VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1937-1945 DuBonntet Knee Action Troubles - Part 1

I have the Dubonnet front end on my '37 and I am in the process of rebuilding them. I have the Service Bulletin rebuild instructions and some others, and rebuild seals, etc. My trouble: After 5 hours of torch (heating) work and fabricating tools to remove center plug I finally got it out; now after 7 hours torch work and working with tool and/or 48" pipe wrench on the cover cap, it still will not come loose. What experience have others who have rebuilt these had? Is this difficulty typical? I fear damaging the units just taking them apart -- and not sure if rebuildable after I get them apat. I have near-complete straight axle, springs, front hangers and shocks and conversion instructions -- any thoughts about whether to stay with the knees or do the conversion. Will need rear front spring hangers. HELP

Jim,
I'll take a look for the parts you need tomorrow, if I can get back to the barn.

I haven't tackled rebuilding the knee actions yet, but I can tell you that if you tour a lot, you'll be real disappointed with the straight axle, if you're used to the Dubonnet. I had a straight axle '37 sedan and sold it after I got my '37 coupe with the knee action. WOW! What a difference, both in handling and ride.

The Dubonnet shocks, IMO, got a very bad name for themselves because owners didn't maintain the oil level in them and they tended to collect a lot of mud, etc. on the mainly dirt roads they were used on and didn't work correctly. Rather than spending the money to fix them (back then), owners took the cheaper, easier way out and converted to the straight axle. After experiencing the difference between the two, I'll take the Dubonnet hands down!

-Bob

Jim, This is my experiance from resealing mine over 25 years and 20,000 miles ago.First I relieved as much spring tension as possible by unscrewing the top adjuster as far as possible.Then using a large pipe wrench I removed the top cover.At this point there is no tension on the spring.Then I removed the front shock covers--be careful--they are "spring loaded" and don't mix the valves or pistons inside.Next remove the set screw that locks the outter arm and its shaft to the lever that works the spring- its accessable thru one of the shock openings.....now you can pry out the outter arm a little-if you go too far the rollers will fall out that the shaft rides on...At this point I did not have seals to put in as they were not available at that time.I dug out the remains of the old cork seals and used plumbers rope (comes on a roll-graphite impregnated rope)and wound it around the shaft-packed it in and wound more-at last filling the seal area.Pushed the big arm back in and tightened the packing nut.I have driven the car over 20,000 miles and check the fluid every ten years as it leaves only a couple of drops on the floor after setting for months.The right one will leak when the front end is jacked up and the wheel is hanging down but this was a common problem with these.If the area where the needle bearings ride or the arms are very loose the unit needs rebuilding.If you can't remove the top cap try prying the amm out a little with the cap on.Just get about an inch of the shaft exposed so the inner end of it stays engaged in its housing. I don't know what the new seals you have look like but doing it my way eliminates disasemeling the unit.I have a friend with a '38 that used the same proceedure with equal good luck.I also did mine while on the car as the king pins hold them in place well for the "bull work"..I would sure make a good effort to fix your knees if you can because there is a vast difference in the ride and handling between the two suspensions.I have mine filled with ATF-cheap and of low viscosity -otherwise hydralic jack oil works too.If you have further questions please feel free to ask--and yes--you may be sorry if you take it completely apart.Also if the big arm has bushings you have "old" rebuilt units on your car.This would make it eaiser to compleetly disassemble if necessary.

Hi Jim
I have just read your 2 postings but I have not had anything to do with Knee action front ends wont comment on them.
But in regards to the spring hangers I had a look at The Filling Station site the other night and they list spring hangers for my 38 1/2 ton which probably be the same as sedan straight axle.
Some of the other readers with more accurate knowledge may correct me on this info, I wont be offended.
You may also find knee action use a different steering box to the straight axle.
Best of luck which ever way you finally go.
CUL Tony

Jim. After doing a memory search I did not remove the top cap but did unscrew it several turns to relieve some of the spring tension but I believe the srm can be pulled out a little with out even doing that.

Jim, I too love the ride the knee-actions give over the straight axle. I rebuilt mine over 25 years ago and they are still not leaking, as the amount of driving is a lot less and the roads are better. There is information in the old G & D's about rebuilding( I can find out the issues in a few days) and also in the shop manuals, etc. The
main thing is to remove the top center plug to remove the spring tension. I remember people telling me never to touch them as they could kill you, but by following the instructions carefully and working in a safe manner I had no problem-I think I was only 21-22 yrs. old at the time. Good luck!

antiqueautoarchive.com has the best document ever authored on this subject under the "resoration tips" section. This is a must read for anyone interested in this type of knee action restoration. Five Points Hydraulic can provide experienced rebuilding service which requires machine work and sleeving of the worn pivot arm to reseal correctly.

Jim,
I checked my 'stuuf' and I do not have the front axle rear spring holder. Thought sure I had some of those parts, but I don't see them around.

-Bob

Thanks for looking Bob. I've decided to stick with the Dubonnet system and repair the units.