I recently acquired an 81 300D, 131k, recently rebuild on the engine. this is my first Benz and I love it, however, I'm a little confused about some things as they relate to the transmission (automatic). I've yet to find the "sweet spots" on the transmission. If i drive it very easy it shifts smoothly and seamlessly changes gears as per the dots on the speedometer, then at times when it shifts, it's almost like it is switching gears with a sledge hammer, it kinda slams into gear out of force over necessity. In addition, when driving in the city, it seems to do a lot of shifting, but, while on the interstate she runs smooth and incident free. I don't feel like it is a vacuum problem as I do not experience any of the problems I've read on this board to indicate otherwise (ie; door locks work, engine shuts off when key is turned,....) I've recently ordered the manual set and eagerly await it's arrival, but, in the meantime I would really appreciate any words of wisdom from long time owners. Thanks.

jeric

http://12.96.14.5/benz.htm

HOT DAMMMM!!!!
thats one hell of a benzo you picked up there!! How much did you get it for? Well anyway about your transmission, mine does the same thing but i also have the same problem as you do on your transmission....shifts really hard sometimes. My mechanic is trying to figure it out...somethings wrong with either the governor or the modulator. Since my 300D is a 78, i dont have a tunable governor that will smooth out or harden the shift....maybe yours does. when you get your CD repair manual, check to see if you have that governor in your car....looks like a white tenis ball with vacumm lines coming out of it. If you do then chances are thats the culprit for sporatic harsh shiftings. If you dont have one.....well you kinda SOL just like me, until i get to find out the heck the real problem is.

hope this info kinda helps out
Allan

It’s difficult to say definitively based upon your description of the problem but…

IF the vacuum modulator is not leaking AND is set properly, IF the governor pressure is up to spec, IF the Bowden cable is set properly, THEN you may want to check that:

A: the vacuum pump is pulling enough vacuum.
B: the lines do not have leaks in them.
C: the proper restrictor orifices are in place.
D: the vacuum valve on the IP (not the shutoff valve). It acts as an engineered leak point to emulate the vacuum conditions of a throttled (gasoline) engine for the vacuum modulator to “read”.

Good Luck

Greetings Eric,

Very nice ride you have obtained, and welcome to the site. Just taking a stab at what your linkage to your tranny might be. If it's all mechanical that crosses over the valve cover then runs along the right side to the tranny, it's easily adjusted to give you semi rigid shifts that are consistant to the load or acceleration. The tranny's that are vacuum operated can also be adjusted, but at the modulator valve underneath the car at the tranny. You'll need to do a search on this site for adjustment as it's lengthy and several members have covered this already. When you recieve your manual it will show several pics of different tranny configurations and their adjustments, which will be much easier to understand then us telling you.

Charles

Thanks Guys for the replies and the advice. This is my first Benz so I'm a little leary about fooling with it until I get the manual, which I've recently ordered. I looked under the car yesterday, and to be honest with you I'm not versed enough to be able to tell if my tranny is using vacuum, linkage, or both?. None the less I am committed to resolving this problem as the car is in too nice a shape to permit any ill will to it's performance. I think between this most excellant site and the manual I should be able to conquer this problem, if not, to the shop she goes. Again, everyone's advice is most appreciated as I look to own this car for many many years to come.

Donkey,

Thanks for the advice, I'm not so much tryin to make it shift smooth, just a little more uniform. I'm learning every time I read stuff in this forum, therefore, I will not make any adjustments until I fully understand what is to be accomplished and expected.

As much as I love my Benz, I love my grass more I've been working that lawn for the past 7 years, so the Benz will only be placed there for photo reasons. I know this more than ever now, just in the short time I've had the car I've already got a brown spot, so thats the end of parking in the green space.

Again, thanks,
jeric