Sounds like your U-Joints are either worn or one is seized drive for a short 10-15min drive and climb under, if its a seized knuckle you are going to feel a hot spot on the shaft in the area of that knuckle. If its a bad joint you should feel it by pushing up or side to side on the shaft. Would be my bets, doesn't sound like a tranny problem at this point, providing no other issues show up. Try the cheap answer then work your way through it.

 

Sounds like the rear gear Modifier is spent. If so, -it should be at it's worst @ about 55 mph.

Also screws up the clutch pack if you let it go.

 

First I'd like to thank everyone for their input. This has been trying on my nerves and having someone here to mull things over with sure does help!

*prepares for growns from the crowd*

I pulled my driveshaft and took it to a drivetrain shop to have the new u-joints put on. I was told: A; I had the wrong joints and needed the ones with spacers. B; after twisting, bending, rotating, shaking, etc I was told "there isnt anything wrong with any of those joints".

So back home and installed the shaft as was.

Sunday I went around trying to find a shop to flush the tranny..to no avail. Four shops could not get me in Sunday, and Monday was to be VERY busy for me...dang.

So off to NAPA I went and purchased a can of "Greased Lighting" (in a bottle no doubt)...transmission mojo. Since adding this in, since Sunday afternoon that is, *knock on wood* no more shudder. So this afternoon I am taking it in for a full flush.

Question: Since I added one type of additive.. should I go back with that after the flush, or is there something better one would recommend (does it matter if I add one, flush, then add something else)?

Thanks again all!!

BTW...coil packs still in on the way ... well, I do have a miss anyway I havnt been able to get rid of.. perhaps they will help with that!

 

Like I said earlier, when the rear gear oil breaks down, it causes this EXACT problem. Feels like the trans or other driveline problem , but it's not. Been there done that, - said that.

After changing the fluid in either trans or rear end, - it takes time to heal. It may take up to 100 miles before she feels better.

 

Thanks, Jbrew.

Yeah.. I was kinda starting to worry about the rear end (not completely out of the woods yet), but since they had replaced the clutches in the RE, and fluids, about 12k ago I was hoping they didnt screw something up upon putting it all back together.

I appreciate the heads-up on the breaking-in / healing.

 

Well okay, but if 8 ounces of friction modifier wasn't added when changed, the oil will loose it's strength pretty quick - way before it's time. 262,000 miles on my truck and she pulls often (heavy). Still running the original (no-zerks) U-Joints, Trans and rear end. They should last the life of the vehicle IMO. That's one area where Ford can shut down the competition,- they can build a drive-train

BUT! - They absolutely NEED the modifier or they won't last. I run that in my trans as well

 

I was going to look at my records tonight and see if they did add it in (sure they would have charged for it).

If they didnt, however, would that require a full flush and fill of the RE.. or could a guy just add it in?

 

If they replaced the clutches in the rear end 12K miles ago, and you haven't had an issue, chances are that they soaked them in the modifier prior to installation
and it is present in your axle. Otherwise, you would hear the "growl" everytime
you made a turn at a stop sign, indicating the noise commonly associated with clutch pack failures due to no friction modifier..

Sounds like you are safe!

FordMasterTech

 

FMT,

Thats what was happening when they fixed it. ..but there wasnt a growl, just felt like the tires were breaking loose on even the slightest and most gentle turns.

Thanks for the heads up.

 

I was having this exact problem at stop signs that I turned at. I did what Jbrew said to do, and I havent felt it since, it's VERY smooth now, I love the way it drives now, and I guess whoever had the truck before me, was offroading or something, but the front differential had a complete milky substance in it from water Id suppose. So after replacing the gear oil(my god the smell combined with XL-3 is ridiculous)it worked great, and drives smoother than ever.

Jbrew you said you use the XL-3 in your transmission?

 

Yea, not sure what XL-3 is. But an old guy up town and Mike Troyer helped with my trans. It was slipping bad at one point @ 185,000 miles. The truck has 263,000 miles on it now and shifts quick under normal acceleration / shifts hard wide open. Yea, modifier was in the final mix after I put it back together. I did allot work to that trans, -didn't cost many anything but time and what it cost for fluid and a shift kit.

The rear end would slip and shudder on the turns. I had to re-align the trans/drive-shaft/engine accordingly. The rear end problem started after new tires were installed. So I took everything loose/ supported properly/ adjusted the trans vertically and horizontally/ installed a new trans mount/ tightened her back up - No more shudder problems.

 

About how much of the modifier did you put in the trans do you remember? 8oz?

Also sorry for saying XL-3 haha thats just what the dealership got me into saying(took an act of god to find friction modifier for our trucks, and no one aside from other ford owners that do their own work know what friction modifier even is, but luckily the dealership is close). I just meant the Friction Modifier, which I guess is named XL-3 because thats what the formula is.

And thats a nice bit of miles, still running strong with all OEM?

 

Yea, I thought it was GL-5 from what I recall, -maybe that was the 75/140 Synthetic rear gear oil - Friction Modifier = Ford has theirs I know, Redline pre-mixes theirs in w/the rear gear fluid, but I purchased it seperate from Murrays along with a few more additives that are recommended by the top DT guys like Red Lube .

Nothing but Amsoil for my transmissions now. Heat kills and I pull heavy quite a bit and that Amsoil knocks the temps right own.

A few add ons -









______________________________

Did some work to valve/accumulator bodies - Replaced pistons and smoothed out the bores/ beefed the springs/ I ended up making my own separator plate.

 

Where do you get your Amsoil from? Im looking at changing my ATF very soon, and I was wondering if synthetic is worth the money for the fluid? or is it preference?

 

Oh yea, I used two tubes of modifier = 16 oz's. But I have a 18 qrt. trans. Amsoil wasn't a preference for names sake. There's others and yes , in these transmissions synthetic is definitely worth it.