My Superior Shift Kit thread (W124 300DT) - Page 4 - PeachParts Mercedes-Benz Forum

gsxr · #1 06-11-2009, 07:56 PM

Quote:

Originally Posted by sixto

The step assumes you have an external vacuum source attached to the VCV. The VCV vacuum supply port should be isolated from the output port at full load stop. If you use a Mityvac on the supply port, a vacuum gauge on the output port shouldn't respond.

Sixto is exactly correct. You need an external vacuum source if you want to measure readings with the engine off, and you really don't want to do this with the engine running, unless you don't mind having your hands and face right on top of a motor spinning to 5000rpm (personally, I don't like that).

I use a venturi-type vacuum "pump", about $15 or so from Harbor Freight, but this requires a compressed air source to power it. Otherwise, a second vehicle (gas or diesel) will work for a vacuum source, just get a 10-foot length of vac hose from McParts, and hook it up to the other car to get a steady vacuum source.

Also - the FSM specs in mbar are kind of a pain to decipher. If you provide 15" (or more) of vacuum into the inlet of the VCV (located on the side of the IP), the output should measure 12-15" (approx) with the throttle at idle position, and this should smoothly decrease to zero vacuum at WOT. At least, that's what I measure on my cars, and mine all shift normally...

Oldwolf · #2 06-12-2009, 10:24 AM

I get it now. Thanks for the explanation. I do have a MityVac that I will try to use. The tip about the vacuum pump from Harbor Freight might come in handy if the MityVac doesn't have enough volume.

gsxr · #3 06-12-2009, 12:08 PM

The MityVac won't work. The VCV operates by bleeding off vacuum at a controlled rate... the MityVac simply can't produce enough volume. Either the HF venturi pump, or a second vehicle, will be required to supply the vacuum. Or, you can do it with the engine running.

Another option is to connect a vac gauge to the output of the VCV with a long length of hose, so you can view the vacuum while driving the car. And also disconnect the kickdown solenoid at the back of the tranny, and the Bowden cable. That will allow you to move the throttle between idle and WOT while driving, without the transmission downshifting.

okcraig · #4 09-12-2009, 02:09 AM

Quick question here I hope. I have a 420SEL and after reading this thread and other sites I ordered the Superior kit. I pulled the valve body today and started replacing the k1 and k2 springs. The k1 went with no problem, but the k2 has an issue. The designated springs in the instructions will not fit inside the accumulator. I sent an e-mail to where I ordered the kit from but thought I would check here as well. Am I missing something. The way I read the instructions, the pink spring should replace all of the other springs and plastic parts except for the accumulator itself. Is this right? TIA

tangofox007 · #5 09-12-2009, 11:16 AM

Quote:

Originally Posted by okcraig

The way I read the instructions, the pink spring should replace all of the other springs and plastic parts except for the accumulator itself. Is this right? TIA

The instructions call for using the red spring in "late models."

Did the original configuration consist of two springs or three springs?

okcraig · #6 09-12-2009, 03:39 PM

I was under told this was an early model but I could be wrong. It had three springs in the original configuration, however it didn't have any of the plasitc internal pieces.. I'll check to see if the red spring is narrower. However, the shorter blue spring still doesn't fit inside the accumulator. Thanks for your help.

I did go ahead and assemble it using the red spring and the original shorter spring in place of the short blue one. Unfortuneately once I got everthing together the transmission will not engage in any gear. Still checking it though. TIA

tangofox007 · #7 09-12-2009, 05:07 PM

Quote:

Originally Posted by okcraig

IUnfortuneately once I got everthing together the transmission will not engage in any gear.

There is a slot in the shift plunger that must be engaged when the valve body is reattached to the transmission.

okcraig · #8 09-12-2009, 05:12 PM

Tangofox007,

Thanks. Wouldn't you know it. Do I need to pull the valve body back off to do this? I'm assuming I do have to pull the pan again.

tangofox007 · #9 09-12-2009, 05:18 PM

Quote:

Originally Posted by okcraig

Tangofox007,

Do I need to pull the valve body back off to do this?

Yes.

okcraig · #10 09-12-2009, 06:33 PM

Quote:

Originally Posted by tangofox007

Yes.

Thanks for the input. Well the good news is I finally got the drain plug out. The allen wrench slot was a bit stripped and I had to work on it a bit. So once its drained I'll pull the pan and then take the valve body down again. I have looked through my books but can't reall find any refrence to doing this. Can you provide any hints? TIA

tangofox007 · #11 09-12-2009, 08:37 PM

The shift plunger on the left, rear side of the valve body has a notch or groove which needs to be engaged (mated) with the shifter mechanism as the valve body is reinstalled. If you didn't do that previously, it is possible that the plunger was damaged as the valve body bolts were tightened. Also make sure that the throttle plunger aligns with the cable bellcrank on the right side. (That usually takes care of itself.)

I recommend that you verify proper shift mechanism operation before reinstalling the pan. (Have a helper move the shifter while you observe from below.)

okcraig · #12 09-12-2009, 08:40 PM

Quote:

Originally Posted by tangofox007

The shift plunger on the left, rear side of the valve body has a notch or groove which needs to be engaged (mated) with the shifter mechanism as the valve body is reinstalled. If you didn't do that previously, it is possible that the plunger was damaged as the valve body bolts were tightened. Also make sure that the throttle plunger aligns with the cable bellcrank on the right side. (That usually takes care of itself.)

I recommend that you verify proper shift mechanism operation before reinstalling the pan. (Have a helper move the shifter while you observe from below.)

Thanks for the info. I have the valve body back off and will see how it looks. Thanks again.

jt20 · #13 07-07-2010, 02:53 AM

The first problem I am having with this kit is lack of experimental data.

How is a professional (the kit is sold to them) supposed to diagnose the transmission issues if he hasn't spent the time in the vehicle?

I began installing this kit but quickly realized I did not know enough about the behavior of this trans to install it.

It seems rather ridiculous to go replacing springs without any info, right? I only have a few trips over 6 months ago with this vehicle.

Are there any suggestions about worthy replacement items without 'knowing' the issues?

tangofox007 · #14 07-07-2010, 09:53 AM

Quote:

Originally Posted by jt20

Are there any suggestions about worthy replacement items without 'knowing' the issues?

You need to know precisely what problem(s) you are attempting to solve before you install any of the kit components. At least that is what my "experimental data" suggests.

Quote:

Originally Posted by jt20

How is a professional (the kit is sold to them) supposed to diagnose the transmission issues if he hasn't spent the time in the vehicle?

The concept known as a "test drive" comes to mind.

jt20 · #15 07-07-2010, 10:44 AM

Quote:

Originally Posted by tangofox007

You need to know precisely what problem(s) you are attempting to solve before you install any of the kit components. At least that is what my "experimental data" suggests.

what is done to a transmission on a bench? Lots of guessing?

...but I agree. just disturbed.

Quote:

The concept known as a "test drive" comes to mind.

it certainly appears there would be a dearth of "experimental data" after a few test drives.