breastroker

I suggest we start a rear end swapping area.

A lot of the C240 sedans are purchased with 3.47s and 3.67s and get horrible gas mileage. Since those of us with 3.27s (2002 Coupes) want those higher ratio rear ends, a swap with just shipping would benefit all. maybe a fer C32s will also get in and but a 3.27.

nevide

OK, before you start hiping about the rear end, how about elaborating on the labor needed to install it and some draw backs other than fuel efficiency? Also some advantage elaboration would be great.

JeT

Now that's wishful thinking!!

breastroker

There are 2 V-6s, the C240 and the C320.

I believe the C320 Coupes and Sedans have always come with 3.27 rear end gears. The engine has lots of torque and needs the lower ratio to get nearly the same gas mileage as the C240.

The C240 Sedans apparently come with either the 3.47 or 3.67 rear ends. The 2600 cc engine does not have the HP or the torque of the 320 or even the supercharged 4 cylinder engines.

Mercedes sacrifices gas mileage to give acceptible acceleration in the C240 by putting the higher ratio rear end in.

Both mine and randy's 3.67 rear ends came from Potomac German Auto in Maryland. Either the dealer or MB has ordered these C240s with the 3.67 rear ends. Customers change out the rear ends t.o get better gas mileage. In a C240 with the stock 3.47 rear max gas mileage is about 26 mpg at 65 mph. With the 3.67 I imagine mileage would be about 22-24. By going to the 3.27 that the C320 uses the C240 mileage should go up to the 27-29 range

The whole purpose of the rear end swap is the 2003-2004 1.8 liter cars are 500 cc smaller and have no HOP UP parts now. The little engine that could is a great engine for it's size and works real well in a lighter car like the SLK. But in the 3400 pound Coupe and the 3600 pound sedan it struggles compared to the V6 C320. Changing the rear end is a great equalizer, low in cost compared to engine hop ups, all stock parts, for a 12% gain from the 3.27 rear and a 7% gain from the 3.47 rear. I expect to loose about 3-4 miles per gallon, even 5 would be acceptible. The C230 Coupe with a 3.67 rear end should be able to blow the doors off a stock C320 coupe, and still get about the same gas mileage.


I should add if someone used his C320 Coupe or sedan only for long freeway miles, swapping to a 3.07 rear like the C32 would increase their mileage a couple.

In the same way a C32 can swap in a 3.27 or 3.47 rear end and do the equivalent of thousands of dollars of engine modifications for $600 plus.

nevide

Now that's interesting. So you have a dyno after the swap? Also, you haven't elaborated on the install procedure. Hehe.

breastroker

Randy described it when he did his. Search?

levelr123g

yea do some before and after dynos.

dont know if the added ratio would be worth it in engine rpm and wear.
go here and check out the rpm differences. also this is just the rear end ratio at 1:1. you have to factor in the tranny ratios also to get a more accurate figure.

Outland

Before and after Dynos? Why? The engine HP isn't gonna change one effen bit. And its not like the 'new' rear end is more efficient! Waste of money. Before and after Gtech runs would be more useful, and certainly more prudent given what a waste that 1000 bucks was.

So few of you 2.3 owners have a pulley, which costs 400 bucks less than the dubious different swap...and will actually add usuable HP. The lower gearing is just gonna make you shift more. Lower gears help when youve got HP, not enough torque, and too tall gears to begin with. Hell, weve got to low of gears...at least in 1st and 2nd, and enough torque to pull a stump out of the ground.

Now, for those of you with 2003 cars, this scenario might yield some results, IF the 2003's aren't already running lower rear end gears, which is entirely possible. But, for over a grand installed, isn't a bigger intercooler, or perhaps a water to air intercooler a better idea? Lower the intake temps to recoup some of that HP lost to HOT AIR...

Or, just put that grand towards a lightweight flywheel...or youre already 1/3 of the way towards that Kleeman Lysholm kit that everyone said was too pricey

nevide

wish that thing ever exists.

Buellwinkle

I agree with Nevide and don't think the taller gears will help much, specially on the 6 spd which already has a pretty low 1st grear. I've done this before and the best you can probably expect is more snap off the line in normal driving, specially in an auto trans car where you can't get the revs up ahead of time on launch. The downsides are slighly poorer mileage and with fuel in my area at $2.39/gallon, that alone may scare some, the other downside is noise at freeway cruising speeds because you are going to be running at a higher RPM. When I did this on our V6 Mustang I was able to chirp the tires which I couldn't do before, gas mileage dropped about 1 mile per gallon, speedo was off and had to be recalibrated and noise at cruise speeds went up slightly but not too noticible because being a convertible, it's noisy anyway.

breastroker

Outland,
I notice your negative guys are all driving the bigger engined 2001-2002 2.3 Liter engine, with stick. Have you spent any time in a 2003 5 speed auto tranny car with the little 1.8 Liter engine?

By default the car shifts into 5 th gear very early. The 5th gear is numerically the same as your 6th (0.83 vs. 0.84). Try running arround city streets at 15-25 in 6th, I doubt it. Even in downtown freeway traffic I shift to 3rd or 4th to keep the revs up above 2000. So basically in order to enjoy the auto Coupe you have to treat it as a stick. It is only a couple of hundred RPM, but that is all it takes to keep the 1.8 in a sweet RPM band.

Now for gas mileage, it will be exactly the same if I back off from cruising at 78 and go to 74. I can handle that.

Guys, why is the SLK faster than our Coupes, besides the 200-300 pounds? Because MB puts the stiffer rear end ratio in, thats why. A couple of tenths of a second improvement over the Coupe keeps the SLK owners happier about forking over the extra 10K-15K.

nevide

I hope you're right. We'll just take a look on the dyno and G tech times I guess? best of luck.