Best,-read Easiest way to replace wagon rear springs? - PeachParts Mercedes-Benz Forum

Alastair · #1 09-11-2010, 06:12 PM

My wagon is having a bit of a renovation....

Along with front end suspension repairs and steering component/ball-joint replacement, rear chassis welding and repairs to sills and floor-pans etc, I need to replace the sagging rear springs....

The SLS currently is not working, but this I believe is the levelling valve, pump seems to be OK.

The ride height with nothing in the car is much lower than it should be, with the top of the wheel level with the arch.
--My other Wagon in same unloaded condition sits around 2"-2.5" above the wheel...

Much more than a small child sitting in the rear of the load area and the arch decends below the wheel by an inch or so....

Ive bought some new springs, and have removed the actuator but it appears there is a hook arrangement that stops the trailing-arm coming down further than a set amount....

Any tips on how to replace the rear springs on a W123 Wagon....?
--Does the subframe need to come down...?

kerry · #2 09-11-2010, 07:17 PM

Sorry, can't help on the removal but I can comment that the hydraulic rams on the SLS are designed to carry part of the load. So, if your SLS is not working, the car will sit low even if the springs are in OE condition.

layback40 · #3 09-11-2010, 09:24 PM

X2 kerry, sounds like you have no pressure from the pump. You should see the car lift a little when you start the motor.
My 250TD W124 1987 is an English import & doesnt have sls, not ever. Work that out !!

Alastair · #4 09-12-2010, 05:42 AM

Hmm....

Thats interesting....

Sure Ive read somewhere here that the main weight/load is taken by the springs, so no matter whether the SLS is working or not, it should sit at the correct height, when unloaded.--In fact, the car should be unloaded to set the position of the SLS valve....

My other wagon that Ive compared the height to hasnt been run for about 6 years (No engine!), been towed halfway round the country to various storage places, and still sits at a 'normal' height with a whole load of parts and junk in the back.....!

If I recall correctly there is a write-up on the W123 SLS done by someone (Biodiesel300TD I think?) who describes how to rebuild the valve and also the 'dragging-butt' syndrome is down to weak springs....

Anyway--I have new springs, need to get 'em in there somehow, regardless whether they cure it--might as well replace 'em now Ive gone this far, and I'll rebuild the SLS valve when I'm down in there....

Layback40--Your 250TD W124 may be some kind of a 'special'--Not seen any W124 wagons without SLS--Even the base-models had it as far as I know....

kerry · #5 09-12-2010, 10:06 AM

Quote:

Originally Posted by Alastair

Hmm....

Thats interesting....

Sure Ive read somewhere here that the main weight/load is taken by the springs, so no matter whether the SLS is working or not, it should sit at the correct height, when unloaded.--In fact, the car should be unloaded to set the position of the SLS valve....

My other wagon that Ive compared the height to hasnt been run for about 6 years (No engine!), been towed halfway round the country to various storage places, and still sits at a 'normal' height with a whole load of parts and junk in the back.....!

If I recall correctly there is a write-up on the W123 SLS done by someone (Biodiesel300TD I think?) who describes how to rebuild the valve and also the 'dragging-butt' syndrome is down to weak springs....

Anyway--I have new springs, need to get 'em in there somehow, regardless whether they cure it--might as well replace 'em now Ive gone this far, and I'll rebuild the SLS valve when I'm down in there....

Layback40--Your 250TD W124 may be some kind of a 'special'--Not seen any W124 wagons without SLS--Even the base-models had it as far as I know....

The reason why your other wagon is sitting at proper height could be that the SLS control valve in it is very tight and has not bled off the hydraulic pressure used to keep it at proper height when the engine was still operating. It would be an interesting experiment to bleed off the pressure in that parts wagon and see where the rear end sits without any pressure.

Your springs could still be bad, it's just that the wagon sitting low with no SLS operating is not a definitive way of determining whether they are or aren't.

