Sitting will be extremely uncomfortable butt (TS&T) I'll make the sacrifice and cross EVERYTHING for you.

BB1

Any discussion with them about the “1/4 discrepancy ?

Rudi wrote:

Any discussion with them about the “1/4 discrepancy ?

 
That was Currie.

Bullet Bob wrote:

TKOPerformance wrote:

  Yukons never make any noise. 

Well actually...the 8" that I gave to Josh (big time garage points) had Yukons with proper BS and a good pattern.  They replaced the Italian Motives which howled like a mashed cat.  The Yukons were better but had an annoying howl from 45 to about 75.

Just sayin'

BB1
 

 
Yuuuuup so do mine Yukon gears.

HudginJ3 wrote:

Bullet Bob wrote:

TKOPerformance wrote:

  Yukons never make any noise. 

Well actually...the 8" that I gave to Josh (big time garage points) had Yukons with proper BS and a good pattern.  They replaced the Italian Motives which howled like a mashed cat.  The Yukons were better but had an annoying howl from 45 to about 75.

Just sayin'

BB1
 

 
Yuuuuup so do mine Yukon gears.

I've installed over a dozen sets in all types of vehicles and never had any of them make noise.  One thing I will say about 8" and 9" Fords is that if they ever broke something that's probably the reason they are noisy.  Contrary to popular belief these rears are not terribly strong, specifically because the pinion bearings are too close together.  This is why they need the pocket bearing on the end of the pinion for additional support.  I've seen several cases that were warped from the gears having run over something.  I learned how to measure them to check for this.  Essentially what's happened is that the pinion bore is out of true with the centerline of the differential (not perpendicular in both axes).  Its a small variation, only a couple thousandths, and no way you'd know without specifically checking for it.  Without knowing, you setup the gears and they look great, good pattern, proper backlash.  The problem is that you only check the pattern in one small area.  Were you to check it in say 4 places around the gear you'd find its different.  Sadly, after 50 years most of these cases are junk.  Possibly they weren't machined right to start, or the iron used had bad metallurgy (it definitely wasn't great or the N case rears wouldn't be such a big deal). 

Another thing you have to be sure to do on rears with side bearing adjusters is turn those adjusters in an equal amount of both sides after you get proper backlash to set side bearing preload.  A lot of guys skip this step.  This leads to the rear initially being quiet, but as the bearings run it the clearance opens up and they develop a howl on deceleration.

I think a lot of mistakes are made when it come side to side bearing preload. N cases never fit my budget. WAB & WAR cases flex easier (spread). The getting harder to find DIF cases are the next best thing to the N.

Only one time I needed to remove and reposition the ring gear 180 deg. to get a good pattern all around. I never figured as to why that workers

red351 wrote:

I think a lot of mistakes are made when it come side to side bearing preload. N cases never fit my budget. WAB & WAR cases flex easier (spread). The getting harder to find DIF cases are the next best thing to the N.

Only one time I needed to remove and reposition the ring gear 180 deg. to get a good pattern all around. I never figured as to why that workers

Flipping the ring gear may have to do with tiny variations in the mounting surface on the diff or the gear.  If they weren't machined perfectly true that would account for it.  I always dress both those surfaces with a flat file just to be sure there are no burs, etc.  I go over the fillet radius on the diff and gear (inside the bore) too.  If that gear isn't true when mounted you'll never get a good pattern. 

Absolutely on the side bearing preload, and the thing that gets me is that its so easy on these rears.  On a Salisbury type (GM 12 bolt, etc.) you can only get the side bearings so tight because you have to drive the shims in.  I spend the extra money to get the shims Yukon sells because they have a pair of heavy shims with a collar in the middle to support the thin shims.  This allows you to get a tighter shim pack because you have something to drive against when you install them the final time.  I've found you can go about 0.005" more than slip fit (0.0025" per side) to set the preload.

Dana rears are trickier still because the shims are under the cones on the diff.  You have to make setup bearings just to get the backlash right.  You really need to use a case spreader for those.  I always borrowed one from a buddy who had a 4x4 shop and probably had set up over 1,000 rears in his lifetime.  Same deal there though, about an additional 0.0025" per side on the final setup when you press the bearing on the diff. 

So many guys omit this step, the backlash opens up and noise, particularly on decceleration, ensues. 

Backlash is another thing a lot of guys are just happy when they hit the tolerance range.  I go to the tight or loose side depending on application.  Drag race and street gears I set up on the tight side.  Endurance racing I go looser, because the gears will heat up and they need some room to expand.  On those I like to see at least 0.012" regardless of spec.  0.0015" is better, especially on larger diameter ring gears (8-1/2" and up).