Tire Pressure

[WHN]

I had used ATF for a while before that hydraulic jack / shock oil and by “feel” thought I had proper damping.
Then I found a perfect shock with no wear and all internal clearances between.001-.002”.
I started with Kubota hydrostatic multi viscosity oil figuring it would have a more stable viscosity through temperature changes.
The test times were way too fast.
Then I bought the higher viscosity hydraulic oil (AW68) the test time was better but still way too fast. — even with the needle valve totally closed.

So I did some looking at relative viscosity of glycerin and other liquids and found that pure glycerin was quite thick.

Then the can of “Check Shock” oil was found and I made a viscosity test cup and found that a blend of 85-140 gear oil with 10% of my 600 gear oil ( Shell Omala 680) matched the Check Shock oil.

With that oil the shock performance with the needle valve at a range of 3/8-1/4 open matches the times in the service bulletins.

So I ask again— Bob what standards and testing were you using to adjust your shocks and what performance were you getting from the test procedures?

Restoration to original specifications eliminates the need for many modifications

You must be retired!

HAPPY HOLIDAYS.

 

[Y-Blockhead]

I had used ATF for a while before that hydraulic jack / shock oil and by “feel” thought I had proper damping.
Then I found a perfect shock with no wear and all internal clearances between.001-.002”.
I started with Kubota hydrostatic multi viscosity oil figuring it would have a more stable viscosity through temperature changes.
The test times were way too fast.
Then I bought the higher viscosity hydraulic oil (AW68) the test time was better but still way too fast. — even with the needle valve totally closed.

So I did some looking at relative viscosity of glycerin and other liquids and found that pure glycerin was quite thick.

Then the can of “Check Shock” oil was found and I made a viscosity test cup and found that a blend of 85-140 gear oil with 10% of my 600 gear oil ( Shell Omala 680) matched the Check Shock oil.

With that oil the shock performance with the needle valve at a range of 3/8-1/4 open matches the times in the service bulletins.

So I ask again— Bob what standards and testing were you using to adjust your shocks and what performance were you getting from the test procedures?

Restoration to original specifications eliminates the need for many modifications

Waayyy back when I installed my Stipe Shocks, ~11 years ago, Bill told me they use ISO 150 Synthetic Hydraulic oil in their shocks. I believe that is around SAE 90 gear oil?

 

[Jim/GA]

Bob, I suspect that your springs need to be lubricated. When I have done that to my cars, I notice the ride is much more comfortable. And then changing the shocks changes the ride (for the better, less like a porpoise).

I added spring covers with oil soaked felt pads to one car so far and plan to add them to the others. This keeps the water out of the springs and keeps soaking oil in. No rust. Great ride. And they look nice and period correct (nicer than tube shocks).

 

[Ruth]

Bob, I suspect that your springs need to be lubricated. When I have done that to my cars, I notice the ride is much more comfortable. And then changing the shocks changes the ride (for the better, less like a porpoise).

I added spring covers with oil soaked felt pads to one car so far and plan to add them to the others. This keeps the water out of the springs and keeps soaking oil in. No rust. Great ride. And they look nice and period correct (nicer than tube shocks).

I have spring covers like shown in post #10. They keep springs well lubricated and clean.

 

[Mike1291]

Waayyy back when I installed my Stipe Shocks, ~11 years ago, Bill told me they use ISO 150 Synthetic Hydraulic oil in their shocks. I believe that is around SAE 90 gear oil?

Yes. I've also used the 20W50 hydrostatic transmission oil that someone else mentioned since that's about ISO 150 when compared to a chart. This chart gives you an equivalence between oil types.

The issue with 20w50 versus a straight grade is that it is thinner at lower temperatures than a straight grade ISO 150. If there isn't enough heat generated, you'll never get the thickness that the viscosity improver present in multi weight mineral oils provide. And since our shock absorbers do not generate the same type of heat that would be present in, say, a hydrostatic transmission, then that's why you may experience unsatisfactory results.

For a more detailed article, here's something that Shell has that explains how this works: https://www.shell.com/business-customers/aviation/aeroshell/knowledge-centre/technical-talk/multigrades-part-2.html