8 3/4 Rear ?

[Beavis]

ok, i fully rebuilt my 8 3/4 sure grip with 3:23 gears. all new bearings including green bearings for the axles. i had whining noise before i rebuilt the pumpkin, now its worse !!

it only whines when accelerating, no noise when decelerating.

im pretty sure i rebuilt it properly and have all the spec mic'd properly


it has 75-140 gear oil (synthetic)

any ideas ??? thanks

 

[65wgn440]

If you didn't change gear set, probably worn ring & pinion, if you did, probably not set up properly.

 

[Beavis]

i did not change it.

 

[Beavis]

any suggestions and who has the best pricing on new gears ? should i switch to different gears ? its for my Adam 12 cop car that has a 440HP in it with 727

 

[Bad Sport]

i did not change it.

When you took it apart did you measure the backlash with a dial indicator before disassembly?

If not, and you put it back to spec, I suspect that's why it's whining worse.

 

[Beavis]

im pretty sure we had it right on.

 

[65wgn440]

Motive makes reasonably priced gear sets.

 

[Beavis]

no 3:23 gears there

 

[Beavis]

.07 on the backlash

 

[dryheat]

Call Doctor Diff ... he has what you need.

 

[Beavis]

what are the best street gears. go on the highway from time to time.

 

[Bad Sport]

any suggestions and who has the best pricing on new gears ?

What center section?

 

[Beavis]

489

 

[33 IMP]

I'm no rearend expert,but one of my best friends owned a one man differential shop, and your experience is exactly what he told me: a noisy gear set will be noisy forever, once noisy they are UNfixable. If they became noisy from worn bearings,or lack of lube, they will be worse with new bearings. He told every customer with a whine, it's time for new gears. But even new gears can be ruined in under 20 miles if setup isn't right.

 

[Bad Sport]

a noisy gear set will be noisy forever, once noisy they are UNfixable.

He is correct.

 

[Bad Sport]

489

10 or 29 spline on the pinion?

 

[Beavis]

is it ok to use synthetic gear oil ?

 

[Beavis]

29

 

[33 IMP]

is it ok to use synthetic gear oil ?

Again, to quote my friend, (who made his living doing this)"i warrantee any rearend with synthetic gear lube for 6seconds or six inches, whichever comes first." He never used anything other than torco.

 

[68Moparmaniac]

.07 on the backlash

.07 on the backlash

There's your problem right there, .07 is way out of spec. The backlash on a 8 3/4 is .006 to .010 cold. You got way too much clearance between pinion and ring gear. The 489 third member is probably the strongest of the 8 3/4 line up. It's got the bigger pinion bearings (1 7/8) than the other cases. Check the gear lands for abnormal wear if they have nasty wear patterns their toast. If they look good re-adjust your backlash to .006-.010, I personally set mine @.008