Checkout this gear pattern, why am I getting howling under load around 45mph?

[homebrewer]

About 200 miles ago I regeared to 4.88s on my JTSD...which is now giving me PTSD.

I don't think I set the pinion depth close enough initially, as the sound appeared within 50 miles or so. I swapped the inner and outter pinion bearings for another brand new set chasing the issue, but that didn't solve it. Finally I spent this 3 day weekend trying over and over until the drive side of the tooth was centered. The noise is still there, comes on around 30 mph quietly then rises in volume till you can hear it over the engine around 50mph.

I assume the ring and pinion set are toast? They look fine, no pitting or obvious wear. The teeth faces look polished, however.

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[homebrewer]

I should mention backlash is set to .003" per the spec listed here:
https://d3qx1uccksbb2n.cloudfront.net/docs/SPECSHEET-JL-REAR-UD44A-D44A-42019.pdf

But now I am seeing 5 to 8 mil listed here:
https://www.jeepgladiatorforum.com/forum/attachments/03-rear_axle_m220_torque_specs-pdf.313756/

this is kinda pissing me off

 

[dmwphoto]

Understand your frustration. Setting those up can be a pain for sure

 

[homebrewer]

and I just realized maybe Yukon has a different spec for their gears than oem?

I ask because yukon does not have the m220 listed in their manual, just dana 44.

 

[drewcnit]

and I just realized maybe Yukon has a different spec for their gears than oem?

I ask because yukon does not have the m220 listed in their manual, just dana 44.

I'm not an expert (and no I didn't stay at Holiday Inn), but literally everything I hear from people I trust is that Yukon's are hit or miss like this on whining even when installed correctly.
If you have the option, you may want to warranty this set and get a replacement to see if you have better luck.
Or get away from the Yukon's altogether - my shop used Revolution gears in my regear, won't touch Yukon.

 

[homebrewer]

I'm not an expert (and no I didn't stay at Holiday Inn), but literally everything I hear from people I trust is that Yukon's are hit or miss like this on whining even when installed correctly.
If you have the option, you may want to warranty this set and get a replacement to see if you have better luck.
Or get away from the Yukon's altogether - my shop used Revolution gears in my regear, won't touch Yukon.

Interesting. I scoured the internet trying to find out if some gears are just noisy and yukon popped up here and there. I don't doubt it, but this is the first time I've done this and I think its far more likely I screw up somewhere. But now that I've rebuild the rear 3 times maybe not......

The front diff is noiseless, however.

 

[Gren71]

I %100 applaud you for taking this on as a DIY project! Im still trying to carve put time to do a trans fluid change…that should have been done 15k+ miles ago ?‍

Follow the thread, very interested to see this get figured out.

 

[Panthers65]

The yukon (and most other aftermarket gears) are a 5-cut gear, the dana-spicer gears are a 2-cut gear.

When spicer calls for a 3-6 thou for the backlash, that is on their 2-cut gears. Aftermarket 5-cut gears should be set with a larger backlash. Check the Yukon spec for the backlash and ensure you are there.

All that to say, if your B/L opened up, it's probably okay. I believe Yukon's spec is 6-10. Yukon's are also just known for howling, like most the other aftermarket ratios.

 

[homebrewer]

The yukon (and most other aftermarket gears) are a 5-cut gear, the dana-spicer gears are a 2-cut gear.

When spicer calls for a 3-6 thou for the backlash, that is on their 2-cut gears. Aftermarket 5-cut gears should be set with a larger backlash. Check the Yukon spec for the backlash and ensure you are there.

All that to say, if your B/L opened up, it's probably okay. I believe Yukon's spec is 6-10. Yukon's are also just known for howling, like most the other aftermarket ratios.

I'll open it up to 8 mil or so. What's crazy is that I'm pretty sure I set backlash to 8 mil originally because I went by the spec I found at the time, but this weekend I set it to 3 mil when I redid the gear pattern. I'm pretty sure I just ended up causing the same symptom in a different way. Well, maybe. Otherwise I'll have to get a new ring and pinion set I assume.

 

[Panthers65]

Open it a bit with the Yukons.

Also make sure the carrier is in there tight, when I did mine I put new carrier bearings in but reused the same carrier, and actually had to add about .01 worth of shim to the carrier to get it to fit snugly in the housing.

It's pretty apparent the tail bearing on these is problematic as well. The one that came in my kit made a sound around 40 mph when I was on the accelerator. I pulled it back out at the 500 mile and put the original back in and the sound went away.

Have to be real careful on the crush sleeve too, can't overtighten and then back off. The pinion in general on these is a weak point.

 

[homebrewer]

Open it a bit with the Yukons.

Also make sure the carrier is in there tight, when I did mine I put new carrier bearings in but reused the same carrier, and actually had to add about .01 worth of shim to the carrier to get it to fit snugly in the housing.

It's pretty apparent the tail bearing on these is problematic as well. The one that came in my kit made a sound around 40 mph when I was on the accelerator. I pulled it back out at the 500 mile and put the original back in and the sound went away.

Have to be real careful on the crush sleeve too, can't overtighten and then back off. The pinion in general on these is a weak point.

I should probably replace the crush sleeve as well. I backed the pinion nut out on accident then retorqued it and that's been in the back of my mind haha.

 

[Vtur]

About 200 miles ago I regeared to 4.88s on my JTSD...which is now giving me PTSD.

I don't think I set the pinion depth close enough initially, as the sound appeared within 50 miles or so. I swapped the inner and outter pinion bearings for another brand new set chasing the issue, but that didn't solve it. Finally I spent this 3 day weekend trying over and over until the drive side of the tooth was centered. The noise is still there, comes on around 30 mph quietly then rises in volume till you can hear it over the engine around 50mph.

I assume the ring and pinion set are toast? They look fine, no pitting or obvious wear. The teeth faces look polished, however.

Increase backlash a little to get the drive pattern toward the heel side. It very close to being correct. But it's no guarantee with Yukon gears that it won't howl still.

 

[Charles 236]

It would probably be okay to reset the backlash again. I haven't used Yukon gears in about 15 years, so I can't speak about current Yukon gear quality, but I had good experience with them in the past. Also, I recall being told in the training center (Chrysler) that if we thought we could reset the gear mesh and make it run quietly that we might as well try. This was back when we were seeing a lot of howling gears in the new Grand Cherokees, around '99 or so. Here is the pattern chart (from the '65 Plymouth Service Technical Manual, but same effect on shim changes.)

 

[AustinL911]

 

[homebrewer]

freaking wow. I saw the video where those gears were installed when researching how to do it...part of the reason I bought yukon gears. I'm glad he followed up on it. Mine is much more high pitch and not as loud.

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