Ramifications of a 190E 2.6 front sway bar on a 190D 2.2??? - PeachParts Mercedes-Benz Forum

volosong · #1 07-01-2009, 10:52 PM

Both W201 bodies. The 190E 2.6 front sway bar is thicker than the one on a 190D 2.2 diesel. What are the negative ramifications of pulling a junkyard 2.6 front sway bar and putting it on the old diesel? Would it help handling and stability, or do I need more (and spend a lot more)?

As always, thanks for any opinions offered or experiences shared.

pawoSD · #2 07-01-2009, 10:58 PM

It would probably work fine, and just stiffen up the body roll a bit. They are the same car aside from the engine.....the engineers just assume that the 2.6 drivers will be having more fun!

t walgamuth · #3 07-02-2009, 05:08 AM

Get the rear bar as well. If you stiffen the front and not the rear it will make the car more likely to push (understeer) at the limit.

volosong · #4 07-02-2009, 09:09 AM

Quote:

Originally Posted by t walgamuth

Get the rear bar as well. If you stiffen the front and not the rear it will make the car more likely to push (understeer) at the limit.

I'll have to double check, but my understanding is that the rear bars are the same thickness. Besides, pulling the front bar is a five-minute job at the pick-a-part junkyard. The rear bar will take a lot longer. I'll check before heading out. Besides the bushings, anything else I should take off the donor car? Thanks.

volosong · #5 07-02-2009, 07:41 PM

Total bummer! I stopped at the pick-a-part last night to pull a few things, specifically the sensor for the windshield washer reservoir that failed in my car. There was a pretty green colored 190E 2.6 that I've been spying for quite awhile. Lots of nice stuff on it. I even consider pulling the lower door panels to "update" my '85.

When I got to the yard at about 9:30 this morning...the car was gone! The whole row was being replaced by "new" stock. So, I could't get the bars. But, I did stop about a block away at a Mercedes specific junk yard. He sold me a front bar from a 2.6 for fifty bucks. About twice as expensive as the pick-a-part, but at least I have it.

He had his help pull the bar while I sorted through some new wheels that I could purchase. Back at the front, the bar didn't look right. It was a funny shape and after measuring, it was no wider than my old bar. "From a 2.6?", I ask. I check myself and sure enough, it was. He kindly did let me purchase a different bar which was indeed thicker. It was off another and is definitely thicker in the center and tapered at the ends.

#6 07-02-2009, 08:00 PM

As far as the sway bars go, you didn't miss a thing. Since there is no difference in the rear bars, you were going to do nothing to your car except to make it understeer MORE.

Stiffening the front bar is a BAD plan, even in the cases where you also stiffen the rear. Most all production cars, MB's included have understeer designed into them. For the average driver, this makes them back off in a corner to keep them from getting into trouble.

Stiffening the rear bar takes away understeer, but stiffening the front bar ADDS understeer. It is quite common to hear people say that they want to, or ARE stiffening the front bar to decrease body sway. THE DEVIL WITH BODY SWAY!!!!!!!! Body sway means nothing when it comes to handling. Good handling involves a car that goes where you steer it.

If you want to improve handling, find a stiffer rear bar and leave the front one alone.

Good luck,
Larry

volosong · #7 07-03-2009, 12:30 AM

Quote:

Originally Posted by LarryBible

As far as the sway bars go, you didn't miss a thing. Since there is no difference in the rear bars, you were going to do nothing to your car except to make it understeer MORE...

Sorry, for once, I can't totally agree with you. If what you say is true, then why does my coupe handle so much better by installing Sportline bars (front and rear) in lieu of the stock bars?

However, you are partially correct. The 2.6 front bar is 25mm at its thickest while the 2.2 diesel's bar is 22mm. That is a 14% increase in the maximum thickness for the front bar. But, the plan doesn't stop there. While the 2.6 rear bar is only 14mm, (only a 1mm increase over the 2.2 diesel bar), the 2.3-16 rear bar is 16mm, for an increase of 23% in maximum thickness.

