My vacation did not start out so well. A few miles from home, pulling the (3500#) trailer, I felt a vibration and heard a noise. The noise was like metal-on-metal.

I turned around and got my other truck and continued on.

Here are the specifics (in no particular order):
-the vibration felt like when you drive over the rumble strips on the highway or the raised lane markers
-the noise sounded like the RV step was not fully stowed and rattling in place. Or maybe a safety chain against the chassis (roughly like 16ga metal on 16ga metal)
-O/D was off
- not in 4wd
-it did not happen with the other tow vehicle
-it seemed to happen between 35-45mph
-I have not heard, nor felt it when I was NOT towing
-it was random, would not always do it at the above speed range
-it was not a misfire (pretty sure)
-it only seemed to happen on a flat stretch (RPM's were lower)
-the check valve has been deleted, extra cooler installed
-trans temp was about 140*, it was only 4 miles from the house

I have:
-checked the rear end, looks great
-checked u joints, seem fine (but will replace, they gave me the wrong ones and have to return them)
-someone mentioned that it could be a bad diode in the alt (happens a lot on fords???) I replaced the alt
-I saw the TSB on driveline angles and such

I am waiting for the RTV to dry a bit before I can go out and try some more test runs to see if I have cured it (probably tomorrow)

It seems like it is the TCC lock up shudder. I need to see if it stops when I taps the brakes and/or popping it into neutral. I may have to look at replacing the TCC/OD solenoid assembly (man, there goes another $75 in atf!)

I am looking for some more thoughts. And any ideas on how to test/check it out without having to tow the trailer (but there may be no other way...)

Thanks, I'm stumped

 

Also, if it is the shudder and it only happens "sometimes" when I'm towing, is it doing any harm?

 

I don't think any shudder is exactly 'good' for the driveline. Tends to stress parts, and not in a good way.

If you have a scanner available, I would be tempted to watch misfire counts while the problem is present, just to make sure that isn't it. (because the symptoms sure sound like it is......)

Do you feel it more thru the steering, or the seat?

 

Definitely the seat. And with the rear slider open, it even sounds like it's the rear end.

No codes though. I'll have to see if my scanner does "live" mode.

 

No codes. No codes pending. I will try a different scanner tomorrow. Looks like it wasn't the alternator.

 

No codes. No codes pending.

No misfires.

Happens (today at least) between 45-52mph.

Stops momentarily after I tap the brake.

Stops if I pop it into neutral.

Sounds like the torque converter???

 

Wonder if torque converter clutch is 'bouncing'?

A good scanner is going to come in handy here.... Especially one that will do data logging. I would take a very close look at what TPS, and brake switch, are doing when the problem presents itself.

 

In post #6, I should have said it stops a moment after I tap the brakes. The shudder stops completely, until I can get it to do it again.

I will review the TPS data recording. (I do have a new TPS on its way).

 

Some Jack-wagon (I won't mention my name) handling the scanner erased the data!
My new TPS will be in tomorrow. I'll throw that in, and check the old one with an analog VM, and test out the truck. This time I'll have a smart person handling the scanner.

 

Gonna have your wife help you?