My inexpensive w123 spring compressor
 

I recently did a front end job and I had to r&r the springs. I'm always interested in expanding my tool collection, and I'm really into making things myself.

It's a 3/4" threaded rod with acme threads (the thick flat threads you see on tools), with one nut welded to one end, and one free nut. Two 3/4" washers. The plates are actually spring perches from a w126. I knew these would work because taking the load of a Mercedes spring is what they're made for!

I cut the edge off of the perches so they could be inserted between loops. I made sure that I retained the part of the perch that dips down, so the plate would end up as helical as possible. Then I used a dremel to cut a 3/4" hole in the middle of the perches (it was the only method available at the time and I was pressed for time).

It worked beautifully. The total cost was about $40. I scored the nuts on ebay for about $15 (these nuts are really expensive so that was a deal). I got the rod from grainger for about $17, picked it up at the store. I had the washers already. The spring perches were a few bucks each from Pick n Pull. I wish I bought w123 perches, because apparently w126 springs are wider! Even with the perches being larger than my springs, it still worked. If I had w123 perches, I wouldn't have had to cut off as much material (for clearing the frame rail).

So now you can have a cheap sturdy spring compressor. The only catch is the welded nut - if you don't have a welder (most people don't) just take it to a muffler shop and they'll do it for $5-10. I used to do that, then I just invested in a little welder.

What's the strength rating on the nuts and the bolts?

Good question. Either way, i like the ingenuity and knight try to go this route when I'm ready to lower my wagon 8-)

The spring perch is the plate that is bolted to the lower control arm?

The plate is a full round piece, cutting off one side seems like it would take away some of its strength.

Some of the force of the spring is pushing on the lower control arm, not on the total plate. How much force is excerted on the plates as the spring is being compressed? now 2 pieces of sheet metal are containing the spring.

When in it`s mounting, one end is contained in the upper cup area, and the lower end is sitting on this sheet metal perch. far less force in this state than when it is compressed.

I also wonder about the strength of the threaded rod threads and the nuts.

You were definately thinking out side the box, I commend you on making your own tools. I have the after market Klann clone spring compressor I picked up on CL, brand new, for $75.00. even that one makes me nervous when the spring compressed.

Charlie

... hmm

The use of the Lower Spring plates is clever!

A longer Nut can be had by using a Rod Coupling Nut used with regular threads and size of the Threaded Rod and Nut could easily be increased if someone is worried about that.
The regular Hardwar stores do not sell them in my area but you can get Grade 5 rod coupling Nuts; that is about 8.8 metric grade.

I had a former job that we used Acme threaded items in the fabrication of the product we manufactured. Standard threads would not work for high load linear applications. You will find that all screw jacks, bottle jacks (the adjustable portion on top) and other types of machines use Acme threads. I have no doubt that this home made spring compressor is safe for it's intended use. If it were made with home center threaded rod, I would holding my computer at arms length for fear of getting hit by the spring!

I was with you right up until I read you welded the nut onto the threaded rod... now you have altered the strength of the bolt.
also, the plate to washer fitment is iffy... ANNND the plate itself gets it's strength from the metal around it, so mounting from the center is weak and prone to pull out...putting a steel plate 1/4" thick behind the entire mount would strengthen it, but it would then be too thick to fit between the coils...

I'd recommend wearing a full-face motorcycle helmet while that system is in use...

:stuart:

...and full leathers with armor plating and the like. I love DIY ingenuity, but...this is sketch

Homemade Spring Compressor
http://www.peachparts.com/shopforum/tech-help/134474-homemade-spring-compressor.html#post987680

Below is a pic of mine that pulls the Spring upwards into the Spring Perch. You need to use a Crow Foot and a bunch of extensions to turn the Nut as there is no room under the Hood for a combination Wrench.

You can also decompress the Spring and remove it but it is a lot of cranking.

The spring perches are not just flat sheet metal. The curved side profile adds a lot of strength to them versus if they were flat. And yes, these are the parts that are attached to the LCA, and hold the bottom end of the spring in the car.

