Knee shocks flush?

From VC-1 to WC64-KD.
Adam in Wa
Technician 4th Grade
Technician 4th Grade
Posts: 79
Joined: Wed Mar 14, 2018 12:04 am
My garage: 48 Power Wagon
42 WC53

Knee shocks flush?

Post by Adam in Wa »

I cleaned up one of my knee shocks. It moved through the range of motion smoothly, but zero resistance. When I removed the fill plug I found a small amount of black oil. I filled it with some zero weight motor oil to work and evaluate it’s function. The shock now has good resistance in one direction and very little in the other. I started to wonder if I should try to flush out the internals with diesel, ATF, detergent motor oil, etc.

Any suggestions that will free up the valves and not injure the seals. Thanks.
User avatar
Gordon_M
Lieutenant General
Lieutenant General
Posts: 2710
Joined: Wed Mar 08, 2006 3:43 pm
Location: Falkirk, Central Scotland

Re: Knee shocks flush?

Post by Gordon_M »

I'm not that sure what the resistance should be in either direction - don't know if it is supposed to be exactly the same. I'd be inclined to let it drain fully then refill it with jack oil and just use it. There are so many used ones around it is probably better to replace with anther serviced used unit that try anything too technical.

If you swap another one in, you can always dismantle that one without worrying about whether it would rebuild.
Gordon, in Scotland

( Now officially given up on any form of politics )
Ray Edsall
Technical Sergeant
Technical Sergeant
Posts: 1238
Joined: Fri Apr 07, 2006 6:35 am
Location: Australia

Re: Knee shocks flush?

Post by Ray Edsall »

G,Day Adam . I personally woudn,t worry to much about the shocker .Flli it up with hydraulic oil{Or equivalent} and see what happens . If it works one way ,Bonus .Telecscopic shockers seem to work hard one way .And not the other way . Check out your other shockers and see how the work .Hard one way and soft the other way,may be . Ray
Adam in Wa
Technician 4th Grade
Technician 4th Grade
Posts: 79
Joined: Wed Mar 14, 2018 12:04 am
My garage: 48 Power Wagon
42 WC53

Re: Knee shocks flush?

Post by Adam in Wa »

The Schematic of the shock in the TM manual shows the arm is connected to a center cam with two equal size chambers. This is why I think it should have the same resistance in both directions. I won’t be able to experiment with it, or examine the others, for about a week; just trying to come up with a plan.
motto
Technical Sergeant
Technical Sergeant
Posts: 1027
Joined: Sat Apr 17, 2010 4:25 am
My garage: Harley Davidson 42WLA, Dodge WC63, Dodge WC57, Chevrolet 1-1/2 ton 4x4. Originally an Earth Borer, Pole Setter. Drilling rig gone and truck now mounts a #7 Set Lifting Frame. i.e.: Light Wrecker.
Location: 70km from Melbourne Australia

Re: Knee shocks flush?

Post by motto »

The Delco Lovejoy knee action shock absorbers used on WW2 US military vehicles as far as I am aware only restrict travel in one direction. The lever will go up with very little resistance but is seriously restricted for the downwards stroke.
This allows the suspension to deflect upwards on contact with an obstacle but is damped for its return to the neutral position. This prevents the vehicle from porpoising which under some circumstances can be quite violent.

David
Ray Edsall
Technical Sergeant
Technical Sergeant
Posts: 1238
Joined: Fri Apr 07, 2006 6:35 am
Location: Australia

Re: Knee shocks flush?

Post by Ray Edsall »

Well there you go .Soft one way .Hard the other way . As i don,t go off roading in my wc53 ,the shockers are there only for show . Why? . Because thats where they were put by Dodge . Ray
Kaegi
Technical Sergeant
Technical Sergeant
Posts: 1436
Joined: Thu Jan 11, 2007 8:47 pm
Location: Allyn WA

Re: Knee shocks flush?

Post by Kaegi »

they actually work quite well. late in the war the 3/4 tons went to tube shocks
Adam in Wa
Technician 4th Grade
Technician 4th Grade
Posts: 79
Joined: Wed Mar 14, 2018 12:04 am
My garage: 48 Power Wagon
42 WC53

Re: Knee shocks update

Post by Adam in Wa »

Update. So I media blasted, and painted the shocks. I found the remaining three shocks still had yellow oil; I just flushed them all out with hydraulic fluid and refilled them. Two of them seem to have the same resistance in both directions, two have more in one than the other.... maybe there is air trapped inside that will work itself out.

Also, to replace the petrified and rotten rubber bushings in the links I found some some urethane bushings that have the correct 1 inch OD, and 9/16 ID. I did need to cut them down length wise to fit. The bushings are a bit expensive; eight sets of two, 16, required for the job was about $80. I ordered them from Speedwaymotors.com
They are listed as Chrysler/Pinto leaf spring bushings, part # 910-43255.

https://www.speedwaymotors.com/Search?query=910-43255
User avatar
Gordon_M
Lieutenant General
Lieutenant General
Posts: 2710
Joined: Wed Mar 08, 2006 3:43 pm
Location: Falkirk, Central Scotland

Re: Knee shocks flush?

Post by Gordon_M »

Good to hear Adam.

I think over time they get very stiff in both directions and need to be freed off. I generally take them off the chassis, work them hard, then drain and refill. In all the time I have been working with them I have only found one that wouldn't free off when worked - and that one is still on the "to do" pile. :D
Gordon, in Scotland

( Now officially given up on any form of politics )
Adam in Wa
Technician 4th Grade
Technician 4th Grade
Posts: 79
Joined: Wed Mar 14, 2018 12:04 am
My garage: 48 Power Wagon
42 WC53

Bushing pics

Post by Adam in Wa »

Image
Kaegi
Technical Sergeant
Technical Sergeant
Posts: 1436
Joined: Thu Jan 11, 2007 8:47 pm
Location: Allyn WA

Re: Knee shocks flush?

Post by Kaegi »

after you fill them your supposed to work them back and forth through the full range to work the air out. do it maybe ten times then check fluid. repeat until fluid level stays the same.

thanks for bushing link
Adam in Wa
Technician 4th Grade
Technician 4th Grade
Posts: 79
Joined: Wed Mar 14, 2018 12:04 am
My garage: 48 Power Wagon
42 WC53

Re: Knee shocks flush?

Post by Adam in Wa »

I did work them back and forth, that’s how I know there is more resistance in one direction or the other :D . They take a surprising amount of fluid.