I did a search and read about this issue. Appears the primary concern is to compress the spring correctly using "center" compression tool. Looks like the bushing can be squeezed in by lubricating it properly and using right size "c" clamp.

Any advice about doing this myself. I'm a careful guy with basic mechanical skills. So far I've replaced shocks, removed/replaced drive shaft, replaced glow plugs, changed transmission fluid, oil, fuel filters.

Thanks,

Nic
'85 300CD

Be careful to support the calipers while doing this or just swap out the brake lines they are only about $8.00 from good sources. Also you may find it necessary to drop the rear subframe mounts to get access to the outer trailing arm bolts. RTV silicone gasket goo makes a great lube for the bushings.

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Bob D.
Parrish, FL
1 SDL, 1 D, 1 TD, 1 Mog

thanks Bob, will definately use the lubricant. and will support everything in sight before bushing is removed. I admit to being a little worried about the "you could die" comments I read re: the spring compression. But I'm determined to replace most suspension parts that wear out and I can see that these trailing arm bushings are asymetrical and cracked.

Nic

NIC,
There is a lot of energy stored in one of those springs when compressed. If you have the right tool it is safe and easy just use common sense. I have a non MB approved spring compressor that fits inside the spring that works for me. In a pinch once I took a rear spring out without compressing it and reinstalled it by compressing it with a floor jack and a length of 4x4 underneath the garage door lentil. I kept it compressed with parachute cord. It is not something I would recommend.

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Bob D.
Parrish, FL
1 SDL, 1 D, 1 TD, 1 Mog

You do need a dependable spring compresser (************************ rents them) for this job...I just did all front and rear suspension bushings...here are a few tips about the front.

General comments:

Get a large adjustable wrench, and proper size crescents (or sockets, half inch drive) for bolts...also get lengths of pipe to place over wrench for leverage, or proper "breaker bar"...these big bolts are tough to remove without leverage...unless you have an air hammer with sockets.

When installing rubber bushings, apply silicone grease (sylglide)...not petroleum grease...to help slide in.

Apply anti seize to all bolts/nuts....very important to be able to adjust during subsequent alignments.

Support front end with good jack stands and apply emergency brake...this work requires a lot of muscle..you dont want to pull the car down on top of you!!

Specific comments:

Before you remove the main bolts for the inner lower control arm (LCA) bushings, mark the position of the washer....this is an off-set washer with a tooth in the inside...the groove in the main bolt fits into this tooth..by rotating the bolt you adjust position of wheel (hard to explain, obvious when you see). this should be adjusted during front end alighment anyway, but get it close to where is was when you reassemble.

There are two inner bushings on each LCA...they are held in place by an aluminum sleeve that passes through the center hole of each bushing and is flared on each end (the main bolt passes through this sleeve). To remove, take out the main bolt, and use an electric drill with a large bit (1/2 ") to destroy the aluminum sleeve.

From here, removing the bushings is very tough...get a huge adjustable channel lock pliers (sears). Grip lip of bushing and twist..tough to get a good grip, but keep trying...eventually you can get it to budge and keep twisting until you get it out (this is a b___buster, but not too bad). The other one can now be knocked out from the opposite side.

To install is a little bit of a challenge...the bushing kit consists of two bushings and a single aluminum sleeve flared on one end. the goal is to install both bushings, with the sleeve passing through both, then use a tool to flare the other end of the sleeve thus holding both bushings in firmly. If you just press in both bushings without the sleeve, the two holes will not likely be aligned, so when you attempt to put in the sleeve...it wont go in. Then you will likely damage the fragile sleeve trying to force it!!! Here is what to do: Push in both bushings (with silicone grease) by hand pressure as much as you can. At this point, you can still rock each bushing by hand, so you can pass the aluminum sleeve through one bushing, then rock both bushings until holes are alligned and you can get the aluminum sleeve started into the opposite bushing. when this is accomplished, just use two c-clamps (one on each side) to press them in..trying to keep everything going straight so the clamps dont slip. When the bushings are fully in, flare out the end of the aluminum sleeve using some type of tool...I used a plier handle with a hammer..whatever. Once the sleeve is flared all around, remove clamps and everything is set to go back together.

