Lynn

Doesn't MB use the wheel speed sensors for the speedometer? If they do, then changing the diff ratio won't effect the speedo. If one selects the correct wheel size and tire aspect ratio combos, such as the so called +1 and +2 applications, the speedo won't be off by much.

gab

looks like you lose more than 10mph+ with the differential upgrade.

for easy comparsion if u bump up 5% you lose about 5mph at top gear about 70-80ish mph so therefore if it the upgrade were 3.4ish then i didnt think you really lost like 10mph++ in top gear

I think a 5mph in top gear is more desirable as the Dinan upgrade for BMW also bump up the differential by about 0.2

it will be perfect if they can bump the differetial up by 0.4, make 2nd gear and 6th gear taller, so you can enjoy both driveability (2nd gear is already very short stock differential upgrade will make it even worse) and fuel economy (6th gear for freeway cruising) .. leaving 3rd to 5th gear for road racing

renncpe

I diid not take it that way, getting used parts there is always a question ?? I wanted to make sure. I used a gear calculator and here are the results. I feel confident now that that it is a 3.69 it lines up with the number I read in the car at speed.
Randy

Lynn

Randy, is that gear calculator on-line anywhere? It would sure be quicker that doing it on my calculator.

renncpe

I put up a copy here.
Gear Calculatior
Randy

Lynn

Thanks, Randy.

KJ-TypeR

How long did it take you to install it?

renncpe

It was only about two hours. It ws in and out not hard at all.

Randy

Zeppelin

Here in California we cruise at 90mph all day long will the constant 3800rpm hurt this engine?

breastroker

I am contacting Potomac German Parts for the same rear end, 3.67 for my 2003 Coupe. Should help keep the engine in the torque curve better. The 2.3 liter engine is much better for torque at lower engine speeds.

The 1.8 liter M271 engine needs help. I could go with the 3.46 rear end but it won't be a lot of bang for the buck. I expect to lose about 5 miles per gallon at 75 mph. So I will only get 25-27 mpg:p

Randy, Have you done a dyno after the rear end change and have you measured the 0-60 and 1/4 mile times.

breastroker

Great news,
Contact Richard Jaques at Potomac German Parts for the same rear end, 3.67!!!

He has a couple more in stock, price is right
Call 1-800-831-7686

Enze6997

Whats the part number????

breastroker

Hey I don't know the part numbers, just ask, they have been in business for a long time and have a very good reputation in the antique Mercedes Benz community.

I bet they can also get 3.47s for you. The C32 is the one which would really benefit, a 3.47 rear end would put it about 4.4 seconds to 60 mph

breastroker

Lynn,
Can you check on this statement by you "Doesn't MB use the wheel speed sensors for the speedometer? If they do, then changing the diff ratio won't effect the speedo. If one selects the correct wheel size and tire aspect ratio combos, such as the so called +1 and +2 applications, the speedo won't be off by much."

Sure would like to know what signals the auto equipped cars send to the trans ECU

hobie

Yeah Breaststroker, I'm auto , too. Any LSD info? If we just get into the traction control, why bother?

hobie

Yeah Breaststroker, I'm auto , too. Any LSD info? If we just get into the traction control, why bother?

c230 fi addict

where does one find this rear? I have contacted Potomac and have been bouncing emails back and forth. I spoke w/ Renntech to try and grab some info too! who has a year for this magical c240 auto!!!????

as for:
Contact Richard Jaques at Potomac German Parts for the same rear end, 3.67!!!

He has a couple more in stock, price is right
Call 1-800-831-7686

does he still work there? i did not have luck reaching him

DamonAnthony

hey c230, how did you go with finding a 3.67 diff? I've come across this thread by chance only because I found out today my W202 diff needs replacing so I have done some searching on diffs and here I am. Now the mechanic told me today that my diff is probably not interchangable with other models but he is only guessing as apparently these don't often go, so he hasn't done many. All I have heard today Is diff ratio's etc etc etc, so I've done some homework too. The 3.67 diff is sourced from the update model w202 c180 and also the W203 C-180 (here in australia, not sure about overseas). I wonder though If these only fit from post face lift W202's, or weather the W202/203 are interchangable in general. The reason I wonder Is because my W202 is a 1995 C180 manual with a 3.91 diff, and the car does feel as quick 0-100 as my 02 C200 Kompressor (without kleenman kit), so naturally this would be an even more effective way to drop time off our W203's bottom end. As for top end speed, I have had the W202 to 205 KM/H(not sure what that is in MP/H) but that was fast enough for me top end, so it would be safe to say that a 5 speed auto with same diff ratio would be a simmilar top end speed.

dmatre

Over there in Germany, the same car cruises all day long at 180-220km/hr.

