not sure what you mean by not using brake till the end if the truck is on the ground and applying the gas ?
Not using the brake till the end of the test was in reference to Rod Knox’s comment that you would not be testing the lockup feature of the torque convertor with the Power Brake test…it would only test the convertors normal mode and not lockup…
To get to the lockup feature… After you power brake it to see if anything feels funny… the next test is to let the trans shift into all gears…once it reaches top gear…it will then enter lockup…and thus…test the lockup feature. It would be good to do this with and or without wheels on… Up to you.
Two tests for two separate things
Blackbird
Have you popped it into neutral and and coasted while it’s vibrating yet?
Yes, ive tried shifting it into neutral many times and no difference.
Ive also tried the power brake test and don’t believe Im feeling any of the same vibrations and/or anything out of the ordinary (other than just trying to keep the brakes from creaking) Im not sure if I was able to let it shift through all the gears though? With brake completely floored the truck want’s to go forward. Also, I had the tranny changed out again and added shudder fix. The specialist tranny shop owner did think it was torque converter from the info. I gave him. But he also said vehicles nowadays cannot be power-tested like that anymore- ? He said if it happens to be the Torque Converter-might as well have the entire tranny rebuilt being that it has 123k miles on it, and be prepared for $3-5,000 bill. (or just let it run its course and apparently the torque converter will wear out enough that it won’t work - but will make gas mpg. worse ?)
Is there any other way to make sure it is the torque converter ?
Yes, ive tried shifting it into neutral many times and no difference.
It’s not the torque converter.
shouldn’t the torque converter send a code anyway?or not always?
Also, Is it true that software updates can resolve some of these issues ?
I don’t see how a rear-end vibration in neutral can be anything but the driveshaft or rear wheel assemblies. The driveshaft would vibrate at about 3 times the frequency of the rear wheels.
im pretty sure, maybe 95%, it doesn’t stop in neutral- but to be honest its tough to be exact because with the slight time lag of shifting, bumps in the road, and instantly slowing speed its hard to tell.
If your truck has a lock-up torque converter, it might be possible to disconnect the lock-up solenoid connector as a test. If the problem goes away, then you’ll know it is torque converter lock-up shudder of some kind. I don’t think that’s the problem, but it might be very easy to try as a test to eliminate the lock-up mechanism at least.
A failing torque converter clutch won’t shutter while the vehicle is standing still or on jacks. The vehicle must be moving and under load (unless you have a dynamometer). A slipping torque converter clutch will only slip when the throttle is open, if you release the throttle or move the shift lever to neutral there will be no load on the torque converter and no possibility of shudder.
I wonder if your vibration is really a ride disturbance. Some 1/2 ton trucks can develop a rear shake or rhythmic hop on particular roads at certain speeds while unloaded.
Try adding 200 lbs of weight to the cargo bed, if this calms down the ride it is a suspension issue. You might try aftermarket shock absorbers to adapt the ride to your liking.
Back to my original thought…and Im still on the shaft as well… I only moved onto the convertor because the shaft was considered to have been ruled out. As @insightful stated…the shaft spins much faster than the wheels. I mentioned this also in a comment about the frequency of the vibration.
Ive somehow become a master of figuring these things out…and the way that is accomplished is by having a good handle on how fast things are moving… the shaft…usually high frequency vibes…the wheels? Much slower… Engine? As fast as the tach…and so on.
This is yet another one of those issues where we need to be onsite…its difficult at best to direct someone from the computer… I change my mind and theory in milliseconds as I do tests…one test begets another…and yet another is to rule out another…its a complex road to troubleshoot things sometimes. And what you MISS is just as important as what you notice. When you do this long enough…you dont miss much.
For instance yesterday…I had a 75’ BMW R60 motorcycle job…as I walked toward the bike I told the owner he has a front wheel balance, and front suspension issue… He immediately said… “But you havent even reached the bike yet” I said…I dont need to …I read your front tire from the garage entrance. Was I correct? You bet I was… He was more than stunned… He said he never had anyone do anything like that before and started calling me the Motorcycle Whisperer on the phone to his friends…who now all want me to look at their bikes… Funny that…
We are throwing ideas and theorys at you from all angles…this is good and bad. Each theory can hold water…you just need to properly prove out the theorem…like Algebra… You also need to be hyper aware of what is what… Noises, Vibes…hell even smells can go a long way to solving the riddle… Its definitely a learned trait… I dont mean to get all philosophical on you…Im just pointing out again…that what you notice is as important as what you miss.
The one thing that I think is getting Obfuscated here is the shaft… Faith in the new U joints…etc…Just my take from my computer desk… I could have many more “takes” onsite …one thing to rule out another etc
Blackbird
I believe that the driveshaft was known to be fine after taking it to get balanced and inspected. Ford also had me purchase a new one (regretfully so) due to their only answer, however, this didn’t seem to fix the problem either.
ps. so I have a spare d-shaft in my garage if anyone knows how I can get rid of it ?
So you are saying that you still have a vibration…and you tested this with the wheels on and off with the truck in the air and there is no change at all ? You also tested it fully assembled and driving on the road and feel the same vibration?
Ive gotten lost in the progression of this to be honest. If it vibes on the road… You lift the truck and test with the wheels on… Then Off… what is the result?
After the above tests…there is not much left to suspect besides the shaft and or the tranny…and they can be ruled out also…
Blackbird
Has anyone ever raised the truck and gotten under it while the vibration was occuring?
So far i’ve had it up in the air and on jacks several times including via Ford dealer, but haven’t tried it yet with wheels OFF- (can prob. try this this weekend)
Even with other people observing no one has yet detected it other than when driving.
Have the tires been road force balanced? Even if they balance by weight they might have other rotational issues that only a road force balancer will diagnose.
Yes, had this done. But may be worth taking to another/different shop just to see
We also suggested a defective tire w a broken band or some such defect.
My suggestion of up in the air…with…and W/O wheels n tires…was designed to help you figure out if its wheel and tire related… It would be a very quick and massively useful test. Which is why it was suggested very early on.
Blackbird
He has stated that it doesn’t vibrate with the wheels off the ground , only while driving .
Did he ? I asked for a refresher on the issue for just such a reason.