Personally, I believe that 15" is too high on these vehicles. The shifts are all mushy and, if the trans is old, you'll get some flare on the 2-3.

I've got the SD at 8" and it's got some crisp shifts.......bordering on banging when stone cold. I like it that way.

Brain - thanks for the tip, Ill look for less tonight.

I think I have found the adjustment you all have talked about on the VCV. Its talked about on the Mbz.org transmission tutorial in a way i realized what I was missing...

http://articles.mbz.org/transmission/adjust/

To adjust my VCV you just need to turn the shaft a few degrees one way or the other. I didnt realize that dome came off. I was removing something else when Brian directed me to take the dome off.

Now I know for tonights tuning exercise. Sweet. It's a good feeling to now know all the knobs I need to turn, and exactly what does what before I go into battle.

dd

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'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

the article i referenced in my previous post talks about making an adjustment of the throttle linkage so that it is 10mm from the stop pin. i made the tool, a 20 mm diameter disc that fits over the stop. but, im confused as to exactly what i am trying to adjust to 10mm. the flat of the lever to the *top* stop pin at idle? that seems awfully far away from what i currently have, i dont even know if i can extend my linkage far enough to achieve that. this must be what its referring to, i cant see what else it could be talking about. i want to get this right before i start mucking with the VCV adjustment.

FWIW, i have 15.5mmHg T'ed into the modulator vac line, diminishing to 0 at full throttle just like it should (small victory). took it out for a quick test drive and my shifts were still harsh. as i understood it earlier from Brian, i should of had flaring if anything if my vac was way too high like that.

also FWIW, the mbz.org article says you should have 5.5-6.5mmHg at the modulator at idle, the brotherton and sun valley articles say 10-15 mmHg.

i feel like im almost there, i just need a little more help to get over the top...i really want to try to do the adjustments by the book instead of ballparking stuff like modifying the shift quality at the modulator at this stage of the game.

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'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

so here's what i ended up doing...

reading the actual mercedes tech manual for the VCV test:
http://www.peterschmid.com/

1.) adjusted the throttle linkage that goes to the VCV to 11.8cm
2.) turn on engine. linkage still not attached. saw reasonable vac readings T'ed into the trans line. 15mmHg at idle, smoothly diminishing to zero at full throttle...just like you read about. woohoo!
3.) from peterschmid mercedes tech manual - made my own 10mm radius disc from cardboard and put it on the upper VCV stop.
4.) moved VCV lever up to edge of disc, noted 7 mmHg. Mercedes spec calls for 4.3mmHg at this point.
5.) adjusted VCV by popping dome off and turning the shaft slightly with 8mm ignition wrench until I got 4.3mmHg with the lever at the 10mm cardboard calibration point. Now i have 10mmHg at idle.
6.) replaced dome on VCV. reattached throttle linkage...not trivial...
7.) adjusted bowden shift cable per sun valley mercedes instructions.

The vacuum system, to the best of my knowledge is now working and delivering the right signals to my modulator. But...my MB still shifts consistently hard on all gears and shifts. The hardness of the shift also doesn;t seem to change based on throttle position. Not that much different than before. Doh. I adjusted the bowden cable about one turn or so to make shifts earlier, around 2200 rpm or thereabouts.

Next I will turn my attention next to the modulator 'T' to soften the shifts...unless there is something that I am potentially missing or additional diagnostics I can run?

Also - when I shift into R and D, the car lurches back and forward respectively, like its snapping to attention. Is this normal for these cars? Someone told me it is...just want to confirm.

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'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

You've done an admirable job of setting the VCV per the specs.

However, I tend to ignore the specs and set it by feel. The SD demanded a setting of 8" at idle to have a crisp shift. However, it appears that you need a much higher setting to get rid of the harshness. So, I'd advise increasing the setting at idle to 15" or more, in an attempt to soften the shifts.

If you find that the VCV has no effect on the shifts, please confirm this by removing vacuum completely from the modulator and see if the shifts get any firmer than they currently are.

If there is no change across the operating range with various levels of vacuum, then it's most likely due to a failed modulator valve. I would advise you not to adjust the modulator pressure at this time.

Thank you Brian...

I took the car for a test drive when it was at 15mmHg idle point and it was pretty much the same as my 10 mmHg 'factory spec' setting. i would imagine at the 15mmHg I should have noticed *much* softer shifting.

new modulator valve it is.

looks like a pain to replace, but i have seen it documented repeatedly here...bring it on.

dd

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'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

DD - Here is my take on the instructions you posted from mbz.org, but first take a fresh look at the photo I POSTed a short while back [in POST #141]:
http://www.peachparts.com/shopforum/attachments/diesel-discussion/38850d1165336744-its-critical-how-you-set-your-transmissions-vacuum-system-your-diesel-mbz-vcv-100_5283-ed.jpg
I believe that first [with the engine shut down], you need to make sure that your VCV-to-Throttle linkages are adjusted for " max throttle " leaving only ~1mm between the VCV's " tang " and the metal stop pin in the body of the VCV.

Then you place the 20mm dia. disc over the metal stop pin [ on the right in my photo ]. This I believe simulates the idle position. Start the engine and [IF necessary] close the throttle to where the metal " tang " contacts the disc and hold this throttle position [possibly a fast idle] with a bungie cord or other means while you make the internal adjustment to the VCV parts under the plastic dome.

Brian - If you are out there and can confirm whether we are on the right track in our understanding of both the external and internal adjustments for the VCV... please jump in here!

Again "DD" I never had to adjust my VCV in this fashion for I was able to get it to function by varying the vacuum input with smaller orifices. I wrenched my back out doing a dashboard dive while working on my Son's MBz so I canNOT bend over the engine compartment to try and follow this exercise up close on one of our cars!

