722.3xx Transmission... today's job - PeachParts Mercedes-Benz Forum

dennislarock · #1 02-26-2017, 06:19 AM

OK... here we go. The *new* '84D has one little problem... with the tranny ...the 2nd to 3rd up shift flare. All other shift points up and down are fine.

I can make it shift fine into 3rd if I take my foot off the accelerator when it begins to shift into 3rd... then, it slides smoothly into 3rd with no flare.

Modulator is receiving 14Hg
Modulator holds vacuum
VCV & Modulator bleed down properly with acceleration

I received the new tranny filter yesterday so I'm headed out in about an hour (it's still dark outside right now) to install the new filter and replace the K1 clutch spring while I'm at it.

I found a good DIY on the K1 installation.

Mercedes w123 Maintenance: K-1 Spring Kit Replacement and Transmission Fluid/Filter Change

I would also like to replace the K2 spring while I'm in there... but, I cannot find a good DIY on the K2. If anyone knows of a good DIY or has some installation instructions on the K2 please let me know.

Any other thoughts on the 2nd to 3rd up shift flare while I'm at it today would be greatly appreciated... I'll be checking back here often.

Fortunately... I suppose, I have two (2) excellent transmissions ready to pull (see signature, below) ...however, I would like to avoid that route if possible.

Thanks!!!

dennis

dieselbenz1 · #2 02-26-2017, 07:17 AM

It is the same as in this link.

http://www.peachparts.com/shopforum/diesel-discussion/379453-k1-k2-b1-722-4-valve-replace.html

dennislarock · #3 02-26-2017, 07:22 AM

Quote:

Originally Posted by dieselbenz1

It is the same as in this link.

http://www.peachparts.com/shopforum/diesel-discussion/379453-k1-k2-b1-722-4-valve-replace.html

There we go!!!! Great Pics... Thank you!!!!

and... Here Comes the Sun ...I'm @ it!

dennislarock · #4 02-26-2017, 09:41 AM

Blow by Blow...
Started out with the primary and secondary fuel filters... then, drove... warmed her up.
On to Power Steering Fluid and Filter Change (No Flush)
Draining Torque Converter now... then, on to Tranny Drain/Pan Removal/Filter/K1/K2
I move kinda slowww....

Update: Well, been waiting two hours for the wind to die down... time to move on to other projects ...we will see what tomorrow brings. Out...

dennislarock · #5 02-28-2017, 10:55 AM

K1, K2 installed... some improvement ...but, not enough. 2nd to 3rd up shift flare (while better) is still there. Time to pull the tranny out of the smashed '85D

ROLLGUY · #6 02-28-2017, 02:37 PM

I would try cranking up the modulator pressure before pulling the trans. It wouldn't hurt, and it also may fix the problem.

kuene · #7 02-28-2017, 05:10 PM

I'm dealing with same thing. I read in a long detailed thread yesterday that some folks swear that you should only have about 11 going to modulator.

dennislarock · #8 02-28-2017, 05:57 PM

Quote:

Originally Posted by ROLLGUY

I would try cranking up the modulator pressure before pulling the trans. It wouldn't hurt, and it also may fix the problem.

Yeah... just dropped some folks at the airport (Mardi Gras) ...my longest drive today. There were moments... depending on throttle position where it shifted perfectly i.e., some accelerator but not to much. So, I agree... try to increase the pressure... and, maybe try a new modulator and adjust it properly... as follows;

http://www.peachparts.com/shopforum/diesel-discussion/190197-w123-modulator-adjustment-diy-measure-right-way.html

Update: I just went into the shed and looked in a couple of parts boxes... sure enough, there is a brand new modulator sitting in my hand right now. Worth a shot.

dennislarock · #9 02-28-2017, 06:10 PM

Quote:

Originally Posted by kuene

I'm dealing with same thing. I read in a long detailed thread yesterday that some folks swear that you should only have about 11 going to modulator.

I put one of those small plastic in line vacuum connection restrictors (I'm sure that isn't the proper name) on the modulator line but only got it down to 13Hg @ idle... I have several others white, brown, green etc. There was a post somewhere that gave the diameter of them... but, I can run through them all pretty quick to see if I can get it down to 11 or 12Hg.

The thing is it flares worse the more I accelerate... the Hg does drops considerably to the modulator on acceleration. Initially, I just unhooked the modulator all together and it still flared, although not nearly as bad (of course every other shift then clunked hard).

dennislarock · #10 03-01-2017, 07:57 PM

Keeping @ it... I did *not* pressure test the tranny ...but, made a quick adjustment (10 min or less) to test Richard's suggestion. I turned the Tee on the modulator *in* 2.5 full turns. It did improve... much less flare (not gone) and a little to firm elsewhere.

So, I will install the *new* modulator this weekend and pressure test and adjust to 2.9 bar (about 41psi). Hope it works.

Richard, I'll be yanking your AC bolt on plate and the Sanden out of the freshly smashed '84D soon!@!

vwnate1 · #11 03-01-2017, 08:38 PM

Thanx Dennis ;

I only turned the modulator adjuster *one* notch and have had very firm shifts ever since .

I wonder of you maybe overdid it ? .

I know an indie M-B Mechanic who was factory trained when our cars (W123s) were new ~ he says to adjust the vacuum signal until it reaches zero " when the throttle is fully depressed .

I'd screw around with adjustments a lot before yanking the tranny out .

dennislarock · #12 03-02-2017, 06:46 AM

I can be extreme... and, the flare was pretty bad. I did not have the time to do it properly so I went BIG and the result was basically the same as when I disconnected the vacuum line from the modulator. I am going to remove the motor mounts and drive shaft on the smashed '85 today in preparation for pulling the engine and tranny just in case the new and properly adjusted modulator doesn't work out. The smashed '85 engine is a parts engine with A/C, turbo, exhaust, starter etc., already removed so its an easy pull. It may be the better route anyway as I can rebuild the '85 tranny while its out... then, rebuild the '84 tranny and have it as a spare.

vwnate1 · #13 03-03-2017, 10:01 AM

Keep us posted how it goes please .

Maxbumpo · #14 03-03-2017, 10:36 AM

I'm not sure an '85 transmission is compatible with an '84 car, you may be opening up a can of worms there. Last year of the 123 had a different transmission, different torque converter, and different rear end ratio.

MBCAJUN · #15 03-03-2017, 03:20 PM

Quote:

Originally Posted by Maxbumpo

I'm not sure an '85 transmission is compatible with an '84 car, you may be opening up a can of worms there. Last year of the 123 had a different transmission, different torque converter, and different rear end ratio.

My son and I put a 1984 trans into a 1985 car with no big problems. We did bypass the "blue flying saucer" in an attempt to correct shifting problems but it might not have been the problem. Car was still running and shifting great when he sold it recently. Only problem was a mile or two difference in the speedometer.