shift points on a 300SDL - PeachParts Mercedes-Benz Forum

banshee350 · #1 12-18-2005, 03:17 AM

My car shifts very early.When starting out at a easy pace it shifts out of 1st before the speedo reachs 10mph 2nd is at 25 3rd at 30 and 4 th is some time before 40 .We only got 22mpg this was around town and freeway but most was freeway.I think if the tranny shifted later and the motor stayed in its power range the mileage would be better.If I shifted it manualy it shifts firm and has much better acceleration.The way it is now the motor is lugging .It seems to stay in 4th all the time unless you totaly floor it.has any one had to adjust the vacuum controls to make it shift better.I would like it to stay in 1 till 20 2nd to 30 and not go into 4th below 45 or 50 unless you are at a cruise.Also would like it to down shift under part throttle acceleration is this posable with this tranny.

t walgamuth · #2 12-18-2005, 07:50 AM

you can adjust the shift points higher. i am not sure how on this model, but i am sure it is easy to do.

but shifting to a higher gear should be giving better mileage rather than the opposite. and 22 for mixed use is excellent in an sd or sdl.

tom w

TX76513 · #3 12-18-2005, 07:58 AM

SDL's can be tempermental in getting that perfect shift that matches your driving style. At the top of your screen is a DIY tab - go down to transmission adjustment. I believe the procedure is for a 123 but the process is close enough for you to get an idea. Before you start adjusting things please take a minute and look for vacum leaks, probably the leading cause of shifting issues. PM me and I will give you some problem areas to look at.

Good Luck!

Brian Carlton · #4 12-18-2005, 09:12 AM

The '87 has the exact same problem. It shifts way too early and is a complete dog around town because of this and because of a needed ALDA adjustment.

Now, the '86 is setup perfectly. You won't get the dreaded 3-4 shift until above 40 mph unless you are just barely opening the rack. If you step into it a bit, the 3-4 will be delayed to over 50 mph. And, if you mash it, the 3-4 won't occur until 60 mph or so.

All of this is related to the Bowden cable from the linkage down to the trans. The cable needs to be tightened a bit to delay the shifts. I need to do it on the '86 as well. But, I'm not fond of working in the cold.

Hit Man X · #5 12-18-2005, 01:40 PM

Another point I'd like to make, I never drive any of my vehicles in 4th around town. At speeds less than 50mph I do not see the need for the direct or OD gear (dependant on the vehicle).

Also there's less wear on the trans.

t walgamuth · #6 12-18-2005, 01:48 PM

would you think there is less wear on the tranny? this doesnt seem correct to me.

i think that you are just burning extra fuel and wearing out everything that much quicker. it's a diesel for heavans sake. it loves low rpm.

sorry to sound negative. that is not my intent.

tom w

Brian Carlton · #7 12-18-2005, 01:51 PM

Quote:

Originally Posted by Hit Man X

Another point I'd like to make, I never drive any of my vehicles in 4th around town. At speeds less than 50mph I do not see the need for the direct or OD gear (dependant on the vehicle).

Also there's less wear on the trans.

I agree. I leave the SDL in 3 around town. High gear is just too tall and the engine is running too slow.

It might be a diesel, but it definitely doesn't like 1300 rpm.

I don't believe wear is affected one way or the other.

banshee350 · #8 12-24-2005, 05:48 PM

I adjusted the bodwen cable or whatever it is called I would refer to it as a kick down or throttle position cable .Any way I adjusted it like I do on american cars hold the throttle all the way open and take up all the slack. Car shifts great now up to 3000 at lite throttle and to 4000 at about 1/2 throttle.This is much better.

Brian Carlton · #9 12-24-2005, 05:56 PM

Well, you went way too far in that it should shift at about 3000 rpm at 2/3 throttle or so and not hit 4000 rpm until about 90% throttle.

But, if you like it that way.......................

banshee350 · #10 12-25-2005, 12:51 PM

Well I drove it to town last night. It shifts fine under normal accel it shifts at a round 3 maybe less.It still does not down shift like I would like, it stays in 3 or 4 and uses the stall of the converter instead of shifting down. If this is a common way that they have these trans are programmed I can see why the front pump seal gets so hard there must be a tramendous amount of heat made by the converter that is transfered to the pump .It will down shift but you have to force it by giving it a large amount of throttle.Time to look for a shift kit.

Hit Man X · #11 12-25-2005, 01:06 PM

Superior has a valve body kit for the 722.X units.

Try just driving in town in 3rd. Many of us do that... I do. Doesn't have to shift 3-4, 4-3 ever and you'll basically be into the boost. 2500rpm is about 45mph or so as I recall.

Also, I always let the turbo pull the car around town at the stall speeds. I've done that with every turbocharged vehicle I've owned.

Brian Carlton · #12 12-25-2005, 01:52 PM

Quote:

Originally Posted by banshee350

Well I drove it to town last night. It shifts fine under normal accel it shifts at a round 3 maybe less.It still does not down shift like I would like, it stays in 3 or 4 and uses the stall of the converter instead of shifting down. If this is a common way that they have these trans are programmed I can see why the front pump seal gets so hard there must be a tramendous amount of heat made by the converter that is transfered to the pump .It will down shift but you have to force it by giving it a large amount of throttle.Time to look for a shift kit.

Yes, what you found is typical. The transmission is very reluctant to perform a part throttle downshift. Once it's in a high gear, it stays there until the vehicle speed comes way down. You can override this tendency by mashing the pedal and contacting the kickdown switch. I do realize that it's a PITA and should not have to be done.

When in high gear doing 30 mph, and requiring an accel to 55 mph, I'll just reach down and drop it into 3rd gear. It's become almost second nature.

As HitMan suggests, if you are driving around town at speeds under 40, just leave it in 3rd.

banshee350 · #13 12-26-2005, 01:39 PM

The problem is that this to be my wifes car and she wants to put it in drive and go.No manual shifting for her.so I will see how it goes the way it is now.It just is a little slow on accelelertion some times when it does not shift down.