Torque converter early lock up

I'm not sure what the connection is between teh shudder problem and the early lock up. My 99 locks up too early as far as I'm concerned (and sometimes immediately unlocks) but never shudders. I've never seen a "fix". if you find one, please post it.

As far as I understand from a Ford mechanic, the TC locks up too early, and then, upon taking your foot of the gas, unlocks and locks up again, hence the shudder, together with a sort of clunking sound. Only happens when TC locks up b/w 30-45mph in OD, no problems at 50+ mph. Any thoughts?

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The shudder I've always heard talked about was a part throttle shudder, not a foot off the gas shudder. But you may be getting more or less the same thing I am, which I think it mainly an error in how they programmed the computer. It's all computer controlled and I think what happens is that based on all the sensor inputs the computer tells it to lock up, then after it's locked that changes the load/rpm relationship of the engine, which changes the sensor readings, which tells the TC to unlock. I suspect the only fix is to get used to it. Possibly a transmission rebuild would have some effect but it's a pretty expensive diagnostic approach.

I agree. my 06 GT has a shudder problem also. But is not the TC. My Shudder is wheel hop.

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Re: Torque c>As far as I understand from a Ford mechanic, the TC locks up too early, and

The shudder I've always heard talked about was a part throttle shudder, not a foot off the gas shudder. But you may be getting more or less the same thing I am, which I think it mainly an error in how they programmed the computer. It's all computer controlled and I think what happens is that based on all the sensor inputs the computer tells it to lock up, then after it's locked that changes the load/rpm relationship of the engine, which changes the sensor readings, which tells the TC to unlock. I suspect the only fix is to get used to it. Possibly a transmission rebuild would have some effect but it's a pretty expensive diagnostic approach.

Thanks, appreciate the reply. Funny thing though is that it only does this below ~45mph in OD. Wouldn't it make sense to have the PCM reprogrammed to only engage TC lock up >50mph, for example?

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It would make sense in a normal world but I'm guessing that kind of change would potentially affect the EPA Mileage numbers which would mean they would have to rerun some series of tests at great expense. So they just say "screw it". There was a company advertising an electronic gizmo that would delay TC lockup but they never brought it to market for the 99 and newer vehicles. They did have such a gizmo they sold for older, less computer intensive, transmissions.

It would make sense in a normal world but I'm guessing that kind of change would potentially affect the EPA Mileage numbers which would mean they would have to rerun some series of tests at great expense. So they just say "screw it". There was a company advertising an electronic gizmo that would delay TC lockup but they never brought it to market for the 99 and newer vehicles. They did have such a gizmo they sold for older, less computer intensive, transmissions.

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Thanks man, I'm afraid you're right.

I've posted a take from another Mustang forum, although these guys talk about the older, pre-99 series Mustangs. Don't know if it's applicable, but thought it's interesting nonetheless...

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Torque converter clutch shudder in AOD-Es in 94 through 98 Mustangs is a know problem. Ford has issued about three or four different Technical Service Bulletins regarding the issue, but no recalls!

At any rate, the symptom is a shudder coming from the transmission (feels kind of like you are driving over a series of those little speed bump strips) when you are driving at ?light to moderate throttle? (the words in the TSBs).

The problem as stated by Ford is two-fold. The first cause is a breakdown of the friction properties of the older Mercon IV and earlier transmission fluid due to heat build up. The second cause is undersized friction plates in the torque converter clutch in the torque converters on all AOD-Es from

94 to 98. The combination of these two problems results in a grabbing-slipping, grabbing-slipping, etc. of the torque converter clutch during shifts at light to moderate throttle. As soon as you ?get on it? the shudder goes away!

I had this problem on my stock 95GT. I followed all the advice in Ford?s TSBs. Replaced the tranny fluid with the new synthetic Mercon V and installed an auxiliary tranny fluid cooler. For the first 2,000 miles after that, I had no more shudder, so I thought it was fixed. But then it came back. (The Ford TSBs say that if the symptom returns within 10,000 miles you have to replace the torque converter because the clutch is just too far gone.)

At any rate, I wasn?t about to go through that expense yet, and I heard about a product by LubeGard called, ?Dr. Tranny?s Instant Shudder Fixx?, that was supposed to work some magic on the tranny and stop the shudder. It?s a small 5? long red tube of what looks like regular tranny fluid, but its actually a friction modifier that acts on the torque converter clutch friction surfaces. About $10.00 to $15.00 bucks a tube depending on where you get it.

I put one tube of that stuff in my transmission, cycled the gear shift lever through the gears, backed out of the driveway, and drove off. No shudder!!! Gone!

So, for $10.00 bucks or so, I?d say give it a shot. It?s only 2 oz. of fluid so you won?t have to drain any out before adding it. Just add it to what?s in there now.

If you can?t find the stuff at a transmission shop, here?s their web site. You can buy it direct from them on line.

From their home page, go to Transmission Products, then to the link for Dr. Tranny?s Instant Shudder Fixx.

After about another 2,000 to 3,000 miles the symptoms returned. After that, even another tube of this stuff would not stop it. The problem is that the torque converter clutch friction plates are just too burned/glazed to recover.

You?ll eventually have to replace your torque converter.

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