Which raises the question "DD"... have you found the vacuum diagram for your car and do you have the restricted orifices [if ANY] installed as called for in the diagram. ?

The vacuum diagram for your 1982 300D Turbodiesel is at:
http://www.peterschmid.com/vacuum/1977_1985/617_95/1981_1984.jpg
and yes #63 there shows a restricted orfice limiting the vacuum being fed to the "Y" connector, the VCV bleed, and the line going down to the modulator.

The diagram also gives you sizes for the various color orifices but does NOT tell you what color/colors should be used! If I remember correctly I worked mostly with the smallest of these listed on this diagram.

Oh, make sure you reinstall the green dashpot [#72] and test it first to make sure there is no leak in this empty plastic chamber with input/output orifices!
Regards,

Sam, if the modulator isn't functioning, all the efforts of precision setting of the VCV are for naught.

Test drive it with full vacuum and test drive it with no vacuum. If the results are the same, no sense bothering with the VCV until the modulator responds to vacuum.

When I shift into R and D, the car lurches back and forward respectively, like its snapping to attention after a short delay. Is this normal for these cars? Someone told me it is...just want to confirm.

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'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

DD, for the federal emmissions group, get the yellow one. It is #63 on the diagram. I did post the part number in another thread, and did confirm that the part numbers posted by Sam earlier in this tread are the correct ones. I took the part numbers and had the parts guys look them up. The yellow restrictor is 2mm ID. You have to order it from MB. I was told it was $3.50 for it. The dealer did not make me pre pay it, and when I went to pick it up, they told me "No Charge", as it showed up as being pre paid. Now if I could have that happen for all the door seals...

Also, at the dealer, the orifice is now called a nozzle.

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RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

99 W210 E300 Turbo Diesel, chipped, DPF/Converter Delete. Still needs EGR Delete, 232K

90 Dodge D250 5.9 Cummins/5 speed. 400K

Gone and still missed...1982 w123 300D, 1991 w124 300D

my #63 right now is blue. what will the increased diameter do for me? other than letting a lot more air through....

I have ordered a new modulator from fastlane..im in a holding pattern until that arrives. ill be doing some research on how best to get that thing out of there...its pretty tight on that side of the tranny.

dd

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'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

Go with what ever one is called for. Mine actually called for 2mm one according to the diagram on the dealer's parts diagram. Federal emissions called for 2mm ID, and California emissions called for 1.1 mm ID.

Less vacuum flow means firmer shifts, more means softer shifts.

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RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

99 W210 E300 Turbo Diesel, chipped, DPF/Converter Delete. Still needs EGR Delete, 232K

90 Dodge D250 5.9 Cummins/5 speed. 400K

Gone and still missed...1982 w123 300D, 1991 w124 300D

my new modulator should get here tomorrow. i have searched and read on it's removal (don't twist, etc. etc.). i have a couple q's...

1.) do I need to drain ATF from the main body of the tranny?
2.) how do i know where to set the pin as a 'default' setting to start the next stage of tuning? i would assume throwing it in there and test driving it is a bad idea.

any tips in addition for removing it greatly appreciated....im ready to get dirty and frsutrated by tight quarters on this one...

dd

__________________
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'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

Brian - Correct me IF my interpretation of the above is incorrect... but by " no vacuum " you mean to simply disconnect the modulator... but by " full vacuum " you mean to send the full engine vacuum to the modulator without the VCV even being connected and bleeding.

RRGrassi – I’d love to know your source on what are the correct size of orifices in these vintage MBZs [your dealer?]. As I have pointed out the vacuum diagrams do not show the size except for in the legend and that is of little use.

DD - A blue restricted orifice is shown as 1mm dia. and red is 1.1 mm and the yellow that RRGrassi appears to be recommending is shown as 2mm as he reported… but my experience was that I needed the smaller orifices [ 0.7 to 0.9 mm ] to throttle down the vacuum so that then the VCV was able to carry out its bleeing function properly. I think this is why the diagrams do NOT specify the orifice size for these might very well be different on different cars right off the assembly line. I’m guessing that the use of these orifices was so that the final “fine tuning” a warmed-up running engine/tranny's vacuum control system could be accomplished merely by putting in a larger or smaller orifice rather than disassembling the VCV and tweaking things. I had a complete set of 6 orifices ready with me to use and as it turned out our car just happen to need the smaller ones. [ this was a newly rebuilt tranny]

RRGrassi – Again, I’d love to know your information source for this.
Also, IF, we start using terms like “vacuum flow” we risk really confusing people for a “vacuum” is often seen as a “lack of air” when it really is just less air… so when you use the term “less vacuum flow”, does this mean less air flow which is the real physical thing that is happening!?

DD – Answers/replies:
[1] – No, I would be prepared for up to 2 quarts to drain when you remove the modulator. Also I would NOT return this to the tranny… top off later with new fluid.
[2] – I would set the new modulator’s adjustment about mid way… so what I did just now was to disassemble [as far as practicable] my old modulator [1980 model 240D/300D] and found that the threaded plastic all-thread adjuster has 16 threads by count. If you can do the same with your old modulator I would suggest the same methodology. For mine, I find that the range of adjustment is about 20 turns so for me I went 10 turns as a place to start. Your’s might well be somewhat different but similar. On my style modulator it is clearly safe for you to remove the plastic all-thread adjuster “thingy” and hopefully yours is the same.
Looking forward to seeing you make that aging tranny still work acceptably for you.
By the way... do you know or can guess how many miles your tranny does have?
Regards,