New 3rd member build gear pattern

[andrewwoz]

New Yukon 489 case, Yukon 3.91 ring and pinion, eaton truetrac, crush sleeve eliminator and honed setup bearings, I think I am getting close but have never done one of these before and would appreciate any feedback. I could not find any info on the ring and pinion for a depth measurement so I just started with .030 (not pictured) and went to .040. I get the backlash to .008 each time, pinion bearings are preloaded to roughy 16in/lb each time.

Hopefully this photo works, as long as its big enough it makes it easier to compare everything I think. .040 looks like the pinion is too deep, to me .037 still looks like a little deep, .035 looks pretty good I think? Wondering if I should try .034 or .036.

 

[493 Mike]

I vote for the .040.
Mike

 

[john-9]

0.037 looks the best ,, you have pretty much full solid contact across the face on the drive side and the coast side , the 0.035 looks good as well but the coast side seems to be washing out ( lighter contact pattern ) a bit.

 

[icetech]

I'm surprised at how much change .003 makes

 

[Cranky]

Do you have a pinion setup tool that measures the depth of the pinion from the ring gear centerline with a dial indicator? I do and the pattern NEVER looked right to me. The first set went into my 'test' car (71 340 Cuda) and they were quiet both on accel and decel after a breakin period. Did the same thing with the next two rears and after that, I trusted the tool and never paid much attention to the pattern again. And if the gears are made in China, all bets are off...

 

[AR67GTX]

I like the .035 and .037 set ups. Not sure which of the 2 is best. I think maybe the .037 as it looks like the pattern on the drive side is moving up (towards heel) with lesser shim.

 

[dvw]

.035"-.037" had the pattern centered the best between the root and the top of the tooth.
Doug

 

[493 Mike]

Can you imagine how fussy the guys were building these pigs at the assembly shop?
Mike

 

[andrewwoz]

Do you have a pinion setup tool that measures the depth of the pinion from the ring gear centerline with a dial indicator? I do and the pattern NEVER looked right to me. The first set went into my 'test' car (71 340 Cuda) and they were quiet both on accel and decel after a breakin period. Did the same thing with the next two rears and after that, I trusted the tool and never paid much attention to the pattern again. And if the gears are made in China, all bets are off...

So I did buy the proform tools but have not opened it because the ring and pinion have no marking I see anywhere calling out a measurement.

Can you imagine how fussy the guys were building these pigs at the assembly shop?
Mike

hahaha, I know, splitting hairs over here.

Speaking of... I redid .040 today because I don't think I was putting enough resistance on the yoke to get a good pattern, I changed my process when I did 37/35/32 yesterday. I also setup .036 and .038 today

updated photos... I think I am leaning toward .036 or .037, hoping to button it up with the other bearings tomorrow, which I'm sure will throw everything off

 

[493 Mike]

Are you spinning the yoke with the ring gear? I spin the ring gear with the yoke as that is how it operates.
Mike

 

[andrewwoz]

Are you spinning the yoke with the ring gear? I spin the ring gear with the yoke as that is how it operates.
Mike

Spinning the ring gear - Yukon's direction say to do that and not spin it by the yoke as did a number of videos I watched. What I did start doing though is putting some resistance on the yoke with my other hand, that seemed to show the pattern better - more squish?

 

[AR67GTX]

I still don’t think the .040 shim is optimum. I’ve had trouble getting clear patterns too. You really have to put a lot of drag on the ring gear while turning the pinion to do so and I was not very successful with it. I ran probably 12 different pinion depths trial set ups and several different backlash settings before I finally settled on this one. It’s not bad but I still have a bit of float whine from about 45-50. I found that the pinion depth range where the drive side looked good did not overlap exactly with the pinion depth range where the coast side looked best. So I kind of had to settle for a compromise where the coast and drive side patters both still looked acceptable.


My experience with 2 different shops I had set up the pattern before I took matters into my own hands, seemed to only pay attention to the drive side as the coast side both came up with was pretty clearly not great. Not sure how typical that is.

Good luck.

 

[oldkimmer]

I still think .040 but would be happy with .038. Can u post a pic of the pinion?

 

[70bigblockdodge]

.037 send it. If it makes enough noise to hear your car is way too quiet.
It will not with that pattern on .037.