VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1937-1945 Knee Action Rebuild

My '38's front end bounced quite a bit. I went out and got some ATF, and filled them up according to the manual. Boy, what a difference...no bouncing at all. It was not very long before they started to leak all over the place. Time to get new seals.

I found a set of seals on ebay at a decent price, and they include lead washers as well. Unfortunately the shocks will need to be taken apart. Reading the repair manuals and looking at pictures was helpful, but a video is even better.

I made several videos, and will post them in steps as I go along. I will include photos as well. Feel free to ask any questions, and I will try to answer them with photos if possible.

Keep in mind that these videos/photos depict what I did, not how it should be done, so if you dare to do it yourself as well, caveat emptor. I am open to better suggestions if you have 'em.

In addition to the typical mechanic's tools that I have; here is a list of specialty tools that made my life a little easier:

8 inch c-clamps
1/4" key stock, 12 inches minimum
Pipe wrench with a minimum of 5" jaw opening
Ball joint spreader
27mm impact socket that you can destroy
Welder

If you live near a Harbor Freight store, you will find many items & tools to get you through this. I had to purchase several sets of SAE tools just for this car, as everything else I've owned was Metric.

I had a pair of spare knee action shocks that were previously reconditioned back in the late '70's. They still needed to be disassembled as the seals dried up. At least they were already machined to accommodate sleeve bearings (bushings).

Here is part 1, which gives a quick summary of how I disassembled the unit:






I had to do all this twice; once with the original shocks, then putting the reconditioned shocks on the car and repeating the process.

You will need to get a set of new king pin hardware.

Hello green427,

The trick to not getting hit with the shock cups is to take one bolt out, add a longer threaded bolt with a nut on it and adjust the nut so it has a 1/4" or more of space between the cup flange and nut. Then remove the other two bolts, tap the cup and the longer bolt will allow it to pop loose but only up to the nut. Remove the longer threaded bolt slowly and it will allow the spring to relax.

You can use this same technic to replace the cups only use three bolt / nut combinations to pull the cup back into place. Once seated, remove one bolt at a time and install the correct length bolts.
I can not lay claim to this idea as I read it in an article about knee action disassembly.

Nice video.

That's the first thing I planned to do, and like you, I read it somewhere as well. I went to all the hardware stores and auto parts vendors in town and the only correct fitting bolts anyone had did not have threads longer than 1/2", and I would have needed to order some online, which is a pain...pay a lot for a few, or order in batches of 100....

I had some leftover threaded rods & other items, so I rigged this to allow me to put the springs back in without poking an eye out, can use it to remove the cups, but it was faster & easier to let them pop out:

Needle bearings were in pretty good condition when I removed the main arm.






Original setup with needle bearings. These were the ones I caught, the rest were still in the gunk inside the shock housing.





Reconditioned setup with sleeve bearings or bushings:





For comparison purposes:




You can see how the hole on the right was bored out to accommodate the new bushings





Each hydraulic control spring consists of 4 parts:




The piston on the left is inside the cup on the right at all times, only moves about an inch or so as the wheel goes up or down:





This big copper washer was used for the top cover. When you remove the cover, don't lose this...finding a replacement will be difficult. The remanufactured units that I have did not have copper washers; they had either rubber or another flexible material that dried up and turned into dust

One of the units that was rebuilt in the late '70's and the box it sat in since. When I opened it up, there was very little grease in there, never saw any fluid, and the smell was like old gas. Green slime was in one. All seals were dried up.




Modified socket used to remove/install spring adj screw








Prev owner added grease fittings to the shock fluid filler plug, so people were adding grease to the shocks over the years, which simply stuck to the main spring. This one was not too bad compared to the other side.




Having this 50lb pipe wrench with a 6 inch jaw clearance came in very handy. Holding it in place is just as much work as turning the cap.







Put everything back together and put the wheels back on. Installed NOS king pin sets, NOS steering arms on both sides, put the tie rods back on, aligned the front end, adjusted steering box play, and lowered the front end after months of being on jack stands.











I stood on each corner of the front axle and tried to rock the car. It would not budge much...maybe an inch on each side. Compared to what it was like, it is now way too stiff. The shocks will need to be "broken in".

And, no leaks so far. Both had been filled for several days with ATF. We shall see how long it will be before they start leaking again....

Will eventually drive it out of the shed and de-grease the whole front end before painting it chassis black.

Just a suggestion - if you don't have access to a large pipe wrench, a chain wrench with a long pipe works equally as well and didn't leave the "bite marks" of a pipe wrench. I used the chain wrench on mine when I rebuilt them.

Bob: The only chain wrench I could find in town was at Harbor Freight, and it snapped easily. Where did you get yours?

The pipe wrench I used belongs to my employer, so I got lucky there.

I found my chain wrench at one of the Hershey swap meets 10 or 15 years ago. It's quite heavy duty and,with a long pipe, did a nice job of removing the covers. I'll check it and see if there's a manufacturer's mark, but I don't recall seeing one.

I also used a friend's mill and opened the bore where the packing material went on each unit, and fit a modern lip seal in them - no more leaks! I don't recall if I took any pics of them, but if I can find any I might have taken, I'll post them.

I used a chain wrench on mine years ago. It was a Riged brand and usually sold at hardware stores, etc. Harbor Freight sells cheap junk.

Man...isn't that the truth?!! And the vast majority of stuff is made in China.

Green427,
The chain wrench I used was a KD-2595. I used it with a 1/2" breaker bar. Here's a couple of pics of it:

http://s443.photobucket.com/user/TagMan/media/KD1_zps82ba6b73.jpg.html

http://s443.photobucket.com/user/TagMan/media/KD2_zps1fa5937b.jpg.html

They are available on the web for around $35.00
My Rigid had an iron handle but the breaker bar would almost be better.