Rear Spring Removal

[Mpgeslak]

I am planning on replacing the springs and shocks on my 250SL.  Have been reading all the content on removing rear springs and need some advice.

A number of posts quote the Haynes method of detaching the forward portion of the trailing arm to release the pressure on the springs.  However, several of those posts also quote the difficulty of re-attaching the arm without a special cone tool that is no longer available.

I have also read a number of posts where a spring compressor has been used, and given the issues mentioned above with re-attaching the trailing arm I think I would like to use this method (not too worried if it takes longer). My question is what type of spring compressor, is it one that fits on the outside of the springs, or is there a way to use a spring compressor that goes through the middle of the springs?

Any help and advice would be appreciated.

Michael

Any advice 

[jeffc280sl]

i detached the front bolt on the trailing arms to remove/replace my rear springs.  on reassembly i used come along straps to align the trailing arm bolt.  its a little tricky to do on your back on the garage floor but its doable

[Mike K]

Have a look at these posts I made a few years ago.
https://www.sl113.org/forums/index.php?topic=25073.msg179238#msg179238

Bushings- I made my own tool:
https://www.sl113.org/forums/index.php?topic=25173.msg180141#msg180141

https://www.sl113.org/forums/index.php?topic=26613.msg190415#msg190415

Spring removal & reinstallation:
Having done this job twice, once when I replaced the springs themselves and secondly when I replaced the trailing arm bushings- getting the springs back in is more of a challenge than getting them out.

Spring removal- drop the trailing arms by easing them down with a trolley jack and the springs will fall out.

My suggestion is to compress the springs prior to installation, secure them with webbing, position them and then once you have the trailing arms in place, you cut the webbing.
Have a look at this:
https://www.sl113.org/forums/index.php?topic=25262.msg180644#msg180644

I hope this helps.

Best,
Mike
 

[Mpgeslak]

Thanks Mike.

Question about the webbing, is there a reason you use it instead of a spring compressor on the outsides of the spring?

[Benz Dr.]

Not hard to do this job with a self made cone. Screw the cone on to the stud mount and then raise the trailing arm with rubber bushing installed. The cone will guide the trailing arm with installed rubber into place. Remove the cone and bolt the retaining plate into place.
I struggled a lot with this job until we made the alignment fixture. Absolute easiest way to do this job.

[Mike K]

Thanks Mike.

Question about the webbing, is there a reason you use it instead of a spring compressor on the outsides of the spring?

It's a really tight fit to get those rear springs back in. First time I really battled with the spring compressor attached.
I found that the 2nd time I did this without the spring compressor in the way, it was much easier  -Dr Benz's recommendation.

So I compressed the springs once they were off the car, secured them with the webbing straps, used masking tape to hold the rubbers
in place, (see pic below) positioned springs into place, raised the trailing arms and once everything was bolted & secured cut the webbing straps & removed them.

Far easier than trying to do this with the spring compressors attached.

[Mike K]

Not hard to do this job with a self made cone. Screw the cone on to the stud mount and then raise the trailing arm with rubber bushing installed. The cone will guide the trailing arm with installed rubber into place. Remove the cone and bolt the retaining plate into place.
I struggled a lot with this job until we made the alignment fixture. Absolute easiest way to do this job.

Absolutely right Dan.

Here's the link to how I made my own "cone" /centering tool (it's not really a cone, it's a shaft which helps guide/align the trailing arm into position)  and what you need:
https://www.sl113.org/forums/index.php?topic=25173.msg180141#msg180141
 
2 X 22mm deep drive sockets welded together and fit & weld an M14 x 1.5mm thread nut to the top, which screws into the stud mount on the underside of the chassis.
Image #1 below.

Very important: do not to use grease to help things slide into place.
Use either liquid soap or talcum powder. I used liq. soap.

Also note when jacking the trailing arms back into place, the position of the trolley jack is very important. Jack  should be positioned further back along the arm as it gives you more flexibility & movement.
I really struggled until I looked very carefully at the pic in the BBB.
See image #2 below.

Should've remembered my physics from university (which I failed dismally) something about "the moment along an arm".....

[Mpgeslak]

Thanks for all the responses, extremely helpful.

One question, how long does the Cone/Centering Tool need to be?  The tool described by welding Two deep sockets would seem to be about 6 inches, the tool in the photo from the workbook appears much shorter.

Thanks,

Michael

[jeffc280sl]

a little more detail about the trolly jack position.  i understand and agree with the point about about moving the jack to the rear closer to the axle.  if you move it forward the jack will want to slip forward along the underside of the trailing arm due to the angle increase caused by raising of the trailing arm to its final position.  i remember making sure the jack was wedged so it could not slip forward out of position and cause a very, very dangerous situation.  think this through please.  the trolly jack is on wheels

[Benz Dr.]

a little more detail about the trolly jack position.  i understand and agree with the point about about moving the jack to the rear closer to the axle.  if you move it forward the jack will want to slip forward along the underside of the trailing arm due to the angle increase caused by raising of the trailing arm to its final position.  i remember making sure the jack was wedged so it could not slip forward out of position and cause a very, very dangerous situation.  think this through please.  the trolly jack is on wheels

All good points - never take safety for granted.
The position shown from the workshop manual is about right. You may have to re-position your jack until you find the sweet spot. Sometimes the workshop manual holds important clues about how to do things and ways that make things easier. Aside from all of the factory tools you could get, some of their self made tool stuff is spot on.   

[johnk]

Took me all of about five minutes a side this way with no special tools just dish soap a junk pipe fitting and a jack. I just pulled it close by hand and then pushed it up in place with the jack.

[Benz Dr.]

