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I have an 82 F100 with a 4.9 motor custom cab
its been a while since I was on here I'm looking to replace or rebuild my rear end.
my question is how to determine what gear ratio I have
If you think the rearend is original, post the code letter that is located on the sticker in the driver's side door jamb.
You can also look to see if there is a tag under one of the rearend bolts in the center. Post a picture of it.
Last resort, jack both rear wheels off the ground. Put a mark on the driveshaft where you can see it, and then mark each rear tire. Get someone on the other side to turn the tire as you turn the other tire one turn. As both rear tires turn one complete revolution, count the number of times the driveshaft turns.
If the driveshaft turns almost 3 times, you more than likely have a 2.75 rearend. If it turns about 3 1/2 times you have a 3.50 rearend.
well I have some updates. This first pic is of where the rear end is leaking. I took it to the car wash and got a lot of the gunk off I thought it was worse then this .. so now my Question is , is this seal easy to replace
so I pulled the tag off the rear end I'm pretty sure this is the original rear end here's a pic of that
Last edited by Cg willie Willie; Aug 15, 2019 at 10:04 AM.
Reason: resize pic
You have a 2.75 to 1 rearend ratio. Should have guessed that is what it was. They are usually found in f100's with inline six cylinder engines. Good rearend for highway driving, and the old six can probably handle that low gear.
That seal can be changed, but certain procedures have to be followed. There are guys who say you have to replace the crush sleeve, but I have done this half a dozen times now without doing that and never had a problem.
1st take the driveshaft loose and lay it aside. You may have to tape the caps on so they don't fall off.
There will be a large nut there. Take a center punch and make a mark on the nut. Then take a hacksaw or use the punch and make a mark on the end of the threaded shaft the nut is on, opposite the mark you made on the nut. You need to get this nut back where it belongs unless you find it's already loose (this is common and might be why the seal is leaking).
Then you need to get the nut loose. This is the hard part. If you have a good air impact, no problem. If all you have is a socket and breaker bar, it can be tough. The truck will try to move as you put a lot of torque on the nut. Sometimes you have to get a piece of metal, drill two holes in it that matches where the u-bolts went, and bolt the piece of metal to the yoke. Then let it swing around till the metal hits the ground and holds the rearend from turning.
Once you get the nut off, pull the yoke and replace the seal.
Put the yoke back in, put the nut back on, and tighten the nut till marks line up. If the nut had worked loose, tighten this nut as tight as you can with a piece of pipe on the breaker bar. It needs to be pretty tight. If it had worked loose a little blue loctite would not hurt.
You have a 2.75 to 1 rearend ratio. Should have guessed that is what it was. They are usually found in f100's with inline six cylinder engines. Good rearend for highway driving, and the old six can probably handle that low gear.
That seal can be changed, but certain procedures have to be followed. There are guys who say you have to replace the crush sleeve, but I have done this half a dozen times now without doing that and never had a problem.
1st take the driveshaft loose and lay it aside. You may have to tape the caps on so they don't fall off.
There will be a large nut there. Take a center punch and make a mark on the nut. Then take a hacksaw or use the punch and make a mark on the end of the threaded shaft the nut is on, opposite the mark you made on the nut. You need to get this nut back where it belongs unless you find it's already loose (this is common and might be why the seal is leaking).
Then you need to get the nut loose. This is the hard part. If you have a good air impact, no problem. If all you have is a socket and breaker bar, it can be tough. The truck will try to move as you put a lot of torque on the nut. Sometimes you have to get a piece of metal, drill two holes in it that matches where the u-bolts went, and bolt the piece of metal to the yoke. Then let it swing around till the metal hits the ground and holds the rearend from turning.
Once you get the nut off, pull the yoke and replace the seal.
Put the yoke back in, put the nut back on, and tighten the nut till marks line up. If the nut had worked loose, tighten this nut as tight as you can with a piece of pipe on the breaker bar. It needs to be pretty tight. If it had worked loose a little blue loctite would not hurt.
many thanks to the both of you. I was at O'reily to day and bought the seal 17 & change
its awful hot here to in TX so I'm wait going to wait for some cooler weather before I start on that
thanks again
The proper procedure for the 9" for pinion seal replacement needs to be followed especially in higher geared rear ends like yours where pinion bearing wear is more pronounced..