Engine wear will increase slightly, but most wear is caused at startup anyway. Unless you're aiming to make a million miles, I wouldn't think that the additional wear would be an issue.

c230 fi addict

I swapped my diff about 3 months ago and it is nice but not great. The mechanical advantage is noticeable and I too was hesitant in orderring due to the "it wont fit" comments.

I got an oil change and took a peak at it was on the lift (not at the dealer).

I thought I was going from a 3.27:1 to a 3.69 (3.67...sometimes called a 3.70). It turns out the 1.8 liters come with a 3.46 rear so the change was about 5.8% in my case and not 11%. The illusion of torque is there and I get to use 6th at 60mph now and not 65+.

Yes it might put more wear on your car but the car will speed up w/ less strain on the rear.
I spoke w/ paul at potomac and he gave me a great deal on a rear w/ like 100miles on it! I saw it in my hands and wow was it clean!!!!! I tested the rear to be sure i had the 3.67 and all went well!

TIP-> 3.67 x 3 = 11 So, turn the flanges 11 times and watch the inside spin 3 times (and not a lil less then 10 and a half (3.46 rear.. easy mistake that CAN happen.))

Hope my write up helped....

If ya need swapping tips just let me know
Bryan

Mercus

Changing the gear ratio on a differential is a fantastic way to gain power. Problem is that it could create situations for the computer. Here's an example of what I mean:

When changing tire diameter on a pick-up (8" lift with 37" Gumbo Monster Mudders) and thus reducing the overal gear ratio (numerically lower), a problem with the Dodge Cummings ECU came up. We ended up putting a numerically higher rear-end to return the set-up to normal (sold by the company from which we got the lift).

I wonder if a re-flash from a tuner would therefore increase the effectiveness of your swap.

DamonAnthony

Hey Bryan, congrats on the conversion, sorry to hear you didn't feel a bigger gain on performance.

I have verbally agreed to buy a 3.69 diff from my wrecker but I am going through the umming and ahrring as mine is auto and I will have to change the EGC + whatever else pops up! He (the wrecker) has sourced me a new AMG exhaust and has been calling me as he has a lower price for me if I buy it all now. But, I have gone and bought H&R coilovers and Brabus replicas, and AMG front bar. If I buy the diff and the exhaust from him now I will be sleeping outside for the rest of Feb!

I really don't know If I still want to do the diff. I have heard so much negative about the conversion that It seems only do-able with a manual tranny. My fear is taking the Benz to work for 1 day to do the conversion and 6 months later giving it back to her to drive.

c230 fi addict

considering you have the 2.3 liter

do the tranny, ecu and diff swap. 11% more mechanical advantage, fun factor...being a manual now.

ohh sell your tranny and rear and ecu to someone who might want it... cut your losses!!!

or get a "fun" car and play with that.

example: a 318TI w/ an sr20det swap or an M3 swap OR.... swap the motor out of any mazda couple and pop... just a about anything in it!!!

DamonAnthony

LOL!!!

My old Merc was a manual, and as much as I loved it I do prefere the auto!
Drove it tonight for the firsr time in about 2 weeks, nice cool evening, filled her up on 98 octain and gave her a good caining!!! I love the 80-120 kay kickdown response the best. I have been really lazy though and I have to hurry up and get the pulley kit fitted, everytime I drive it I imagine how much quicker it will be and I can't wait!

I'm thinking I might do the coilovers, wheels, front bar and pulley kit all in one go, let the bank account build up again then do the exhaust, and mabey, just mabey I might reconsider doing the diff!!!! Time will tell

c230 fi addict

Now that I have the rear in my car and all things are running fine. Cruise control was a lil wacky at first. I am looking to get the gains I originally expected.

The jump the 2002's get is what I am looking for.

2002 has the 3.27:1
2003 has the 3.46:1 (i found out after doing a manual test w/ the rear in hand)

I installed a 3.67:1 (or 3.69 or 3.70 as some people call it)

I got a 5.8% increase when I hoped for an 11% increase. The main thing is the illusion of torque due to the mechanical advantage. AND the reduction in top speed... (I wanted to USE 6th).

bottom line.... I NEED a customer rear gear to do this and I am hoping for a referral. I plan to mail out my 3.46:1 rear to where ever...

I am looking for a gear close to 3.88:1 or 3.90:1.


any help is good help,
Bryan


Ps.. my mileage did not go down the crapper as many thought.. I get 32mpg HWY w/o an issue.