Getting one side in isn't too bad but getting the other side becomes more difficult due to a bit of pre-load on the entire axle. The one good thing about using the screwed on cone is that it's a pretty safe way to do this job.

[Mike K]

Thanks for all the responses, extremely helpful.

One question, how long does the Cone/Centering Tool need to be?  The tool described by welding Two deep sockets would seem to be about 6 inches, the tool in the photo from the workbook appears much shorter.

Thanks,

Michael

Michael- I would say about 10 to 12cm (approx. 4 to 4 1/2 is the right length. It can't be too long or you'll struggle to get the end of the trailing arm aligned & through the centering tool.

Valid points re safety. Make sure you wedge the trolley jack wheels so they don't slip or slide.


Best,
Mike

[jeffc280sl]

i want to make clear that when i was speaking about a wedge to keep the trolly jack from slipping i was thinking about this location.  wedging the trolly jack wheels is another idea. u

[Mpgeslak]

Thanks to everyone for the information, incredibly helpful.

My plan is to make a centering tool and replace the springs using the approach of lowering the trailing arm this weekend.  Will report back on how it goes!

Michael

[jeffc280sl]

good luck,

good opportunity to replace bushings and spring pads

[Mpgeslak]

Update:

Made a tool following the basic approach Mike K suggested:  I used an extra deep 22m socket 5” in length; the depth for the nut is about an inch so I put some Epoxy Weld glue at the bottom on the ledge and the wall, dropped the nut in and placed weight on it until it set.  Worked perfectly using hand soap as suggested.

Replaced all four shocks and the back springs, spring pads and the trailing arm bushings.

Springs came out with no problem at all.  Two issues putting them back in:
1.  The bushing didn’t go perfectly over the “nub” the bolt comes out of and the bushing fits over.  No matter what I did it would go fully over the one side and be just not quite fully on on the other side.  I assumed that when I put the plate on and tightened the nut it would seat fully into position.
2.  Seems I have a bit of positive camber on the rear wheels.  I definitely had some positive camber before I did the work, but thought it would improve.

All in all, I think it went well.

Thanks for all the advice, it was a huge help.

[Mike K]

Michael - thanks for the feedback. Pleased it went well.  These things can get complicated some times.

From what I recall the bushings don't fit evenly, and yes once you bolt the plate back on they should sort themselves out.

Re positive camber: I stand to be corrected, however our cars are prone to an element of positive camber.
Have a look at this link:
https://www.sl113.org/forums/index.php?topic=4228.0
Download the 2 images in the first post, it should give you an idea.

If the camber's way out of spec you may need to replace the compensating spring & rubbers. I replaced that spring as well when I replaced springs & shocks. It's fairly straightforward to replace.

Best
Mike

[Cees Klumper]

You can also adjust the bottom plates that the rear springs sit in. I believe they have three positions. That straightened out my car's positive camber on the rear wheels, at least when the car is sitting at rest.

[Mpgeslak]

Thanks for the tips about the camber.  I think I have more than standard positive camber. 

Two questions about the position of the lower plates:

1.  Is there a way to tell the position from looking at the plates, possible by the direction of the bottom of the spring?
2.  Which position corrects for the positive camber, the manual says position 1 is the highest stage and position 3 is the lowest stage.

As for the compensating spring, what type of spring compressor did you use for the job?

[Cees Klumper]

From memory, it should be relatively easy to see the position the bottom plates are in. They are held in place by two bolts I think. From there, it's intuitive as to what the other positions would do to the camber but, referring to your terminology, I would guess that the lowest (3) setting would decrease the camber the most as that should lower the springs the most. Although I may have that backwards!

[Mike K]

Thanks for the tips about the camber.  I think I have more than standard positive camber. 

Two questions about the position of the lower plates:

1.  Is there a way to tell the position from looking at the plates, possible by the direction of the bottom of the spring?
2.  Which position corrects for the positive camber, the manual says position 1 is the highest stage and position 3 is the lowest stage.

As for the compensating spring, what type of spring compressor did you use for the job?

Here's some reading material on the Compensation Spring & Camber.
https://www.sl113.org/forums/index.php?topic=26039.msg186577#msg186577

https://www.sl113.org/forums/index.php?topic=25001.msg178745#msg178745

Compensating Spring with pics:
https://www.sl113.org/forums/index.php?topic=18599.msg131315#msg131315

The way I did it was to jack the car up at the rear to take the weight off the axle, placed jack stands under the chassis both sides.
Removed only the lower shock mounting bolts on both sides.
Make sure you place support under the wheels as well or you could rip your brake lines/hoses as the wheels drop.

Loosen the 2 bolts on the bracket -see pic #1 below.

Remove the right bolt completely so that the bracket swivels and the spring will detension and fall out.
See pic #2

Be careful as the spring detensions!

EXHAUST: You may also need to unhook the rubber hangers towards the rear of the exhaust to make some room.
I unhooked the rubber hangers and loosely secured the exhaust with some nylon cord.

I then compressed the new spring off the car, mounted new rubbers & secured with masking tape.
Used webbing straps to keep the spring compressed.
Put the spring into place and secured & retightened the bracket.
Cut the webbing straps once all is secured & bolted.
Reconnect shocks, exhaust hangers etc.

NOTE: The pics are not mine, they're from a W108 however the procedure is the same.

It's a tight fit in there  -I've read stories where people have removed the fuel tank to do this spring replacement.
I've done this job twice using the above method, without having to remove the fuel tank.

Hope this helps.

Best
Mike

[Mike K]

Michael- while you're at it, & if not already done, you should also check the condition of the differential mount which is located in the boot/trunk under a square plastic cover towards the rear of the boot in the centre.

I did this when I replaced, shocks springs, rubbers etc. The mount was completely collapsed. 

Best,
Mike