dcrasta

Is it possible some 86.5 year cars have 87 model 4 speed autos' ?

alabbasi

I've owned a number of v8 Mercedes with the same 722.3 transmission. They are set up to start in second gear. The older 722.0 3 speed trans from the 70's are more like a 2nd, 3rd and 4th gear. It's not difficult to set them up with a 1st gear start and it's a common conversion for the SL and SEC guys in the Mercedes world.

SMTCapeCod

^^

How about some additional info on the method used in the Merc crowd?

Mine is second gear start, unless selector is moved. Bowden is correct..actually a shade on the pretensioned side of 'drop on'. Modulator was changed prior to my ownership, no other indication of trans work.

I've installed the shift kit pictured, did result in improvement in firmness/shift points but I just went with the standard firmness option.

If someone does a deep-dive, I believe there is a thread here about someone that tried to swap the spring per the schematic and ended up heading in for a rebuild or similar.

One professional trans person/firm was doing work along these lines and workign up a first gear start kit, but he's gone silent (Cattaneo).

s4bill

What are the pros and cons of a full time 1st gear start?

Was it based around fuel economy when the engineers designed it to start in 2nd?

SMTCapeCod

Lifted from a Benz forum, http://www.mbca.org/forum/want-first...art-1990-30-sl. Gregg or Brutus can probably chime in and square this away immed. The variability is odd/frustrating. Seems like it should be one common fault, or one configuration, but with the same part# on the trans...Would be nice to think LSD or high diff cars got first gear start/FGS, but haven't come across any basis for that.

"First gear start
Here's what I have:

Finally after four years of wretched frustration, information gathering, and
failed experiments, my 91 300SL (R129) starts in first gear at light
throttle. The technique involves no transmission valve body modifications.
Much thanks to Roger Ellingson (list contributor)and Erick Jones (shop
foreman of Knoxville Motors) for putting me on the right track. The method
involves use of an electronic circuit which monitors the 5 volt square wave
speed signal that is piped to various modules throughout the car. The
circuit switches on a 12 volt solenoid drive signal when the vehicle speed
drops below 5 mph and switches off when the speed exceeds 12 mph.

The stock control pressure cable is replaced with a newer one that has a
vacuum actuator built into it (this may be the first helpful thing to come
out of the pollution control laws). The actuator is intended to delay
upshifts on cold starts and bring the catalytic converter up to operating
temperature rapidly. By adjusting the vacuum actuator for maximum travel
and triggering a vacuum diverter valve to port vacuum to the actuator when
the 12 volt signal is present AND at the same time applying the 12 volt
signal to the kickdown solenoid (both are required because the vacuum
actuator doesn't have enough travel by itself) Ist gear starts have been
achieved at 60 degrees F on one vehicle. If it lasts and works reliably in
hot and cold weather, I will make all technical details available to all
who want it free of charge. Parts cost is around $200.00 but can be
substantially lower if you are resourceful and are at home in the junk yard.

Moore@icsun1.ic.ornl.gov
(865)574-7253
Oak Ridge National Lab
P.O. Box 2008 Bldg. 3500 MS 6006
Oak Ridge, Tenn. 37831

Date: Tue, 24 Aug 1999 12:16:59 -0500
From: Richard Easley
To: gsxr@jps.net, mbca-general@mbca.org
Subject: Re: First gear starts
Message-ID: <01beee54$797c37c0$e5aa3e81@ccc-easley>

It's my understanding that one cannot modify the 722 tranny to start in
first automatically until the late 89 or early 1990 model year (though, see
below for possible qualification). The modification is *not* difficult from
what I understand (also, see below).

Finally, do not attempt to do this modification yourself unless you have
access to the MB (*not* aftermarket) service literature (e.g., microfiche).
I would attibute the below info to a source (it's not mine, BTW), but I'm
not 100% certain of its origin.

Instructions for Converting 722.3 & 722.4 Transmissions to 1st. Gear Start.

* Remove valve body.
* Remove the cover plate for Valve "41". Remove the spring from valve "41".
Draw a diagram of the arrangement of the valve and spring. Label and save
the spring in case it is necessary to replace it.
* Seperate the top and bottom sections of the valve body and remove the
spring from Valve "44". Draw a diagram of the arrangement of the valve and
spring. Label the spring and save it in case it is necessary to replace it.
* Reassemble the valve body and install it in the transmission. Fill the
transmission with fluid and test drive the vehicle.

These valves are in the governor controls and both springs must be removed
to make the vehicle start in 1st. gear. If the book is studied carefully
the springs will be found in either side of the valve. The late model
vehicles are all the same and may not match the book. If this is tried on a
1986 vehicle there may be a roll pin in one of the valves. If the roll pin
is not removed the vehicle will not start in 1st. gear.

End of procedure.

Richard Easley
Waco, Texas

__________________
Regards,

George Murphy

MBCA Technical Director

865-482-9175

1999 C43 AMG"

PorKen

All my S3 autos have had loose control pressure cables when I got them.

I run stock (socket drop on ball) plus two turns. It is quick to drop a gear (or two), which really helps this big ol' luxo barge move out.






