I am a new member and a recent purchaser of a 1937 Master Deluxe 4-Door Sport Sedan.

One of my surprises on this car was the issue with rebuilding the front knee action shocks. With a cost of about $1,100 per pair for rebuilding, I am wondering how long can you expect these shocks to last?

My goal is to keep the car as stock as seems prudent. It won't be a "show" car, but rather just something that I wanted to be able to drive around in sometimes. It needs to be safe and reliable, but, as much as possible I want it to be stock. That being said, I am likely to replace the 216 with a '56 235 that I have already located. I have seen the Mustang II front ends that would not cost that much more than the rebuild cost for the DuBonnet's.

I would appreciate any comments that anyone might have on this subject.

Thanks,

Rich

I have a 1939 Master Deluxe 2-Door Sedan that I've been driving for about six years.
I have knee action shocks, but don't know the type. All I know is I've only serviced them with lite oil thru a plug on the top.
I can tell when to check the oil by the way they ride. The oil has to be added very slowly. Hope they keep working good.
By the way, I just installed a 261 last year that's running great. Now I wish I had disc brakes when somebody pulls out in front of me.
39 Den

Ken,
Your 1939 has the open coil spring susprnsion which was all new for 1939 and continued unchanged through 1948. The 1934-38 cars had the enclosed coil spring Knee-Action, a very different animal. Was very large and contained over 2 Qts. of fluid.

I have a '37 Sports Coupe with the DuBonnet shocks and have been driving it 2-3k miles a year for 15 years or so. I don't have any idea if they were ever rebuilt before I bought it, but the car now has about 80k on the clock. The DuBonnets started leaking a year ago, just before a 3600 mile trip to S. Dakota. Not having time to do much, I filled them up and went on the trip. They are still leaking, 20 nmonths later.

I plan to look at them this winter. I saw the $1100 cost from Apple Hydraulics, so I decided to try and rebuild them myself.

the 35 on the members photo has dubonnet front supention . they are not hard to work on . there is some real good pictures in the parts book . i repaired these about six years ago . no problem . i found a factory rebuilt one at chic. oklahoma took it apart they removed the needle bearings and installed bushings so that is what i did also machined the housing installed modern lip seals on another one i used o rings instead of the packing . the rub comes in when the shaft is worn that is when it gets complicated. you have to excuse me sometimes i get carried away most do not have the tools out in the shop especially machine tools but usally in town there is a machinest that do the small stuff . hope this helps

Rich:
New member to VCCA? Welcome!
You don't say what's wrong with the units you have, but presumably you have some leakage. Re-seal kits are available and frequently appear on Ebay. A full rebuild typically usually includes replacing the needle bearings with ball bearings and replacing all the seals.
Keep them topped up with fluid and you should get many miles of smooth driving.

I may be wrong, but it seems to me that I read somewhere, that the later DuBonnet units ('37 & '38) had bushings instead on needle bearings.

All year Knees had needle bearings.
The 1934-36 king pins had rollers instead of bushings.
The 1937-38 had king pin bushings.
After 1937 the new king pin sets came with bushings and covered 1934-38.
The rollers were not a good idea for the king pins either.

Simply put, my shock absorbers don't absorb any shocks. Also, when I got the car, they were dry as a bone. I did fill one shock with a couple of quarts of ATF and this made no difference in the dampening action. The good news is that that oil has been in there for a couple of weeks with no sign of a leak. From what little I know of the history of my car, it was last driven in the 70's by the "little old lady" that we have all heard of. I doubt that the car had any maintenance on the shocks during the latter years. I would rate my mechanical skills as a 5 on a 1 - 10 scale and quite frankly would be a little hesitant to rip them apart. While I am not looking forward to dropping a big chunk of change on them, at least a pro rebuild would give me lots of miles on the units.

I want a "stock" car as much as practical. If the rebuilt units have a decent life span, that would be great. If they are only good for a few years, I am not going to get them rebuilt. From what I am hearing is that they are good units when properly maintained.

Thanks for the feedback.