69shovlhed · #6 09-12-2010, 10:35 AM

your rear springs may be broken. my td had the sls removed before i bought it, and the lr spring was broken. sagged badly and bottomed out constantly. if you don't fix the sls, you will need heavier springs. there is a thread here w/ a spring chart someone was nice enough to put up for us.
to replace the rear springs, you need an internal spring compressor. remove the rear shocks and slip the spring compressor up inside the spring. tighten it until the spring falls out of place; you may also need some spring clips to help get the spring short enough to get it out. if you can rent or borrow the MB compressor it is a relatively easy job. i got a cheap aftermarket compressor, i had to cut the bolt down by about 2" for it to fit. you need to take the sway bar links loose at the top to slip the spring out over top the brake rotor. warning! a compressed spring is very dangerous. it can kill you if it unloads on you, and will hurt you bad even if it only hits you a glancing blow. no $#!+.

Biodiesel300TD · #7 09-12-2010, 10:52 AM

I'm no help for replacing the springs as I've never done it. But I do know that the springs AND SLS maintain unloaded ride height. It's in the FSM. There are several reasons your rear can be sagging. If it's dropping over night but comes back up to level when the car gets turned on, your loosing pressure in the system which means you've got a leak somewhere, usually in the valve. If it's always low even when running, which sounds like your case, the pump isn't providing enough pressure, the springs are tired, or the valve arm needs to be adjusted to lift the rear.

Let me know if you need o-rings for you valve.

charmalu · #8 09-12-2010, 11:05 AM

From my experience, you don`t need a compressor for the rear springs.

I have removed the springs from my 85 300D and several at PNP including a 79 TD, w/o a compressor or the use of a floor jack.

Once the vehicle is safely jacked up, remove the rear wheels, remove the caliper, and hang it off the sway bar. remove the rear links on one end.
remove the shock at the upper end. then remove it from under the trailing arm. place a jack under the differential, remove the 4 diff mount bolts. then lower the differential, and the springs will fall out.

On the TD, remove the hydraulic hose at the top end of the shock first, before disconnecting the shock nuts.
I just did this on a TD last friday.

working on the front springs, definately use the spring compressor.

Charlie

83TD · #9 09-12-2010, 05:10 PM

The SLS valve is designed to maintain a minimum of about 560 psi in the struts when the vehicle is unloaded. If the valve is leaking internally, it will allow this pressure to leak down when the engine is shut off, such as overnight. If the pistons in the struts have an effective projected area of, say, one square inch(I have never taken a strut apart so do not know the exact area, but this is probably somewhere in the ballpark) , that makes 560 pounds of force from each strut to help the springs support the rear of the vehicle. Not a trivial amount given the weight of the vehicle. Even if the pistons are .5 square inches, that is 560 pounds total assist to the springs.
It may make sense to fix the SLS first if you have reason to think that it is not working properly and see if that cures the sag. It worked for me.

Alastair · #10 09-13-2010, 04:18 PM

Well, Ive managed to replace the rear springs, by a mixture of all your methods and the use of two external spring-compressors to take them down just a little,--about 1.5" to allow them to come out/in

I removed the outer subframe mount-bolt and the bracket held by the two bolts to the floor-pan, this gave me just that little extra to get the job done.

I didnt undo the diff-mount-bolts, but did disconnect the sway-bar links, and brake-pipes (Needed to replace those too, as they were looking a little tired)

What I did notice, when compressing the springs, the new ones did appear tougher to tighten down with my two compressors, so maybe they were a bit soft....
--We'll see when Ive got the rest of the rear end jobs done and back on its wheels...

Ive tried for an hour to loosen the fluid-pipes to the SLS valve-- Heat, abuse, shocking with big 'ammer, cursing, nothing would shift the buggers.--Gave up, as all I was doing was bending the mount-bracket on which the valve is mounted...
I thought any more abuse, and I'm gonna break summit important -knowing my luck lately!.

