The Ford Barn

CatMan1 · 08-09-2022, 12:22 PM

I've noticed that all 4 shocks on my '28 are leaking. I know I should rebuild them, but I have a show coming up and won't have the time. I've been reading up on the recommended fluid, but I'm confused as there are so many options. Is there a universal type that might be best? How are they filled?

bruceincam · 08-09-2022, 12:33 PM

When I was faced with the same questions, I bought a bottle of shock oil from Snyder's. I have no idea what was in them, but no compatibility issues so far. It's been over a year since I refilled them. They're filled through a hole in the top of the shock body; remove the plug. i just filled them til the fluid dripped out ---- you can't see into them. Technically I over-filled them. Mine don't really seem to leak badly. They're just always moist. FWIW

rotorwrench · 08-09-2022, 04:05 PM

The wing shafts wear against the body and slowly exhibit more leak by as they wear. The tool that was used to check them was an arm with a weight on it. They were adjusted to take a specific amount of time for the calibrated weight to drop all the way down. On worn shocks it can take a hydraulic oil with higher viscosity rating to get them within specs. In cold weather they might get pretty stiff. This is why glycerin was used so long. It doesn't get affected by cold weather as much but then it's not very viscous either.

Bob Bidonde · 08-11-2022, 07:38 AM

Because the Houdaille Shocks a pain in the derriere to get to, I do not often service mine as I should. I did a test and found out that automatic transmission fluid and glycerin are not soluble in each other. Moreover, the glycerin has a higher specific gravity, so the automatic transmission fluid floats on it. This is good news as the glycerin will leak out first, so I am replenishing the fluid in my shocks with automatic transmission fluid. Eventually, my shocks will have all transmission fluid in them.

katy · 08-11-2022, 10:51 AM

Quote:

Originally Posted by Bob Bidonde

transmission fluid

I'm assuming you mean ATF, not gear oil?

Brentwood Bob · 08-11-2022, 01:17 PM

Sponsored Links (Register now to hide all advertisements)

I have used 85-140 wt hydraulic oil, adding STP on the worn rebuilds.

Oldbluoval · 08-11-2022, 06:19 PM

BB-
Agreed same here

Bob Bidonde · 08-12-2022, 07:26 AM

Katy,
Good catch. I edited my post to say "automatic transmission Fluid."

katy · 08-12-2022, 10:08 AM

katy · 08-12-2022, 10:16 AM

Quote:

Originally Posted by Brentwood Bob

I have used 85-140 wt hydraulic oil, adding STP on the worn rebuilds.

Where do you get the 85-140 hydraulic oil? I did an online search and all I found was 85-140 gear oil.

Kevin in NJ · 08-12-2022, 10:44 AM

The oil you need depends on the amount of wear in the shock.

You will find the standards to which the arm has to move with a 6 lbs weight over a certain time. Nice to know, but not always practical.

You need an oil that make it hard to move the factory arm in one direction and a little easier in the other direction.

I have very slightly worn shocks and oils close to factory are not close to giving enough resistance. With the KRW tool (well a copy of one) it was not even close to the correct time of movement.

So all you can do is experiment.

Keep in mind if there is any movement back and forth on the shaft, that is the bushing is loose, then the shock will never work right.

Brentwood Bob · 08-12-2022, 12:11 PM

It's the 85-140 gear oil. The cheapest.

rotorwrench · 08-13-2022, 09:27 AM

Most hydraulic oil uses an ISO rating for viscosity so a person has to look up a comparison chart for ISO versus SAE viscosity. Most hydraulic fluids are straight grade with no expanding polymers. The multi grades in SAE use the polymers to get the thin (SAE 85) when cold and then the polymers expand with heat to give the thick (SAE 140). The shocks don't warm up like a transmission or a rear axle so the viscosity is likely somewhere from SAE 85 when cold to somewhere in the middle between the extremes at 100 degrees F on a hot day. ISO 100 to ISO 150 would be in the neighborhood. Even gear oils are rated different than motor oils in the SAE system. SAE 50 motor oil is about the same viscosity as SAE 90 gear lube.

Hydraulic oils would be ideal but they are limited in size of container. Most companies sell it in 5 gallon or 1 gallon containers. It's not easy to find it by the quart.

nkaminar · 08-14-2022, 06:10 AM

Shock fluid: $439 per pint. Shocking.

08-09-2022, 12:22 PM	#1
CatMan1 Senior Member Join Date: Jun 2021 Location: Pella, IA Posts: 337	Shock Fluid I've noticed that all 4 shocks on my '28 are leaking. I know I should rebuild them, but I have a show coming up and won't have the time. I've been reading up on the recommended fluid, but I'm confused as there are so many options. Is there a universal type that might be best? How are they filled?

