Really confused - Auto Transmission 1978 300D - Page 2 - PeachParts Mercedes-Benz Forum

hawthorne90250 · #16 04-27-2006, 11:42 AM

Quote:

Originally Posted by rgnprof

Thanks for all of the help -my kickdown switch works fine, just like described - but I don't have any FM, or Haynes information on this car - how many mm's etc? All of the online manuals do not have any transmission information. Anyone have another source? I keep looking to purchase a Haynes - see them on eBay.

ryan

That Info is under Accelerator adjustment, you adjust you IP trottle linkage as per the manual and have you tranmission linkage disconnected, when you have the IP linkage correct you put the transmission linkage back on and adjust so as it fits correctly. I will send you the info if you give me your Email.Also go back into the online manuals and check under Acc.. adjustment.

Samuel M. Ross · #17 04-28-2006, 03:10 AM

Q1 - Is the KickDown "button" an electric switch?
Q2 - Have you tested the KickDown by flooring it just after it has shifted into say 4th gear ~30 mph?

Sam

rs899 · #18 04-28-2006, 06:32 AM

imagesinthewind-

Your 78 W116 should have both a TV rod (seen at the top of the valve cover) and a vacuum modulator- if it is like my '80.

Rick

97E300D · #19 04-28-2006, 06:51 AM

There is no Vaccume on my 77 300D and I Didn't think the 78 had one either but I could be mistaken. The kickdown button works when you are at a stop and floor it, it will jump down to 1st gear other wise it starts in 2nd. And I think he has a W123 not a W126. The W123 had 722.118's Also Regarding the Manual giving the adjustments for the rod length... this is great for a factory new car but with 200k+ miles on the system I'm sure the adjustments are going to be just a bit different from Factory Spec's. Ever lined up the Camshaft marks and looked at the Crank pulley they can be as much as 6 Degree out of wack on a high mileage car.

brownbear · #20 05-01-2006, 11:20 PM

Quote:

Originally Posted by 97E300D

I played around with my Trans on the 77 300D a bit. You have a "TV" Rod no Vac-Mod. The TV rod connects to a turn buckle on the right side of the engine along with the "throttle" (Accellerator pedal) linkage. If you shorten the length of it will allow the trans to build less presure and shift earlier. If you lengthen it, it will shift latter but may slip or flare. You need to find the right combination. There is also a bolt that can be removed from the right rear of the trans that allows access to a sort of K1 type spring. You can tighten it to reduce slipping. But I heard that if it is to tight it can lock up trans, I haven't adjusted my spring yet. I'll search for a post I had that contained some very usful info on these Trannys, and post it for you.

This is good info, as I too have a 77 300D. Mine shift late and hard. Also it always seems to start in 2nd. Will adjusting this TV rod help get it to start in first?
Is there no Vac mod at all on my transmission?

I know the floor switch works on mine. But my second to third is quite a jolt. I always have to let off the throttle a little to slip it to 3rd. 3-4 is not as bad but still late and hard.

I do have vac leaks, this I know. Its also hard to find vac diagrams for this early model. The ones I find on here are later. And very hard to read to see what color means what.
I have deactivated the door system, but need to find which lines to plug off and stow. I have no need for the door system. Thats why I never fixed it.

97E300D · #21 05-02-2006, 09:09 AM

Actual I think I miss quoted myself regarding the length of the TV Rod "it will shift latter but may slip or flare" The truth is if you lengthen the rod the trans is building up more pressure as the engine RPMs climb, the shift will be delayed but will be stronger. If yours is shifting hard that is actually good, less chance the bands will wear out. But you can back off the rod length to soften the shift and make it come on earlier. I'm going back to correct the earlier post.....

Put it this way when I got the car the rod was disconnected, you would take off and it would quickly shift 3rd then 4th, it was not a speed demon if you can imagin 4th gear at less then 20 MPH. If you held the pedel down it would not shift at all... just flare as if it missed 3rd and fourth all together and was in neutral. If you let off on the gas (diesel) pedal it would real quick jump to 3rd then 4th.... And away you would go every so slowly until it got up to 40-45 then the power band carried it along nicely...

As far as startng in 1st I believe that can only be achived with the kick-down switch. The TV Rod will however allow the trans to kick down to a lower gear just not 1st as far as I can tell.

brownbear · #22 05-02-2006, 03:14 PM

[QUOTE=97E300D
As far as startng in 1st I believe that can only be achived with the kick-down switch. The TV Rod will however allow the trans to kick down to a lower gear just not 1st as far as I can tell.[/QUOTE]

Thanks for the info. It seems strange to me tho, that a car would be designed to start in 2nd. I feel you have to push the pedal almost to the floor to get to move. Where if I start in 1st with the lever back, its not soo bad.

Thats where a manual tranny would change this vehicle, quite a bit I'm sure. I have no problems with the accel on this vehicle. It actually gets up and rolling fine. Just wish the first 10-20 feet didn't require such pedal movement, like to the floor to engage the first.....

Thanks, BB

brownbear · #23 05-03-2006, 01:25 AM

ok I need to get this straight.....

I found my rods under the intake and exhaust. Freeking hard to get at. Really hard from under the car and really hard from above. I found the only way was by pulling the airbox and forcing my arm in....OUCH I have thick arms.

I have lots of slop in everything. Probably not helpful for my adjustments.

Both the Throttle linkage and the transmission(TV rod?) were lengthened pretty far, and the check nuts backed off about mid way.

My shifts prior are hard thunking shifts, really late and need to be helped into gear with letting off the throttle..

I adjusted the inner rod(goes to the tranny) shorter. I adjusted about half of the threads worth. Turning the ball end in. No difference except it seems harder to let off the throttle to get it to change gear(up). But that could also be the throttle linkage, I had to adjust it slightly in as the rod end was too close to the ends of the threads.

So should I screw the ball end in more??

Looking at the manuals on the skinnerbox.steaky is impossible. Scanned PDFs are hard to read.

Whats the turn barrel you refer too? I see a springy thing that looks like a turn barrel on the throttle linkage.

So shorter will make it shift sooner and softer eh? Not the other way? This thing is like a swiss watch

brownbear · #24 05-03-2006, 09:01 PM

Ok spent a few hours in there today. Damm my arms are too think, and I refuse to pull the ac to do this.

I had to pull the bellcrank that sits below the exhaust....uugh. Because the darn rod end would not release for me. Not easy.

So my final results... I lengthened the throttle rod to max and shortened the tranny rod all the way in. I do now have a better shift.

I could improve it more, but I am fully out of adjustment. I think all my ends are just too sloppy.

To help throttle response I filled the gap on the one rod before the injector pump lever. The gap I figure is there for a null when advancing the power. But The slop in my linkage is fine for that.

But I am going to buy a bunch of new ends. Do you think I will need new ball ends too? I had some loose ones, but a few taps on a rivet gun had them seated better....

Thanks, bb

babyjames · #25 05-04-2006, 12:37 AM

I just put a tranny in a '79 300D. There was a bushing on the "TV" rod that had disintegrated. You can take that entire rod out of there relatively easily. Sounds like you've had the front end off, and that is the tough one. You may have to drop the rear of the transmission down - - remove the crossmember/chassis fixing bolts - - to get to the bracket, but it is doable. I'd bet that bushing is toast. If so, it will give you a bunch (4-5mm) of slop in the linkage.

Jay.