what makes shocks non rebuildable?
- Thread starter tim54889
- Start date
1930artdeco
Well-known member
If you are referring to the original shocks they are rebuildable. You just need some specialized tools to do it.
Mike
Mike
Kurt in NJ
Well-known member
Labor cost, machinery investment cost
To have proper poeration all the clearances need to be good ---there are so many complex machining operations involved that it is easier to start making new parts using the same machines ----I don't see how the 70$ rebuilt shock can be returned to original tolerances on all surfaces ---not even working for burger flipping wages let alone the machinery investment, about all that price can do is bush the shaft so it is tight, but most won't have the opriginal adjustable 60/40 action
To have proper poeration all the clearances need to be good ---there are so many complex machining operations involved that it is easier to start making new parts using the same machines ----I don't see how the 70$ rebuilt shock can be returned to original tolerances on all surfaces ---not even working for burger flipping wages let alone the machinery investment, about all that price can do is bush the shaft so it is tight, but most won't have the opriginal adjustable 60/40 action
Bill Underwood
Senior Member
There are 13 wear surfaces each tolerance dependent on the others
Plus the are more precise than one would think
Plus the are more precise than one would think
Kevin in NJ
Well-known member
Shocks are a tricky little device. Soo Simple, but very complex.
The shocks were made doing a bunch of operations on a jig keeping a center. It never left the jig and all reference to center was precisely maintained. So a big vane could be setup in a machined chamber with .001" or better accuracy. This included screwing a cover on and keeping tight tolerances top to bottom.
The problem today is getting the shock back to the original tolerance.
What I found was that one with just a very small amount of wear would have significantly less shock absorbing ability then the one at factory tolerance. I was quite surprised at how tight a shock needs to be to work.
Then there is the knowledge of what it means to be a good working shock. You need to look at the KRW Tester and realize how slow a fairly heavy weight is allowed to fall to be considered a pass. I have a feeling that many shocks are not even close to factory in their function. Quite frankly, until recently I would have considered a lot of shocks as being good. When I tried my close guess to the factory tool I found the shocks were not even close.
So in summation:
It is far from trivial to do a decent job rebuilding shocks.
Quite frankly, it will be very expensive to make a non-rusty but slightly worn shock good. It would be even more expensive (in labor) to get them back to factory.
You need to take a close look at the KRW Tester and realize what it means to be back to factory standard.
The shocks were made doing a bunch of operations on a jig keeping a center. It never left the jig and all reference to center was precisely maintained. So a big vane could be setup in a machined chamber with .001" or better accuracy. This included screwing a cover on and keeping tight tolerances top to bottom.
The problem today is getting the shock back to the original tolerance.
What I found was that one with just a very small amount of wear would have significantly less shock absorbing ability then the one at factory tolerance. I was quite surprised at how tight a shock needs to be to work.
Then there is the knowledge of what it means to be a good working shock. You need to look at the KRW Tester and realize how slow a fairly heavy weight is allowed to fall to be considered a pass. I have a feeling that many shocks are not even close to factory in their function. Quite frankly, until recently I would have considered a lot of shocks as being good. When I tried my close guess to the factory tool I found the shocks were not even close.
So in summation:
It is far from trivial to do a decent job rebuilding shocks.
Quite frankly, it will be very expensive to make a non-rusty but slightly worn shock good. It would be even more expensive (in labor) to get them back to factory.
You need to take a close look at the KRW Tester and realize what it means to be back to factory standard.
Kevin in NJ
Well-known member
Some guys are doing things with the somewhat worn shocks to make them better. They are willing to pay for good cores. Even better is you can pack a lot in a USPS one rate box. So you might consider selling them.
Also, you can tell shocks that have a chance on working at flea markets. I would practice taking a few not so good shock apart if you are considering going that route.
Also, you can tell shocks that have a chance on working at flea markets. I would practice taking a few not so good shock apart if you are considering going that route.
BRENT in 10-uh-C
Well-known member
Answer this question below....
Kevin in NJ
Well-known member
Instructions for the KRW tools are in the Service Bulletins.
More details on the actual tool were posted here a while ago.
Brent, to get the divider out is easy. Just cut the case around it.
The devil is always in the details. I have not tried, they can clearly be a nightmare to take out nice.
Previous shock discussion Shocks
More details on the actual tool were posted here a while ago.
Brent, to get the divider out is easy. Just cut the case around it.
The devil is always in the details. I have not tried, they can clearly be a nightmare to take out nice.
Previous shock discussion Shocks
Bruce Lancaster
Member Emeritus
I think the central problem is that once the central axis wears, everything else can move far enough to contact the opposing metal surface. Once the moving vanes or pie slices start wearing, fluid can bypass more and more weakening the shock action...and once there is enough wear at center for the fluid to exit, wear accelerates and all pretense of damping disappears.
If the fluid loss happened in 1935, and the car was driven that way until 1952, there isn't going to be much left in there.
Restoring the center leaves everything else with too much clearance to pass the KRW test, and restoring the missing metal would have to be done by welding, machining, and somehow achieving the original level of tolerance while doing it.
Note the last part of the original rebuild instructions after all has been cleaned and reassembled...test the thing with the KRW weight, discard the shock if it fails!
I wonder how many passed, even a few years after they were built.
If the fluid loss happened in 1935, and the car was driven that way until 1952, there isn't going to be much left in there.
Restoring the center leaves everything else with too much clearance to pass the KRW test, and restoring the missing metal would have to be done by welding, machining, and somehow achieving the original level of tolerance while doing it.
Note the last part of the original rebuild instructions after all has been cleaned and reassembled...test the thing with the KRW weight, discard the shock if it fails!
I wonder how many passed, even a few years after they were built.
Kevin in NJ
Well-known member
Central axis is not the real problem, but it is all connected.
The real problem is anything more then a small clearance (on the order of .001 or so) with the vane to the body and the oil can leak around the vane. This severely reduces the shock action of the vane.
The shock wears as a unit. The shaft is the easy thing to fix, kind of. If you can not close up the vane clearance to the body then you do not get the action you need. Yes, it will have some shock effect, but in terms of factory effect, no it will not be close.
I did some experimenting on shocks and found some basics. That is what I am basing my above comments on and now that I have more details about the KRW tester I plan to do more. I need to purchase some heavier oils to use as fluids and proper characterize what I state above. Not in much rush and I am busy making speedo rebuild tools and fixing stainless radiator shells.
The real problem is anything more then a small clearance (on the order of .001 or so) with the vane to the body and the oil can leak around the vane. This severely reduces the shock action of the vane.
The shock wears as a unit. The shaft is the easy thing to fix, kind of. If you can not close up the vane clearance to the body then you do not get the action you need. Yes, it will have some shock effect, but in terms of factory effect, no it will not be close.
I did some experimenting on shocks and found some basics. That is what I am basing my above comments on and now that I have more details about the KRW tester I plan to do more. I need to purchase some heavier oils to use as fluids and proper characterize what I state above. Not in much rush and I am busy making speedo rebuild tools and fixing stainless radiator shells.