Rich

if you are not absorbing any shock both have to full of oil . i use hydraulic jack oil if they are full of oil then the valves in the shock part are stuck or the mechanical parts are broke that operate the shock cylinders this includes the springs . operating them with no oil can do a lot of damage from bearing failure to the cylinders freezing up and breaking . most all of the parts inside are harder than wood pecker lips so they wear really well . i have some that are over ten years old never added oil work fine . but the other thing is i dont put very many miles on a year . another tip is every now and then i take the bottom bolt out and check to see if any water has collected inside . you can drain the oil and take the cylinder covers off and check the valves for trash in them . every now and then there is gaskets and the seals for the bolts on e bay hope this helps pushrod

Well, you are right, I only have oil in one shock. I will put oil in the other one and see what happens. The car has zero miles on it since I bought it. I have just grabbed the front bumper and bounced it up and down a few times to see how the shocks were working. When you release the bumper, it takes about 4 bounces before it stops. I figure that to drive this car the way it is you would get motion sickness and puke on the new upholstery.

I too have seen the rebuild kits for the shocks and may give this a try. I just don't want to invest in the rebuild kits, do a bunch of work and then find that I haven't solved the problem.

Rich

This web site explains about Dubonnet front suspension.
<http://home.znet.com/r1937/Knees.htm>
I'd shy away from the Pinto (AKA: Mustang II) front end. They may be cheap but they never tracked too well when new and will never parallel a trolley rail like the Dubonnet. . .
. Good Luck, Lou

Chevy's of the 40's sells a reseal kit for $70/each. From what you can see in their picture, there is not much "stuff" in the reseal kit.

Has anyone installed these kits? Did it solve the problems?

Thanks,

Rich

Most inits will need more than a reseal kit due to wear on the shafts and needle bearings.

Can any of the worn parts be easily replaced, or do you need a machine shop to take care of worn parts?

Thanks,

Rich

http://www.antiqueautoarchive.com/folders/Restoration/kneeaction/kneeactionpdfcompressed.pdf

This site has some great Knee action rebuild info.

Merry Christmas to all!

Thanks, this is a very well written article. Now I have to decide if I want to tear into this myself or take the easy, but not cheap, way out.

Rich

Even sending the units to Apple Hydraulic would still require a fair amount of work (like removing front fenders and removing the units), not to mention the shipping cost as these guys are heavy. You would still want to renew the king pins while the knees were off. I would try to enlist a buddy to help and take a copy of the article to a local machinist so they can better estimate machine work and if they want to do machine work. I have yet to do mine on my 38 coupe project. I did manage to find a nice tool to unscrew the spring top tension plugs and have the gasket set. When they dampen the bumps right, these knees do make for a very nice handling and riding old Chevy. At least this is how I remember mine when it was last in one piece many years ago. Converting the front end to a straight axle or hot rod suspension would (in my humble opinion) be a real shame.

It is not necessary to remove the front fenders to remove the knees. The two major parts to remove would be the king pins and radius arms, both of which are usually also worn out. These parts should be replaced also.
I still don't understand what the dampenining means.....The front suspension will be softer tha any present day cars. If the bumper bounce test is done it will be possible to bounce the car quite frrely. The test is how long it continues to bounce after you stop appling pressure. Should level off after the last "push"...The real test is when driving, the front end will bob up and down when coming to a fast stop when the shocks are not working.....The shocks are only a small part of the knee action units and can be inspected by removing the two round cups on the front of the knees. Be careful when removing as they are SPRING LOADED....There are the shock pistons and valves under the round covers. They are the parts that offer the resistance or dampening, not the spring inside the unit. If the knees do not leak when filled they probably do not require rebuilding. The other problem would be their being very stiff (no wheel travel) which could be caused by stuck shock pistons or a stuck coil spring guide. If this were the case most likly one side would be stuck (stiff) and the other side normal.

Gene,

It is quite likely that my expectations are way off. I am thinking this car should respond similar to a modern vehicle when you try to bounce it up and down. I am not all that far from being able to do a road test. Perhaps the best thing would be to just fill the shocks and see how it drives.

With a little luck, I can be on the road for testing in just a couple of months.

I really appreciate all the good advice I am getting on this site. I started to repair antique radios about 8 years and found a good local support group and a forum quite like this one where some very smart people have provided many hours of time teaching dummies like me how to do things that they were never trained to do.

Rich

Soon, I will be getting my shocks rebuilt. Chev's of the 40's does it as well as Apple Hydraulics. I do know that Chev's of the 40's does it locally and does not send it on to Apple Hydraulics.