Note:


While you have the spring compressor, you should also replace the bushing where the brake rod (aka guide rod, track rod) attaches to the LCA...it attaches right below the main spring. Compress spring, remove the spring pan (three 13mm bolts, very easy) for access, remove center bolt for this bushing and replace...cheap part, easy and straightforward.

While you have the spring compressor, and when the LCA is detached, and brake rod is detached...you might as well replace the guide rod mounts (the things located where the guide rod attaches to the frame near foot wells. Very easy and self-explanitory.

Finally, remaining front suspension parts are easy and straigtforward to do...you dont really need a spring compressor, but the job is somewhat more convenient with one. Even ball joints aren't bad (press tool is essential to press in ball joints). Upper control arms, anti sway bar bushings, tie rods, steering damper etc......very easy, very self-explanitory. (you need pickleforks to separate compression fittings on tie rods, ball joints, upper control arms)

Lastly, if you attempt the ball joints without a spring compressor (not really needed, but nice), do not remove the shock absorbers as they act as a spring stop!!! You will need to use a bottle jack to apply pressure to the LCA to allow the weight of the car to compress the main spring to varying degrees for disassembly and re-assembly. But the time to do this work is when you have the spring compressor....compress the spring, rip it all appart and do it all at once....one LONG day, most likely two days for the entire front end rebuild...pretty easy on the 123 chassis cars, and you'll save lots of $$$$!!

good luck,

mark

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1984 300TD Wagon, 407,800 mi (current daily driver)
1985 300DT Sedan, 330,000 mi (gone to that great autobahn in the sky)

Mark,

Well, those are great instructions. I'm fired up. Just borrowed a spring compressor from PepBoys (at no cost can you believe) so am only awaiting parts in mail, which I then have to sneak by "she who must be obeyed". For some reason, my wife thinks I spend to much time and money on this car........I'm sure no one else has this problem.

Thanks to all for info. If I survive, will report back on actual results.

Nic
'85 300CD

I'm not sure what kind of spring compressor is available from pep boys, but if is the standard pair of threaded rods with hooks on each end, which are applied to the outside of the spring, I'm not sure how well it will work. You might find that its hard to attach it and compress the spring. The best type has a shaft that goes through the center of the spring through the hole in the engine compartment, then a plate is inserted through the spring, catching the shaft. Once the spring is compressed and pulled up against the chassis, you can work on all suspension components without worry about the spring compressor shifting and releasing the spring.

Anyway, good luck with the job.

Oh yes, I also have a "she-who-must-be-convinced-that-the-work-I-do-to-keep-my-baby-running-is-well-worth-the-effort-and-would-cost-ten-times-more-if-I-brought-to-a-garage-even-though-I-buy-tools-to-do-the-work-and-keeps-us-from-having-another-car-payment-and-really-is-fun-for-me-even-though-I-swear-a-lot-when-I-work-on-my-car......."

I will admit, sometimes I order parts and have them shipped to me at work...she just doesnt understand!!

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1984 300TD Wagon, 407,800 mi (current daily driver)
1985 300DT Sedan, 330,000 mi (gone to that great autobahn in the sky)

good advice again. they one they gave me is the two part "outside" unit. I believe it would work (seems quite heavy duty and there is room for it) but I'm going to look for the right kind to be safe.

thanks,

Nic

For Novices, I am reporting my experience with this repair.

1) Most important that the spring be compressed fully. I failed to do that on first side and found that getting everything back in place was very difficult due to spring's pressure not being completely eliminated. Its really best if you can remove the spring entirely while doing this stuff. Be careful as there is mucho power in that spring. Should use a mercedes specific spring compressor. Not all "center" compressors are alike and some won't fit (I found that out the hard way).

2) When MarkM said that the large nuts can be hard to remove he wasn't kidding. You must have the right size wrench or socket set and will need to use a "breaker" bar to increase tourque. The nut on the lower control arm inner bushing is the bad boy. It will turn, just have to really apply the tourque.

