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Discussion Starter · #1 ·
Hi, I'm wondering if anyone has ideas for this problem. After driving a while, the rear has grinding/clunking noise on turns only. I've repacked the bearings and changed the Diff. fluid with Friction Modifier. I've been told that it may take more driving for the new fluid to work with the disks in the Diff. I'm concerned about the gears and damage. Or, could it just be worn bearings? Yet, no noise on driving straight.
Thanks.:eek:ut:
 

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It is the clutch plates chattering against each other in turns. The friction mod should work it's way in but they may be too far gone. If it doesn't get any better you may have to replace them.
 

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Repacked the rear wheel bearings ?
 

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Discussion Starter · #4 ·
Thanks Canuck623. I've only driven it twice since the fluid change, so I'll give it a little longer before going after the disk.
 

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Discussion Starter · #5 ·
Hi Phantom. Yes, I repacked the wheel bearings. I was about to replace them until I researched more regarding the grinding noise.
Thanks.
 

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Never heard of repacking a sealed bearing thats why i asked.
 

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Discussion Starter · #7 ·
Hi Phantom, A quick note on those rear floating axles. When you pull the axles, the hub has the outer bearing held in with the ratcheting retainer, whereas the inner bearing pack has the large spinning (expensive) seal, then the bearing pack is out.
Thanks.
 

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Wow I didn't realize that they used that rear end.I learned something now can I go home ?
 

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I wasn't trying to be a smart butt,Its something we say here at work.I really didn't realize they used that rear end.
 

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Discussion Starter · #11 ·
Apologies for no recent update. I finally did a physical inspect on diff. Looks like a Posi to me. No clutch packs, no shavings, no abnormal gear lash. Re-seal and fill with new fluids, no leaks. However, grinding noise returns and an hour or more of driving, then making turns.
 

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What do you mean? "looks like a posi" "no clutch packs". If it is a "posi" (old terminology) it has a clutch pack. You have to remove the internal gears using the special Ford tools and then re-assemble using the Ford special tools. This rear diff is not a place for an amateur.

When you had the cover off did you see any marks on the case? The bearings can wear and the pinion gear can contact the diff case. Is this a 9.75 diff or the larger Dana 10.5 inch.
 

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Discussion Starter · #13 ·
Hi, Sorry to offend the Pro's out there with my old Chev 12-bolt "Posi" description. However, being the amateur, if you take away this Ford Conventional 10.5" size, it's Anti-lock Speed Sensor Ring, and the Full Floating Axles, I see similarities. That being said, I don't plan any attempt to tackle this myself. I've talked to many "Pro's", most say that the problem may be hard to duplicate since it seems to occur only after driving fo quite sometime. So I may have to burn some fuel, then have them use sensors or therms to isolate
specific problem location?
Thank you for the replies!
 

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Discussion Starter · #16 ·
Thanks Dominick for the parts breakdown and the links. I assume that the side gears and pinion gears counter-rotate on turns, so if they're worn and getting hot, I may not notice obvious noise driving straight?
Thanks.
 

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That could be.
I had a 1967 ss427 Impala and when I turned the corners I would have a shutter type noise.
Going in a straight line i was fine.
It had the spicer type rear and way back then I had to live with it as per the Chevy dealer.
But maybe on yours a clutch pack would take care of it.
 

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Discussion Starter · #18 ·
Thanks Dominick. Reference your diagram. Which is close to accurate, aside from the rear cover,etc., there are no clutch packs. After a little research, I believe I have the Ford 10.5" Diff. made in Sterling,MI by "Visteon Corp". 3.73:1 Ratio, 35 Spline Full-floating axles. My current target troubleshooting leads me to believe the spider gears are worn enough to heat-up, open up, and bind on turning.
Thanks.
 

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Why don't you get the tag # from the rear differential and call your dealer and see if they make
a 4026 case assy with the gears and clutch pack in it
or a 4945 clutch pack.
If you get a 4026 assy you will have to replace the side carrier bearings also.
 

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Discussion Starter · #20 ·
Thanks Dominick, I'll give the dealer a try. On a different thought, I've heard others discussing bearings (the outside hub bearings) and packing grease vs. using the synthetic gear lube on the bearings. Is it possible for bearing grease to make it's way to the gear oil and break it down enough to make it ineffective? Thoughts?
Thanks.
 
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