Oil Fill shock strut

[lamarglobe]

Have an older 4 place QB. Starting tomorrow on the shock strut NPT oil fill. Previous owner put the shock strut together without drilling the oil fill. The plans look like the hole is drilled 90 off of the lower part of the strut (airfoil) on the top as per page 9 of the manual. The shock strut is temporarily installed (on the gear). Looks like an easier location for servicing the oil fill is inline with the leading edge of the strut and have an access point through the floor board (still searching for floor board patterns if anyone may have them). So, I either drill 90 degrees from the leading edge or inline with it. Any suggestions? I want to get this first step right. Thanks

[Battson]

If I had to design it myself..... I would put them on the "top" side of the strut (in 3 point attitude), so you can pour fluid in with the struts installed, by lifting the floor.
But there must be a good reason why they are where they are?

[lamarglobe]

drilled as per the plans. It came out well. Thanks

[Gavin Chester]

If you fill them on there side with the oil bypass hole on the top side inline with the filler hole and tip back and forth as you fill, before you install them on the plane, you will get almost all the air out, that is trapped inside the piston rod and you will get better rough ground performance.
I had taken mine off to repair a bent one and decided to re seal the other one at the same time to keep them even. I had previously filled them on the plane and with nothing to compare to I thought they were good but this time it was like having a totally different ground performance as it was much firmer.

[Mark Goldberg]

Pouring in the ATF through the top of the piston tube (with the rod end out) is the way to do it. Mark

[marcusofcotton]

I believe there is an area of common misconception regarding the struts. Following Mark's filling method (rod out while having the strut placed with the shock/spring end higher) is necessary to ensure that there is air trapped inside the rod. The air is necessary because it is compressible, the oil is not. If all voids were filled with oil, the oil will be forced out past the seals (or result in bent rods or other damage) when compressed due to the additional volume of the rod tube steel now being forced into the cylinder.

While on the subject, anyone flying in serious winter weather may want to consider using 5606 fluid instead of ATF. At very cold temps, ATF is considerably more viscous and will result in more stresses due to suspension stiffness.

[Gavin Chester]

The rod side of the strutt has less volume than the piston side so full of oil is no issue. Marks method is a lot quicker to fill I just wanted to get a perfect seal with the rod end threads as I had enjoyed prior to the re seal and the loctite product I used needed a cleaned and primed surface and no contact with any fluid until it had cured.

[svyolo]

I pulled the shock struts to refill them according to Mark G's post. I previously filled them from the threaded plug. I got somewhere around 4-6 oz out (a guess). I tried pouring it in the top, and only got maybe 1 oz back in before overflow. Is that correct? Was it overfilled before?

Thanks

[Steve W]

I’m a little confused from some of the comments here. When filling the strut, isn’t the goal to have it filled 100% with fluid, no air, which allows the piston, which has a hole in the disc, to move through the fluid providing the dampening effect?