So, yes, the front bar will be thicker, but the rear bar will be a "lot" thicker, relatively. 14% thicker on the front, 23% on the rear. But, that is not all.

In addition, I'm chucking the OEM struts/shocks and installing Bilstein HD struts/shocks. The Bilstein Comfort are the equivalent of the OEM struts/shocks and the Bilstein Sport are akin to MB Sportline. I have Bilstein HD on my 300CE, and couldn't be happier.

And one more. Going are the original 14" wheels that are only 5" wide. The recommended tire for the 14x5 ET50 OEM tire is 175/70R14. It can be pushed one size to run 185/65R14. I picked up two 15x6 ET49 wheels today with a 201 part number that has a recommended tire size of 185/65R15, which can be pushed one size to 195/60R15 (as the two I picked up have). What this means is that instead of a 7" wide tire with 6" in contact with the ground, I can now have a 7.75" wide tire with 7.25" on the ground. That is an increase of 21% more rubber in contact with the asphalt.

So, while agree with you that only doing the front bar is dangerous, going with thicker bars front and rear in addition to wider tires and HD shocks result in a package that will handle a whole lot better than the stock setup. Before making my changes to the coupe, it tended to drift on the road. After the suspension upgrade, it tracks straight and true. I noticed that the diesel will tend to drift too. Not as much as the coupe used to, but more than the coupe does now. With the full package, it should have a positive, confident handling characteristic to it.

Besides...with only 72 horsepower, I'm not going to be blasting through any mountain roads anytime soon. I just want more positive handling. It worked on the coupe, I have no doubt that with all three, (thicker bars, heavy duty struts/shocks, wider wheels/tires), that the diesel sedan will see a likewise improvement.

pawoSD · #8 07-03-2009, 12:46 AM

I was about to say, isn't this quite a bit of performance mods for an already really slow car?

#9 07-03-2009, 06:55 AM

Quote:

Originally Posted by volosong

Sorry, for once, I can't totally agree with you. If what you say is true, then why does my coupe handle so much better by installing Sportline bars (front and rear) in lieu of the stock bars?

However, you are partially correct. The 2.6 front bar is 25mm at its thickest while the 2.2 diesel's bar is 22mm. That is a 14% increase in the maximum thickness for the front bar. But, the plan doesn't stop there. While the 2.6 rear bar is only 14mm, (only a 1mm increase over the 2.2 diesel bar), the 2.3-16 rear bar is 16mm, for an increase of 23% in maximum thickness.

So, yes, the front bar will be thicker, but the rear bar will be a "lot" thicker, relatively. 14% thicker on the front, 23% on the rear. But, that is not all.

In addition, I'm chucking the OEM struts/shocks and installing Bilstein HD struts/shocks. The Bilstein Comfort are the equivalent of the OEM struts/shocks and the Bilstein Sport are akin to MB Sportline. I have Bilstein HD on my 300CE, and couldn't be happier.

And one more. Going are the original 14" wheels that are only 5" wide. The recommended tire for the 14x5 ET50 OEM tire is 175/70R14. It can be pushed one size to run 185/65R14. I picked up two 15x6 ET49 wheels today with a 201 part number that has a recommended tire size of 185/65R15, which can be pushed one size to 195/60R15 (as the two I picked up have). What this means is that instead of a 7" wide tire with 6" in contact with the ground, I can now have a 7.75" wide tire with 7.25" on the ground. That is an increase of 21% more rubber in contact with the asphalt.

So, while agree with you that only doing the front bar is dangerous, going with thicker bars front and rear in addition to wider tires and HD shocks result in a package that will handle a whole lot better than the stock setup. Before making my changes to the coupe, it tended to drift on the road. After the suspension upgrade, it tracks straight and true. I noticed that the diesel will tend to drift too. Not as much as the coupe used to, but more than the coupe does now. With the full package, it should have a positive, confident handling characteristic to it.

