Broken Seat Springs - A Better Fix
 

As part of a thorough check & repair of the few nuisance items found in a recently acquired 1982 W126 300SD, I used a different method of repairing broken seat springs in the driver's seat.

Instead of using tie-wire or safety wire as described elsewhere, I used cable clamps like those intended for use with flexible steel cable. The threaded U-bolt that pulls a grooved casting towards the bottom of the U works very well to hold the inserted broken ends of the spring wire.

If the break to be repaired is near a 90 degree turn in the spring wire, it is possible to realign the ends by a fair amount to make them closer to parallel, to better align them to fit into and through the clamp. Use the closed end of a box-end wrench (13mm) held tightly in a locking-type pliers to slip over the broken end and twist the wire to realign; the spring wire can bent even though it has some carbon in it to produce stiffness.

Tighten the nuts well on the U-bolt, using lockwashers or liquid thread-locking compound.

Remove the seat from the floor of the car as described in other threads here, but do not remove the Phillips head screws found inside the ends of the seat rails, in an attempt to remove just the seat box itself. Take the entire seat out after removing only the five 10mm bolts and place it upside down on a padded surface.

That sounds well and good, but without pics it just doesn't do a whole lot....;)

To repair mine, I just molded some JB Weld around the break in the spring. Worked great.

I used steel brake line for springs,and used swimming pool noodles for worn out horse hair.

On this note when the seat is fully assembled how much pressure should the springs be under?

i used injector line anti vibration clips. You clamp them down on the springs, then you weld the hell out of it

I'm going to try the fake Harbor Freight version of JB Weld, and factory MB "pool noodles" to fix my seat this week. :)

He used one of these:

With all these fixes floating around, they may be well and good. and may last for a while.

Just as easy to pick up a good seat bottom at PNP. usually the passenger
side box frame is tight. it will fit on the drivers side.

It seems from what I have read, the 126 and 123 seat bottoms fit either
car.

I just went through this last year with 2 broken springs. now iam good to
go another 200,000 MI plus.

Charlie

Gene Horr:

With the seat assembled and ready to go back into the car, I'm not sure how to estimate how much pressure should exist against the padded seat surface... My preference is to have a rather firm cushion to sit on... when my fix on three broken springs was done, I could still move the spring wire with moderate pressure using only the thumb and first finger - I'm sure that the springs are not to be so tight as to require two hands to move them. I was very satisfied with the results of my fix as the seat still has some "give" and I'd suspect that it's again close to its original condition.

Richard Howard

I appreciate the info. The original leather has just about disintegrated. Interior replacement is not on the list for several months unless I can find a used set in good condition. I am using generic covers in the meantime and was going to use elastic strips to provide pressure on the springs but didn't know how much to apply. Sounds like 3-5 #/spring should be in the ballpark.

Take care.