I have a 79 f150 and ive got a ton of play in the driveshaft. When I am reversing and put in the clutch There is a thud/clinking noise. When I let off the gas driving forward and then press on the gas again there is another thud and clinking noise. Like its really bad now. I am going to pull open my rear diff cover and look at my ring and pinion. I am assuming i will need to replace them. Is there a way To fix this instead of replacing the ring and pinion? Should i replace all my bearings while im in there or can i leave them if they look okay?
Trying to stay on a low budget.

Does anyone know the gear oil i should use?

 

Before you pull the ring and pinion, pull off your driveshaft. I guarantee its a bad ujoint.

 

I would check the u joints first and the hangar bearing to see if it's ripped out before I would go into the rear end. be careful as gear oil stinks for life if you get it it on your clothes I use 90-140 in my f350's it's a bit heavy for you, try 80-90.

 

Before you pull anything, put the parking brake on, chock the wheels, put it in neutral, and get under there and twist the driveshaft back and forth, and see what's moving.

If the play is in the rear end itself, it's usually not the ring and pinion, it's usually the side gears, spider gears, or axle splines that are loose. But if the pinion yoke moves in and out, then you might have a bad pinion bearing.

 

OkayI don't need a limited slip additive do I?

 

The u Joints all look good. The slip n Spline is going to need to be rebuilt but. Hopefully this video will work

 

Can you tell anything from this video. Where do you think i should start?

 

How did you check the ujoints? You must grab the drive shaft and push and pull it from up and down and left and right. Any movement and they are shot.

 

Okay it does seem like 1 of my u joints is shot that is noticeable. But can all my clinking when I step on the gas just come from u joints and the slip n spline

 

I just went throught this with my 76' HB. Check your motor mounts. All of mine were loose, I tightened up all the bolts and now now more noise.

 

Yes a bad u joint will click and shatter. Mark the slip yoke (before you remove the drive shaft), you do not have to take the slip yoke apart, just saying in case you decide to. That way you put it back in "in phase".

X2 on chalk the front and rear wheels, remove the drive shaft, replace what it bad u joint wise and while you are under there grab the pinion yoke and see it the pinion nut is loose or there is a ton of play in the yoke splines.

Just watched the video, that is WAY to much play in a 9", it seems like you have a very bad ring and pinion gear....I would still drop the d/s and ck the pinion nut.

 

Yes it can. When taking off a bad u joint can have a 1 inch of movement. That's the shudder you feel or banging sound when taking off. I agree on to much movement in that 9inch rear end. Drop the drive shaft and check it. If it's bad you will ruin a new ujoint.

 

Also a bad u joint in the rear will ruin pinion bearings, or vice versa. And if the slip yoke/stub shaft on driveshaft is bad it will also ruin ujoints and bearings.

 

Like others said, there should be NO PLAY in the universal joints, none that you'll ever feel anyway. If you feel any, the joint is bad.

Also the slip joint in the rear driveshaft does not get lubed like one on a transmission tailshaft so you have to grease it when greasing the U-joints and it can take a bit of grease in a gun to satisfy.

Some slack in the pinion when the wheels are tightly locked is not bad, like OK if it rocks back and forth a little when twisting the driveshaft.

My '77 F-150 has 105,xxx miles since new and just a few thousand on it's third set of rear driveshaft U-joints. The originals went to about 50,xxx, then the ones I put in made it to just over 100,xxx when I started hearing noises and clunks and noticed a slight vibration at road speed when between geared down and acceleration when there was no load on the U-joints. I rolled under there at oil change time and found that the rear U-joint at rear axle was shot .... I replace all three and the center support bearing that time.

Those in the front driveshaft are tight and OEM, the frt axle's U-bolts got replaced with wheel bearings, etc about 10,xxx ago.

Also .... do NOT overly tighten those U-bolt that retain the bearing caps of the U-joints in the yokes, just good and snug is OK. If the nut's too loose to stay, get new locking nuts. 15-20 ft lbs is enough. Double check to make sure your new U-joint's caps fit the saddle in the yokes too .... some Fords use two larger caps in U-joint where they are secured in the yokes.