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Post by vmf241 on Sept 24, 2006 10:19:39 GMT -5
After considerable research, and multiple visits to wrecking yards, I believe the best course for replacement is one of the following: Remove struts/shocks from wreck, test for consistant movement of piston , and install. This has worked for me. Next part is dicey: Try to install ( while on the car) a zirk ( grease) fitting in the BOTTOM of the strut, fill a large grease gun with a non-detergent 20W oil, and inject using same. this has worked for a while for me, it may not for you, and I am only relating what I have done for my car. You do this at your own peril. I had to be extremely careful to not over drill the holes for the zirk fitting, lest they be blown out and oil gush onto the car park. Regards.
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Post by jaredperry on Dec 15, 2011 1:04:21 GMT -5
Has anyone done this, or found a new method for a low cost repair?
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Post by madmatt on Dec 15, 2011 15:05:01 GMT -5
Okay... I'm just saying this "can" be done... not that you "should" do it... I couldn't afford the super bling suspension yet... but our stock dampers are a bit underdamped for the heavier springs. soooooo I drilled a hole, drained the oil and replaced with a slightly heavier oil. Tapped the hole with 1/8 npt and installed an air valve. I used a mix of 68 weight Compressor oil and 20/50 at about a 60/40 ratio to get a much stiffer damper rate (just by feel) then compressed to 30 psi to help reduce the foaming (however the compressor oil has anti foaming agents...) You could also get motorcycle fork oil... various weights. BUT!!!!! This won't do you any good if your upper seals are totally shot and blowing oil out! If they are just leaking a bit, the fresh oil will help. So if you're current stuff is mediocre and still has some fluid left, but are pretty nasty, it's worth a shot. HOWEVER, BE CAREFUL! The shock is a dual tube design, and when you break through the first tube, there is only about a 1/2 inch before you will hit the second (most important!) tube. If you drill through it, or even bend or dent it, throw away your damper... Also, DON'T overfill or you will lock the damper... when you go to fill, compress the piston all the way down, then fill, and still don't fill all the way... If you fill with the piston out, there will be no room for the piston to compress into the body. ALSO!!! these are not gas charged dampers... DO NOT do this on gas charged struts, you'll get a face full of oil. Matt
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Post by jaredperry on Dec 15, 2011 16:13:51 GMT -5
Apologies ahead of time for the flood of questions... Do you have any close up images of the valve that was installed? Do you know in terms of volume how much oil was used, or was it a trial and error gig? And lastly, are the shocks still holding up to this day? I have done several suspension hacks for koni inserts and other swaps, so I am looking to give this a try. The current shocks I have now will not rebound after being compressed, so I dont think I really have anything to lose in trying this. These schrader valves have a pretty wide range working load and operating temperature: www.mcmaster.com/#air-fill-valves/=fdlnh7
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Post by madmatt on Dec 15, 2011 16:37:35 GMT -5
Well...
Re: the schader I used... Common air supply stuff, the one pictured was a "snifter valve" but I didn't like how large it was (rally car, rocks, smashed...). So I swapped it out for more similar to what you posted. I thought about getting a presta valve because of size, but they are harder to fill without the fitting.
Now, you state yours won't return/rebound? The stock are not gas charged... so they won't. So if that's all that's "wrong" they may be fine.
As for volume, as I said, I just compressed the damper, then filled and left a bit of space. Notice I put the valve at the midway section under the spring perch? I tipped the damper to about 5 degrees and then filled it... That left some extra air space.
Again. This is a "getto mod" I know has been done in the past (the National P1 Champion Justy ran with a similar set-up)
As for how long it will last? Good question. I wish I could tell you, but the only rally we've run since was Pines, and that was a disaster... Car handled well though, and we hit some pretty tough stuff. They still have the valves in them!
Matt
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Post by Armageddous on Dec 15, 2011 21:33:42 GMT -5
I would say if the shock is not leaking to begin with, and you want to replace the old oil with new stuff in an attempt to make the shock perform better maybe you could measure the fluid that came out. If you are really skilled, you could even run a viscosity test on the crude oil and try to gauge your replacement fluid on that. Terry
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Post by madmatt on Dec 16, 2011 9:52:26 GMT -5
Terry,
For sure re the viscosity test! Simple way is to punch a hole in the bottom of a paper cup, fill to a level and time it as it runs out , then mix and match the replacement oil.
I didn't bother. I just poured out the fluid, said "hmm that has the pour weight of ATF... I want thicker... Hmm, here's some heavy compressor oil, not thick enough, I'll add some 20/50"... done"
Having pulled apart several of my junky shocks, even the ones that didn't look to be leaking varied in the amount by 50 ml. The average (not a calculated value! LOL) was around 200 ml. I put more back in, probably close to 250-300. But I didn't actually measure that!
Edit...
But the whole "what I did" might be a bit moot here... and then yes a visco test to match would be good. I have fears that I may damage valves... Not sure. And, I would not want to drive the car now as a DD... but who knows what straw broke that camels back, the shell prep, the spherical joints, the stiffer springs, the stiffer dampers....
So, if you want to keep good ride quality and think your shocks are just leaking a bit... you could drain the oil, replace with a good motorcycle shock oil, and cap the hole with whatever... a nice bolt with a rubber o-ring... no pressurization and likely be better off then with what I did.
Having looked at the very simple valving in these shocks... I don't think the valves would die (unless you're trying to force 20/50 through them on a gravel rally stage!!!!). So most problems will be from leaking/losing fluid and fluid contamination. Given the seal that leaks is more likely to leak on re-bound, then filling with new oil might last a while!
Matt
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Post by madmatt on Dec 14, 2014 11:11:04 GMT -5
just an update...
I've switched to straight 20wt motorcycle fork oil in both the front and rear. seems to work great!
and the rears are unpressurized. just using a pipe thread plug in them, no valve.
Oh, and the car has a lot more miles on it now... and they seem to be holding up just fine. I think you could put the hole closer to the top and be fine, wherever.
a bung could be welded on for the plug, but I now have 4 struts with for plugs, the schaeder valves up front, and just the plugs unpressurized in the rear. the 1/8 npt pipe threads work great, with no need to use a rubber seal.
Honestly this can take a "done" pair of struts and breath new life into them for quite sometime. If you have oil pouring out of the seals, it's not going to last long, but if the strut is reasonably dry, with old oil on the outside, and bouncy... try it.
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Post by madmatt on Mar 30, 2016 7:11:19 GMT -5
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