Mercedes transmission part numbers and ratios
 

Is there a good resource for information on the ratios, part numbers, and applications for the 722 Mercedes transmission? If not can we make one here?

Max, are you looking for transmission ratios? or are you looking for rear axle differential ratios. Transmission ratio in 4th gear is one to one, but there is a little loss in the automatic so it is a little less then that. You can kind of get a feeling for the loss by watching the tack. On a level highway at 60 mph, when you go from normal cruise to complete deceleration, you will see the tack drops immediately by 40 to 60 rpm and that loss is in the torque convertor. Late model Mercedes do have a lock up convertor function, which really minimizes the loss. There are ratios in the individual gears of the automatic transmission, but they vary only slightly. Some cars start in 2nd gear at less then full throttle. Rear axle ratios vary a lot and are not to hard to change if you can find the correct or preferred axle differential. They have been published on the forum and I think a good search will find them. Wheel and tire size will also change the ratio, so there is a lot to look at. On the W123 diesel engine car I think they run from a low speed of 4:11 to a high speed 3:08

I am looking for transmission ratios. I was able to calculate (ballpark) the ratios in my SLC and W124 but I'm wondering what ratios other cars have. If they are similar that's good but I'd like to know what they are.

I'm looking at swapping the engine in the SLC and I'll need to figure out all my gearing so my rear end makes sense with the transmission I go with.

Generally speaking a V8 car with a 25" OD tire performs well with a 11:1 first and 3:1 or so top gear and I'd like my swap to end up in that range. I feel like the ratios of the 722.3xx in my w124 would work well with a 560 and 3.27 rear end and it would be nice to confirm those are the 560 transmission ratios.

Attachment 132546
up to 08/1988 722.3

Attachment 132547
As of 08/1988 722.3

Bad pictures, but hopefully you can see them.

Thanks! So all 4 speeds are close to the same ratios and a 3:1 final or even less would work well assuming I get a trans with a first gear start.

I'll write them out here in case anyone else comes across this thread.

Pre 1988
1: 3:88
2: 2.41
3: 1.44
4: Direct
R: 5.14

Post 1988
1: 3:87
2: 2.24
3: 1.44
4: Direct
R: 5.59

Yup, they are all the same or very close. Just like the stairs in your home, they are all very close, but not identical. I think Sun Valley Transmissions list all that stuff on their web page. But why not do it the easy way. Find the engine and transmission you wish to use. That is the difficult part, procuring it and transportation and install. When you are all finished and don't like the performance or you might feel it could be enhanced, then look around for the differential set up or wheel and tire set up that would give you the change you desire. That is pretty easy as compared to the engine and transmission.

To generalize, most, though not all, 722.3xx valve bodies from diesel engine transmissions had full time 1st gear start. 1st can be selected in all, either with the shifter, or with the kickdown switch. A hand operated kickdown bypass switch can be a convenient alternative. A momentary activation of the KD valve sets the trans in 1st; shift points thereafter occur in accordance with the range selected (D, 3, L).

All US cars delivered with a V8 & 722.3 had a 2.47 final, and some euro cars had a 2.24 final.

I'd like to engineer the system to work well and also buy parts concurrently once. So I get what you're saying and that's basically what happened on the 5.0 Supra but that had really common Ford powertain and Toyota 8" rear end parts.

Do you know if a gas valve body can be modified with diesel parts to have a full time first gear start? Or possibly using the gas springs in the diesel valve body? I'd imagine swapping the entire diesel valve body onto a gas transmission would mess up the shift points. I assume they have weaker springs for those 3000rpm shift points. I could probably do some research on this on my own but I figured I'd ask.

My SLC currently has 2nd gear starts with the 3 speed and I do not like having to manually select first. It ruins one of the few positives about autos IMO. If I'm going to have a torque converter I don't want to have to put thought into gear selection.

1) I do not have first hand knowledge on this point, however, since the valve body castings are the same, it's my view that any drillings that are different can be duplicated, and the pertinent valve spool substituted.
2) It might be possible to approach things that way.
3) Yes, I'm quite sure the shift points would be too low.

If your SLC is all '74 engine & trans, then that trans (722.0xx) while labeled a "three-speed", is actually a 722.1xx with 1st permanently disabled. Hence, it operates in 2nd, 3rd, and 4th.

That makes a lot of sense and explains my ratios assuming it needs L to get into "2nd"

The ratios of the 722.0:

1st: 3.98 (blocked)

2nd: 2.39

3rd: 1.46

4th: 1

Yeah that's what I got from testing it.

Ive done a bunch of work on my 722.3 valvebody. 1st gear start is very difficult to acheive with a gasser v/b. Ive swapped a diesel v/b but it didnt shift and its casting was different. Ive used the 124.034 v/b which was ok but shifted a bit weird. Im currently running my original v/b with mods to start in 1st. It doesnt hold as long as I'd like but works pretty well for daily driving.

What mods did you have to do for the first gear start?