5r55e long hesitation going into forward gear

[Ngrimm]

Forscan shows no fault codes. There is no delay going into reverse and the transmission works perfectly once it finally goes into drive. Also it doesn't matter which forward position the shifter is in. I have checked both line and EPC pressures and they appear to be within spec and don't really change while I wait for it to engage. The delay can be up to 30 seconds when cold and as little as 5 seconds when warm. If I blip the throttle a little it will engage quicker which I assume is due to higher pressure. I don't like to do that since it jerks into gear. So I'm trying to figure out whether the problem is more likely to be caused by a valve in the valve body sticking or leaking as opposed to a piston seal etc. Any ideas? Norm

 

[Tech By Trade]

Check your fluid

 

[Ngrimm]

Check your fluid

I previously replaced the filter and filled the trans with fluid. I think the trans had been sitting for a while as it came from a wrecked truck. Thank you.

 

[Ngrimm]

I ordered valve body gaskets today. I have a spare 5r55e from slightly older truck. I figured I could put that valve body in the 5r55e since it is supposed to be the same. Anyone know of a way to test the forward clutch piston using air pressure without having to buy a test plate?

 

[Ngrimm]

The whole thing started when I had to swap out the transmission since the one that was in the truck turned out to be a slightly older 5r55e and it didn't doesn't have the center speed sensor (I don't recall which one that is) and it would throw a code. The seller told me it needed a new sensor but he didn't say it was because it had the wrong transmission. He included what he said was a good transmission out of a wrecked truck. That one has the middle sensor. I took his word that it was good so I now have the correct transmission with no codes.

Since it hesitated going into drive, I replaced the valve body with the one from the good albeit wrong transmission that I pulled out and it seems that the problem changed a little. It is still very slow to engage in the D position when warm but R, 1 and 2 respond pretty quickly. When cold it works pretty well. When warm If I start out in manual 1 or 2 and then switch to D, all is good. The line pressure seems high enough but while waiting for 1st to engage in D, the gauge vibrates and the needle flutters. Once it engages, the gauge is smooth again. Epc pressure is smooth. Thank you for any help. Norm

 

[Ngrimm]

I decided to remove and rebuild the transmission. The good thing is that I have the other transmission for parts. I thought about getting a j/y transmission but who knows how good it would be. I read the 5r55e Rebuild Diary and watched several videos. Norm

 

[Ngrimm]

I found my problem. The forward clutch pack was smoked but everything else looks pretty good.

 

[Ngrimm]

Between the two transmissions I salvaged enough good steels and bands so that with a set of Borg Warner disks and a Precision gasket and seal kit I got it put back together. One of the copper seal rings for the forward clutch bearngs was worn thin so I think that may have contributed to the clutch failure. I really like the Precision kit, especially the seal rings. The ends over lap instead of having a gap. When I air pressure tested the clutch pack through the center support it took very little air to make it engage. I went ahead and got a rebuilt converter and a bonded separator plate because of what I learned from this forum. Plus I bumped up the EPC pressure slightly and removed the forward engagement spring from the valve body. I noticed when I had the exhaust off the truck that one catalytic convertor was plugged with what must have been burnt oil I guess so I fixed that. So far it is running and shifting great. I was surprised how well this thing moves now even with 35" tires. Btw, I found an easy way to air test the the clutch packs without a test plate. I took some pics but haven't uploaded them yet. Thank you. Norm