Incorrect Koni Inserts

[chris_seven]

We recently had a 1967 Historic Race Car in our shop for a repair to the shell caused when the car undertseered terminally into a tyre barrier.

We needed to fit the car to a jig and removed the front struts and discovered leaking fluid and some vertical play between the insert and the casing.

We decided to strip the strut and find out what was happening.

The insert being used was 8642-1039 Sport - these inserts are painted yellow and are gas filled and top adjustable. The top adjustment is a very attractive feature and may be the reason they were selected.

The Koni catalogue list these inserts as being for a 1975-1989 Carrera with BOGE strut casings. (There is some debate that they don't fit this application either but that's another issue)

The photograph below shows the difference between the end of the different inserts. The 'Red' insert is the correct 1967 Koni.

The radius on the end of the Red Koni (not too clear) matches the internal radius at the bottom of the strut casing and prevents any radial movement of the insert.

Clearly the square ended peg on the end of the 'Yellow' Sport insert will be a problem.



The other problem is that the Yellow insert is about 1/8" too short to lock vertically into the casing.

The 'solution' on 'our' Race Car was to drop a 0.2" thick washer into the bottom of the casing. This sat the insert higher and allowed it to lock vertically. It didn't, however, provide any radial location and the insert must have been free to float around. This problem was solved by filling the gap between the casing and insert with hydraulic fluid - hence the mess and fluid leaking all over the place. The washer had also bent allowing the insert about 0.1" vertical clearance after a relatively short distance.

To make a spacer with the correct radius to sit into the casing and to have a feature to correctly locate the insert radially isn't exactly rocket science.



It is now all bolted up and working well.

[304065]

Chris,

Did the clients car have Boge Struts or Koni struts? I assume it had Boge struts, but I don't see a gland nut in the photos or integral with the inserts.

Don't be too hard on the PO for the hydraulic fluid, that was probably included to facilitate heat transfer between the insert and the strut body.

[66S]

The fluid is for rust prevention. I always put oil around the strut inserts. The threaded cap must hold the insert in place. If a gas Koni compresses too far it can break the gas chamber. This happens with lowered cars.

[chris_seven]

I do agree that an oil fill will improve heat transfer.

I don't know about which legs we have as the casings were in generally poor condition.

The standard red Koni insert was a good fit both axially and radially.