Oh, so a four speed 240D will hit its 5400'ish governed redline at about 105 mph with size 185/70/R14 tires.

A 300D with a 3.07 should go up to 123 mph.

etc., etc.,:)

FWIW, my 83 300TD and 84 300D both have 3.07:1 final drives.

Only one problem with that 240D calculation - it doesn't have the power to get there! Factory reported top speed for a 240D is 84 mph. Mine is especially strong, and will bury the 85 mph speedometer, but 105 is verrrrrry optimistic.

True, but if you get a long slope downwards, a 240D should be able to reach it.:)

I'd LIKE to see an '83 240D showing 105 mph on the speedo!

I can get the rear end from a 380SEL in a local salvage yard. The Adsitco site lists it as 1:2.47 ABS. Will the ABS part make any difference? Will being taller than the '85 'Ds 1:2.88 and my current 3.07 be too much for my little TD?

Side question: Is there a DIY way to recalibrate the mechanical speedo?

115
 

Can I use a 123 reareand in my 115 240d or is there a 115 rearend that will work better?

I am assuming the 115 240d will have a 3.69 and I will want a 3.07.

Surprise
 

Look what I found

Used Differentials : 115

Model/
Description: Notes:
Part Number:
220D,240D RATIO 1:3.92 135-1510
280,280C,300D RATIO 1:3.69 135-1511

:eek:
No wonder the 4 banger is really banging at 85. I will check mine and then look for a 3.69 or 3.45.
Thanks,
Brian

The 116.036 rear is the 450SEL 6.9.:D I would like to change my
3.07 to somthing around 2.65, to lower rpms some.

A 2.88 is fine. I mean, where are you going to go 130 + mph(if you can get there)? A track perhaps? That's about it!

In the Spring(in New England, Spring comes in June), I plan to take a car to the track, just to give it some excercise. Maybe record the whole thing on DV. I don't care about racing, I just care about letting the poor things stretch their legs once in awhile.:)

I guess I should worry about going 130 + mph, since I only have "T" rated tires on my cars.:eek:

If the 3.69 rear end from the 280C I can get to is good, I wonder if it will help the 20.9seconds my TD did at the 1/4 mile...

Does anyone know if a rear differential from an 1986 560 fit into a 116 1980 300SD without any problems?

In 1985 the 300D Turbodiesel came with a 2.88 gear. It also came with a higher stall converter.

My 1984 300D Turbodiesel came with a 3.07 gear. In 1990 I modified the air filter system, which reduced lag and improved performance. Details of this are well documented in this forum.

In 1999 based on information from "Stu Ritter" in Colorado I replaced my torque converter with a 1985 model with a higher stall. '82- early '84 have a smaller pilot hole for the torque converter. Late '84 and '85 crankshafts have a 35 mm pilot which this torque converter fits.

I attribute my off the line performance, smoke right rear with ease, to this modification.

I drive the Florida Turnpike alot at speeds up to 95 mph. The 2.88 gear would be extremely favorable for sound reduction, reduced engine wear and fuel economy. But to give up this acceleration would be a crime.

I believe the stall difference is 400 rpm's higher.

Did you have to have the pilot end of the torque converter to
fit the smaller hole?

No the crankshaft on my car had a 35 mm hole. Lucked out

I have an '85 300DT and I didn't realize that it had a 2.88 rear end. I always thought it had the 3.07 since at 75MPH the engine seems to rev fairly high. My tach doesn't work so I have no idea what the RPM's are. I go up a fairly steep hill on the way home and it does fine. Off the line its OK. The MPG's though are nothing to brag about. Last fill up only got me 21.8 MPG. That's my usual average.