Has anyone ever put a Diesel trany with a gas engine? I know you could do this with V.W. Rabits. It gives you higher gears. Higher top speed and lower rpms at a given speed. I don't even know if there is a single M.B. engine that would hook up to a trany out of a Diesel, but it would be neat.

I doubt that a diesel tranny would alter the actual top speed gearing of a 'gas' drive train as the top gear ratio of any trans (as i understand) is always 1:1, any noticable differences would be in the intermediate gear ratio's which would be set-up to suit the different torque/engine type applications.

The main 'gearing' difference between gas and diesel vehicles is in the final drive which, in the case of diesel (due to its greater torque at lower engine revs), is a higher ratio than the gas engined equivalent and this is what gives the higher speed/lower revs advantage.

In the case of the VW Rabbit you mention, the difference in top speed, etc is because the Rabbit tranny is a front wheel drive 'transaxle' (this is a combined gearbox/final drive all in one unit) where the "higher top speed", etc is a result of the 'built in' final drive ratio of the diesel transaxle which is a higher ratio than if it were for a 'gas' engined Rabbit.

Well that makes sense. So the gear ratio in the differential of a Diesel car is different then that of a gasoline car. Do you know what the ratio in my '80 300D would be? Has anyone ever put a diff. from a Diesel in there gasoline car? And, if I havn't asked too many questions already, could a rearend in a Diesel handle the higher H.P. of a gas engine. Thanks.

Sorry, i dont know what the final drive ratio is in your 300D............

I would guess that putting a diesel engined final drive into an equivalent gas engined vehicle, due to the higher gearing, would result in that when you move off in first gear it would feel like you are in 2nd gear, 3rd would feel like 4th and so on..........in a manual tranny you would need to slip the clutch more when moving off and an auto would probably 'hunt' between the gears due to a torque/power/road speed imbalance...

Just my guess!

i did this with a 280e that i bought with a bad tranny. i had a good tranny from a 240d that i converted to stick.

the gear ratios are the same but the diesel setup makes it shift at a lower rpm than would be normal for a gas engine.

my brother is still driving the car and finds it fine once accustomed to the shifting characteristics.

tom w

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[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.

I've swaped axles in other vehicles to get a different gear ratio. I went from 4.11 to 3.83 (I think) in one of my Scouts. The higher ratio might have made it a little harder to start out in first but it was so nice to have lower RPMs at 55mph. My automatic '68 Plymouth had a high gear ratio. I could hardly spin the tires but it would do over 150mph. I think it shifted into second around 45-50 mph. I dont see how a higher geared diff. would make a I guess I'll find out what happens.

The diff will handle all the HP the gasser can deliver and is very beefy. A diesel has more torque than the gas engines available in the 123 chassis so it is not going to fail unless you find 300 HP or more for it.
The '80 200D is, I believe, 3.46 and the ratio is stamped on the lower left ear of the housing.
I moved the 3.07 diff from my '83 300D turbo into my '71 220 (gasser w/ stick shift) and it improved the top end very much and the engine isn't revved up all the way like it was to do 70. You may not want to do this with a automatic trans though, a stick shift can handle the swap much better without lugging.
Swapping differentials is the easiest way to alter performance but you can go too far if your'e not careful of the set up your running as well as your anticipated driving conditions like whether you have to drive in the mountains and so on start to factor in.
Gassers are more critical than a diesel because of possible lugging due to steeper torque curves.

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'95 E320 Wagon my favorite road car. '99 E300D wolf in sheeps body, '87 300D Sportline suspension, '79 300TD w/ 617.952 engine at 367,750 and counting!

Thank you guys so much. You have answered my questions and I am a smarter person for it. My car was a Diesel and will probably become a gasser (unless I find a good Diesel for cheap). I would love to get good fuel econemy at highway speeds. I need to go on a couple trips around the North West and down to Cali. With the Diesel differential I should do well. Thanks again.