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Filling strut with oil


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I have heard it suggested that adding a little oil in with the cartridge helps with heat transfer.

 

If you're building a rally Z then that would make sense, otherwise, just very lightly grease the inside of the strut tubes and the inserts so they don't corrode togther 5 years from now.

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Having oil in the strut tubes IS important. I have always just reused the original strut oil which came with the car. The type of fluid probably doesn't matter (atf- light engine oil-strut oil). Heat transfer and anti-rust properties are the important issues.

I have wondered if this trick was truly important. During a suspension restoration on a 70 I ran into a set of KYB GR2 (normal gas replacements-the silver/grey ones) which had been installed in the car 8 years previously(by someone else) without the oil. The outer housings of the strut inserts had collapsed in the bottom 40 percent of their length. Fronts had most damage but all 4 were affected. Discoloration and damage was obviously heat related and almost unbelievable- Damaged area formed 1 inch wide troughs which dropped into strut 1/4 of the diameter, were between 1 and 4 inches long and limited compression depth. Car is a pampered original which is driven briskly on street but not raced. Car has never been abused and was using Nissan European rate stock springs at normal length.

RossCs method is how I've always filled the struts.

Use something as a heat transfer agent or replace struts more often.

Wish I had taken pictures of them now.

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The outer housings of the strut inserts had collapsed in the bottom 40 percent of their length. Fronts had most damage but all 4 were affected. Discoloration and damage was obviously heat related and almost unbelievable- Damaged area formed 1 inch wide troughs which dropped into strut 1/4 of the diameter, were between 1 and 4 inches long and limited compression depth. Car is a pampered original which is driven briskly on street but not raced. Car has never been abused and was using Nissan European rate stock springs at normal length.

 

Sounds like the heat damage was caused by the failure of the struts (loss of gas pressure most likely with the GR2s) not the other way around. Koni recommends adding 50ml of oil and Bilstein specifically says not to add oil with their inserts. You can add the oil, it won't hurt anything.

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The GR2s had 20 k miles on them and still had their gas charges. I couldn't believe the damage either but I saw it. I have been an automotive (Import vehicle) technician for 20, have installed many GR2s in many different brands and recommend them as a stock replacement for anything (have a set on my wife's minivan). Correctly installed I have yet to run into another bad GR2 much less a complete set. The missing heat transfer liquid killed this set.

One of the selling points of the strut for my customers has been the lifetime warranty and I haven't had to replace any of the struts I have installed (a serious selling point for me- Don't have to eat 2nd strut job). This customer upgraded to Tokico blue and did not want to pursue getting the KYBs replaced.

This is not a plug for KYB GR2 struts. For performance I prefer Tokico and Koni- GR2s are too soft

Yes, I have removed inserts that were dry and did not have any obvious heat damage but I now wonder if they would have lasted longer with the oil bath.

Most strut installation instructions recommend it. I agree and would not warranty a job if the customer requested them dry.

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No, don't ever install them dry, they'll never come back out! I just coat the inside of the strut tubes and the inserts themselves with Redline HP CV2 grease. Haven't had a problem in years of racing, but then again the struts come in and out every couple years anyway.

 

I have the GR2s on my 810 and are happy with them. Sounds like that particular customer lived off 20 miles of washboard gravel road.

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