Oils today are much better today then they were years ago. You should spend $25 and get your oil analysed at 8 or 10k. If the soot loading isn't too high I'd suspect a 10k change won't harm things.

-J

__________________
1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket

Tesla Model 3. 205,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
2014 Cadillac ELR
2013 Fiat 500E.

I agree that soot loading is the major concern, but shouldn't be too bad with my gapless rings.

__________________
Did you just pass my 740 at 200 kmh in a 300SD?????

1978 300SD 'Phil' - 1,315,853 Miles And Counting - 1, 317,885 as of 12/27/2012 - 1,333,000 as of 05/10/2013, 1,337,850 as of July 15, 2013, 1,339,000 as of August 13, 2013



100,000 miles since June 2005 Overhaul - Sold January 25th, 2014 After 1,344,246 Miles & 20 Years of Ownership

Nothing new to report just yet. But the diff sure looks good and doesn't leak it all...:-)

__________________
Did you just pass my 740 at 200 kmh in a 300SD?????

1978 300SD 'Phil' - 1,315,853 Miles And Counting - 1, 317,885 as of 12/27/2012 - 1,333,000 as of 05/10/2013, 1,337,850 as of July 15, 2013, 1,339,000 as of August 13, 2013



100,000 miles since June 2005 Overhaul - Sold January 25th, 2014 After 1,344,246 Miles & 20 Years of Ownership

When I installed this gear set I immediately noticed a quieter, smoother car overall and a reduction in engine operating temperatures, no doubt due to a 700 rpm reduction. The car still climbs a 6% grade (over 3 miles) without ‘kicking-down’ and power with the modified 617 is still good.

With the 3.07 axle, my best mileage was 34, but that depended on me keeping the car down around 55-60 mph, a difficult thing on modern freeways. Best fuel economy seemed to come in around 2400-2500 rpm.

Although my first tank of fuel with the 2.47 netted me 37 mpg (36.7) I don’t consider one tank anything I can rely. I drove the car really easy on that tank and the driving was 100% freeway.

Now I have had the chance to put several tanks of fuel through the car and will post my observations.

Most recently, I subjected the car to several days of in-town driving, short freeway hops between cities, a 400 to 4000 ft/asl hill climb several times and even allowed the car to idle with the A/C on while looking at properties. After 4 tanks for fuel the mileage stayed right around 22-24 mpg under these conditions.

When freeway driven exclusively, the car is knocking down 30-34 mpg consistently; not quite as much as the 40 mpg I was shooting for, but the most amazing part is the 30-34 mpg is being delivered at a consistent 75-80 mph.

With the 3.07 axle, 75-80 was 3200 rpm, whereas now I can cruise comfortably (and super quiet and smooth) and 80 mph turning only 2600 rpm.

While there is still more testing to come, I think I got what I wanted and that was to be able to get my 55 mph best mpg (34) with an increase in cruising speed to 80 mph, which is consistent with the flow of traffic on most freeways.

More to follow…

__________________
Did you just pass my 740 at 200 kmh in a 300SD?????

1978 300SD 'Phil' - 1,315,853 Miles And Counting - 1, 317,885 as of 12/27/2012 - 1,333,000 as of 05/10/2013, 1,337,850 as of July 15, 2013, 1,339,000 as of August 13, 2013



100,000 miles since June 2005 Overhaul - Sold January 25th, 2014 After 1,344,246 Miles & 20 Years of Ownership

I too would not throw 30-34 miles per American gallon at 80 miles per hour out of bed either. Especially in a very heavy thirty year older car. Congratulations.

I wonder if it will still pick up a little fuel milage as the weather warms? Perhaps it is even hot now where you are though.

I really was never quite sure why volkswagons old indirect 1.6 litre diesel gained signifigant fuel milage on really hot days but my examples of them did.

If someone could solve this it may be a help for other indirect diesel engines. It is pretty obvious combustion may have been improved with hotter air introduced to the equation. Even though there was less oxygen as the air was far less dense at higher temperatures.

If this were true there is no way to scavenge enough heat from the exhaust system to improve it as air consumption is so high. Still there may be a way. Even if it is somewhat of a compromise if anyone eventually figures out exactly what was occurring with those older volkswagons.

It looks like my 1977 R107 speedo is calibrated for a 2.88:1 axle, since it is a W1155 unit. Assuming it is correctly calibrated for a 2.88, I would think that using it with a 2.47 axle should have only about a 15% error.

My estimations are as follows:

INDICATED ACTUAL

20 MPH 24 MPH

30 MPH 35 MPH

40 MPH 46 MPH

50 MPH 60 MPH

60 MPH 71 MPH

70 MPH 84 MPH

80 MPH 95 MPH

90 MPH 105 MPH

100 MPH 120 MPH


Did I do my math right????

