Better gear ratio for W123 Diesel – What axle would fit ?? - PeachParts Mercedes-Benz Forum

lutzTD · #1 11-15-2008, 08:28 PM

Quote:

Originally Posted by MercedesOtto

On your picture it ook like you have bigger wheels as well. How does the 2.47 drive and out of which car did you get the axle???

I LOVE the 2.47. The only drawback is my speedo is off by 40%. also the wheels are large but the tire OD is actually smaller so that makes the 2.47 a little higher. I have a manual trans so an auto probably wouldnt notice the 1st gear takoff sluggishness I have. once I get to 5MPH first is like 2nd gear used to be and 4th is like an overdrive

I was watching my speedo closely with regard to RPM, this is what I have. At 45MPH (corrected to 63MPH) I turn 2200RPM. I think I have mis stated this in the past because I was guessing but this is the right numbers verified today. 4th has all the power I need to climb hills and will accellerate just fine. If I need to pass 3rd is the same as 4th used to be

I took the 2.47 from a 380 or 500 sel I cant remember.

MercedesOtto · #2 11-15-2008, 09:31 PM

Quote:

Originally Posted by lutzTD

I LOVE the 2.47. The only drawback is my speedo is off by 40%. also the wheels are large but the tire OD is actually smaller so that makes the 2.47 a little higher. I have a manual trans so an auto probably wouldnt notice the 1st gear takoff sluggishness I have. once I get to 5MPH first is like 2nd gear used to be and 4th is like an overdrive

I was watching my speedo closely with regard to RPM, this is what I have. At 45MPH (corrected to 63MPH) I turn 2200RPM. I think I have mis stated this in the past because I was guessing but this is the right numbers verified today. 4th has all the power I need to climb hills and will accellerate just fine. If I need to pass 3rd is the same as 4th used to be

I took the 2.47 from a 380 or 500 sel I cant remember.

Does the flexdisc fit from your car? I know that on gas cars different sizes are used from V8 to I6.

lutzTD · #3 11-15-2008, 09:34 PM

Quote:

Originally Posted by MercedesOtto

Does the flexdisc fit from your car? I know that on gas cars different sizes are used from V8 to I6.

I removed the 3 hole flange from the back of an old transmission I had and used it on the 2.47 from the SEL. I guess you can also use the one from the rear you remove but I wanted to keep mine intact in case I didnt like it or I wanted to put in a five speed

JackG · #4 11-16-2008, 07:00 AM

Quote:

Originally Posted by lutzTD

. The only drawback is my speedo is off by 40%.

Is there anyway to correct that?

lutzTD · #5 11-16-2008, 07:32 AM

Quote:

Originally Posted by JackG

Is there anyway to correct that?

I am looking at correction devices, unfortunately there is no cheap solution. there are mechanical ones with set ratios around $80, but Im not sure they will screw on and there are electrical drivers that are much more expensive but infinitely adjustable and again not sure if the threads are the same. I do the calc in my head for free

#6 11-16-2008, 09:10 AM

You can always get the speedo from an 81 300TD. Since its an electric drive (the only one in the W123 line for some reason...) it should be much easier/cheaper to alter it.

lutzTD · #7 11-16-2008, 11:33 AM

Quote:

Originally Posted by ForcedInduction

You can always get the speedo from an 81 300TD. Since its an electric drive (the only one in the W123 line for some reason...) it should be much easier/cheaper to alter it.

in all of my yard prowls to date, I have never seen an MB wagon. what about a later model speedo after 85? arent those also electronic? has anyone made a sender for one?

DeliveryValve · #8 11-16-2008, 12:48 PM

Quote:

Originally Posted by lutzTD

in all of my yard prowls to date, I have never seen an MB wagon. what about a later model speedo after 85? arent those also electronic? has anyone made a sender for one?

You can try to modify a 380SE speedo to fit in your car. Forum member Apotheoun did a version of this with his 300SDS had it done with his 4 speed conversion with magnets.

Quote:

...... There is a lot of thought planning and measuring twice involved before cutting. You will need to invent or create a home made rotational electronic pulse signal generator to run the speedometer, odometer, and cruise control, or you will have nothing to read on the dash.

This is the case with my conversion, which was finally made right. It formerly utilized a poorly hooked up 240D speedometer that was horribly inaccurate, and now it has a correct 300SD speedometer. To make it work though, Kurt had to invent a new signal generator by welding four magnets onto the drive shaft and attaching a nearby sensor, completely hand wrought. It works great, but nearly self destructed in the first two miles due to faulty clearances. The magnets are still bent over from the initial snafu, but work just fine. What a noisy racket that made!

lutzTD · #9 11-16-2008, 01:45 PM

Quote:

Originally Posted by DeliveryValve

You can try to modify a 380SE speedo to fit in your car. Forum member Apotheoun did a version of this with his 300SDS had it done with his 4 speed conversion with magnets.

yeah, not sure this will work for me, the 300CD uses a mechanical pickup for the cruise control and I would rather not lose that.