Upgrade transmission ?

[jon_s_brady]

I have an 05 Ford Explorer XLT with the 5R55S transmission. From what I can tell it is the 3.55 gear ratio (sticker on the door says "45"). I'm getting clunking - particularly when reversing out the driveway of a morning and what I think is slippage (car seems to rev a lot higher for given speed than before). That car has 146k on it now. I'm figuring I'm up for a new/re-conditioned transmission if I want to keep the car. Since it's in great condition otherwise it's worth the expense in my books.

The thing is...I want to tow a 4500 boat and trailer with the car. My reading of this and other forums leads me to think I need a 3.73 gear ratio with limited slip as it can handle up to about ~5500 lbs of trailer.

Does the 5R55S come in both 3.55 and 3.73LS? Or do I need a different model transmission? Are there any tricky problems in putting a different transmission in this vehicle? I'll probably do it myself with a re-conditioned transmission. I've re-built engines before and do most of my own maintenance including changing manual clutches but an auto transmission will be a first...

Advice is welcomed!

 

[tower]

The tranny does not care what rear end you have. I have towed with the 3.55 with no issues, you can change the rear if you want but you will need to change the front as well (if you have a 4X4).

Where is the clunking coming from? I had a clunking in my 02 and it was the rear end.

Changing out the tranny is not bad except for the cross member bolts (they break) and you need to line up the flex-plate and TC (there is a tool to do it $$).

 

[jon_s_brady]

The clunk sounds like it's directly below me. The situation is that I'll get in the car, turn the engine on, do up seatbelts etc, put a foot on the brake and shift it into reverse. I'll put my foot on the accelerator and give it some gas but the car will sit there for a moment or three and then with an almighty clunk shift into reverse and start moving. Often when I'm on the street and ready to move forwards, I'll then shift the car to D and it will again hesitate before jumping into gear and taking off like a startled rabbit...the strange thing is that this may or may not happen. Sometimes it works just fine (and smoothly).

Any ideas?

 

[Mr Dubya]

Any ideas?

Sounds like it might be in need of a new solenoid pack (reverse is known for going first). Easy replacement. A good search on the forums will turn you up lots of info.

That's from my limited experience and research. Consult a second opinion sir.

 

[roush9799]

Sounds like the pack to me too. Mine is starting to hesitate a bit, I'm gonna have to do mine before long too. I need to change the fluid out anyways.