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Hello everyone. As you can see, I am new to this site, even though I have browsed many times before learning what I can about the 4R70W trans I have in my car. I am starting to have a few issues after 175,000 miles, and I was hoping someone here might could help steer me in the right direction as what to do next. First of all, my 4R70W is in a 2000 Mustang GT, not a T-Bird or Cougar, so I hope this doesn't disqualify me from you knowledge. The car has quite a few bolt on mods, and has been dyno tuned early in life, which included adjusting the parameters on the trans to shift firmer and hold the rpm's longer before shifting. This was done by a guy that worked at Ford and used to travel around and do dyno days throughout the country. He was also said to have worked on or had a hand in the design of the 4R70W while he was at Ford. From the time I bought the car till now, the fluid and filter have been changed 4 times and replaced with Royal Purple synthetic ATF fluid every time. I also drain the torque converter, but I haven't flushed out the cooler when I do these fluid changes. One week ago, I noticed that occasionally when driving along at around 40mph in 3rd gear, I would slowly start applying power and for a split second, feel a shutter(like hitting a series of rumble strips). Also, it seems as if I have picked-up a vibration that wasn't there before, along with an occasional weird howling noise when stopped at a light or moving slowly. Another symptom seems to be a slight whine that increases or decreases with engine speed. This reminds me a lot of the sound the old Trans Am cars used to make on TV that ran straight cut gears, only not nearly as loud. This couldn't have come at a worse time, because I am in the planning stages of getting a new car by mid to late summer, but I also need this one to be dependable in the mean time, and to be in good working shape by then when I sell it. By the way, when I first noticed the shutter last week, I immediately did a fluid change with the Royal Purple thinking it was a friction modifier break down, but the shutter is still present. I would really appreciate any information as to what you think is happening here, whether or not it needs to be addressed immediately, and any suggestions on how to go about resolving this. I could potentially do the work if it was something like replacing the torque converter, but if it is going to require a complete build, then I might have to find someone to do this. I live North of Atlanta Georgia, near Cumming Georgia. If anyone has, a recommendation of a (trusted) person that is experienced in rebuilding or diagnosing Ford transmissions, then that would be great.
 

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I am starting to have a few issues after 175,000 miles,

From the time I bought the car till now, the fluid and filter have been changed 4 times and replaced with Royal Purple synthetic ATF fluid every time.
a bolt on car that's driven aggressively should not make it to 40K before you change the trans fluid.

seriously 4 times in almost 200K?

if I were you I'd be doing it at 20K or 30K intervals tops.

your just experiencing normal fluid breakdown.
Purple color does not mean you ignore service intervals.

edit.. I just caught the last part of your very text heavy comment.

you probably have killed the friction material on the torque convertor because you extended the service intervals too far....

There is a slim possibility that after a couple of hundred miles it'll go away.
IN the mean time... do not try to "make it happen".. drive in a manner that the car "doesnt shudder"

If you keep "testing it" your definately going to KILL the convertor.
Treat it kindly for a week or two..and PRAY
 

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With that being a y2k mustang, it should have Mercon V fluid. I'm not familiar enough with royal purple to comment about it, but if you are using Mercon V type fluid and it is shuddering, then you have issues.

New torque converter, possibly including trans rebuild would be my guess.
 

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Get rid of the royal purple, and put just plain merconV in it. I am willing to be that will cure your converter shudder for at least 15K miles.
 

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+2 to the above 2 posts...

screw royal purple, put some good ole mercron 5 in it.
 

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I will put in my vote to get rid of all the RP that you can and put in a good fluid. Definitely at least Mercon V, but I am really starting to like Mobil 1 ATF.

But let's also consider that maybe it isn't the converter or transmission at all. It's possible that you have a failing COP causing a low grade misfire or a problem with the EGR system.

Darrin
 

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That is a very good point Darrin.
My 95 Mark when I got it had some shudder that turned out to be a bad plug wire that was breaking up..
It "sure" felt like the rumblestrips shudder, but it wasn't I got the "real" shudder later on.

Mob1syn is good stuff too.
 
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