A couple of years ago I converted my 1984 190D from automatic (factory option) to manual 5spd. This worked out quite well, but after getting used to my E200CDI with an automatic transmission, shifting gears kind of lost its appeal (except on track-days).
I recently got hold of a complete 722.5 5spd auto including all electronics, shifter gate, etc, from a 1993 320TE that I figured would be cool to install. I've done some research on this, and found that I should probably be able to make the electronics work (with adding a simple switch for overdrive as a backup should it not work out), but so far I've had no luck figuring out how the transmission which is used to a rev-area of 800-7000rpm would cope with the rev-area in my diesel which span from 600-4500rpm. Will it shift automatically once peak vacuum is reached, or will it keep pushing and wait for the next 2500rpm? If I have to drive in a silly way, lifting my foot every time I want it to shift, I can just stick to my manual transmission, so unless I can modify it in a way that it will work properly I won't do the conversion.
I've found that the 722.4 4spd-transmission that my car was originally fitted with, was also used up until and including the E280 and 300D (NA). Is there any mechanical difference in these transmissions depending on whether they are used in diesels or gasoline cars, or is it all a matter of different working, governor and modulator pressure? Could I combine parts from the original 722.4 transmission with the 722.5 transmission to make it work on my diesel? Can I swap valve houses and/or some other components to make it work?
I found that the 722.5 is about 4 inches longer than the 722.4, so I realise that I have to swap/modify the front part of the propeller shaft in order to bolt it up. Is the front part of the propeller shaft the same on 124s and 201s, meaning that the difference in length is fixed in the rear half of the shaft, or are they all different? In other words; Could it be that I could use the front half of the shaft from the 320TE in my 190D in combination with the 722.5?
I searched and read through some posts here and found several interesting threads on use of the 722.6 in older cars in combination with a custom TCU - this would of course be the ultimate way to do it, but unfortunately my budget won't support that right now - the 722.5 I have now was practically for free (despite its recent overhaul costing the PO about 3000$ (in Norway)), which is why I wouldn't mind trying it out.
All input, documentation, wiring diagrams, measurements, etc is of interest!
Here's a pic of what my car looks like now btw. I've had the car for more than 11yrs, and have driven it from 256.000km to 400.000km. I have completely converted it to facelift, and pretty much installed all possible options in it (including airbag and COMAND), and the interior came from a donor car in Las Vegas. I still love it!
12-02-2009, 07:42 AM
722.5 5spd-transmission in a diesel?
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