You have no idea why the seal has failed. Has the seal just failed due to wear or has it worn out and leaking due to excessive play in the pinion bearings.
The pinion nut should be replaced but the crush sleeve MUST be replaced.
The easiest way to do this job is to remove the pinion carrier assembly from the rear end and work on it on the bench, especially if you do not have access to a hoist, this will require a new pinion carrier O-ring (4669 on the above diagram).
Do not lose the shim between the pinion carrier and the case as this spacer help sets the backlash and tooth contact pattern in the gear set.
Once the pinion carrier is removed the pinion nut is removed, if you are planning on reusing the pinion bearings the pinion nut should not be rattled off with an impact gun as it may damage the bearings.
Once the driveshaft yoke is removed (4851 on the above diagram) it's seal surface should be inspected if it is grooved, install a speedi sleeve to restore the sealing surface.
The pinion can now be removed from the carrier and the crush sleeve (4662) replaced with a new one.
The pinion seal can then be removed with a seal puller or other suitable tool and replaced with a new one.
Reassemble the pinion carrier assembly with a new Pinion nut. The reason for using a new pinion nut is the face of the nut is coated with a sealer that seals the splines of the pinion and it is one use locking nut. You can get away with using the old nut if allowances are made to seal the face of the nut and a removable thread locker is used.
Run the pinon nut down ( again do not use an impact gun as it may damage the bearings) till a pinion turning torque of 8-12 inch-pounds for old bearings and 17-27 inch-pounds for new bearings is achieved go slow as if you over tighten the pinion nut and needs to be backed off to get the correct turning toque the crush sleeve will need to be replaced.
Fortunately on the 9" and 8" rear ends the pinion carrier can be removed (unlike the 8.8 and 7.5" rear ends) and this is much simpler to do on the bench and allows for much more accurate bearing preload readings/settings.
See below Youtube for doing the preload turning torque on an 8.8" rear end. Yes, different rear end but the procedure is the same.
I have had two 8.8 axles grenade on me about 9 months after changing the seal without a new crush sleeve. (One I just stepped on the gas and it grenaded the other I was doing a one wheel burnout in the mud but still). If the truck will see regular road use do it properly.
For a yard truck or truck that sees very few miles you may be fine just changing the seal and putting a new nut with loctite. If you do this route do not tighten it as much as possible with a breaker bar as mentioned above. As you tighten it you are adjusting pinion bearing preload. On the 8.8 100-120 ftlb is the most id go (keeping things tight but not risking going overboard)
new to site but need help on gearing ratio. i have a 97 F 250 HD 4x4 on 35in tires. with 3.55 gearing with a factory limited slip.in a 10.25 differential
have a 351/5.8 motor
I do lots of freeway driving when I tow so I'm torn between 4.11 or 4.30 gears due to the possible high RPMs on freeway.
witch ratio would be best?
can I still use the factory limited slip and if so does brand of gear matter?
if not, what is the best brand to use with a Detroit locker?
and can you tell me how to determine if I have a Dana 44/50/or 60 been told many things and the dealer doesn't know, even when i give them my vin #
new to site but need help on gearing ratio. i have a 97 F 250 HD 4x4 on 35in tires. with 3.55 gearing with a factory limited slip.in a 10.25 differential
have a 351/5.8 motor
I do lots of freeway driving when I tow so I'm torn between 4.11 or 4.30 gears due to the possible high RPMs on freeway.
witch ratio would be best?
can I still use the factory limited slip and if so does brand of gear matter?
if not, what is the best brand to use with a Detroit locker?
and can you tell me how to determine if I have a Dana 44/50/or 60 been told many things and the dealer doesn't know, even when i give them my vin #
Thanks you for any help you can give me.
Look on your door sticker. The FAWR (Front Axle Weight Rating) will be 3850lbs if you have a dana 44hd. It will be in the neighborhood of 4400lbs if it's a dana 50. You will not have a dana 60 if it's the original axle, they did not put dana 60 frontends under f250's, only f350's after 1985.5. I would go with the 4.10 gears. They are a very common option and you could actually swap the complete axles if you did not want to mess with the gearing. They should be easy to find in the junkyard or underneath a donor truck.