__________________
Did you just pass my 740 at 200 kmh in a 300SD?????

1978 300SD 'Phil' - 1,315,853 Miles And Counting - 1, 317,885 as of 12/27/2012 - 1,333,000 as of 05/10/2013, 1,337,850 as of July 15, 2013, 1,339,000 as of August 13, 2013



100,000 miles since June 2005 Overhaul - Sold January 25th, 2014 After 1,344,246 Miles & 20 Years of Ownership

Anybody got a 2.47:1 R-107 speedo???????

__________________
Did you just pass my 740 at 200 kmh in a 300SD?????

1978 300SD 'Phil' - 1,315,853 Miles And Counting - 1, 317,885 as of 12/27/2012 - 1,333,000 as of 05/10/2013, 1,337,850 as of July 15, 2013, 1,339,000 as of August 13, 2013



100,000 miles since June 2005 Overhaul - Sold January 25th, 2014 After 1,344,246 Miles & 20 Years of Ownership

Try on the parts wanted portion of our site. Someone there may have a parts available 107 type. Has to be newer than 82 I think as the earlier ones used a higher ratio.

There has to be owners of these on the gas portion of our site as well that may be helpful. Or a dedicated 107 site on the web.

Hmmmm.....

My 1977 450/560 SL speedo may be a 2.65:1 ratio, in which case I would only have a 3 MPH error...

Anybody have R107 ratios for 1977????

__________________
Did you just pass my 740 at 200 kmh in a 300SD?????

1978 300SD 'Phil' - 1,315,853 Miles And Counting - 1, 317,885 as of 12/27/2012 - 1,333,000 as of 05/10/2013, 1,337,850 as of July 15, 2013, 1,339,000 as of August 13, 2013



100,000 miles since June 2005 Overhaul - Sold January 25th, 2014 After 1,344,246 Miles & 20 Years of Ownership

RE: Diff info?
Years, Model, Engine, Differential Ratio, Differential Case Size

R107
1st Generation mounting
1972-1980, 350 SL/SLC, M116, 3.46, 1.1 Liter
1973-1980, 450 SL/SLC, M117, 2.65 / 3.06, 1.3 Liter
1981-1985, 380 SL, M116, 2.47, 1.3 Liter
1981-1982, 380SLC, M116, 2.47, 1.3 Liter
2nd Generation mounting
1986–1989, 560SL, M117, 2.47 / 2.47 ASR / 2.47 LSD, 1.3 Liter

http://www.superturbodiesel.com/std/showthread.php?tid=2570



Notes: 107, 114, 115, 116, 123 and 126 differentials interchangeable up to 8/85.
9/85 and newer 107 and 126 are interchangeable.

Thanks, Partscarver....

My R107 speedo is a 1977, so I suppose it is calibrated for a 2.65:1 axle

__________________
Did you just pass my 740 at 200 kmh in a 300SD?????

1978 300SD 'Phil' - 1,315,853 Miles And Counting - 1, 317,885 as of 12/27/2012 - 1,333,000 as of 05/10/2013, 1,337,850 as of July 15, 2013, 1,339,000 as of August 13, 2013



100,000 miles since June 2005 Overhaul - Sold January 25th, 2014 After 1,344,246 Miles & 20 Years of Ownership

Two four seven ratio was used in some 107s I believe. I though it would be the common one after 1983. I think the 4.5 engine ones may have used it. Not absolutely sure though.

Correct, I just gotta find one...

I am correcting my speed/odo for the 16% error...

__________________
Did you just pass my 740 at 200 kmh in a 300SD?????

1978 300SD 'Phil' - 1,315,853 Miles And Counting - 1, 317,885 as of 12/27/2012 - 1,333,000 as of 05/10/2013, 1,337,850 as of July 15, 2013, 1,339,000 as of August 13, 2013



100,000 miles since June 2005 Overhaul - Sold January 25th, 2014 After 1,344,246 Miles & 20 Years of Ownership

According to my mb buyers guide book the ratio was 3.07 from 73 to 79, 2.65 in 1980 and 2.47 from then on.

Its usually but not always correct. These are for us models.

__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Thanks, Walgamuth....

__________________
Did you just pass my 740 at 200 kmh in a 300SD?????

1978 300SD 'Phil' - 1,315,853 Miles And Counting - 1, 317,885 as of 12/27/2012 - 1,333,000 as of 05/10/2013, 1,337,850 as of July 15, 2013, 1,339,000 as of August 13, 2013



100,000 miles since June 2005 Overhaul - Sold January 25th, 2014 After 1,344,246 Miles & 20 Years of Ownership