2003 Town Car Transmission Shudder

[Smashcbn]

HELP! My Town Car has 270,000 miles and the transmissions shudders at 59, 68, and 73 miles per hour. Is there an additive that can help. The shudder occurs at those sppeds then dissapears. I I really get on it, not too crazy on it but give it the gas harder than normal it happens as well. The trans does not slip but that shudder concers me as i drive for a living. I was told to use a Lucas Oil Trans additive. Thanks for all the help.

[All2kool]

Originally Posted by Smashcbn

HELP! My Town Car has 270,000 miles and the transmissions shudders at 59, 68, and 73 miles per hour. Is there an additive that can help. The shudder occurs at those sppeds then dissapears. I I really get on it, not too crazy on it but give it the gas harder than normal it happens as well. The trans does not slip but that shudder concers me as i drive for a living. I was told to use a Lucas Oil Trans additive. Thanks for all the help.

I can't see how an additive is going to fix a Harmonic Balancer issue but go ahead and try.

[Smashcbn]

Ok. Thanks. Is that Harmonic Balancer attached or in the torque converter? Any ideas what to do with it or how to fix it? Thanks.

[Blue)(Fusion]

The 4.6 Modular motor is balanced internally and therefore do not have a harmonic balancer, but they have a harmonic dampener which is the big pulley at the bottom of the motor which drives the serpentine belt.

Your problem has nothing to do with the harmonic dampener (but it should be checked periodically as the rubber in it dries out and can fail).

Does the shudder feel like you are driving over the rumble strips on the side of the highways? If so, this is the Torque Converter lock up Clutch (TCC) not able to get a good grip so it grips, slips, grips, slips, etc. and is felt as shuddering.

There are two causes TCC slip:
1) Worn Automatic Transmission Fluid (ATF)
2) Excessively worn TCC clutches

The worn TCC clutches does not happen too often unless you never change your ATF and let them burn out, but by that time usually all of the clutches need replacement.

Replace your ATF with MERCON V. Do NOT buy anything that says universal, compatible, multi-vehicle, etc. Use strictly MERCON V ATF. You can buy it at your local Ford/Lincoln/Mercury dealership or at any auto parts outlet. I used Castrol MERCON V when I changed it last and have no complaints with it.

A word of warning. If you do a T-Tec or similar transmission flush, be sure that the shop is in fact using MERCON V. Most small shops save money by buying a universal one-size-fits-all ATF and this leads to shudder either right away or in a short while thereafter. Some even claim they use MERCON V and just use MERCON/DEXRON III and put in some additional friction modifier, which may extend the ATF life a little more, but is still not a true MERCON V fluid.

If you do your own car work or take it to a garage that does not have a T-Tec flush machine, dropping the transmission pan alone is not sufficient! Dropping the pan only removes about 4-5 quarts of fluid and the system holds nearly 14 quarts. Drop the pan, drain the torque converter (although I believe in 2003 Ford decided to remove the torque converter drain bolt so you may not be able to), and drop the valve body. Dropping the valve body will remove about another 5 quarts of fluid. After dropping the valve body and not draining my torque converter, I filled my transmission up with 10 quarts of fresh fluid. The other 4 quarts were in the torque converter and cooler. My old fluid was still clean and in good condition and is why I did not opt to flush the torque converter or cooler. I did it to remove some springs and drill some holes in the transmission

If your shuddering does not feel like driving over rumble strips and feels more like an occasional misfire of one or two cylinders, it is likely caused by a worn spark plug, dying Coil-On-Plug, or the EGR/DPFE system.

[Smashcbn]

@ Blue Fusion Thank you very much. Yes it does feel exactly like I am riding over rumble strips. No the fluid has not been changed in a LONG time. I guess with 270,000 miles on it the trans is just wearing out. I guess I should start looking for a new trans. Thanks again for the info. It makes a lot of sence now.

[Smashcbn]

Has anyone had any success using the Lucas Oil trans fix additive?

[Blue)(Fusion]

Flush your fluid before replacing parts since it has not been changed in a long time. You can likely get away with just this. But like I posted above, be sure to get as much of the old fluid out as you can to make it a successful flush!

Either pay a bunch of money for T-Tec flush, or drop the pan, drop the valve body, and (if able) drain the torque converter at home on ramps or jack stands for under $100.