HELP REAR AXLE PROBLEM

[Fireman40]

hey guys I have been noticing a huge drop in mpgs. I just put a new set of tires on her the other day and I noticed when doing the rear tires I had a very hard time getting the rear tires to spin. The parking brake was off and it was in neutral. When I did manage to get the axle to spin both tires went the same way. When I did this about a year ago one tire went one way and the other way. I do not have posi traction. I had my buddy hold one tire and I tried to spin the other tire and could not do it. However if im in the mud and in 2x4 ony one will spin. I just recently changed my gear oil and after long tows I would get one hell of a vibration from the rear when turning. At one point it would dam near rattle my door. I put the fiction modifier in from ford and that solved this vibration. what do I do. I really don't want to have to drain $100 worth of new oil to look at the gears. Everything looked good when I changed the oil but I didn't really know what to look for either.

[melmount]

drain to a clean bucket

[Fireman40]

I was thinking I could do that. Anyway any ideas of what to look for once I get in there

[GAS]

look closely at the spider gears. I'll bet ya will see some obvious damage.

[jethro]

you definitely have a problem and most likely a big one it sounds like either A. your spider gears are trashed B. your bearings are shot or C. your ring gear is shot the last one is not as likely as the first one and you should have no need for friction modifier in a non posi rear end

[Fireman40]

ok well I have faced it that this is going to cost me alot. I was thinking of maybe just getting a good used axle assembly. I dont know what gear my truck is not but when Im doing 70mph its at 2000 rpms exactly. I just put a set 0f 35x12.50x16 on her and figure it wont hurt to change up the gears. If I change the gears is there anything I need to do with my speedo or tranny? and if I go higher with gears will it make my gpm drop from and increased rpm?

[melmount]

just jack the rear wheels off the ground. Mark the rear yoke and the housing. MArk the top of the tire, put tape on the fender to mark the tire in line with it. Have someone spin the tire(put truck in nuetral, no e brake) Count how many times the yoke spins from the housing. Most likely 3-3/4times that will be 3.73
if it goes 3.5times 3.56 and just over 4 times equals 4:10
or read the tag bolted to it if itsstill there. But i would verify, easy to put the tag on a wrong rear. The gears need to stay the same or you will break 4wd parts when in 4wd.

[Fireman40]

Ok I have the tag ill have to clean it off and look. I never thought about changing gears and using 4x4 thanks for bringing that to my attention. My next question is does anyone know how much parts for this cost. I don't know whats wrong yet but lets say the bearings are shot with destroyed the spider gears and ring gears. do you think it would be beneficial to get a certified used axle assembly.

[bigcountrysg]

Originally Posted by Fireman40

ok well I have faced it that this is going to cost me alot. I was thinking of maybe just getting a good used axle assembly. I dont know what gear my truck is not but when Im doing 70mph its at 2000 rpms exactly. I just put a set 0f 35x12.50x16 on her and figure it wont hurt to change up the gears. If I change the gears is there anything I need to do with my speedo or tranny? and if I go higher with gears will it make my gpm drop from and increased rpm?

Well if you have owned the truck since new. You know that the gears have not been swapped out. When you changed the fluid you should have noticed an axle id tag held in by one of the cover bolts. That id tag tells you what axle and gear ratio you have. If you do not have that axle id tag.

Open up your driverside front door. It will tell you your axle code and what gear ratio you have.

[bigcountrysg]

Originally Posted by Fireman40

Ok I have the tag ill have to clean it off and look. I never thought about changing gears and using 4x4 thanks for bringing that to my attention. My next question is does anyone know how much parts for this cost. I don't know whats wrong yet but lets say the bearings are shot with destroyed the spider gears and ring gears. do you think it would be beneficial to get a certified used axle assembly.

If your axle needs rebuilt. Just upgrade to a locker or tru trac for the rear diff.

I would not use an axle that is used. But that is me.

Oh another thing is when you pull the cover do to your inspection. Look at the ring gear will be stamped on the flat side what ratio it is.