Hello guys, have a question. When I accelerate from a dead stop I have this squeeking that comes from the back of the truck that goes away after a few seconds. Then when I get up to about 50mph I have this really annoying vibration. Its not a real heavy vibration but it is there. I am thinking it could be the universal joints, am I way off here or what?

 

Good chance. Easy to check .... put truck in neutral, set parking brake, block wheels even .... but trans in neutral.

Crawl under and grab the driveshaft and twist and pull and shake and look for loosenmess at the 2 or three U-joints as the case may be.

Also, make note if you have clips holding the joint bearing caps in .... of it they are staked. Hope for the clips.

 

Normally will be the rear joint.

 

Thanks for the input guys. I am about to go and look. If they look tight I am gonna see if they have the nipples on them so I can pump them with some grease.

 

Not likely to find any nipples.

Even if you did, if it's already making noise or vibrations, it'ld be too late.

 

changed out the rear universal joint and all problems fixed. realized while i was under there i have rearend leak that i have to fix. is the front seal expensive and how hard is it to replace? also what kind of gear oil is best to use?

 

Pinion seal you say?

My method is to first get the truck / car parked or raised and secure where I can get under it. F-150, I'ld just back it up on my 8" ramps. Set parking brake and block front wheels .... (don't need tire tracks on my shirt). Put trans in neutral, paint or punch mark driveshaft at rear yoke so it can go back same as removed, then remove driveshaft from rear axle at U-joint.

Now, I clean the exposed threads of the pinion shaft, the nut, the rear flange / yoke ... with wire brush if needed. Once clean, I take a sharp center punch and hammer and I punch mark ... the end of the pinion shaft ... the pinion nut ... and the yoke or flange at same "clock" position.

I also measure the length of the threaded pinion shaft sticking out past the nut and count threads, ... and I write it down.

This way when time comes, I can put that yoke back on that shaft and tighten that nut back to exactly the same relationship ... and NO FURTHER. I do NOT want to compress any crush sleaves any further, I want to retain the exact same bearing clearences .... I just need a new seal wrapped around it all.

Now, I use a BFW and remove the nut and yoke and then pull the old seal and install a new seal (and if it's a lose fit inside the housing, you can use a locktite product on the outer side of the seal to fill voids but not on the lips) driving it straight in (not cocked at an angle) ... lube it's lip ... slide yoke back on so it's punch mark is same relationship to that punch mark on the end or the shaft ... and then I slip the same nut back on with same side against yoke as it was when removed ... and apply some locktite on the threads.

I tighten it until close to original setting, then I sneak up to final setting so when I stop, the three punch marks are in the same relationship with each other and same length of shaft sticking out as when I started .... and NO FURTHER.

DO NOT GO TOO FAR.

I then .... if the nut was a loose fit, may take a punch and punch the threads of the pinion shaft in two spots just to make sure the nut doesn't loosen, though the locktite should prevent that .... and prevent any future sweating of oil that might work it's way out through the threads making it look like another leak.

But that's just my way. I've done it on my vehicles a few times over the years, even a couple police cars ... always sucessfully.

Seal and grease aren't too bad. My book says 5.5 pints for 8.8 / 9.75 rears (about 6.5 for the 10.25) ... Motorcraft SAE 75W-140 Synthetic Rear Axle Lubricant XY-75W140-QL / WSL-M2C192-A

Oh yeah, if it's a Trac-Loc rear ... add 4 oz. of Additive Friction Modifier XL-3 or equivalent meeting Ford specification EST-M2C118-A, for complete fill of 8.8 inch and 9.75 inch Traction-Lok axles ...
.... and 8 oz. if a 10.25 Axle.