I want (to know if there is) a magic spring kit to fix a slow 3-4/D-R shift.

Lizard928

Ken,
Adjust the brake bands to spec, and ensure the piston seals are in good order....

simos

Sorry for the late response, I'm on vacation and no time/chance to follow the forums at every day..

I did replace the 1 -2 shift spring to one step softer, but don't think it's necessary. The 1-2 shift has always been soft on my car.

I also replaced the 2-3 and 3-4 springs to even more firmer springs, but perhaps only one step firmer would have been enough for me.

It would be better to go one step firmer and see how it goes after that. After you have done the valvebody removal once, it's not big deal to do it again.
Also, some of the springs can be replaced without dropping the valve body(This is mentionned in instructions).


Paul, thanks for the engouraged comments about changing the Governor Pressure Boost Valve spring locations for the first gear start, will try this one day to see how the car behaves, when it starts always at first.
I'm glad that you like my new hood ornament

Don Carter

I have the 14th to the last 86.5 built and it starts in 1st every time.

dcrasta

Another S3 here- Always starts 1st Gear. Holds first if I keep the foot on the floor and shifts to second.

If you are 'starting in second' your bowden cable may be too loose.

Full throttle shifts (flat on floor) 1-2 will spin (hard chirp) the tires (no lsd)

2-3 will also produce a light chirp . (no idea if there is a shift kit installed but I doubt it).

shifting the stick. Putting in 2 holds 1st until redline or until i go to 3 then back to 2 will hold 2.

If i start with the selector in 3 a full throttle 'launch' will hold first until redline. any lifting (or loose cable) will shift at various RPM points (depending on how loose the bowden cable is) but it will hold 3rd

Startin in 4th 'launches 1st' and will hold each gear if the foot is on the floor . Bowden cable adjustment controls the shift point (It seems). Too loose and it would seem to start in snd as the 1-2 shift happens quickly if the cable is too loose.

PorKen

K722A-G kit installed because of a 3-4 shift flare (which had come on suddenly).
Turned out one of the K2 control springs was broken in two places!

I went with extra-firm on the 2-3, which also raises the shift point.
In theory this fills the 2-3 'hole' of the 4-speed, but it takes some getting used to compared to the normal-firm 1-2 and 3-4.
I may revert this back to normal-firm, or go to extra-firm on the 3-4 (by adding back the smaller stock spring).
Tuning the K1 and K2 control springs can be done without removing the valve body after the initial install.

'Firmer' means quicker shift (at higher rpm).
Extra-firm is not 'neck snapping' on this 150K mile '86.5 trans. Mostly it's the higher rpm point that is noticeable.
So far, I have turned the modulator 'T' 1/2 turn CCW and loosened the control cable two turns from where I had it for a little more comfort.


Note 'sporty' SL600 filter (w/weighted F/R inlet plugs) - 1292770195


(1) body separated - keep the plate firmly against the upper body(!), there's nothing which falls out of the lower body


(2) K1 & K2 normal-firm - tabs slide out towards the inside, why the valve body must be removed


(3) K2 3-4 normal-firm (retain smaller spring for extra-firm, step 5)


(4) K1 2-3 extra-firm (omit this step for normal-firm)


(7) B1 1-2 normal-firm (two levels softer are possible via steps 6 & 8, stock is extra~firm)


Upper valve body, upside down, note *****/springs/pistons (You removed the separator plate, didn't you! )


Transmission with valve body removed - the valve body is held together with two screws, it comes off in one piece - no gaskets

SMTCapeCod

That's a fair amplification of the 'instructions' that they provide(d)!
I kept the stock K2...but then went back and retrofit the current Benz upgrade to stave off any flaring issues.
Now which of these valves can we implicate in the first gear start fiasco?
BTW, you sometimes connect with an interesting character when pinging in to the mfg for details/info.

PorKen

The instructions were kind of confusing. (I numbered the pics above according to the instructions.)

I did the small white springs last because I could not figure out the 'tabs' as I called them.

Good luck if you manage to dislodge the check ***** and things in the upper body - the instructions DON'T tell you where they go!


After a few adjustments, I like the result. I softened up the shifts to a stock plus speed. The 'extra-firm' 2-3 now only has a higher rpm shift, with a not too noticeable quickness. The rpm is perfect for the 2-3, for me.

1989porsche928

lol instructions. I had to call the designer. He seemed very rude at first but eventually I was able to communicate with him. I really think I should write for dummies articles for porsche 928 maintenance. One ball is bigger than the other in the valve body. You will need a micrometer or caliper to measure it (unless your eyes are calibrated). When I split my valve body some of the ***** stuck to different halves then fell. I had to dig through many Mercedes articles and bother forums members to put it all back together. I really do believe my post requesting help do help people. from a mechanics view you probably think wtf is this guy doing trying to do this.

Avar928

Early '86 here. Mine starts in first unless I let her idle roll off from a dead stop then she switches to second almost immediately and is a little boggy accelerating. Transmission needs rebuilding after being neglected for what is probably her whole life. I'm hoping to put in a Euro A28.06 or 08 in there with the shorter gearing and higher stall speed.