Cost is about the same, shipping to Apple would be a little more for me, but I was wondering if anyone has any experience with either of these companies with this type of rebuild.

Thanks,

Rich

Have you checked the Mr. Goodwrench Forum on Tech Talk on this site? There is a site identified there as having info on knee action work. Beamer

Yes, I have checked this site. I have read the instructions on rebuilding the units. I am very tempted to try to rebuild them myself, but I don't want to screw it up.

In the rebuilding instructions, I don't really see where the "shock" itself it repaired. Needle bearings are replaced with a bushing and a bunch of seals are replaced, but I don't see how the shock is returned to function. Since mine is a '37, it appears that the needle bearings are already replaced by a bushing. That should make rebuilding easier.

Rich

If your 1937 knees were never rebuilt it will have rollers. If it has aftermarket rebuilts it will have busings. If it does they probably don't need rebuilding. If leaking around the big arms probably just seals. Most will leak when wheels are raised off the ground and hanging down.There isn't much to rebuild as far as the shocks go. There is the large shock pistons (two, an upper and lower in each unit) and some times the pistons get rusted in place. This will make the front end very stiff. The only other part of the shock area is the valve and I have never seen one give trouble. If the shocks are not working the front end will hit a bump and keep bouncing. Or if you bounce the car from the bumper it will keep bouncing rather than make one dip and then stop. Will be much easier to bounce than a modern car. If all is OK and you want a firmer ride a heavier fluid can be used.If they are working and the unit is at least 3/4 full of fluid this will not happen.(the continued bouncing)

Gene,

You sure are right about the increased leaking when the car is up on jacks. I have that situtation now. I have no idea if they have been rebuilt or not. However, there is NO dampening action at all. The left shock was dry when I got the car. I filled it with ATF and there was no difference at all in the action. The right shock did have fluid, but no dampening action. Since the front end is not stiff, and filling them with fluid did not make any dampening action, should I remove the two pistons on the front of the shock to see if something obvious is wrong?

Thanks,

Rich

Yes, remove the shock covers and inspect. You will probably find that the shock pistons are siezed. Don't mix the shock valves between upper and lower.....and use caution when removing the covers. There are heavy springs behind them and the cover will come off with great force when bolts are removed. I would recommend do this with the weight on the suspension so every thing is centered.

Gene,

Well, I got brave this afternoon and removed the shock covers on the left side of the car. They were not too difficuilt to remove, but the bolt heads on the lower unit were eroded away. I could just barely get vice grips on the bolt heads. A wrench would not do it at all. While the pistons have a light "stain" on the sides, they both seemed to move freely enough. This tells me that perhaps my ATF was too light a fluid.

I can now see how the fluid was forced back and forth the small valves. I am going to clean all the parts and put it back together for now.

Rich

Well, I did reassemble the shock I took apart. I filled it with 30 weight motor oil, and believe it or not, it seems to be working. I can still bounce the bumper, but as soon as I release it, it stops with just one more partial bounce. I drove it around the neighborhood this morning and hit some dips, and the response was acceptable.

Rich

Sounds as if your on the right track...did the fitting arrive?
Do you think the piston was stuck in the bore and removing the cover freeded it up?

Gene,

Yes, the fitting arrived and I have it installed. Thanks for that and for the article on my car. I appreciate it. I also got your application form for the VCCA. I will use it and you will get the credit for me joining.


When I reassembled the front shock, I also managed to install a rubber "O" ring on the main shaft. I did this without disassembly. In my radio repair hobby, sometimes I use large "O" rings to replace belts that were used to drive the tuning capacitor. I have found that you can use a razor blade to cut them in half and glue them back together with super glue. The "O" rings will have a much tougher test on the car than on a radio, but I looked this morning and after about 18 hours, I don't have any sign of a leak (I did both sides.) As to the piston being stuck, I don't think so. It moved very freely in the cylinder. I really think that the ATF fluid I used was just too thin. I am temped to drain a little oil back out and put in a little gear lube just to thicken it up some more. I am also looking at this as a short term solution. The shocks will have to be rebuilt sometime in the not too distant future, but at least I don't have to spend that chunk of cash right away.

Rich

I think this was my first posting on this site. Anyway, I have finally ordered the rebuilt shocks for my car, they will arrive next week.

