4.300 Differential Grinding Diagnosis?

[Oldskoolsk8r]

This is my first post/question, so bear with me. My '87 non-turbo has always had a slight grinding noise in the rear diff when making a parking lot speed, tight left turn. The rear gasket on the diff had a leak. When I got a new exhaust system, I had the shop drop the diff, replace the seals and put in new fluid. The diff from that moment felt like it was dragging; I think they put in the wrong fluid, too thick. After a few months, the diff grinding became more pronounced, and I took it to the Toyota dealer for a diagnosis. They replaced the LSD fluid and the problem seemed to fix itself; NO noise for a few months! Then, the grinding came back with a vengeance; I have severe grinding now at higher speeds and what sounds like binding on left turns.

OK, dropped the diff, but No metal on mag plug (recent fluid change?). Some backlash on ring and pinion, but no heavy wear on gear teeth. The diff gears seem to bind a little when drive shaft turned forward and back. There isn't any severe gear teeth damage visible when looking in the diff, but I haven't taken it apart. I can't see the clutches, yet.

It has to be the differential, right? Are there any cost effective ways to replace the internal gears to the differential? I don't need a track proven racing diff at $1000 or an OEM at $1900. What have others done?

Thanks for the advise in advance. Mark

 

[ms07s]

They can be rebuilt in most cases.

If you just want to drive around, source one at a local junk yard. In my area they range from $50-65 for a complete pumpkin with a 30 day guarantee, but you must pull it yourself. 4.3 LSD will be a bit hard to source but an open 4.3 diff should be relatively easy to find.

 

[gofastgeorge]

Some backlash on ring and pinion, Mark

Define 'some backlash'.
There should only be a few thousands, like .007" when checked with a dial indicator.
(look in TSRM)
If you have noticeable back lash slop, that's too much.

 

[Oldskoolsk8r]

Define 'some backlash'.
There should only be a few thousands, like .007" when checked with a dial indicator.
(look in TSRM)
If you have noticeable back lash slop, that's too much.

It would have been much more than 7 mils, though I'm not clear where this is measured from. In rotating the drive shaft back and forth, it would have been numbers of degrees play, before the output shafts would turn. Also, it had a surprisingly distinct "klink-klink" between when the drive shaft turned and the output shafts started to turn (on the bench, without fluid). In checking this, sometimes the differential gears would bind such that you would have to turn the shaft with both hands.

 

[gofastgeorge]

Dial indicator placed on a ring gear tooth, on the tangent,
with the pinion locked, the ring gear movement, back and forth should only be a few thousands of an inch (check the TSRM).

If your pinion moves degrees, most likely that is the problem.

 

[amichie]

My guess is when they changed the front seal they didn't change the crush tube. If the big nut on the front is loosened off then the crush tube must be replaced.

 

[cuel]

Wouldn't hurt to check the bearings. They usually go first when run without a sufficient amount of oil. Would start with the pinion bearings, as they're the furthest forward, and get the least amount of oil.

I'd also take a close look at all the wheel bearings, since your hearing your noise worst when transferring weight to one side.

 

[Jeff Lange]

Thread Moved.

Jeff