Not sure about later W210, but my 1997 E420 speedometer is driven by the front left wheel... not the rears.



5% difference is HUGE. The W124's only tolerate 1-2% difference, at 3-4% the cruise will engage at low speeds only. Mixing tire diameters is a Very Bad Idea if you want ABS/ASR/ESP to function correctly.

Comment about the lockup function: I had an interesting chat with a dealer master tech about the 722.6 lockup function. At least on the earlier 722.6 (late 90's), the lockup was not particularly smooth, even with the factory TCU. It was bad enough that they had dozens of customer complaints where the dealer may have been forced to buy back the cars. Anyway, the fix was to modify the valve body and permanently disable the lockup function - problem solved, no more jerky engagement. This must have been fixed on later 722.6 with newer valve bodies & controllers. But on both of my 97's, I disabled the lockup.

Also, the lockup allegedly only increased fuel economy by a tiny amount, like low single digit percentages. It wasn't a huge change like switching to a manual transmission. IMO, the primary attraction to the 722.6 is the overdrive 5th gear, and when tuned properly it can shift absolutely beautifully - a very noticeable improvement over the 722.3/.4 trans.

Very cool to see one in a 124 behind a 603!!

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Dave
Boise, ID
Check out my website photos, documents, and movies!

I'd love an overdrive, ratio? So there isn't much TC slip on the freeway in a 722.6?

My Allison transmissions would lock up beginning in 3rd gear, made for a bit harder shift but I'd be willing to make my own controller using a TPS and speed input if all I need to run a 722.6 is TC lockup output and electronic speedo.

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Gone to the dark side

- Jeff

I believe 5th is 0.833. As far as lockup goes, it is one of my favorite features! The controller has quite a few lockup options. You could lockup every gear if you wanted even in auto mode. I have it set up to lockup only in 5th at 70mph and up. It unlocks at 80% tps and coasting. I also have it set to where it will lockup 2nd- 4th if i put the shifter in the desired gear i'd like it to lockup in. So lets say i put the shifter in "3". It will shift normally until 3rd, then if TPS and speed suitable for a lockup it will do so. Works great in 4th if you're pulling hard up a hill. Your torque converter is making no heat and wasting energy. I have found it makes a huge difference letting the engine stay in the 2500- 3000rpm zone where it has all it's torque instead of a slushy high stall converter slipping and revving above that area. But the torque converter itself has MUCH less slip than my 722.3. That thing was a total slush box. Not the shift firmness, definitely converter. And as far as lockup firmness, i like it all the way up lol. But when i was first playing with it, i found you can for sure have as soft as you want it. It is PWM controlled. Not like the early GM 4l60e's that were on or off.

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83 300CD- sanden, dual p/f condensers, 160a alternator, ect
91 300TD- 722.6, #22 head, 3.5L IP, w140 manifolds, ect

Yeah, I'm sold. Dropping my cruise RPM from 3100+ to 2500 will make things so much happier, I will start taking Belle on trips!

I agree with the lockup, I will likely lock the TC in 3,4,5, would like have the trans lock up and use gears unless I'm using a lot of pedal or are at low RPMs.

So now I need to figure out where to get one.

Mount same?
Driveshaft same?
Shifter from donor work?
What else will I need?
Is yours from a gasser or diesel?
Did you rebuild or just install as-is?

__________________

Gone to the dark side

- Jeff

To be fair E420 is an oddity. A lot of parts in that car are E420 only.

My 97 W210 E320 with M104 and my 98 W210 E300 with OM606 both are driven by rear ABS sensors. I know because I've had both cars on a lift and put them in drive. The speedometer still works.

5% tolerance is pretty small, actually. It translates to what, 1.8% speedometer overspeeding? There are cars with 10% tolerance or more. And I did say that in practice it's much less than that.

Got some more work done. Removed dash, hvac box, seats, and carpet. Will be cleaning pretty much everything i remove. After removing the carpet, i carefully cut off the sleeving for the factory stereo harness so i can run all 6 speaker wires to my amps under the rear seat. I believe the original copper speaker wire is plenty thick even for a nice system. There aren't any long runs either. I am also going to clean the floor really well for another layer of sound insulation. I was super excited to find i have the comfort/ convince control module!

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83 300CD- sanden, dual p/f condensers, 160a alternator, ect
91 300TD- 722.6, #22 head, 3.5L IP, w140 manifolds, ect

Pulled the hvac box because i had just put a new all aluminum evap in my old car and was going to transfer it over along with cleaning it all and putting some fresh thermal compound on the blower transistor. I also have a new blower and good vac pods. can't imagine this car moved much air or smelled great. 148k of dirt!