The washers I'm using are very thick and broad. A larger thicker washer could be used if you're really worried about it, but what I used worked well.

I do wear face protection when using any spring compressor, especially one that's never been tested before!

The tool did not deform or bend in any place, even when fully compressed. I once used a harbor freight macpherson strut spring compressor on a small 120 lb/in coilover spring, and it started to deform when approaching full compression, so I knew to watch out. The tool I made held up well.

To really test it, when I was doing the 2nd spring, I decided to compress it as much as I could. The nut started to become too hard to turn, and the spring was more compressed than in the pic above but still not compressed all the way. I left it like that over night. The tool didn't deform or anything.

I forgot to mention - I clean and oil the threads every time I use it. Oiling the washers helps a lot too.


Diesel911 - that's a cool tool too. So the piece of stock goes at the lower end of the spring, and the larger washer at the other end jams against the body in the engine bay? That's a nice trick - just leave the spring in the car while you do the work. In my case I was cutting a little bit off my springs so I had to take them out. My only suggestion would be to add a little lip at the edges of the bar stock.

The tensile strength of the rod is 60,000 lbs. My springs are the p/n 41 which has a stiffness 310 lb/in. I didn't measure how much I compressed them, but I'd guess around 5 inches from their full length (which is like 17.7"). Even if they were compressed by an absurd 10 inches, that's still only 3100 lb of force on the threaded rod.

Certainly the rod/nuts are not the weak part of the tool. The perches would probably yield first, and they worked perfectly. I mean, they're designed by MB, who (used to) over-engineer things, to hold the springs. :)

Hello Admiral,

This is great, thankyou for sharing your creativity. Can I ask, how did you cut the plate?

Regards

Peter<><

On the Bar Stock I just made it so that it is one inch longer on each side than it is needed; that way there is no way it can slip out. You cannot tell but the Bar Stock has an oval hole in the center so that it can tilt a little.

I think I got the idea from one of our Members who also did the same.
But, evidentaly Mercedes also had a Tool that did the same and it shows up in some of the Manuals.

The big dissadvantage of the Tool is that you cannot close your Hood; or of you forget it is there you could dent your Hood.
You can also only do one side at a time.
At the time I was desparate to make something that would work.

Later I made the Hooked Tool in the right picture so that it could be used on something else besides a Mercedes.

Peterac, I cut the plates using an angle grinder with a cut-off wheel.

Diesel911, on that hooked tool, how thick is that rod? Looks like 1 inch. I've seen a similar tool with thinner rods used on a Benz and they bent like wet noodles. Yours looks beefy! I have a heavy duty macpherson strut spring compressor which I use on all my other cars. It is really robust but the hooks are a bit too thick to fit between the coils of the Benz springs.

Admiral,

Thanks for the reply I will be making one!

What are your thoughts about the welding of the nut and strength of the rod?

Peter<><

I didn't worry about it at the time, but I guess the heat could reduce the tensile strength at that location. The alternative is to jam 2 nuts together. Maybe if you use a long nut, and just put 2 spot welds on the end, then the part of the rod that will be (slightly) weakened will be the part not doing any work.

Good point, I was thinking along the same lines.

Very much appreciate you design and sharing!

All the best

Peter<><

The threaded Rod used on both of my Tools is 1 inch, and I don't think the Rod is garde 5 due to the fact it did not cost much.

I made the Hooks on mine and it took some time to fit them to the Mercedes.

I had an issue with My Lower Control Arm Bushings. I actually managed to safely pull off the Springs with the Cheapie Harbor Freight Spring Compressors.

But, the Bores inside of my Lower Control Arms had thick scaley Rust in them and when cleand out they were enlarged. But, I had to get the Car on the Road and I installed the Bushings anyway.

After That I got some used Lower Control Arms and had to do the job over again. That next time I bent up the Harbor Freight cheapie Spring Compressors.
I replaced the threaded Rods on the with Thicker Rods and they still Bent.
After that I made that Tool that pulls the spring up into the Spring Perch.

