Question for H.T. - Transmission Trouble

I have a Santa Fe with the 3.5L engine with the 5-speed transmission that takes that world famous Mitsubishi fluid. Lately, at about 40 mph, my transmission (which I suppose could also be the differential or even better,
the lock-up torque converter), has been giving me a "shudder" when I am "cruising" (not w. cruise control - neither accelerating or decelerating). I can stop it by usually accelerating, making it shift to a lower gear. It doesn't seem to be a problem above 50.
I have not known or heard about this transmission giving trouble. But I don't know what to think, and am heading for a longer trip soon.
The vehicle has 108,000 miles on it, so it is "JUST" out of warranty (of course). Yes, I have changed the fluid every 30,000 miles.
Ideas?
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Sounds like torque converter clutch shudder. This is caused by a slip/ stick of the torque converter clutch. I thought I recalled a reprogram to address this condition, but a quick check revealed that it was for 2.4 and 2.7 Santa Fes.
Torque converter clutch shudder was the original reason Hyundai switched from Dexron fluids to Mitsubishi fluid. If it has been a while since the last fluid change, you might try a flush to see if anything changes. If it doesn't go away, I'd say you're probably looking at needing a torque converter replacement. With the price of new converters, it's not likely to cost much less than an entire remanufactured transmission. I don't normally recommend things like this, but if the condition doesn't get better with a flush, perhaps add an aftermarket (such as BG) fluid conditioner or friction modifier to see if the condition improves. Do this only if you've verified that the converter or transmission is the cause of the issue. There's no guarantee that the additive won't negatively affect other facets of transmission operation, so it should be done only if you'd be looking at a replacement transmission anyway.
As for the trip, I'd say to take another vehicle unless the issue has been resolved. An slipping converter can cause a transmission to overheat on long trips, potentially leading to other failures or a breakdown.
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Ouch - that is not what I wanted to hear, though I understand it is what I need to hear.
Will try a fluid flush & change - VERY SOON!
Thanks for the info.
wrote:

Sounds like torque converter clutch shudder. This is caused by a slip/ stick of the torque converter clutch. I thought I recalled a reprogram to address this condition, but a quick check revealed that it was for 2.4 and 2.7 Santa Fes.
Torque converter clutch shudder was the original reason Hyundai switched from Dexron fluids to Mitsubishi fluid. If it has been a while since the last fluid change, you might try a flush to see if anything changes. If it doesn't go away, I'd say you're probably looking at needing a torque converter replacement. With the price of new converters, it's not likely to cost much less than an entire remanufactured transmission. I don't normally recommend things like this, but if the condition doesn't get better with a flush, perhaps add an aftermarket (such as BG) fluid conditioner or friction modifier to see if the condition improves. Do this only if you've verified that the converter or transmission is the cause of the issue. There's no guarantee that the additive won't negatively affect other facets of transmission operation, so it should be done only if you'd be looking at a replacement transmission anyway.
As for the trip, I'd say to take another vehicle unless the issue has been resolved. An slipping converter can cause a transmission to overheat on long trips, potentially leading to other failures or a breakdown.
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Another thing to check before you get into this too deep. At that speed (40mph) it could just be the engine lugging due to low RPMs and the torque convertor locking up. An easy check is to disable the TC lockup and see it it goes away. I haven't had the occasion to look on the Hyundais to find the way to disable it, but on some of my other cars it was as simple as disconnecting a connector.
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First thing I did was flush with Diamond ATF SPIII. Problem (so far) seems to be gone. If not completely in a month, I will drain a 2nd time, and refill, substituting a quart of some kind of transmission conditioner (a couple of people around here are recommending Lucas - comments H.T.?).
But if I didn't know better, the problem is solved. Maybe I got to it in time. Time will tell.
wrote:

Sounds like torque converter clutch shudder. This is caused by a slip/ stick of the torque converter clutch. I thought I recalled a reprogram to address this condition, but a quick check revealed that it was for 2.4 and 2.7 Santa Fes.
Torque converter clutch shudder was the original reason Hyundai switched from Dexron fluids to Mitsubishi fluid. If it has been a while since the last fluid change, you might try a flush to see if anything changes. If it doesn't go away, I'd say you're probably looking at needing a torque converter replacement. With the price of new converters, it's not likely to cost much less than an entire remanufactured transmission. I don't normally recommend things like this, but if the condition doesn't get better with a flush, perhaps add an aftermarket (such as BG) fluid conditioner or friction modifier to see if the condition improves. Do this only if you've verified that the converter or transmission is the cause of the issue. There's no guarantee that the additive won't negatively affect other facets of transmission operation, so it should be done only if you'd be looking at a replacement transmission anyway.
As for the trip, I'd say to take another vehicle unless the issue has been resolved. An slipping converter can cause a transmission to overheat on long trips, potentially leading to other failures or a breakdown.
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I don't really know anything about the effectiveness of any of the additives at eliminating slip. I'd guess that if it works, it's probably only a short term solution. That's another reason I recommended this only as a last ditch attempt.
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Update: After getting quoted a price between $700 - $1100 for a van/SUV rental for where I was going and how long I was going to be gone, and after having gone about two weeks without even one further peep out of the tranny, decided to take it on vacation anyway - against your advice.
Put 3,000 miles on the Santa Fe, including driving through the Appalachians with a luggage topper and full of passengers. I had no problems whatsoever. The fluid problem seemed to solve the dillemma.
Thank-you again HT for your useful insight.
wrote:

Sounds like torque converter clutch shudder. This is caused by a slip/ stick of the torque converter clutch. I thought I recalled a reprogram to address this condition, but a quick check revealed that it was for 2.4 and 2.7 Santa Fes.
Torque converter clutch shudder was the original reason Hyundai switched from Dexron fluids to Mitsubishi fluid. If it has been a while since the last fluid change, you might try a flush to see if anything changes. If it doesn't go away, I'd say you're probably looking at needing a torque converter replacement. With the price of new converters, it's not likely to cost much less than an entire remanufactured transmission. I don't normally recommend things like this, but if the condition doesn't get better with a flush, perhaps add an aftermarket (such as BG) fluid conditioner or friction modifier to see if the condition improves. Do this only if you've verified that the converter or transmission is the cause of the issue. There's no guarantee that the additive won't negatively affect other facets of transmission operation, so it should be done only if you'd be looking at a replacement transmission anyway.
As for the trip, I'd say to take another vehicle unless the issue has been resolved. An slipping converter can cause a transmission to overheat on long trips, potentially leading to other failures or a breakdown.
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