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83 300CD- sanden, dual p/f condensers, 160a alternator, ect
91 300TD- 722.6, #22 head, 3.5L IP, w140 manifolds, ect

Don't forget a new center vent vacuum pod which the air box is apart.

Sixto
83 300SD

Interesting info - thanks! May be a unique .072 "feature". Or something that started as of MY 1998.


What the speedometer say is kinda of irrelevant. ABS and ASR compare wheel speeds, anything over a few percent and the computers assume bad things are happening and intervene in the interest of safety. This is a non-issue for most people, just use matching tire diameter/circumference, and the systems are happy.


I'll take Sixto's recommendation one better: Replace ALL the pods under the dash while you're in there. It will never be easier. If you haven't tested them, it's an almost certain bet one or more have failed and you didn't even know it. Particularly the main air (recirc) flap "small lift", which prevents the recirc from fully closing. On a side note, the center vent pod is NLA so you have to buy the repair diaphragm from Performance Analysis Co. For the other pods, don't rebuild them, buy new. There's a couple of detailed threads on this topic elsewhere on the forum. With new pods in you should never have to pull the dash again.

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Dave
Boise, ID
Check out my website photos, documents, and movies!

Haven't made much more progress as i have been bust with other projects and need to order some more parts. As far as vacuum pods, i'm thinking of doing everything but the recirculate ones. I really don't like the "fresh air" in Dallas! From what i understand, the only time it uses recirculated air is when the temp wheel is clicked all the way down to cold or when you push the recirculate switch but it has a timer. Have any electronic guys here thought of figuring out a way to remove the timer function from the CCU? For now, I think i'm just going to keep the door forced closed which is how it's been. Now on to more fun! I have a W140 3.5L manifold I really want to use. It's almost identical to the euro 603 turbo one with a port for an EGR pipe. I will be using a 603.970 Garrett TB03 55 trim turbo. originally pressure actuated wastegate. but will be using the vacuum actuator and the wastegate/ outlet assembly from the 603.971. I'd just use the whole turbo from the .971 but the compressor housing and wheel have some damage. I am using the vacuum wastegate so i can also use the boost control on Ole's 722.6 controller! So there should be no wastegate "creeping" and i can change boost at any time. I believe you can also use it for "torque management" during shifts which is cool! So my main question is regarding the downpipe. I could have my stock one welded and the bend modified to fit on the different outlet that sits at the rear of the manifold but i noticed this setup is nearly the same as the 2.5 turbo? I can't find a part number for a euro w124 om603 turbo downpipe but i wonder if it's the same for the 2.5 turbo? I can buy a brand new one for under $120 if that's the case! Here are some comparison pics i found and some of my own.

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83 300CD- sanden, dual p/f condensers, 160a alternator, ect
91 300TD- 722.6, #22 head, 3.5L IP, w140 manifolds, ect

Euro 603.960 (124 chassis) turbo downpipe is p/n 124-490-67-19 if you want something that will bolt up without custom fabrication and welding. I got one from a US dealer about 5 years ago. Should be ~$250 or so from a discount dealer. And no, it's not the same as the 2.5 turbo pipe.

Thanks for part number! Do you know the differences between the 2.5? Is it the same diameter? I think it'd be a better starting point than my stock one. I noticed the flange that connects to the rear exhaust is a 3 bolt instead of 4. No big deal as long as it's correct until that point.

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83 300CD- sanden, dual p/f condensers, 160a alternator, ect
91 300TD- 722.6, #22 head, 3.5L IP, w140 manifolds, ect

I don't know the exact differences. I believe the length is different but I'm not positive. Quite likely the diameter is also different. I no longer own a .128 so I don't have anything to reference. You are correct that the rear flange is 3-bolt and it will require the matching 3-bolt middle muffler / resonator (124-491-01-00) if you want a bolt-up exhaust. Rear muffler is a slip-fit and should be the same, IIRC.

Great info thank you!!! I'll see what i can do on getting the euro downpipe and then transfer the 4 bolt flange over and weld it back underneath. I was mainly concerned about the proper shape and contour off the turbo and around the trans and firewall area. Did you notice a difference withthe euro style manifold? Sure looks way cleaner if nothing else. Couldn't even see a turbo originally haha.

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83 300CD- sanden, dual p/f condensers, 160a alternator, ect
91 300TD- 722.6, #22 head, 3.5L IP, w140 manifolds, ect