I have a one-page part of the Chevrolet Service Topics on Servicing Knee-Action Units 1934-1938. In this they mention a "special wrench" used to remove the steering arm nut and then driving out the steering arm with a brass drift. Is a "special wrench" necessary and could an oak dowel be used to drive out the arm? Other than this minor item, this all looks pretty simple. I also have NOS king pins to install at the same time as the shocks.

If anyone has any words of wisdom or tips on the process, I would like to hear them.

Thanks,

Rich

when installing the king pins pay close attention to the locaion of the thrust bearing . get your book out . hope this helps

Rich,
I sent you an email with a photo of the 'special' wrench. It's a large open-end wrench that fits on the gland nut; I don't recall the size at the moment. As I recall I used either a very large adjustable wrench or a plumbers wrench to get mine off.

Be sure to find and loosen the small set screw that is on the nut before attempting to back off the nut! If you have a difficult time getting this off use a little penetrating oil or heat to coax it off. If you are rebuilding the units take the top cover off as well, again using pen. fluid and/or heat and a large wrench.

Hope this helps.

I am taking the easy (but not cheap) way out here. I have purchased rebuilt units from Apple Hydraulics. This way, I don't have much to do except remove and replace the unit. The photo that Coach Hill sent to me is to remove the arm that supports the front wheel. I won't have to do this. The "special wrench" is mentioned only on the removal of the steering arm. I was under the car last night looking at the nut that has to be removed and while access does not appear too good, it looks a socket should be able to get it off. Unless there is something that I won't be able to see until I get into the process.

Rich

My bad...haste makes waste. I am not aware of a special wrench for removing the steering arm.

I'm nearing the end of rebuilding a pair of Dubonnet shocks from my '37 Sports Coupe. I wouldn't spend the $1100.00 to have them rebuilt and I'm glad I didn't !! I got rid of the packing and reworked the cross shaft bore to accept a more modern lip seal. So far they've been sitting for two weeks without a drip, so I guess they should be OK. Once I'm done with the project, I plan on writing a tech article for the board. Not a difficult job at all, but since I retired, there doesn't seem to be enough time to get things done anymore....wonder why that is ?? :confused:

I digress, however - the real reason for this post is to let anyone that's interested know that the steering arm nut takes a standard 1-1/4" socket to remove. Access is easy after the spindle arm has been stiripped of the the tire / rim, brakes & backing plate off of it, cotter pin from the nut and the arm is hanging down.

SHOCKS

This and numerous other technical INFO is located in the TECH TALK in this forum.

OK......guess I won't bother.

Bowtie Bob,
No matter how much is written about anything, fresh information on anything by someone who has hands on experience I think will always be welcomed. We can then hash it over.
:) :vcca:

Well, I got my rebuilt shocks and new king pins installed today. It was not as big a job as I was thinking. The part that took the longest was that I cleaned and painted the front end parts. Chiseling off 70 years of petrified oil encrusted dirt was quite a chore.

The entire process was quite straight forward and there were no stumbling blocks. I haven't driven the car yet, I need my wife to assist with bleeding the brakes, but I don't anticipate any issues.

I guess that I will need a front end alignment now, but as far as I can see, about all that can be done is to adjust the toe-in. Is that correct?

Rich

The caster and camber can be set at a good alignment shop as well.

:) :grin:

How are the other adjustments made? Everything looks solid steel with no way to make adjustments.

Rich

Check with an alignment shop and they will give you the details. Solid axles can be set up for the correct caster and camber.

:) :grin:

I looked in my service manual. It looks like it takes special equipment. I will check with my local alignment shop and see if this is something that they can do. I suspect that if they cannot do it they will know a shop that can do it.

Thanks,

RIch

Yep, it does take special equipment, but a quality alignment shop can do the job with no problem.

:) :grin:

I redid my 41's front end 3 years ago and worried about getting the alignment right or at least close. I redid everything and after checking things out at an alignment shop everything was ok with just a few minor adjustments. I accomplished this by taking measurements of everything possible before taking things apart, from the length of the tie rods to using a micrometer on all the bushings that are adjustable. I highly recommend that this approach be tried. Even the best alignment shops don't see many old cars and need the car's manual and your help. Mechanics used to computerized alignment equipment just scratch their heads when they see our old toys. Yes, the car handles well, but is nothing like my 77 Impala that you just point in a direction and it runs straight as an arrow. Thanks, Mike