“Clunks” can also be a defective ball joint or incorrect hardware at the top mounting.

Many (most?) struts have the manufacturer’s markings and numbers stamped into the strut tube. That will help you determine what struts you have. Go back and find your invoice for your replacement shock inserts. It may be as simple as you were sent the wrong inserts for your struts.

Is there anything else we should know? Has the car been significantly lowered? Are the rubber bump stops original and in place? Is the shock cover in place?

Best,
Grady

[dickster]

thanks again guys for all the info - will check it out.........

[dickster]

i have boge struts with bilstein inserts.

identifying boge dble tube gas shocks??

don't buy bilstein shocks in the uk until you've read this!!

i have HD fronts P36 0114 and Sport rears B46 0975

A right hand turn will load the left front as the weight transfers and vise versa. As the weight transfers it may change the noise or clunking of loose components

david,

it is left handers that show up the noise - coming from the right side.

[Chuck Moreland]

The oil-in-housing for heat dissipation trick doesn't apply to the bilstein inserts. It does work for koni/boge inserts.

The bilsteins are inverted, the heat generating components are on top - mostly sticking out of the housing.

In the case of bilstein struts, they wouldn't even hold oil. It will drain out the roll pin area. If you managed to seal the pin and fill with oil you'd create a hydraulic lock situation due to the design of the insert.

[dickster]

chuck,

i have boge struts - no roll pins.