coil spring compressor

[diesellieber]

I did a search on this subject and found a plethora of information including a thread that lead to numerous people signing up to a group buy for a special imported spring compressor that cost 700 bucks in quantity. I especially noted the many warnings about attempting to use non-Mercedes Benz intended compressors. Having a somewhat recalcitrant nature, I decided to come up with a way to compress my springs that didn't cost 700 bucks even though the suspension on my 77 300D is still working ok.

Here is what I did:

I found a piece of two and a half inch square tubing with 3/16ths wall thickness that is about 18 inches long and placed it inside the engine compartment directly over a hole leading to a coil spring. Then I attached a chain to a 10 ton pull back ram and dangled the chain and the piston of the ram all the way through the tubing to the bottom of the spring. I got the ram from Harbor Freight for about 50 bucks about a year ago. I've been trying to figure out a way to use it. Then I hammered a long half inch drive socket extension between the bottom spring coils.. through the last chain link... and out the other side. When I pumped up the ram, it compressed the spring, but not evenly. The spring kind of bulged out on one side as the chain went completely over to the edge of the spring. It worked ok but it bothered me, so I eased the tension off and dropped a couple of half inch threaded pipe couplings down inside the spring. Using one of those extendable magnets they sell at autozone, I was able to thread the socket extension through a pipe coupling, through the chain, through another pipe coupling, and then out the side. Now when I pump it up, the spring comes up evenly as the chain stays in the middle. I lifted the spring about a half an inch away from the control arm and left it there for a while.

I've done more than a few suspension rebuilds, and I've rented several different kinds of spring compressors. More than anything, I hate having my head and my hands that close to the spring as I am compressing it. I don't care what kind of compressor it is. It was nice to be standing in front of the car as I pumped this up. It was especially painless to let it down.

[diesellieber]

Here is a shot of that pull back ram

http://www.harborfreight.com/cpi/photos/33600-33699/33611.gif

[Cannoli]

Very creative ... thanks for sharing!

[Steve Gutman]

I just ordered one for $41.02 from thetoolwarehouse.net. I will let you know how that works.

[csnow]

Clever.

How did you attach the top hook on the ram to the 2 1/2 square tubing?

I would feel more comfortable with a more secure setup on the bottom end, but hey, can't argue much with success...

[diesellieber]

The top hook wasn't used. The square tubing was just big enough to let the piston hook in diagonally, and the piston fit in ok, but the larger tube of the ram rested against the tubing. I'll post a picture.

I agree that the bottom end seemed to move around a little, but I don't know if its worth the effort to make it more secure. The spring really can't go anywhere with a chain through the middle of it. I'll post a picture of that, too.

[diesellieber]

Here is the picture of my spring compressor in action:

[diesellieber]

And, here is the connection to the bottom of the spring using a half inch socket extension:

[diesellieber]

And finally, here is how the spring looks compressed:



It's a bit hard to see, but the spring is not touching the control arm any more. You can see how the spring is flexing a little because of uneven pull on the sides of the coil, but don't worry --- It's not going any where. It has pulled a little off center from the spring perch, but it went right back as soon as I released the pressure. Once it hung up a little on the edge so I helped it with a crowbar. The trick is to let it touch but keep most of the pressure on the ram. It went right back into place with almost no effort. If I had the parts, I could have this whole thing apart in about ten minutes.

You can view this and more with your browser at http://www.ohran.com/richard/1977%20mercedes%20300D/index.htm

[csnow]

Nice pics.
I SEE what you mean. Pictured something else in my mind...

[diesellieber]

csnow,

By email to me, Jim Harris, who has a 300D, has pointed out that a more secure connection to the spring could be made by doubling the chain and arranging the two sections of chain to ride on the socket extension at the outside close to the coils by placing spacers made of pipe couplings in the center. This would significantly reduce the strain on the socket extension and make it less likely to fail.

[Honus]

Well done. The part that worries me is how secure this arrangement will be when it comes time to manipulate the spring back into place. I would be nice to have some positive way to prevent the extension from slipping out the back of the spring. Does that make sense?

[csnow]

Had not actually thought about the shear strength of the extension itself. I imagine they very in strength.
I must say I have never once seen a 1/2 extension break, even cheap ones under massive twisting torque.

I could imagine a safer setup using, say, 3 locking 'quick-links' going right around the coil, each attached to a short length of chain going back to a hook or shackle on the 'main' chain. Both the links and the chain would have a known rated capacity. Coil would be truly captive regardless of any imaginable manipulation.

..or a heavy plate with a serious loop welded onto it.

Just some ideas. The likelyhood of your setup slipping is probably quite small, but I am paranoid about such things.