Transmission shift points?

[donlawson84]

hello, my 1971 Mercedes 250 shifts weird. I have never owned one before so i am not sure if they are the right shifting points and unsure if i can adjust them.

1st-2nd = right away less than 5mph
2nd-3rd = 15-20mph
3rd-4th = 20-25mph

also the first car i have owned that in such high RPM's at 65

[vandor]

AFAIK they are supposed to start off in second gear, unless you floor it with the shifter in Low. Sound about right to me.
The engine should be turning 3200 rpm at 60 mph.

Mine is a V8 and it sounds like it is at high rpm on the highway, but in fact it is not.

[tyl604]

No, that is not right. Look on your speedometer. The shift points are painted as ''' near the mph numbers. That will show you when it is supposed to shift, as I remember, under heavy acceleration. Certainly not into fourth at 25mph.

[vandor]

Originally Posted by tyl604

No, that is not right. Look on your speedometer. The shift points are painted as ''' near the mph numbers. That will show you when it is supposed to shift, as I remember, under heavy acceleration. Certainly not into fourth at 25mph.

It should only shift there if it's floored (wide open throttle). It would shift way earlier during normal driving.
During normal driving mine shifts into top gear at ~25 mph, but the shift point for top gear is at ~90 mph! Quite a difference.

[bcbens@embarqma]

Originally Posted by donlawson84

hello, my 1971 Mercedes 250 shifts weird. I have never owned one before so i am not sure if they are the right shifting points and unsure if i can adjust them.

1st-2nd = right away less than 5mph
2nd-3rd = 15-20mph
3rd-4th = 20-25mph

also the first car i have owned that in such high RPM's at 65

The first thing you have to do is make sure that the rod from the carbs linkage to the transmission is connected. This is exactly what happens if it is not connected. If that is connected, start adjusting the length of it until you start in First gear. I think it should be shortened. Take a big swing at it. If you get it too short it will just stay in first too long and will not want to shift to the other gears very easily. When you reach this stage, start backing off on the length until it shifts where you like it. Start with that and let me know what you find. Your '71 does NOT start in second gear unless it is severely mal-adjusted. You have a fluid coupled K4C25 transmission and they are supposed to start in First gear. Starting in '73 the Transmission was changed to a Torque Converter type trans. and they start in second gear. Lastly, the better your vacuum is the smoother the shifts will be. If it shifts hard like banging into gear your vacuum going to the vacuum modulator is probably low. Make absolutely sure that you have very good vacuum or this car will never run right. Lastly, you can actually push or pull start these cars with the fluid coupled transmission but cannot with the '73 and up torque converter transmission. Just a small bit of almost useless data. The high RPMs are the result of your 3.92 rear end.

[tyl604]

Vandor - agree; heavy acceleration. I had a 1973 450SEL and it certainly did not shift into fourth gear at 25mph. As best I remember is was more in the 35mph area. Just thinking about it this sounds more like what the Germans would have designed the car to do.

[bcbens@embarqma]

Originally Posted by bcbens@embarqma

The first thing you have to do is make sure that the rod from the carbs linkage to the transmission is connected. This is exactly what happens if it is not connected. If that is connected, start adjusting the length of it until you start in First gear. I think it should be shortened. Take a big swing at it. If you get it too short it will just stay in first too long and will not want to shift to the other gears very easily. When you reach this stage, start backing off on the length until it shifts where you like it. Start with that and let me know what you find. Your '71 does NOT start in second gear unless it is severely mal-adjusted. You have a fluid coupled K4C25 transmission and they are supposed to start in First gear. Starting in '73 the Transmission was changed to a Torque Converter type trans. and they start in second gear. Lastly, the better your vacuum is the smoother the shifts will be. If it shifts hard like banging into gear your vacuum going to the vacuum modulator is probably low. Make absolutely sure that you have very good vacuum or this car will never run right. Lastly, you can actually push or pull start these cars with the fluid coupled transmission but cannot with the '73 and up torque converter transmission. Just a small bit of almost useless data. The high RPMs are the result of your 3.92 rear end.

Are you interested in shift points or not??

[donlawson84]

Yes thank you. Will be looking into everything once work slows down.

[vandor]

I've been driving mine quite a bit lately and in easy to moderate acceleration it shift into top gear at 27-28 mph. One has to give it quite a bit more gas for it to ship up later, and even when floored it shifts into the next gear much before the mark on the speedometer.

[berfinroy]

Vandor: Your 1972 280SEL4.5 doesn't have the same transmission as Don Lawson's 1972 250. You have the new that year 3-speed torque converter transmission, while his has the older 4-speed torus transmission similar to GM's original hydramatic, which was also a 4-speed. The increased flexibility (and smoothness) of the torque converter obviated the need for the stump pulling first gear....although as has already been pointed out Mercedes' torus type design managed to avoid a first gear start (and abrupt 2nd gear upshift) under light acceleration.