3) I found that lubricating (with Sly- Glide) the lower control arm bushings and installing one first was easier than trying to install both at once. After the first one goes in (using a large "c" clamp), you can insert the aluminum sleeve into it and then the second bushing goes right in where it should. The busings are not perfectly round and need to go into their housing correctly aligned.....look at how the old ones are installed before removing them.

4) I found it easy to remove the old ones by using a hammer and screwdriver to first remove the inner aluminum sleeve (just beat it out in whatever shape). The two old bushings came right out with that sleeve gone.

5) While doing the bushings, go ahead and consider replacing the two tac rod holders (the large contraptions on the firewall that are linked to the bottom of the outer suspension). MarkM suggested this and I found that both of my old ones had lost their "tension" compared to the new replacements. Getting the old ones out and new ones in is no problem once you have the spring compressed sufficiently (must first remove the plate that the spring sits in on the control arm).

Bottom line is it can be done. Be prepared to learn a bit on the first side (that took me 4 hours!) that will help a lot on the second side (about 1 and 1/2 hours).

Nic
'85 300CD @ 148k miles

Most of the advice has been correct. The two part outside compressors do not work (I have a Snap-On unit and it slips before the spring is fully compressed). Rent the unit from Performance Products, IMO. The front springs are 18+ inches long and want to bend as you compress them. The M/B Factory clone that Performance rents works very, very good. My other comment is: Don't use silicones to lube any bushing of this type. The bushing works by twisting; the I.D. is locked down by the compression the bolt provides and the O.D. is locked in the control arm. Silicones will allow the bushing to slip in the control arm. Use dish soap or a non-silicone rubber dressing. Even bar soap can be made into a paste that will work. I know. I made that mistake on the trailing arm bushings on my 114 chassis 250. I ended up redoing the job.

In prehistoric days it seemed we used dilute Muratic acid on rubber installations. ( Ru-glyd ?) it was slick when applied but dried ... also I think we used to measure the working position of the part( contol arm for instance ) and have it in that location when installing the bushing..so as to not have it cocked in tension when in static mode ( sitting around ). It was also used to spray on rubber bushings to keep them from drying out... or so we thought... and it did stop many a squeak on old cars... Greg, remant from prehistoric period...

Vince,

This car stuff is a little like nutrition advice, there are lots of opinions out there.

I've read umpteen posts about Syl-Glide saying that it is the stuff to use. I went to several different auto supply places to find it. And now I read your comments about not using silicone as a lubricant. And what you say makes sense re: the functioning of the bushing.

Well I'm gonna just wait and see what happens. Car is riding great right now. Taking the things out is not an option.

Others who pursue this repair will need to consider what you say carefully.

Nic

Nic, I promise you that what Vince said it true...Greg

I've been following these suspension threads in anticipation of some front end work on my 87SDL. I have noticed that the use of syl-glid or similar product is usually as a lubricant to aid in the placement of the rubber type bushings. After reading this thread and understanding the point of not wanting lubricated bushings in place at the end of the procedure that would counter act the fuction of the bushing, I would offer this thought.
I am a commercial diver and in our business we have latex rubber tubular seals on the wrist and necks of our dry suits, these seals have a very high coefficient of friction and will often time rip as your hand or head is forced though them. At over a $100 a peice to revove and replace plus the loss of work this can be an expensive problem. Some times divers will use soap or soapy water as a lubricant to help. A couple of years ago an old North Sea diver wised us up. The best lubricate is K-Y jelly! Its' water based, thick, and eventually dries completely. We buy a dozen tubes at a time, the junior most diver gets this job, its hilarious when he gets some 17 yearold girl or a 60 year old lady at the register(Big Party! Just Some of the guys coming over! I'm dating your daughter/freind/spouse!) You can buy CVS generic at $2.99 a tube. One tube should last about 2 or three front end as a little lube goes along way and the right lube makes life alot easier!!! Slippery hell yeah!! Try it, you may like it!!

Has anyone put together a parts list (with numbers) for the 123 suspension rebuild? It would be real handy.

Regards,

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D