I have a 1998 F-150 5.4 4x4 that shudders around 40 miles per hour. Some days it is more noticeable than others. This morning it was more pronounced and this is first cold day of the year. I have established that its not the tires. I had the transmission fluid changed about 17K miles ago, but I don't think they changed the torque converter fluid. At the time the fluid was changed it was in pretty bad state, dark with some shavings, but since the change it has looked normal. I attributed it to the orginal owners driving habits and kind of put it aside. But it is getting worse and I want it fixed. Any thoughts? Oh, I did put the Ford transmission conditioner in when they changed the tranny fluid.

 

I'd change the transmission fluid. This time get it done correctly and change the torque converter fluid, too. By only changing the fluid in the pan you are changing less than 1/2 of the total fluid.

Here's a link to a DIY procedure that will change all the fluid:
http://www.ford-trucks.com/articles/...hangingatf.php

 

TheBigBad,

If your transmission fluid was brown and smelled bad, your tranmission has been damaged by excess heat and slippage. The only fix for a transmission that has burnt fluid is a rebuild. I'm sorry if it turns out you need an overhaul but I used to rebuild transmissions for AAMCO and I wouldn't lie as I've got nothing to gain from you.

If your tranny shudders at 40 mph, then I'd guess it's your direct clutch pack slipping and that's probably what caused the fluid to be dark and smelly as you described eariler. As for the torque converter, it too has a clutch but I'm not absolutely sure when it locks up but for some reason 45 mph seems to come to mind, hey I could be wrong. For sure, the torque converter doesn't lock up at higher than 45 mph and it may be at a lower speed, I'll see if I can find it and post later.

Good luck and let us know how it turns out if and when you get it inspected.

~DM~

 

A shudder at 40 MPH in a 4R70W is almost always the torque converter clutch. Changing the fluid eliminates the shudder in about 90% of the transmissions.

A rebuild is only necessary in the most extreme cases.

 

I had the fluid changed by a trusted expert and it still does the same thing. In fact , on a cold day the other morning while I was coasting at about 40 mph it felt like the tranny was going to fall out. I'm taking it back to CarMax for warranty repair today. I have told them I think it needs a torque coverter rebuild. Is there anything else I should tell them?

 

I'd tell them it shudders. I wouldn't tell them it needs a torque converter rebuild because it probably doesn't.

The torque converter isn't doing anything while you are coasting. Try coasting at 40 MPH and shift to neutral. That will eliminate the torque converter as a cause of the shudder. You may have something like a u-joint that is going.

 

Ok, I just got my truck back and they reconditioned the transmission and put in a new torque converter. It seems to have fixed the problem. ..