First gear start + turbodiesel diff = ultimate combo?

[rmasteller]

I pick up my 1997 E300D on Thursday and I was thinking about future (1+ years from now) improvements. On this specific model year, with the N/A engine and the 5-speed transmission, has anyone thought about the combination of first gear start and a taller diff?

The transmission would have to be tricked, er, I mean reprogrammed, to always start in 1st gear. Adding a differential from a 98-99 turbo diesel would then make all the gears "taller", so first gear wouldn't be so jerky or abrupt. Also, 4th gear would become an overdrive and 5th gear a super overdrive! On hills, if the car shifted down to 4th gear then it wouldn't be a big deal. It might shift to 3rd frequently with the measly 135hp or so.

Speedometer/odometer would have to be modified.

Anyway, that's just some "pie in the sky" rambling thoughts from a new-to-diesels guy.

[bsmuwk]

There's no programming, you hit the button to "S" instead of "W" and it's starts in 1st gear. W is 2nd gear.

[rmasteller]

Oh! I assumed that just modified shift points for summer/winter, doing early, low RPM shifts for winter. That's nice, I'll have to try it Thursday and make sure it works!! :-) Can't wait to get my hands on that owners manual and start reading. If that's what S/W is for, then I just have to think about how drastic the differential change would be. I'll try the S mode for a while. Thanks.

[Since66]

Oh! I assumed that just modified shift points

It does that, as well as the 1st gear start. The shift points become more abrupt.

[bsmuwk]

you have the 722.6 trans in that ole girl.

the best upgrade you can do for it, if it hasn't been done in the transmission's life, is putting a brand new conductor plate in it with an overall trans service. you could also throw some E55 solenoids into it before putting it back together. it may be overkill for the little gutless wonder 606, but the driving experience changes for the better. she'll hold gear for a bit longer and the shift's will be much crisper

[DieselPaul]

Fourth gear is 1:1 regardless of what the rear axle ratio is.

Since you mostly do long highway commuting it would probably work, but remember the non turbo 606 does not have much power so making the gears taller comes at a big detriment around town. The 606 is pretty high revving for a diesel and is happy at those bigger rpms, it does not like to be lugged around.

[rmasteller]

I don't think I'll be changing the rear axle ratio. If I have a reason to take the transmission apart, then I'd do upgrades at that point. So far, it's shifting fine. Thanks everyone.