stacked shifts

[ivandrocco]

1984 300cd

Been ignoring the stacked shifts for a while, but now trying to figure it out.

1-2 = 20mph
2-3 = 25mph
3-4 = 40mph

I've bypassed the EGR are removed the switch on top of the valve cover. I've also bypassed the locks, climate control, and reservoir. Basically all that's hooked into the vacuum line is the shut-off, ALDA, and transmission. The bowden cable is backed almost all the way out. If I bring it in, the stacked shifts get closer. I also changed the ATF to Mobile 1 and replaced the filter.

Wondering if maybe my bowden cable is just stretched out and needs to be replaced, or if I shouldn't have completely removed the switch on top of the valve cover (I read somewhere on Peachparts it was fine to delete it all along with the EGR).

I've also read about replacing the Bowden and it sounds like a PITA... dropping the tranny etc.

Not sure where to go from here, there are a ton of threads on tranny adjustment, but they mostly refer to adjusting the Bowden. Any ideas?

[JamesDean]

It sounds like your car is shifting a bit late, at least compared to my 300SD.

I believe my 300SD shifts 1-2 at about 7-8 mph. Then 2-3 around 15-20 maybe, and finally 3-4 around 35-40.

Its been awhile since I've driven it but I think thats about right.

There is a kit avaialble with springs that one installs into various parts of the transmission to help with shift quality, one of the items it is supposed to address is stacked shifts.
http://www.superior-transmission.com/Product_Page.cfm?ID=19

[sleepstar]

dot for watching this thread later. my 3-4 is stacked really bad, about 3-5mph after 2-3, and i'm in 4th by about 25mph

[ivandrocco]

the quality of my shifts is good. they feel nice and solid. I think the 1-2 shift is at the right spot, more or less. The 3-4 also feels right. The 2-3 shift just comes too soon!

[tangofox007]

Originally Posted by ivandrocco

the quality of my shifts is good. they feel nice and solid. I think the 1-2 shift is at the right spot, more or less. The 3-4 also feels right. The 2-3 shift just comes too soon!

Under light load, the 1-2 should be well before 20 mph. Seems to me that your problem is a late 1-2 shift.

[ivandrocco]

Been messing around with the Bowden, so the shifts are slightly different.

Normal acceleration:

1-2 = 17mph
2-3 = 23mph
3-4 = 38mph

All shifts occur at around 2250rpm

Tango, just went to double check that my 1-2 was at 20mph under light load, and it's not. It shifts 1-2 at 20mph with the pedal punched. The delay also pushes the 1-2 shift from 2250 to 3000rpm. This still seems late according to your comment, but it feels good. I feel like i'm accelerating well in first and second, then it shifts early to third and is notably sluggish until I pop into fourth.

[tangofox007]

Here are the shift speeds in the 722.3 operations manual:

Idle: 13/22/33 km/hr
Full throttle (not in kickdown): 42/67/140 km/hr
(Gear selector in "D.")

[ivandrocco]

pardon me, but i'm assuming idle means "normal" acceleration?

so mph, approx:

idle: 8/14/21 mph
full throttle: 26/42/86 mph

If so, mine are WAY off. Does yours shift like this? Idle seem so low, and full throttle so highI'll report back with full throttle shift points in a bit.

[Govert]

Originally Posted by ivandrocco

Basically all that's hooked into the vacuum line is the shut-off, ALDA, and transmission. ?

Why is the ALDA connected to the vacuum?

[ivandrocco]

brain glitch on my part. the alda is not connected to the vacuum, but to to the exhaust manifold, per usual.

[JamesDean]

Originally Posted by ivandrocco

pardon me, but i'm assuming idle means "normal" acceleration?

so mph, approx:

idle: 8/14/21 mph
full throttle: 26/42/86 mph

If so, mine are WAY off. Does yours shift like this? Idle seem so low, and full throttle so highI'll report back with full throttle shift points in a bit.

I just drove my one 300SD today and its pretty close to those, give to take. All depends on how much you push the pedal.

Perhaps you've got your bowden cable too tight?

[Govert]

Originally Posted by ivandrocco

brain glitch on my part. the alda is not connected to the vacuum, but to to the exhaust manifold, per usual.

Why do you connect the ALDA to the exhaust manifold?

Anyway, it is good to read that it wasn't connect to the vacuum system, that might have caused problems.

Did you check the workings of the vacuum system with a vacuum gauge?

[ivandrocco]

I think the line to the ALDA runs from the exhaust manifold. This could be another brain glitch. It's because the ALDA is a diaphragm that actuates in response to pressure created by the turbo. Yes, I checked everything with a mityvac and it's good, except for the ALDA which leaks a little more than it should, but according to others here at peachparts not enough to effect performance.

[ivandrocco]

govert, at what RPM do the shifts occur?

[Govert]

Originally Posted by ivandrocco

I think the line to the ALDA runs from the exhaust manifold. This could be another brain glitch. It's because the ALDA is a diaphragm that actuates in response to pressure created by the turbo. Yes, I checked everything with a mityvac and it's good, except for the ALDA which leaks a little more than it should, but according to others here at peachparts not enough to effect performance.

The ALDA is connected to the intake manifold, so when the pressure in the intake manifold increases, the diaphragm of the ALDA is actuated and more fuel can be injected.

The VCV most work correctly, so 10" Hg at idle and around 0 at full load. The vacuum must respond directly and instantly upon movement of the accelerator pedal.

The modulator must hold vacuum.

Bad vacuum can cause problems with shifting, although the shift points are mainly controlled by the bowden wire.