08-09-2022, 12:33 PM	#2
bruceincam Senior Member Join Date: Mar 2021 Location: Camarillo, Ca Posts: 167	Re: Shock Fluid When I was faced with the same questions, I bought a bottle of shock oil from Snyder's. I have no idea what was in them, but no compatibility issues so far. It's been over a year since I refilled them. They're filled through a hole in the top of the shock body; remove the plug. i just filled them til the fluid dripped out ---- you can't see into them. Technically I over-filled them. Mine don't really seem to leak badly. They're just always moist. FWIW

08-09-2022, 04:05 PM	#3
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 16,436	Re: Shock Fluid The wing shafts wear against the body and slowly exhibit more leak by as they wear. The tool that was used to check them was an arm with a weight on it. They were adjusted to take a specific amount of time for the calibrated weight to drop all the way down. On worn shocks it can take a hydraulic oil with higher viscosity rating to get them within specs. In cold weather they might get pretty stiff. This is why glycerin was used so long. It doesn't get affected by cold weather as much but then it's not very viscous either.

08-11-2022, 07:38 AM	#4
Bob Bidonde Senior Member Join Date: May 2010 Location: Long Island, NY Posts: 3,470	Re: Shock Fluid Because the Houdaille Shocks a pain in the derriere to get to, I do not often service mine as I should. I did a test and found out that automatic transmission fluid and glycerin are not soluble in each other. Moreover, the glycerin has a higher specific gravity, so the automatic transmission fluid floats on it. This is good news as the glycerin will leak out first, so I am replenishing the fluid in my shocks with automatic transmission fluid. Eventually, my shocks will have all transmission fluid in them. __________________ Bob Bidonde Last edited by Bob Bidonde; 08-12-2022 at 07:25 AM.

08-11-2022, 01:17 PM	#6
Brentwood Bob Senior Member Join Date: May 2010 Location: brentwood, ca Posts: 4,246	Re: Shock Fluid Sponsored Links (Register now to hide all advertisements) I have used 85-140 wt hydraulic oil, adding STP on the worn rebuilds.

08-11-2022, 06:19 PM	#7
Oldbluoval Senior Member Join Date: Jun 2015 Location: Signal Mtn, TN (SE TN) Posts: 2,372	Re: Shock Fluid BB- Agreed same here

08-12-2022, 07:26 AM	#8
Bob Bidonde Senior Member Join Date: May 2010 Location: Long Island, NY Posts: 3,470	Re: Shock Fluid Katy, Good catch. I edited my post to say "automatic transmission Fluid." __________________ Bob Bidonde

08-12-2022, 10:08 AM	#9
katy Senior Member Join Date: Jun 2015 Location: Red Deer, Alberta Posts: 5,046	Re: Shock Fluid __________________ If you don't hear a rumor by 10 AM, start one!. Got my education out behind the barn!

08-12-2022, 10:44 AM	#11
Kevin in NJ Senior Member Join Date: May 2010 Location: South East NJ Posts: 3,398	Re: Shock Fluid The oil you need depends on the amount of wear in the shock. You will find the standards to which the arm has to move with a 6 lbs weight over a certain time. Nice to know, but not always practical. You need an oil that make it hard to move the factory arm in one direction and a little easier in the other direction. I have very slightly worn shocks and oils close to factory are not close to giving enough resistance. With the KRW tool (well a copy of one) it was not even close to the correct time of movement. So all you can do is experiment. Keep in mind if there is any movement back and forth on the shaft, that is the bushing is loose, then the shock will never work right.

08-12-2022, 12:11 PM	#12
Brentwood Bob Senior Member Join Date: May 2010 Location: brentwood, ca Posts: 4,246	Re: Shock Fluid It's the 85-140 gear oil. The cheapest.

08-13-2022, 09:27 AM	#13
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 16,436	Re: Shock Fluid Most hydraulic oil uses an ISO rating for viscosity so a person has to look up a comparison chart for ISO versus SAE viscosity. Most hydraulic fluids are straight grade with no expanding polymers. The multi grades in SAE use the polymers to get the thin (SAE 85) when cold and then the polymers expand with heat to give the thick (SAE 140). The shocks don't warm up like a transmission or a rear axle so the viscosity is likely somewhere from SAE 85 when cold to somewhere in the middle between the extremes at 100 degrees F on a hot day. ISO 100 to ISO 150 would be in the neighborhood. Even gear oils are rated different than motor oils in the SAE system. SAE 50 motor oil is about the same viscosity as SAE 90 gear lube. Hydraulic oils would be ideal but they are limited in size of container. Most companies sell it in 5 gallon or 1 gallon containers. It's not easy to find it by the quart.

08-14-2022, 06:10 AM	#14
nkaminar Senior Member Join Date: Jan 2012 Location: Western North Carolina Posts: 3,897	Re: Shock Fluid Shock fluid: $439 per pint. Shocking. __________________ A is for apple, green as the sky. Step on the gas, for tomorrow I die. Forget the brakes, they really don't work. The clutch always sticks, and starts with a jerk. My car grows red hair, and flies through the air. Driving's a blast, a blast from the past.