Converted 4 speed, 300 Turbo delivers 31.8 mpg
 

My son is finally driving his converted manual 4 speed, 300D Turbo. First tank delivered 31.8 with the differential brought over from an '83. Calibrated the odometer with a GPS and I think we're pretty accurate.

Will know more after several more tankfuls but so far he is spanking our other 300D's.

Don

Don,

Wish I had one! Sounds like a great conversion. Jim

Are the stock MB odometers easy to adjust? How would I go about doin it?

What kind of milage hit might a 617 Turbo take with the 3.96 (or 3.69)? rearend of a 240D?

I miscommunicated when I stated that I calibrated my odometer. I just drove with the GPS on for about 10 miles to discover that my odometer was 15% off. Then I made the mental adjustment.

If you put a differential in from a 240D, you'll have two issues: 1) much lower mileage. I'd guess around 22-24 and 2) the rpm's will be up there.

We drove ours for a couple of months with the original differential in from the 240D. Didn't like the shifting points, rpm's and mileage. The differential from the '83 300DT made a significant difference. If my memory is good, I believe it was a 1:3.07

Don

It should be possible to transplant the guts (gears) from a 300D/CD/TD in the 240D odometer. If not, finding a 300D speedo, replacing the 240D speedo, and adjusting the miles (Very easy to do on a W123 :rolleyes: ) would make mental notes unneeded.

:)

Agreed.

I've done a number of instrument cluster removals. I have a couple spares from 300's but I'm not in the mood. I'm also teaching my son some mental calculations such as speed and distance.

He is adjusting nicely to the 4 speed. If all goes well he'll learn from the ground up (not everything works perfectly on every car so one must learn to think). Then he can go about getting a nicer deal if he wants to.

Have a great day

Don

Marlene's speedo displays about 5-8 mph fast at 65mph and the odometer is approximately 10% fast (measured against Interstate Hwy mileposts at 1, 5 and 10 miles intervals). For the time being, I adjust my driving and cyphering (for mpg) accordingly.

One of these days I'd like to have it read more accurately so, after I finished the manual conversion on Marlene, I visited with someone at Overseas speedometer (www.speedometer.com.) here in Austin about the calibration issues I had. He explained to me that the gauge head of our particular model of VDO only came in three different internal ratios. Depending on the car's final drive (differential ratio) MBZ evidently picked out a speedo that provided a close and reasonably accurate reading.

Overseas Speedometer graciously offered to let me 'try before I buy' so that I could get a speedo head that was close. I plan to do that or, more likely, I'll start collecting instrument clusters and build up one of my own.