Ive got this mad idea I'm gonna try and rebuild the thing while its still attached to its pipes....
--Maybe I can, Maybe I cant--Be fun trying!

Biodiesel300TD, I would like to buy two kits if thats OK....?

kerry · #11 09-13-2010, 05:53 PM

Quote:

Originally Posted by Alastair

Ive tried for an hour to loosen the fluid-pipes to the SLS valve-- Heat, abuse, shocking with big 'ammer, cursing, nothing would shift the buggers.--Gave up, as all I was doing was bending the mount-bracket on which the valve is mounted...
I thought any more abuse, and I'm gonna break summit important -knowing my luck lately!.

When I replaced my accumulators, I initially tried to bleed off the pressure with the bleed screw on the valve. Nothing I did would loosen it. I finally gave up fearing damage and bled off the pressure via the banjo bolts. Could it be that dissimilar metals are causing the extremely tight fittings?
My system sometimes sags when parked if the weight in the wagon puts the SLS valve in just the right position. Other times it stays up weeks on end. If I was confident that removing the valve would be an easy proposition, I'd rebuild it but for the moment, my failure with the bleed screw has me living with an occasional saggy butt.

69shovlhed · #12 09-13-2010, 06:07 PM

Quote:

Originally Posted by charmalu

From my experience, you don`t need a compressor for the rear springs.

I have removed the springs from my 85 300D and several at PNP including a 79 TD, w/o a compressor or the use of a floor jack.

Charlie

there must be some difference in our cars, because mine has stops on the rear control arms that will not allow them to drop down far enough to get the springs out w/out a compressor.

Sev · #13 09-13-2010, 11:06 PM

"Layback40--Your 250TD W124 may be some kind of a 'special'--Not seen any W124 wagons without SLS--Even the base-models had it as far as I know...."

as far as you know is the key phrase. SLS was an OPTION on all wagons, and actually even other, non-wagon w124's. i've seen 230e's with SLS front and rear. in the UK

by the way, 124 chassis wagons are T124's, not w124's.

charmalu · #14 09-14-2010, 01:34 AM

Quote:

Originally Posted by 69shovlhed

there must be some difference in our cars, because mine has stops on the rear control arms that will not allow them to drop down far enough to get the springs out w/out a compressor.

Did you remove the calipers? if not, the brake hose will be stretched to its limit (not good) and will keep the trailing arms & sub frame from saging down far enough, when the diff mount is unbolted and lowered.

I haven`t had any problems with the stops, but maybe mark their positions with a pencil, and remove them. think it is one 17mm bolt. (doing this from memory)

First time I had the springs just fall out, was a 85 380SE at PNP. some one had already removed the shocks. I was removing the 2:47 diff. and when the diff mount was unbolted and lowered, I heard this clunk, and the L/R spring had fallen out

./ surprised me. then I lifted the other spring out. the stops were still bolted on.

About 3 wks ago, I replaced the rear springs on the 85 300D with a set of progressives., doing as I listed above w/o any problems.

Could be the the SLS valve on the rear sway bar causing a problem? The TD I mentioned above, is the first TD I have worked on. took me a bit to locate the upper shock mount, and the hyd hose fitting on the top end.
after that, as I remember, it was the same as the 300D for removal.

Charlie

Alastair · #15 09-14-2010, 06:11 AM

Quote:

Originally Posted by Sev

"Layback40--Your 250TD W124 may be some kind of a 'special'--Not seen any W124 wagons without SLS--Even the base-models had it as far as I know...."

as far as you know is the key phrase. SLS was an OPTION on all wagons, and actually even other, non-wagon w124's. i've seen 230e's with SLS front and rear. in the UK

by the way, 124 chassis wagons are T124's, not w124's.

Ho-Hum....

--Accuracy is everything.....

All I can say in my defence is, SLS must be a VERY popular 'Option' on T123/4!