Help diagnosing 4R70W shudder | Ford Explorer Forums - Serious Explorations

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Help diagnosing 4R70W shudder


New Member
May 31, 2006
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City, State
Daytona Beach, FL
Year, Model & Trim Level
1996 Explorer XLT
I've been reading a LOT of stuff over the last few weeks here regarding the 4R70W transmission. I'm learning a ton from the rebuild diaries but I still can't seem to nail this shuttering problem that I'm having.

A few months ago I picked up a '96 Explorer - V8 with the 4R70W trans (113k miles). A few weeks ago it started shuddering. I'm no transmission expert but it seems to start the shudder at the top end of my acceleration - almost at the point where it wants to level off the speed while my foot is still on the gas (maybe this is when it's shifting into OD??) I tried turning OD off and it still does it but not as bad. Reverse works fine and shifting from 1 to 2 is pretty smooth. If I let off of the gas while it's shuddering, it stops.

So, after reading these forums, I decided to try changing fluid/filter and changing to a Merc V fluid. I don't have the history on this vehicle but I am pretty sure that the fluid was never changed (113k miles - yikes). My fluid change consisted of dropping the pan, draining the TC and blowing air into the lines to the cooler. I was able to get around 11 qts out. The pan still had that little plastic plug that comes from the factory, this is why I think it was never changed. The fluid was still pinkish, didn't smell burnt but was pretty dirty looking. Here's the thing that I'm worried about... the magnet had some superfine metal 'dust' stuck to it. It was almost like a metal paste - like a toothpaste consistency. The entire magnet was covered in about 1/8" of this stuff. There were no big metal shavings, I even cracked open the old filter and I didn't see anything of concern. I installed the new dacron filter and Mercon V and all of the levels seem ok (although that dipstick is a pain to get an accurate reading from).

After the fluid change, it ran great and didn't shudder for about 15 miles, then it started shuddering again.
I haven't tried pulling any codes yet - I guess that's my next step. From reading, it sounds to me like it might be the EPC solenoid or a band or something.

I'm thinking about pulling the valve body and rebuilding it. This is my daily driver though and if I can easily rebuild the valve body in one weekend, I'll do it... I just don't know if I'm going in the right direction or not.

Anybody have any suggestions for me? Thanks in advance!!

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The 4R70W has a history of torque convertor clutch shudder problems, which is what you are experiencing. Sonnax has two products that if used together may likely fix your problem. They offer a pressure regulator replacement valve and a spring for higher line pressure. They also offer a bypass clutch control valve replacement. Total cost for the pair is about $50. I recommend this fix.

You can also try Lubegard's "Instant Shudder Fix". People report good results with it.

There is also an electronic gizmo on the market that is supposed to address this problem - it costs about $50 but I have no experience with it.

Ford has issued several TSB's on this subject, but they mainly deal with switching over to Merc V, which you have done.

Don't worry about the metallic paste - that's pretty much normal.

Thanks Glacier! Your rebuild diaries have taught me a lot about how these things work. I used to be pretty intimated by them but they really don't seem to be that bad to work on.

I just want to make sure that I'm getting the correct parts:

1.) Main Pressure Regulator Valve and Spring:

2.) Transmission Bypass Clutch Control:

Are these the parts that you are referring to? Also, should I just go ahead and get a new EPC solenoid and replace it while I have the valve body taken apart? or would that be a waste of time and $? Thanks!

Yes those are the parts. The EPC in the 4R70W is not prone to the problems that the 5R55E experiences, and is of an entirely different design, But then, of course the part only costs about $35 to replace too.

I am doubtful your problem is in any way related to the EPC, but if you would feel more comfortable replacing it while you are in there "just to be safe" I cannot argue.

ps, in the 4R70W the EPC sits in the case itself, not in the VB.

Glacier, can you describe how the shudder would feel like?

It is like a staccato interruption of the smooth flow of power.... maybe rulouder can take a stab at a description.. BAD shudder can feel like a series of lurches or jabs of power....

To me, it feels just like when you drive over those 'rumble strips' that they put in the road to keep you from crossing over the center line... like these:

BTW - I ordered those suggested parts, only cost me $50 with new VB gaskets. I'll be working on it this weekend and I'll post back with results.

Thanks again for everyone's help - this forum is extremely helpful!!

I think you are going to find your problem will be solved. No guarantee but I'll be surprised if it is not. Don't forget that the "Instant Shudder Fix" does help. I am not a believer in what an old time pro called 'Smokey' Yunick called "mouse milk" fixes, but the shudder is a complicated thing that occurs at the friction/steel/fluid interface.... and the Lubegard guys understand that science real well.

ps. I knew you'd do a better job describing it since you are living it!

pps. Anyone who puts pix in their posts automatically gets my vote !

Don't overlook the possiblity of a bad spark plug or wire. Feels very similar. But if the shudder went away for a short time, I think you're on the right track.

Bent Bolt! I was hoping to hear your input.... confirming or otherwise. And Ya know I once had someone complain about a "shudder" at high load only to have it be ignition related. Your insight is always good. Thanks.

(The things I never think of.)

Don't overlook the possiblity of a bad spark plug or wire. Feels very similar. But if the shudder went away for a short time, I think you're on the right track.

That is a possibility - I would be willing to bet that these are the original plugs and wires as well. It was on my 'to do' list... just got moved to the top. Sounds like I'll be busy this weekend! :D Thanks again for everyone's input - it is much appreciated!