I scored a set of 89 Carrea Boge struts to use my 914 inserts in.Pulled the 89 insert out looks like the valving set up used in motorcycle front forks Anyway my 914 insert fits in ok just got to come up with centering rings for the insert , my question is do I fill with some kind of coolant , the Paragon article states either oil or antifrezze , or is this not neccesary for a sealed insert unit ??
Strut prt # 911.341.041/042.04

Do fill with fluid or not ??

Jaxdream

I always do, otherwise you've made a dandy vacuum bottle...

I do not like the idea of anything aqueous in a steel tube...

I use a light oil - it doesn't take much.

Something like an ATF, although I've heard air-tool oil has some anti-corrosion properties so that's probably what I'll put in the next set of struts I do. Marvel and Lucas make air-tool oil - I think I got a quart of Lucas oil from Summit for not much.

Things like some of the 5 mile an hour bumper struts from the era used mineral oil to lube and prevent corrosion. I have taken a couple of these apart and they look pristine inside. Might work in this application too...

Primary reason to add oil is to help heat transfer to the outer housing. Like Rich said, ATF works fine.

so thats why the negative term "fish oil" is used with cheap shocks, makes sense now. by no means do i know what i'm doing, but i've used hydrolic oil in koni's with good luck... seemed to make sense in my chaotic mind.

Unless your racing, how much heat do you think your shocks will generate?

Our roads aren't as good as they are in BC apparently. Shocks oscillate thousands of times per minute creating lots of heat. Racing could even be better as the asphalt is often better and the transitions smoother.

It doesn't really matter...
A quart of ATF will do both struts (with a bunch left over) and it's an easy "no downside" As Long As. Consider that what are commonly called 'shock absorbers' aren't (the springs absorb the shocks...) they are really spring dampers and the axial forces can easily be 3X the spring rate. They get hot, and the heat serves no purpose.

Have you ever pulled open an original-to-the-car Boge strut - the ones with *no insert* ? Yes, folks, as delivered from the factory, the pistons ran directly in the strut tube (this was true for /6's, I donno about /4's). I've done that job twice and the Boge hydraulic fluid is as horribly nasty smelling as anything you'd never hope to come across. Dead fish is a good approximation...

I have been told by Koni tech to use antifreeze (they also spec antifreeze on the install instructions). I would expect that if you are using a Boge insert, that Boge's installation instructions should say what to use?

I suspect the problem with oil is that if water does get in that it can/will float the oil out the top leaving a pocket of water at the bottom. This pocket can rust and/or freeze.. While if water gets into the antifreeze that it will still have the anti-rust additives of the antifreeze and it should still protect against freezing in the winter even if diluted somewhat.

Never mind.

Yep , it was some nasty stuff that came out of the strut. Thanks for the replies , me thinks the Konifolks may be onto something with the antifrezze . That's what will go in upon reassembly.Thanks again...

Jaxdream

When I did the konis on my 924 I used antifreeze.