2-3 shift flare issue. | Ford Explorer Forums - Serious Explorations

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2-3 shift flare issue.


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November 9, 2009
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Boynton Beach, Fl
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Hello Everyone!

First time....first post. Looking for some help for my 01 Sport Trac - transmission slipping between 2nd and 3rd when accelerating. It just started yesterday. I've read several posts & find it refreshing that I'm not alone. As a matter of fact I've just read this is called the "2-3 Flare" problem. Recommendations: 1) replace valve body gaskets or 2) change the shift solenoid malfaunction. Can anyone validate either of these 2 recommendations? Thanks.

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Welcome to this forum! I've moved your post into its own thread in the transmission section. There are many factors involved in a shift flare. It's a loss of hydraulic pressure in a specific gear range. A worn valve body, leaking servos or bad gaskets could cause this problem. Sometimes replacing the EPC solenoid might help. Other times you might need a new boost valve, end plugs with O rings, and servos.

I've rebuild mine and lasted about four months and the flare issues came back. Lots of work and time consuming but you'll learn a lot but I'm not going to do it again anymore because of my back. Follow the "rebuild diary" and you can't go wrong. Good luck!

O.K. heres a good one. My 93 EB was using trans fluid but not leaving a puddle. Got on this forum and found out if the vac modulator diaphram is bad, the engine will suck the fluid into the intake and burn it. I cut the exhaust off so I could get to the mod, and replaced it.I put an adjustable one on, got it from Precision Transmission,$25. Would not shift at all, only manualy. I called my exhaust guy to replace the piece I cut out and told him what was happening. He said what I did should have fixed it, he has put them on and had no problem, "it ain't rocket science", as he put it. So he gets one from Autozone same money and it works. Great. So now I have the "flare" problem when shifting from 2-3. It revs about 500 R.P.M.s between shifts. 1-2 is smooth as glass, 3-4 is fine and it NEVER did this before.Was I just lucky? I have tried adjusting it with no luck. My truck has 135,000 with regular maint, and I threw a quart of Trans-X in when I topped off the tranny. Oh and I changed the oil, it had about 6-7 quarts in it, so it clearly was not burning all the fluid. I am lucky I did not have hydraulic lock up! Any help would be appreciated.

Uhmm, no. I wiped the pin off, and replaced the small section of hose attached to the modulator. So do I need a wire brush small enough to fit the hole the pin goes in ? I am not very tranny savy as you can tell, so thanks for all the info.

Will do. I hope this works because if it does not it sounds like there could be a few other problems that are all more costly. Does it hurt the tranny to leave it that way? It seems like the "slip" between shifts would damage the discs eventually.

Bummer, thats what I figured.I see many visits to the forum in my future. Thanks again.

a4ld shift flare after changing modulator


I am having the exact same problem after changing the modulator.
My 91 2wd Explorer now has a "flare" at about 18 mph.

Will cleaning out he transmission bore where the modulator pin travels fix this??

My trans wouldn't shift until the engine/trans heated up a bit. This would be after a mile or so... then it would operate normally. I replace the modulator, finding the vacuum line full of fluid.

The trans works fine exept for the "flare". Any other ideas as to the cause???

First lets get back to alcapjet's tranny which by the year mentioned is some variant of the 5R55E or newer. These trannys are electronically controlled and so I recommend getting some pressure readings of the EPC and line pressure before replacing any parts. I am assuming you have the proper fluid and level-Hot. Any codes stored or pending?

a4ld shift flare after changing modulator


Thanks for your information. Here is the answer you requested about my 1991 Explorer 2wd.

I'm a car parts man with decades of experience and bought the part from a trusted supplier. It appeared to be an exact replacemtent. I purchased it from O'Reilly's, car line PIO, part #747008.

When I changed the modulator yesterday, I put it in without knowing about the pin. That's when the flare showed up last night. This morning, I reinstalled the modulator with the pin that I found laying on the ground under the truck. It had fallen on the ground. I didn't know to clean out the bore or lube the pin. I did hold it in place with a small amount of vaseline, put on the end of the rod to hold it into the modulator while I installed it.

I drove the truck about 30 miles on the interstate this afternoon, let it sit about a half hour and drove back the same route. The truck shifted perfectly normal after the long trip.

After the truck sat for about 3 hours tonight, I just drove.... It's now shifting at a higher RPM than normal. The flare issue seems to be gone now...

Any ideas???????

The transmission fluid is used is Mercon V from OReilly's... only to top off fluid lost when removing the modulator

a4ld shift problems

I got up in the middle of the night........ drove the truck........ It is shifting late, at higher speeds and higher RPM's. It didn't flare last night..

I bought this 91 Explorer used from my neighbor. It looks like it's time to see if she ever had the filter/fluid changed. If so, I will go ahead and do this....if not, I don't think that I will have it done since the detergent in the ATF is known to cause problems if the fluid hasn't been changed.
A darn good parts man I know says his Ford did this when the filter was stopped up.

Do you think that the modulator I got could be a poor brand and should be changed with a better brand part? Should I take it off clean out the trans bore with a brush and wd40 the shaft?

Or if the flare seems to be gone, maybe it's time to do what my transmission shop say... that is to bring it in for adjustments and inspection.


a4ld shift problems

UPdate on the 91 Explorer...

I just drove the truck about a quarter mile this morning and the darn thing shifted fine............... What the heck is going on ???

I did find out that the truck has serviced regularly so I will go ahead and change the atf/filter this weekend.

If it still acts up after that, I will maybe clean out the modulator bore and lube the pin.... and then take it to a shop if it continues.

Any ideas?????????????????????

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4ald transmission

This evening the trans acted up again.... It took about 1/4 mile for the trans to shift, then it was fine for the rest of the night.

My mechanic friend thinks it's the speed sensor on the side of the transmission. Any experience with this?

What servos are you referring to, and where are the servos????