Besides...with only 72 horsepower, I'm not going to be blasting through any mountain roads anytime soon. I just want more positive handling. It worked on the coupe, I have no doubt that with all three, (thicker bars, heavy duty struts/shocks, wider wheels/tires), that the diesel sedan will see a likewise improvement.

One paragraph at a time.

When you put sportline bars on BOTH ends of your car, you were stiffening the rear bar along with the front. Additionally, you are saying that your car "handles better." How are you determining that? I will remind you that handling improvement involves making the car go where you steer it, NOT decreasing body lean.

Now as for stiffness increases, let's go back to some seventh grade math. The stiffness of the bar is NOT determined by the diameter, rather the cross section. Using a simple calcluation of the area of a circle, the front bars in your examples have a 29% difference in stiffness, while the rear bar, again in your examples, have a 51% delta. SO, in the case of changing the sway bars you cited, you are almost doubling the added stiffness of the rear sway bar as compared to the added stiffness of the front sway bar. This means that this sway bar change is STIFFENING the rear bar significantly more than the front, thus taking out SOME of the understeer. THAT's why this combination is improving handling.

Your third paragraph is indicating even MORE reason why this combination is improving handling. The sway bars are only one part of the equation. Stiffening springs on the same end of the car has the same effect as stiffening sway bars. Most people who seek to change handling don't go so far as to change springs. It is quick and simple to change sway bars, so they stop there. Also changing sway bars will not effect ride except in very particular situations like going over a speed bump at an angle.

Your tire/wheel combination is indeed part of your package and is indeed part of the equation and I'm glad it all works for you.

All that said, the fact remains that, with no other changes involved, stiffening the rear sway bar takes out understeer while stiffening the front sway bar ADDS understeer. The context of my earlier post was aimed toward the OP. It sounded to me as if he was changing sway bars ONLY. He was not undertaking a total suspension makeover as you did. There's nothing wrong with stiffening the front sway bar as long as you are stiffening the rear bar considerably more and if springs are being changed, that is taken into account as well.

SO, in the case of improving the handling of a relatively stock, non performance car, via no changes other than sway bars, leave the front one thin and stiffen the daylights out of the rear one.

#10 07-03-2009, 07:06 AM

Quote:

Originally Posted by pawoSD

I was about to say, isn't this quite a bit of performance mods for an already really slow car?

It's all a matter of taste, but I really like what volo did. The car might not be the fastest car in town stoplight to stoplight, but for me a nice handling car puts more fun in the driving experience than lots of blinding acceleration.

Of course, having both handling and torque isn't a bad thing either. I live in the boondocks 20 miles from work. My drive is a winding, hilly, FUN road. I change between a few different cars, but right now my daily driver is a manual transmission 88 Corvette that I've had for about 15 years so it's no longer a spit shined show car. It will pin you into the back of the seat as well as press you hard against the side bolsters of the seat. The best of both worlds.

My old 5 speed 300E on the other hand, won't mash you back in the seat and it won't press you against the side bolsters either. But the quiet, smooth, effortless driving with very precise highway handling is a pleasant experience as well.

I guess when it comes to my driving I'm sort of a Dr. Jekyl and Mr. Hyde.

volosong · #11 07-03-2009, 11:16 AM

Quote:

Originally Posted by LarryBible

...The context of my earlier post was aimed toward the OP. It sounded to me as if he was changing sway bars ONLY. He was not undertaking a total suspension makeover as you did...

Must have missed that, Larry. I am the OP, but for the sake of brevity, I did not detail the extent of modifications. It sounds like you basically agree, if I do ALL of the mods, (as was done with the coupe).

And, yes...I want the car to go where I steer it. As is, from the factory, and as I mentioned earlier, the car will tend to drift and wander. That is what I DON'T want. I do want it to only go where I point it. It worked for the coupe...I fully expect the same for the sedan.

Thanks for your advice. I value it, in all your posts and threads.