Leaky 9" diff.
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Posting Guru
Joined: Aug 2002
Posts: 1,493
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From: Great NW
Leaky 9" diff.
My 9" rear end seems to be leaking around the main seal where the bulk of the rear end (3rd member?) bolts to the housing. Unsure of terminology here...
Is it possible to replace the seal there without throwing off the geometry on the interior of the differential?
Or is this one of those things that is best to do while the differential is being rebuilt?
TIA
GS
Is it possible to replace the seal there without throwing off the geometry on the interior of the differential?
Or is this one of those things that is best to do while the differential is being rebuilt?
TIA
GS
Posting Guru
Joined: Apr 2002
Posts: 1,187
Likes: 0
From: CT
Leaky 9" diff.
It's a pain in the butt to replace the 3rd member seal on a 9". You have to pull all of the brake components off (replce with new ones) then you have to pull the axle shafts out(replace the bearings on shafts) then you can pull the 3rd member out to replace the seal. So yeah..it's a good time for an overhaul.
Post Fiend
Joined: Jun 2002
Posts: 13,873
Likes: 3
From: Atlanta GA
Leaky 9" diff.
Not to disagree, but, all the previous is not true on Ford 9 inch axles, at least on my 1971 or my 80s Broncos. You do not have to remove axle bearings or brake parts. It is one of the beautiful things about the nine inch. First time it will take (not counting the waiting) about 1.5 hours. With practice this is a 45 minute job.
It is as easy as this and costs about $12 including the fluid, gasket, and RTV.
Put the gear lube on the floor of your truck near the gas pedal!!!
Jack up and put the rear axle on jack stands, but, not too high. If you are doing this yourself it helps to be able to slide a floor jack under the third member while removing it. I removed my bed floor and took my third member out easily without strain.
Mark the driveshaft/rear yoke so you can line them up on the same side again when reinstalling. Set the parking brake, remove the driveshaft at the rear yoke. Leave attached to the truck, just push out of the way. Do not lose the UJ caps. Masking tape helps. Release parking brake.
Remove the wheels and drums.
Take a 3/4 inch socket or 4 way lug wrench and remove the four nuts from the bearing retainer. Gently slide the shaft out about two inches and put a nut back on to keep the backing plate attached to the axle.
Slide the axle about four inches out. Do the other side.
Remove the drain plug NOW. If it is frozen in place, you do not want to get too far along in the job.
Place a pan under the axle. Take off all the lower bolts, loosen the top ones. If all nuts turn okay, NOW, wobble 3rd member while pushing up and pulling. Pull out more at bottom and let drain. When finished, remove top 4 bolts, slide completely off.
Clean both gasket surfaces and any junk in the axle. Clean stud threads.
On mine I put (smeared) a thin layer of black RTV on the 3rd member, put the gasket on, and smeared a thin layer of black rtv all over the axle mating surface. Especially around the studs. Put third member back on, torque to specs. How I torque them is tighten evenly in a criss-cross pattern. Third time around, I do it clock wise starting at the top until i complete the circle. I do it by feel, with a short wrench or 3/8 ratchet, you can't really torque over 40 ft lbs without going nuts.
Smear and smooth out the squished RTV.
Reinstall everything.
Wait a few hours and let the RTV set up.
Remember the first step? That is so you would not drive it with an empty axle. Refill and drive.
It is as easy as this and costs about $12 including the fluid, gasket, and RTV.
Put the gear lube on the floor of your truck near the gas pedal!!!
Jack up and put the rear axle on jack stands, but, not too high. If you are doing this yourself it helps to be able to slide a floor jack under the third member while removing it. I removed my bed floor and took my third member out easily without strain.
Mark the driveshaft/rear yoke so you can line them up on the same side again when reinstalling. Set the parking brake, remove the driveshaft at the rear yoke. Leave attached to the truck, just push out of the way. Do not lose the UJ caps. Masking tape helps. Release parking brake.
Remove the wheels and drums.
Take a 3/4 inch socket or 4 way lug wrench and remove the four nuts from the bearing retainer. Gently slide the shaft out about two inches and put a nut back on to keep the backing plate attached to the axle.
Slide the axle about four inches out. Do the other side.
Remove the drain plug NOW. If it is frozen in place, you do not want to get too far along in the job.
Place a pan under the axle. Take off all the lower bolts, loosen the top ones. If all nuts turn okay, NOW, wobble 3rd member while pushing up and pulling. Pull out more at bottom and let drain. When finished, remove top 4 bolts, slide completely off.
Clean both gasket surfaces and any junk in the axle. Clean stud threads.
On mine I put (smeared) a thin layer of black RTV on the 3rd member, put the gasket on, and smeared a thin layer of black rtv all over the axle mating surface. Especially around the studs. Put third member back on, torque to specs. How I torque them is tighten evenly in a criss-cross pattern. Third time around, I do it clock wise starting at the top until i complete the circle. I do it by feel, with a short wrench or 3/8 ratchet, you can't really torque over 40 ft lbs without going nuts.
Smear and smooth out the squished RTV.
Reinstall everything.
Wait a few hours and let the RTV set up.
Remember the first step? That is so you would not drive it with an empty axle. Refill and drive.
