W124 Rear Sway Bar - PeachParts Mercedes-Benz Forum

DieselPaul · #1 06-04-2012, 11:18 PM

I have an E420 rear sway bar to go on my 1987 300D to match the sportline front bar I already installed on the car.

I am under the impression the subframe has to be dropped on an E420 to get the sway bar out, but someone told me on the 6cylinder cars the exhaust is different and you don't have to have drop the subframe to do the sway bars, and then someone else told me if you just take out the back two subframe mounts the subframe will tilt down enough the sneak the bar out.

What's the truth?

JayRash · #2 06-05-2012, 12:03 PM

u will need to drop the frame on both, unless TE is different from sedan

whipplem104 · #3 06-05-2012, 01:04 PM

I do not know the size of the e420 rear bar but unless it is a lot bigger then it is a lot of work for a mm or two. I noticed a difference at 17mm with a w210 bar and a big difference at 19-20. The w210 bar fits well but it does rub a little on the fuel feed from the tank. Not enough to do damage but it does. Ran that bar for about 5 years. I have a w204 bar in my car now but the ends need to be bent in a little. The 171 chassis bar is the same diameter but I do not know the exact measurements and have not tried it. I have been thinking of using the w203 rear wheel spindles and using the w203 rear sway bar setup the under mounts. The w203 spindles have a drop in them also.

DieselPaul · #4 06-05-2012, 01:50 PM

So it needs to be dropped from all 4 points, just taking the back two out won't tilt it?

Jeremy5848 · #5 09-01-2012, 12:13 AM

This is not a complete DIY but simply some comments and notes from the work on my 1995 E300. Over the last couple of days I removed the stock rear sway bar from the W124 chassis and installed a 16.5mm bar from a 1994 E420 (M-B 124 326 24 65). The change gives an increase in stiffness of approximately 30%. The procedure should be the same regardless of sway bar size.

The job looks worse than it is, especially when you're doing it for the first time. I got some practice by removing what was to be my new sway bar from a 1994 E420 in the local "Pick and Pull" auto dismantling yard.

Here is the original 14.5mm sway bar (M-B 124 326 18 65). It is held to the car by a rubber bushing in a clamp (13mm wrench) and a plastic [metal in T-sedans] link (17/19mm wrenches). Once these are removed, the old sway bar still will not come out because the space available is not large enough. (Mercedes installed the sway bar on the subframe before the latter was attached to the car.)

In order to get the sway bar out, it has to be moved forward of the subframe. In the picture above, you can see the sway bar and the top front of the subframe, which is shaped like the peak of a roof.

With the sway bar forward of the subframe, there's room to wiggle and maneuver the sway bar out. It can come out from either the right or left side.

In order to lower the subframe with the differential, the driveshaft must be disconnected (3 bolts and nuts, 15/17mm wrenches) and pushed forward. The flex disc will probably stick to the flange on the differential and may need some prying to get it loose. There is also a pin on the differential flange that protrudes into the driveshaft. The driveshaft must be pushed far enough forward so this pin will clear as the differential drops. (Before this, the support clamp on the mid-driveshaft bearing has to be loosened but not removed. To access the clamp in late diesel models the heat shield above the muffler (catalyst?) must be removed (3 screws, 8mm, then rotate the shield and remove it. Other models I do not know.)

In order to make the necessary room, the front of the subframe needs to drop a minimum of 2 inches. I decided to loosen the rear subframe bolts (19mm wrench) a couple of turns to give more flexibility but this may not be necessary. The front of the differential has to be supported with a jack while the subframe bolts are removed. I didn't find it necessary to disconnect the ABS sensor on the differential -- the cable is long enough. The subframe bolts are really tight; you'll need a 19mm socket, an extension, and a long breaker bar (I used a 23-inch bar).

With the front of the subframe 2 inches lower, there's enough room to get the old sway bar out and the new one in. Once the new sway bar is roughly in place, the subframe can be raised back up and the bolts replaced. FSM calls for new self-locking bolts but I was satisfied to thoroughly clean the old ones and re-install them with blue Loc-Tite®.

Once the subframe is back in position, the driveshaft can be reconnected, the sway bar bolts installed (with new rubber bushings, please, they're only a few dollars each), the driveshaft clamp tightened and the heat shield reinstalled.

The new sway bar has 30% more cross-sectional area and thus should be that much more resistant to twisting than the original. There are other sway bars that are even stiffer.

Jeremy

sixto · #6 09-01-2012, 02:18 AM

That's enough reason to not upgrade

I don't recall the safety hoop for the tail end of the prop shaft on '87 300Ds.

Sixto
87 300D

DieselPaul · #7 09-01-2012, 02:33 PM

There isn't one on my '87.

Thanks for the how to, when I get around to it I will put mine on. I have a bigger bar up front and I need to even it back out.

-Paul

JayRash · #8 09-01-2012, 02:38 PM

U will love what that rear bar will do
To the car. I installed the sportline one up front and by chance found a 16.5mm rear bar. I never knew it cam on the 420 till now but I tell u the car will handle so sweet.

DieselPaul · #9 09-01-2012, 02:44 PM

Sportline is what I have up front and the rear I bought from a member off of his E420 project. I need to get it on for the next autocross.

I just did E420 4 piston front brakes on my car and that made noticeable gains.

Frank Reiner · #10 09-01-2012, 07:26 PM

Re: Stiffness

Although the area of the 16.5mm bar is 30% greater than the 14.5mm bar, torsional stiffness varies as the 4th power of the diameter. Hence, the 16.5 bar has a stiffness that is 1.677 times that of the 14.5 bar!

Jeremy5848 · #11 09-01-2012, 09:36 PM

Quote:

Originally Posted by Frank Reiner

Re: Stiffness

Although the area of the 16.5mm bar is 30% greater than the 14.5mm bar, torsional stiffness varies as the 4th power of the diameter. Hence, the 16.5 bar has a stiffness that is 1.677 times that of the 14.5 bar!

Thanks, Frank. I hoped someone would have the real info. Mechanical was not my type of engineering!

Jeremy

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