problems upshifting on my 87 300D
 

I have a problem with upshift on my 87 300D
It shifts fine from first to second. When it is time to shift from second to third, it hangs. It will hang until it gets well over 3500-4K RPM before it shifts(depending how hard I am accelerating) Then, when it does shift to third, it goes immediately into fourth.
I can lift on the accelerator, and it still doesn't shift from second to third until I re-accelerate. I can also put the gear selector in third, and then it will stop in third gear, and then I can manually put the selector in Drive, and it will shift into fourth at the appropriate time.
Some people have told me that it is the modulator, but if that were the case, wouldn't it have issues shifting into all the gears, not just one?
Some have suggested vacuum, but I dont have any other vacuum related issues, and then again, if it were vacuum, wouldn't it have issues shifting into all the gears? I have put a vacuum gauge on the vacuum line going to the modulator, and it holds vacuum just fine, so I dont think there is a pinhole, or anything else wrong with the modulator.
If it were the filter, again, I would think that it would have issues shifting into all the gears.
I use dextron III with Mercron. The fluid level is full, and the fluid look very clean, and no burning smell at all. I have taken the pan off, and the pan is also clean(no metal shavings, dirt, etc in the bottom of the pan)
I suspect that one of the Bands needs to be adjusted. Can the Bands be adjusted externally on this trans??
Any thoughts/comments?? Thanks

A problem I found on mine was a sticking Kickdown Switch behind the Accelerator Pedal. It was dirty, with some of the carpet fibers caught inside, and wouldn't release all of the time. Once I cleaned the switch, and trimmed the carpet, there were no more issues.

Thanks, Sam. I disconnected my Kickdown several years ago, that is not the problem here. I have also adjusted the Belden Cable with no success.

There is a table on the forum that shows the K2, B2, etc and which are used on each shift. Maybe that would help to spot the problem.

Have you changed the ATF and filter in the last 15k miles? What brand filter? If you didn't use a Mann or MB-from-the-dealer filter, other filters have a nasty habit of collapsing which causes all kinds of shifting problems.

My '87 wagon shifted very poorly when I got it, I changed ATF and filter, used the Mobil 1 synthetic ATF, and over the next several thousand miles the transmission shifting got better and better and better until it was nearly perfect. Others have reported that the Febi ATF will have a similar effect.

This could be an issue with the famous K1 accumulator spring (search the forum for it). It'll cause extremely crappy 2-3 engagement with late engagement, really sloppy/slow engagement, or flaring during the shift.

My SDL had hideously horrible shifting before I serviced the transmission. K1 accumulator spring was broken into 3 pieces. Changed that out, new filter and cheap-o Valvoline Dex III from Wal-Fart and it drives like a completely different car, nice crisp and firm gear changes. No more sloppy engagement or horribly late/hung shifts. 3-4 still happens a bit early for my liking in slow traffic, but I attribute that to a gearbox with 200K+ on it.

Thank you for the replies\input.
Based on the responses, I think I will change the oil/filter and spring.
I see that Pelican Parts had the K1 Accumulator Spring Kit for bout $7.35. Wouldnt it be wise for me to change out all the springs?? (B1, B2,B3, K1, K2 while I have it apart??


Maxbumpo-I have never changed the filter or oil because the oil is clean, and it is obviously pumping oil. I think I will change it anyway.

Thanks again.

I changed the K1 Accumulator Spring yesterday, The original one was not broke, and it was about the same length as the new one. I changed it anyway.
No change in the way it is shifting.

Any other ideas??

Have you adjusted your bowden cable that will affect your up shifts.

Did you ever check the chart to see exactly which ones are involved in the problem shifts? Obviously it was not your k1 but the chart might help.

I don't think it's the Bowden cable, because if it was all the gears would shift late. I would bet it's internal wear on the k2 clutch. These boxes are pretty easy to rebuild if that's the case. I did one on early 90s SL in about an hour on a bench.

transmission chart?
 

I'm looking for this chart too.
Anyone know the location?
Or good search words?

Thx

Transmission shift chart
 

Wow; that was really hard but I finally found it.

The chart is in this thread.

www.peachparts.com/shopforum/diesel-discussion/327394-722-4-transmission-now-shifts-first-fourth.html

Thx