lever shock questions

'51 Special

Active Member
Well, now that my 51 Special is back on the road after many years, it is plain that the shocks are a bit sloppy, and the fluid levels are low or very low. The manual says to fill with "only G. M. or Delco Shock Absorber Fluid." These products are no longer made. I recall someone once mentioning "jack oil" (which I assume is the product used to fill hydraulic jacks), but I'm not sure what is the best substitute for "G. M. or Delco Shock Absorber Fluid." Any suggestions? Thanks for your thoughts.
'51 Special
 

suntreemcanic

Active Member
Jack oil and shock absorber oil both have anti-foaming additives. So just experiment with anti-foaming oils of different weights till you get the ride you are after. All oil designed for hydraulic systems has anti-foaming agents, transmission fluid and rear differential grease. Just experiment with different weights. I gave up those old style shocks and went to tube shocks. Best modification I ever made.
 

'51 Special

Active Member
Jack oil and shock absorber oil both have anti-foaming additives. So just experiment with anti-foaming oils of different weights till you get the ride you are after. All oil designed for hydraulic systems has anti-foaming agents, transmission fluid and rear differential grease. Just experiment with different weights. I gave up those old style shocks and went to tube shocks. Best modification I ever made.

Long-

Thanks for your thoughts. I just did a quick and dirty viscosity test (drops of different oils on a metal sheet, tilt the sheet, see which drops moved the quickest and farthest), and conclude that the jack oil I have is of considerably lower viscosity than the existing oil in the shocks, Dextron type ATF is of somewhat greater viscosity than the jack oil but still less viscose that the existing shock oil, and 90 wt. gear lube is considerably more viscose than any of the other oils. Do I understand correctly that the gear lube should provide the (desired) greater damping effect? Do you see any danger that the gear lube is so viscose that it would actually prevent the shocks from functioning, blow gaskets, or otherwise cause problems?

Also, I would be very interested in the approach you took in converting to tube shocks. Like what fabrication was necessary, how you selected shocks, whether or not (and how) you disabled or replaced the original front shocks. I suspect there are others with the same questions. Would you be willing to provide that information?

'51 Special
 

'51 Special

Active Member
Well, I went with the 80-90 wt gear oil. Both front shocks were so low on fluid they might as well have been empty, one rear was very low, and one (which obviously has been leaking) was near to spec. I followed the manual directions for filling them, except (lacking the "Shock Absorber Gun KMO 1026" and "Adapter J 1611") I used an old thumb-action oil can to fill the rears. Also, I found that a 1.5" drywall screw dropped in the filler opening is a quick way to gauge the fluid level in the rears. The bounciness went away, and it feels much less like driving a boat. The ride maybe a bit more harsh than I had anticipated, but, all in all, a big improvement.
'51 Special
 

suntreemcanic

Active Member
'51 Special, If you do a search for "Front Tube Shock Installation" I submitted pictures and a description of my conversion in May of 2011.
 

firstofeight

Active Member
shocks

suntree, I have read your conversion pictorial. May have to use it. I had my shocks rebuilt but after about four years, one leaks badly. I will try to install a new seal. If that does not work, on to your way.

Did you do the back ones as well?

Thanks
Ben
 

RandyR88

Member
I have owned a '51 Special since 1973. My front shocks were basically not offering any resistance and I eventually put 30 weight motor oil in them. They worked for a while and it leaked out, so I will send them to be rebuilt (finally, after all these years!).
Point is: there are several vendors rebuilding these: Apple Hydraulics comes to mind; they are putting some kind of oil in them. There must be something available.
I remember reading once that the GM Shock Fluid was later sold as Morey's Engine Oil Stabilizer. Does not help as I can't find this either.
 

suntreemcanic

Active Member
suntree, I have read your conversion pictorial. May have to use it. I had my shocks rebuilt but after about four years, one leaks badly. I will try to install a new seal. If that does not work, on to your way.

Did you do the back ones as well?

Thanks
Ben


Yes I have tube shocks on the rear also.
 

'51 Special

Active Member
Well, as I started this thread six years ago, and received some useful thoughts, I decided to raise a further question (or idea). As some of you my know, about 9 years ago I bought a junkyard '50 Super to aid in my switch from the Dynaflow to a stick shift in my '51 Special. My deal with the yard was I could take anything I wanted from the Super while it sat in the yard. So, in addition to the 263 and its transmission (from it's radiator back to the driveshaft), I pulled odds and ends off of it. The rear shocks ended up in my garage, with the thought they might be useful. That time may have arrived. The rear shocks on the '51 Special, which I filled with jack oil, have leaked every since. To the point I slide sheets of cardboard under those shocks whenever I parked it inside.

So, I decided I should have the rears on the "51 rebuilt. That meant pricing out the job, and learning it would cost from $400 to $600, plus shipping my old shocks out in the hope they could be rebuilt. I conclulded that I could avoid having the '51 sit "shockless" by instead having the rear shocks salvaged off of the junkyard Super rebuilt. I dug them out of my garage to get some idea if they were likely rebuildable.

I first checked to see if they had gotten locked up while sitting. They had not. In fact, the levers moved (stiffly) through the entire designed range. Next, because they were covered both in rust and packed dirty oil, I checked to see if they were dry. They were not dry. They were full. And, because of the appearance of the screws on the cover, I then knew both shocks had been opened, and thus possibly serviced at some point in the past, and that they were not leaking. (There was greasy dirt all over the bottom of the junkyard Super, and the differential housing was as grimy as the shocks.)

This gets to my question: Should I just put the junkyard shocks on the '51, and see whether or not I still need any rear shocks to be rebuilt? Remember, its no show car, and I never wanted it to be otherwise. And I am disinclined to waste money.

Whatcha guys think?
 
I don't know why you would not. It is not a big job. The Super shock may be set up for a little heavier car, which most would feel would improve the ride!
Hope it works.
 
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