4R75E Harsh Downshift

[dogememe]

08 CVPI, 167K miles, tranny fluid and filter done with genuine Motorcraft Mercon V about 15K miles ago according to previous owner. Fluid doesn't look bad but not super clean - to be expected since it was only a filter service, not complete flush. At full or near full throttle it shifts so hard it chirps the tires. Even at moderate throttle it's still a pretty hard downshift. If I drive gently it shifts fine... Is it normal?

 

[Colt45ws]

What gear? I wonder if somebody took the springs out of the accumulator, because that will make it shift like a sledgehammer.

 

[dogememe]

Originally Posted by Colt45ws
What gear? I wonder if somebody took the springs out of the accumulator, because that will make it shift like a sledgehammer.


i'm guessing 2nd, but i'm not 100% sure

 

[Colt45ws]

Thats downshifting into 1st its doing that. I wonder if its coming from 4th and its locking up the driveshaft as it brings the Forward clutch back on before it has dumped the OD band.

 

[dogememe]

Originally Posted by Colt45ws
Thats downshifting into 1st its doing that. I wonder if its coming from 4th and its locking up the driveshaft as it brings the Forward clutch back on before it has dumped the OD band.

That sounds really bad? Is it going to damage something? How do I fix that?

 

[JLTD]

I had a friend that had a poorly shifting transmission with the same mileage. He changed the fluid (pan drop and refill) and the problem returned in about 5000 miles. He repeated the pan drop/refill procedure 4 more times, the problem was gone for as long as he owned the car for another 100k miles or so.

Clean fluid can work wonders in an otherwise sound transmission.

 

[Linctex]

A normal (Factory) CVPI doesn't shift THAT hard!

I wonder if you have a broken accumulator spring

 

[Colt45ws]

Originally Posted by Linctex
A normal (Factory) CVPI doesn't shift THAT hard!

I wonder if you have a broken accumulator spring

I agree. Or someone pulled one of the springs. Or left it out. Possible rebuild? Maybe someone has tried to tinker with the EPC or some such non sense.

I dont know if you saw the video, but he was cruising around 30-40mph and matted it, it kicked down to 1st and squawked the tires. Thats the right speed range for a CVPI to be into OD which makes me think the forward clutch is coming on before the OD has had a chance to dump, causing it to try to lock the output shaft...

Hmm, OP, you should try that again, from the same speed, with O/D locked out and see what it feels like.

 

[dogememe]

I tried it with "OD OFF" and it's normal... Not harsh at all.

 

[JLTD]

Originally Posted by dogememe
I tried it with "OD OFF" and it's normal... Not harsh at all.


They said it had been changed, but they can say anything they want to. A fluid change is relatively inexpensive, so that might be something you want to check out.

 

[dogememe]

Originally Posted by JLTD
Originally Posted by dogememe
I tried it with "OD OFF" and it's normal... Not harsh at all.


They said it had been changed, but they can say anything they want to. A fluid change is relatively inexpensive, so that might be something you want to check out.

Yeah, I might do a pan drop and install an aftermarket plan with a drain plug while I'm at it and see if some more fresh fluid makes a difference. I wonder how hard it is to check the accumulator spring while I'm in there... I'll try to find a video on it.

 

[dogememe]

Just an update... I had the fluid completely flushed at Valvoline Instant Oil Change and it seems to have resolved the issue. At least on the drive home I tried to get it to do it a few times and it seems a lot better. Let's see if it stays fixed or if my transmission explodes because I had it serviced at a quick-lube place.