VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1937-1945 Is anyone driving a car with DuBonnet Shocks?

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