One of the transmission gurus on the forum suggested I start my own thread so here goes. I have a 93 f150 Flareside regular cab with a 302. 2 Wheel drive only. When I am driving with the overdrive off in town in 3rd gear I sometimes get a vibration or a stutter in the truck when I give it gas. When on the HW and I am doing above 60 with OD the same thing occurs. The guru said it sounded like U-joints so I checked them and found no looseness at the joints. What I did find was some slop at the yoke shaft going into the transmission tail extension. Could this be causing my vibration in certain gears and only when I give the truck gas?

 

When you checked the ujoints was the driveshaft in or out of the truck? If you checked them with the driveshaft in the truck you have no idea if the ujoints are good or bad.

 

Since your vibrations come in at different speeds I doubt it would be the drive shaft, from you description it would seem the vibrations are engine speed related, maybe a slight misfire or maybe a miss that only shows up under load... How long/miles since last "real" tune up?

 

I just did a complete tuneup and this has been happening for quite a while. I lifted the rear end of the truck off of the ground and turned the drive shaft by hand. I used a large screwdriver to try to move the ujoints and they look good. The engine runs flawlessly and pulls hard all the way thru to OD on the highway but once I left off of the gas and it shifts into OD, if I give it gas again its like a droning sound. I still have power but its vibrating.
BTW, thank you guys for your input. I am about to pull the ujoints anyway because that is cheaper than replacing the tail extension bushing.

 

So I pulled the drive shaft and found that the slip yoke is broken on the end. The Ujoints look good but I am going to replace them anyways. Looking at this photo, could this cause the noise I am hearing that I mentioned above and what is the proper name for this part of the drive shaft. Having a hard time finding one.




Drive Shaft Yoke that goes into back of E4OD transmission

 

Yeah that's not good. Were you able to find the broken chunk?

 

Not unless I pull the tailsection of the transmission. I suspect that it was broken before it went in base on the peen markings I saw on the yoke. I even have a dent in the driveshaft. That all has me worried.

 

Dent in the driveshaft? It's junk. It is not straight anymore, thus the vibration.

There is always some slop at the slip joint. If the slip yoke is not worn where it rides, then that is not the vibration.

Never saw a slip yoke broken like that? Did it break a u-joint in the past and jam the shaft forward? That could be a possibility.

Time for a new driveshaft.

 

Ok so I changed out the yoke and the U-Joints and the vibration is still there. After I bought the damn yoke the guy behind the counter told me all I needed to do was cut off the broken piece and reuse the existing yoke. What a D I C K. I blew $80 on a yoke I did not need.

 

When was the transmission last serviced? perhaps it could be a torque converter issue? Try Dr. Tranny instant shutter fix. My F250 was having a similar issue and it cleared it up.

 

That yoke was trashed and should NOT be reused. It needed to be replaced.

I think that is the cause of the vibration.

 

Bring your driveshaft to a local driveshaft shop and have it re-tubed. A dented driveshaft is junk.

 

Yeah, I think that or the tailsection bushing is the next thing. The guy wanted $200 to retube the shaft and balance it. The new yoke is 1.5 inches shorter than the old yoke which is why he told me I could cut the end off the old yoke. Man I want to get rid of the dddddddd vibration in 3rd and 4th but am tired of spending money on a truck I want to sell. Torque converter? Can it make a vibration only in 3rd and 4th just as you are accelerating. That's whats happening now.

 

Try this: Drive the truck, get up to 3rd gear where it is vibrating and slip it into neutral and rev the engine. Does the vibration stay the same? Yes? Then it is the driveshaft.

My '95 F150 has a vibration about 30-40 mph right now. New u joints. Driveshaft looks fine, but I think it is bent or just junk from the factory(only 70K miles on truck). It's annoying for sure. I've had truck for a year.

How are your tires? Could have a bad tire that will give you a vibration. I just put tires on mine and had one that had belt separated. That took care of 1/2 of my vibration(only thing left is driveshaft). I tried the neutral rev and mine stays the same. I put truck on jackstands and run up through the gears and still feel the shake in the seat.

 

Just left the transmission shop. He told me that its the clips holding the pistons inside the transmission have failed. No doubt about it. Well at least I know its not the ujoints or the yoke.