380SL Tension Rail Pin Removal
 

HELP! I'm into changing the upper slide rails and the tension rail. The slide rail pins were removed quite nicely with the 6mm bolt .and washer stack. When I removed the tension rail plug , I expected to find a simililar threaded pin. But no such thing! It is a hollow pin that is not threaded so how do you get it out? The maintenance manual says to use a screw driver> How does this work...there is nothing to unscrew or attach to, to extract the pin>. As usual thanks for any insight>

John Ewen

It's kind of tricky, although the people who wrote the manual didn't seem to think so. I used a hooked piece of very strong wire with only about 1/16" 90 degree bend at the end to hook the far end of the hollow cylindrical bearing and pull it. You need to wiggle the tensioner arm itself while doing this.

Putting it in is also a little tricky; I used a drill bit of very slightly smaller diameter to guide it in, also while wiggling the tensioner arm.

Thanks Strife. From what you are saying the pin is a slip fit and not pressed in like the guide rails. That's a good insight. Thanks

Well, it's a pretty close-tolerance sort of slip...

I tried a hooked home made tool that strife suggests with no luck. Mine was really varnished in there. Then I used a 3/8" tap and attempted to thread it into the pin. It caught by less than 1/2 thread. Once the tap grabed a little bit it started to rotate the pin and I was able to gently sort of pull on the tap while rotating.

John Roncallo

Okay... I tried the bent wire...couldn't dislodge the bushing.
I then made a tool with a small 1/16 tooth and that didn't work.
I then tried the .375 tap, it just didn't grab but it rotated the bushing.

So off I went to the hardware store a got a 5/16 o.d. expandable concrete stud about 3 inches long. It just fit in unexpanded and after i tightened it up snug.. I pulled and "viola" it came right out.

Now I have two very stubborn upper rail pins that are refusing to come out.....I "power blasted"(penetrating oil) them for the last three days and still can't budge them with the 6mm bolt and washer trick.... or with a makeshift impact hammer. What do you think about heating the the casing??

I had a few of those pins that were very stuck and came out with a real "pop". I bought screw-type tool that is sold for this purpose but even after spending $50 it took some fooling around with (stacking washers) on the 380 (116) because the shape of the head is different than on a 560 (117).

This WILL work, but be aware of the following:

1. Use a grade 8+ bolt, and lots of threads (thread all of the way possible). Stripping the pin or breaking it would be a disaster.

2. ALWAYS keep the bolt absolutely 90 degrees perpendicular to the head. I know that this is tricky because of the ledge but you gotta do it in your case by stacking the right number of washers/spacers. You do not want to bend (bad) or break (EXTREMELY bad) the bolt in the pin.

BTW the expandable sinker (?) is a great idea.

Thanks Strife.... I just got up from the garage .... after screwing, impacting, screwing, impacting...the two pins finally released. Now onto the intended job..to change the rails.

Thanks for the support.

Another trick you can try. if it absolutly have to, drill it out and tap 1/4" X 20 TPI. Then use a 1/4" bolt and washers, It so much stronger and you get more pull but you probably will need a angle drill. Do this before you break the normal one off inside the pin.

John Roncallo

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I have a pdf file with pictures and dimensions of a simple puller I used to drag out rail pins on a 380SL. They wouldn't move with a 2-lb slide hammer but pulled easily with this puller. Send me an email and I'll get you the pdf.earnest37@sbcglobal.net

Simple slide ramp pin puller.
 

I'm going to try and get this picture loaded but can't promise anything. I'm trying both a jpg and pdf. Good luck.:cool:

Here’s how I made mine.
1. Took a piece of mild steel ½ x 1 x 3¾ “ and center punched hole locations as shown in the drawing.
2. Drilled and tapped the two end holes 3/8-16 for two 3/8-16 x 1¾ hardened bolts.
3. Drilled 5/16” hole as shown for M6 bolt (if I recall correctly). As you can see in the picture the bolt was a little long for the job so I spaced it with washers.
4. Withdraw the 3/8” bolts until they are flush with the bottom of the steel plate.
5. Screw an M6 bolt into the pin at least 5 to 6 turns.
6. Tighten both 3/8” bolts until they make contact with the head, then tighten each about a half turn each alternating from one to the other until you feel the pin break loose.
When I got enough pressure to break the pins loose they sounded like a “crack” rather than a “pop”. Initially thought I might have broken something but it was just the pins breaking loose. I think whoever put those pins in to begin with must have used something like a thread locking liquid.
I had tried to break the pins loose with a 2-lb slide hammer with no success whatsoever. Hope this idea helps. I also think this is less stressful on the pins than a slide hammer anyway.

thanks ernest

I managed to remove the pins and completed the job in 2007. Good tool for future rail fixes.