Is it time for a trans?

stroke6.0 · Jun 26, 2014

I have 215k on my truck, had a sct with gearheads tunes for 10k miles was stock before that. I recently started to notice that SOMETIMES, it has a delay going into reverse then would clunk in. Iv always had a firm engagement into drive since a tuners been on it. Iv changed to different tunes and still does it. I reset trans adaptive tables and also put a direct solenoid in it. It seem ok for about a day with new solenoid now it's back to it. It seems like of you start it up and drop it on reverse it goes in, but if you have to go forward and backwards to get out of a parking spot or something by the third time it's got the delay and is super firm going in. When your in drive every shift is perfect. It doesn't skip a beat or slip. The fluid wasn't bad either. Is there anything else to look for or am I looking at a build ?

Mark Kovalsky · Jun 26, 2014

That type of problem is almost always a sticky solenoid. Sometimes new MERCON SP or MERCON LV fluid will fix it, sometimes it needs a new solenoid. The reverse engagement is controlled by Solenoid E in this photo:

stroke6.0 · Jun 26, 2014

Does that mean it's sticky and once I'm going it's fine and that's why I have no shifting issues?

Mark Kovalsky · Jun 27, 2014

You have no shifting issues because you're probably not shifting to reverse going down the road. If your issue is only with reverse engagements the solenoid that is suspect isn't used when shifting going down the road.

MrOneEyedBoh · Jun 29, 2014

Hey mark... Aren't you the 5r110 engineer or something? I'm sure you touched on this, but what's your outlook on the nodded DD solenoids? Are they worth the hassel if you have no issues? Do the act as a preventive item, or if the trans is going to fail...its going to fail regardless of the DD solenoid?

Mark Kovalsky · Jun 30, 2014

I have heard about modified direct solenoids. That's all I know about them.

MrOneEyedBoh · Jun 30, 2014

What do you think about the added pressure it applies? Good/bad?

Mark Kovalsky · Jun 30, 2014

Just adding pressure is always bad.

The 3-5 shift is a synchronous shift. That means that the intermediate solenoid must release the intermediate clutch as the direct solenoid applies the direct clutch. If you add pressure to the direct clutch it will apply faster. If it applies any faster than stock then the direct clutch will come on before the intermediate releases. This causes a tie up. A tie up is where ALL elements of the planetary assembly are held to the case. The output shaft stops turning RIGHT NOW and either the wheels skid or parts break.

Since I haven't heard of a lot of failures from these modded solenoids I have a couple ideas of what's happening. First, the adaptive software will recognize that the direct clutch is applying too fast and reduce the commanded pressure. This will get the pressure right back to stock. So how does the modded solenoid help in this case? The pressure is going to be the same in the end with either a stock or modded solenoid.

The only other thing I can think of that wouldn't cause failures as soon as this solenoid is installed is that they really don't add pressure. But I'm just guessing, I don't know ANY details about these solenoids.