78 rear end problem?
Posting Guru
Joined: Feb 2007
Posts: 1,996
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From: Pittsburgh,Pa.
I'd take a look at the universal joints first.Park the truck on flat ground,block the wheels solidly, put it in neutral and crawl under.Check for looseness at each u-joint, also check for signs of rust coming from the end caps.Both are signs of u-joint failure.Also take a look at the rear suspension.Watch for broken parts and rust stains that usually indicate something is moving that shouldn't be.Then have a look at the rear.Grab the input yoke and try to turn it by hand.It should have some movement.The term for this is backlash and at least some must be present for the rear to operate.Hope this helps.
Please make sure you BLOCK THE WHEELS.If the truck moves you may not get the chance to make the same mistake twice.
Please make sure you BLOCK THE WHEELS.If the truck moves you may not get the chance to make the same mistake twice.
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Freshman User
Joined: Mar 2007
Posts: 30
Likes: 0
thanks, redcat i have changed all u-joints on the truck front to back so i'm pretty sure those are not it do i have to take the drive shaft off when i turn the yoke or can i still leave it attached and turn it
Senior User
Joined: Nov 2005
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This is a long shot but I had a similar problem many years ago and it took me quite some time to find the cause.
If, like me, you have the Ford Trac Lock rear end there is a set of spring loaded clutches inside it next to the spider gear. One of the “pressure plates” (wrong term but it works) has a set of holes that secure it to the spider (I think). In my case a fracture or break between all the holes occurred and the two pieces would slip in and out of fitting together when I stopped and started causing a noticeable “clunk”. My rear end shop said it was not uncommon and was the result of less than perfect engineering.
Like I said this is a long shot and you may want to explore all other options before disassembly of the third member.
If, like me, you have the Ford Trac Lock rear end there is a set of spring loaded clutches inside it next to the spider gear. One of the “pressure plates” (wrong term but it works) has a set of holes that secure it to the spider (I think). In my case a fracture or break between all the holes occurred and the two pieces would slip in and out of fitting together when I stopped and started causing a noticeable “clunk”. My rear end shop said it was not uncommon and was the result of less than perfect engineering.
Like I said this is a long shot and you may want to explore all other options before disassembly of the third member.
Posting Guru
Joined: Feb 2007
Posts: 1,996
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From: Pittsburgh,Pa.
As beartracks stated leave the shaft in place when you turn it.Next try to push the yoke vertically.If it shows noticable up and down movement you likely have a bearing problem.Going from the year of your truck the rear is most likely a 9" Ford unit.These use a small bearing on the inside end of the pinion often called a pocket bearing.It rides in a small web in the case.The webs are known to break allowing the pinion to run out of center.It usually destroys the gear set.Before you go any further I'd suggest checking the lube.Water,signs of rust,or a metallic appearance in the lube are good indicators something is wrong inside.
Craigster1 , I've never heard of the Track Lock problem you mentioned but I'll log that one in my noggin.Thanks for the info.
Craigster1 , I've never heard of the Track Lock problem you mentioned but I'll log that one in my noggin.Thanks for the info.
New User
Joined: Jan 2008
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Tp get rid of the Ford driveshaft clunk...remove the driveshaft and put a handful of disc brake wheel bearing grease inside the front yoke.
Once inserted on the splines on the back of the trans the grease provides a buffer and clunk disappears
This application lasts about 2 years...
Once inserted on the splines on the back of the trans the grease provides a buffer and clunk disappears
This application lasts about 2 years...
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Ford Parts Specialist
Joined: Nov 2006
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From: Simi Valley, CA
Originally Posted by Redcat Diesel
Going from the year of your truck the rear is most likely a 9" Ford unit.These use a small bearing on the inside end of the pinion often called a pocket bearing.It rides in a small web in the case.The webs are known to break allowing the pinion to run out of center.It usually destroys the gear set.Before you go any further.
C2AZ-4625-B .. Bearing, driving pinion Pilot 9 inch (Industry# R1535 TAV)
C6AZ-4625-A .. Bearing, driving pinion pilot 9 3/8 inch (Industry# M5204 TV)
B7AZ-4627-A .. Retainer, driving pinion pilot bearing (all 9" or 9 3/8")
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Posting Guru
Joined: Feb 2007
Posts: 1,996
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From: Pittsburgh,Pa.
Thanks for those numbers Bill. I'm gonna stash them with some other 9" info in the file cabinet then I'll pass them on to a buddy who uses a pair of 9" rears in his mud bogger.He's been known to break 1 time to time.
Clay
Clay