Hello all - there have been a few posts recently about hard shifting automatic tranny's so i thought i would post the fix for my problem.

After replacing my Idle Stablizer Valve in my 87 S4, i found myself with a high, but stable idle (around 1500 RPM), and a hard-shifting transmission. I dug around the vacuum connections, and found that the vaccuum tube connected from under the intake to the 5 way splitter was disconnected (of course, it was disconnected under the intake ). So, back off came the intake and i connected it back up. Buttoned everything back up, took her for a test run, and the idle was better, but the shifting was as hard as ever.

So, back to the detective work. Tested the vacuum for the line from the 5 way splitter back to the transmission - no vacuum. Took the vaccuum connection off the transmission - was a bit chewed up, but looked ok. Plugged that connection and tested again - still no vaccuum. The vaccuum line runs along the top of the torque tube, and is a combination of plastic vacuum line, flexible rubber vaccuum line, and metal vaccum line, but I could not get my hands up to the top of the torque tube to check for problems.

Well, i resigned myself to pulling off of the exhaust, and the heatshields to get to the top of the torque tube, and lo and behold, the connection from the plastic vacuum line to the metal vaccuum line was completely disconnected! There is no way i could have checked this without a full exhaust removal - crazy in my opinion. Hooked this up, tested vaccuum, and finally had it (except it wouldn't hold vaccuum). So I clipped about 1 CM of the chewed up rubber line into the transmission, reconnected, and had full vaccuum that held for 20 minutes.

Reinstalled the heat shields and the exhaust, took her for a spin this morning, and all was well - nice and smooth shifts - amazing!

Hope this helps someone in the future - if you don't have vacuum from the 5 way splitter all the way to the transmission, you have 3 connection points to test, plus the vaccuum lines themselves - anyone of these could be the culprit Good luck!

Here is a picture of the nasty bugger that was so hard to get to...

 

You certainly have better self-control than I do. I wouldn't have had the patience to get that picture!!

By the way.... what is that open piece of pipe poking through the grommet behind the torque tube?

 

What a bugger to get to. I remember seeing that coonector when we pulled Big Dave's engine and thinking, "Boy, I sure would hat eot have to get at that little guy." Good job!

 

Thanks guys - it has certainly been challenging - felt great to have a smooth shifting car again. Huge pain in the butt, but i guess we don't love these cars because they are easy to work on

Brian - i have no idea what that that leadss to - i imagine it contributes to my heat issue in the cabin - which is why i stuffed a bunch of insulation up there. Maybe something to do with a 5sp tranny?

 

Good find Bill -- so many fixes with these cars are easy -- once you dig your way into where the part is! BTW, that tube is the drain from the AC, I believe.

 

Hey Bill,

Are we talking about the car that was involved in the semi timing belt change? If it is, glad to see it's back on the road.

 

Yep, AC drain tube.

 

Hey John - no, this is my 87 A/T - my 88 5sp is still in the garage awaiting a new timing belt - slow but steady progress :-)

 

Putting it back together is easier and a little faster. (edit: sorry, missed your thread about the cam gear). Let me know if you need any tools, help, etc.