D911, I don't see any threads in the rod. Is that an optical illusion? Trying to figure out how it works. :confused:


http://www.peachparts.com/shopforum/...r-mine-aug.jpg

I was thinking the same thing. The threads look very fine if they are there.

This just came to mind. A source of Acme threaded rods may come from house jacks (for jacking sagging basement joists).

McMaster-Carr has Acme rod and nuts in a variety of sizes and materials.

Yes, the threads are 1"x14 threads per inch and the threads may still have some grease in them.
I had thar Rod left over from another project.

When I did the hooked Spring Compressor I used the same 1"x14 threads per inch rod.

The end of it turned down and smooth so it will center into the Nut Bottom Nut. The Nut is not attached to the Plate.

If you search- ACME threaded Rod some also shows up on eBay.

Some also showed up when I searched Amazon.

Just as a reference point, I bought my 3-foot acme threaded rod from Grainger for $17, and I still have 2 feet left.

Here's an important note!
The 3/4" nuts used with this tool are used with a 1-1/4" wrench. My 1-1/4" socket BARELY fit through the hole in the engine bay. So if you want to use something larger, beware, your socket won't fit!

The idea is to use a socket wrench from above through this hole for the welded nut, and then use an open end wrench through the spring coils on the free nut at the bottom.

Closer to home, how about the threaded rod inside the factory jack?

the factory jack has a pretty thin threaded rod. I'd not think it could handle the expansive forces...

Factory jack! Great idea!

Vstech, the acme thread in the jack is designed to lift one corner of the car but not strong enough to compress the spring?

slightly different forces there, compression vs expansion, also, the spring is designed to support the car through bumps and cornering... the jack only has to lift it in a stable state... and it often tips over.
if the rod is the same structure and width as the spring compressor rod, I'd agree it's capable of the job, but keep in mind, the spring compressors have a steel sleeve with locks on it for if or when the rod breaks...

Guys, you can get the rod at Grainger for less than 20 bucks... if nothing else, then it's worth it to not dissect a good jack. No?

I paid $10 for the same Mercedes Jack that came with the Car at the Junk Yard and apparently a lot of people onwn Parts Cars so it might be Cost effective.

I have no plans to disect any of my Jacks.

Despite the fact that the Car hangs on the threads of the Stock Jack I would prefer a thicker piece of threaded Rod; unless the Rod is thicker tan I remember.

My 82 Volvo also uses a similar Jack.

Admiral, I have to ask, how did you cut the spring seats out if you didn't have a spring compressor in the first place?

The $64,000 Question
 

The $64,000 question (Drum Roll) and the Envelope please..........:D



Charlie

I can offer my experience with removing the spring without a compressor, but it may not be how the OP obtained the spring seats he used. I was scrapping a car (123 front and rear damage), and needed the front end parts. I just did it "junk yard" style, and took everything off that was keeping the spring from extending (shocks, upper ball joint etc). I then took a big pry bar and pried the spring out of it's resting place. Yes it did fly a couple feet away, but I knew it would happen. I just made sure I was out of the path of it. It was not as big of a deal as I thought it was going to be, as the spring was almost fully extended (LCA at about 45 degree angle).

Whether or not it's how the Admiral did it isn't relevant to me. I want to know how I can do it! Good info!

Putting the car on jack stands and using a jack under the LCA will allow the removal of the upper BJ, and the shock. Lower the jack, and pry the spring out. It's just that easy. Be safe though. You could also run a length of wire rope through the spring and around the crossmember and clamp the ends with a cable clamp. That would keep the spring from flying across the yard. You could also place some sort of pillow and/or blanket inside a trash can that would catch the spring.
I needed the parts to rebuild, so I could just install new parts (new BJ's and LCA bushings) in them for the 123 front end I was rebuilding. That way there was not much down time on the car.

Could it really be that easy to get the springs out? What about getting them back in? I am intrigued by this idea as I am about to do ball joints and control arm bushings.

Easy to get them out without a spring compressor, IMPOSSIBLE to put them in without a spring compressor.
Check out:
http://www.peachparts.com/shopforum/diesel-discussion/332997-123-suspension-front-end-rebuild.html