Has anyone put a 5-speed auto in a 4-speed W124 E320?

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BorisRusafov

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Joined
Apr 4, 2014
Messages
47
Location
London, UK
Car
1993 320E W124
Is it a straight swap? I've had two w124s, one an estate with the 5-speed auto, and my current '93 E320 with a 4-speed box. The tranny might be starting to slip a bit, so I'm thinking: can I do a swap to a 5-speed rather than rebuilding mine?
Thanks in advance for any advice!
 
If it is slipping in all gears it may be possible to improve the situation a little by upping the modulating pressure just by turning a screw on the side of the box. If it is slipping on 2-3 upshift only there is a spring kit that can be installed to help with this without having to remove the box itself.
But, as always start with the cheapest option first - has the oil and filter been changed within the last 60 000 kms...?
 
Thanks a lot for the advice! To answer your question, it's only 1st gear that is acting out - when I press the accelerator from a standstill, it revs quite a bit and seems to take off quite sluggishly - the feeling is almost as if it's spinning in place before catching and moving the car. On the upper gears it goes well. Last weekend I had a jaunt on an empty motorway with quite high speeds and it's absolutely effortless in high gear. And I just changed the transmission oil, filter, and switch on the side of the box only a month or so ago.
Why do you say that a 5-speed box cannot be fitted where the 4-speed is now? After all, these cars came with a 5-speed as a factor option. One would think that it would be a straight drop and that all fittings and connectors would be the same. Just asking because logically it would make sense...
 
The 5th gear selection is controlled by electronics not fluid.

It has it's own ECU and associated sensor links, so is not a straight
swap.
 
Right, I see... Yes, I knew that 5th gear is electronically controlled; just never made the connection that a different ECU was needed. Again though, I'm sure these could be sourced used quite in the cheap, no?
 
Right, I see... Yes, I knew that 5th gear is electronically controlled; just never made the connection that a different ECU was needed. Again though, I'm sure these could be sourced used quite in the cheap, no?

It's not a different ECU it is an additional ECU for the gearbox alone.

It will have diagnostics from pin 13.

You currently have nil from pin 13.
 
OK, I understand now. In this case though, what is it that DOESN'T make it a straight swap? If the physical sizes and shapes of the two transmissions match, and there is an additional 5-speed tranny ECU to be added (which I would assume will be easily enough sourced together with the 5-speed box), then is there an added difficulty in figment? Oh, and the floor-mounted 5-speed auto stick with the overdrive action...
Sorry to be a pest, just trying to push through this very desirable option should I go the new transmission decision.
Thanks.
 
Different transmission size and different final drive ratio from the box so I believe you need prop shaft and diff in addition to the previously mentioned parts.
 
Becoming a bit of a chore then... Might be best to stick with what it came out of the factory then. But if it's the torque converter though, it still requires all the labour of removing and opening the box, right? How much am I saving by not simply dropping in a factory-fresh recon transmission?
 
Changing the box is easy if you can get the car high enough and get a good jack to support the weight.

I changed the box years ago in my old 190E 2.6 by myself in a couple of hours with 2 axle stands and a trolley jack. It's the same procedure on your car.
 
Do these guys actually sell factory reconned parts, or brand new parts?
 

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