VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1937-1945 1937 Knee Action. Dubonnet

I am just starting to disassemble my knee action shocks to check the condition of the needle bearings and replace the main support shaft seal. I have the G & D article by Jim Leman and also another article I found at www.antiqueautoarchive.com that covers this repair. I also have read the post by Chev Nut dated Mar 2, 2003 and other posts and discussions. (1) Relief of spring tension: Do you completely remove the adjuster nut from the cap and/or how do you know when the spring tension has been removed? (2) The support arm surface that contacts the upper shock piston is pitted from rust. Any opinions on whether this is a problem?

you can remove the height adjuster nut it takes some of the tension off the spring then remove the spring cap normaly if some one has not added spacers to the spring before the cap is all the way loose it will not have any tension on the spring if it does you will have to put it a press and take the tension off by putting a bar in the height adjuster hole and press it down a little to take the tension off . the last two or three i have done i did not have to lift that heavy thing into the press . as for the rusted arm these parts are harder than wood pecker lips you may put them on a stone and smooth them some times the caps show wear and i repair this like i do valve rockers and take the bearings out and put bushings in .lets talk when you get the shafts out see what kind of shape they are in . a frend of mine sent his off for repair he has a 35 when they came back he installed them finished the car the last thing is installing the hub caps did not fit called me and i gave him the news that they were 34 which has a longer shaft and hub i think he said he was going to cut a hole in the cap .

rck46,I hope you don't come across any wood pecker lips.

I was successful in getting one of the knee action units disassembled today. I have a lot of rust pitting on the surface of the main shaft where the shaft contacts the needle bearings. This would be the outer bearing surface and not the inner one where the seal and large nut is located. Anyone had any experience with this? Can the rebuilders handle this? Are there any sources for spare parts for these units? Any suggestions anyone might have would be appreciated.

you can call one of them i am sure they can repair for about 550.00 they should . i was expecting that there was a problem in this area . a while back another person said he repaired the shaft with a thin shrink on sleeve had no problem . i guess he used a undersize bushing and seal . this area of the shaft is the same size as the splines so you can not under cut and slide a sleeve over it . i dont think a thin sleeve will hold on the bearing area . i took mine to my crank shaft rebuilding co. had them metalized and ground to standard no problem yet . a machine shop may be able to do this and make the bushing . i have used the shrink on sleeve on the seal area of shafts many times with good results . hope this helps get back with your choice

Pushrod: Thanks for you help and advice. I am going to take your suggestions to a few machine shops and see what they say. When they make a bushing do they have to enlarge the hole in the housing? Also, how do the bushings hold up?

Just thought I'd toss in my 2¢, for what it's worth.

I tried the "Jim Leman" repair before I left on my S.Dakota trip a couple of months ago. I was able to do "fix" of the shocks as directed in the article, but couldn't loosen the main shaft set screw on the second one, no matter how hard I tried. After trying several methods and consulting with some other good mechanics, I finally had to give up and reassemble the #!&*% thing for the trip.

After coming back from the 3600+ mile trip, the one shock with the repair is leaking, although much less than before, while the "unfixed" shock is still leaking like a son-of-a-gun.

Looks like a complete disassembly is in order for this winter. :(

-Bob

no the housing does not have to be machined just make the bushing for a press fit and a thou. clearance on the shaft . you can machine the housing and install modern lip seals i did not i put o rings in and tighten up if it seaps i tugg on it a little . as for the bushings the needle bearings that are original are fine on a shaft that rotates 360 such as u joints but not on a shaft that turns a quarter turn. gm tried it on king pins in 35 and took them out after a short time . i came up on a set of shocks at a swap meet in the center of the us that had been rebuilt back in the 40,s still had the brass tag at first i thought they were new when i got them back in the shop and apart they had installed bushings that is when it dawned on me . hope this helps

Here's an update. Took the dissassembled unit to a machinist today. He was recommended to my by two people and will be able to make new bronze bushings and turn the pitted shaft down as pushrod suggested. Said it would be no problem. Looks like it will cost about $300 for both. He checked the shafts for out-of round and said they were only off by a half a thousandth. He noticed one possible problem with the splined shaft that I missed. Looks like the splines may have been twisted slightly - they are not quite straight. I haven't taken the other unit apart yet to see what it looks like. Has anyone run into this problem? He also mentioned that he was reluctant to weld on the shaft to repair the pits because he didn't know what the make up of the steel was. Anybody have any suggestions for this?