Regearing 8.25 Pattern Advice and Help

[Qban]

Before you start tearing into the axle, are you sure the pinion angle is correct? Do you have a SYE? Is the axle pinion 1-2 degrees below the tranfercase yoke? Maybe it's axle wrap causing the noise. Just want to rule that out first.

Yeah I was considering that at first. That axle is lifted 3 inch with an aal, no sye but a 1inch tcase drop. The howling noise is only at a speed between about 50-70, and only when accelerating. I can pretty much feather the gas and make the noise come and go without having to heavily punch the gas so I think that rules out driveshaft and bearings etc...

Anyways, I set it up again on saturday and added 0.006 to the pinion depth, making the total shim 0.034 and the backlash was a comfortable 0.008 to make a nicely centered pattern. I think It's getting closer as the pattern had a good diffused oval look to it near the top of the tooth but not at the root of the tooth.

It still howls, but not as loud as before. I'll try some more and take my time with it until I get fed up and just pay someone else to do it. I just don't want to admit defeat yet, or ever for that matter =) I'm stubborn when it comes to trying to do something correctly.

Ratech makes a spacer replacement for the crush sleeve. PN 4114

Thanks for this suggestion!

I got one of those and it worked well for me, especially now that I may have a few more attempts and have to drive on it to know if it's set up properly.

I also found a nice trick for pulling the pinion bearing off. I'm using a bearing separator with the shop press pressing on the threaded side of the pinion, but on the sides of the separator I put some long bolts to pull the two sides of the separator to the underside of the press table and keeps the separator from deflecting upwards and binding on the bearing cage. I'll post a picture next time so hopefully it helps anyone.

 

[MoparManiac]

I also found a nice trick for pulling the pinion bearing off. I'm using a bearing separator with the shop press pressing on the threaded side of the pinion, but on the sides of the separator I put some long bolts to pull the two sides of the separator to the underside of the press table and keeps the separator from deflecting upwards and binding on the bearing cage. I'll post a picture next time so hopefully it helps anyone.

So you didn't use a setup bearing to get your original patterns? You've been pressing the same inner pinion bearing on and off?

I'd be afraid it's loosened up at this point. Could be what you're hearing as far as howling, especially if it's only while on the gas.

 

[Qban]

So you didn't use a setup bearing to get your original patterns? You've been pressing the same inner pinion bearing on and off?

I'd be afraid it's loosened up at this point. Could be what you're hearing as far as howling, especially if it's only while on the gas.

Yup I did use setup bearings which is how I arrived at my first real setup as per the previous page with Pinion Depth of 0.028 and BL at 0.005 and did the final setup once, this was howling. Then I have done one more setup since that first one without setup bearings where the PD is 0.034 and BL is 0.008 which is also howling.

Sorry if I wasn't clear. If it's the same howl on both setups and the first time only had one press of the bearings then I wouldn't think the noise is because the bearings loosened up.

Thanks for the idea though

 

[Keekleberrys]

Yeah I was considering that at first. That axle is lifted 3 inch with an aal, no sye but a 1inch tcase drop. The howling noise is only at a speed between about 50-70, and only when accelerating. I can pretty much feather the gas and make the noise come and go without having to heavily punch the gas so I think that rules out driveshaft and bearings etc...

Anyways, I set it up again on saturday and added 0.006 to the pinion depth, making the total shim 0.034 and the backlash was a comfortable 0.008 to make a nicely centered pattern. I think It's getting closer as the pattern had a good diffused oval look to it near the top of the tooth but not at the root of the tooth.

It still howls, but not as loud as before. I'll try some more and take my time with it until I get fed up and just pay someone else to do it. I just don't want to admit defeat yet, or ever for that matter =) I'm stubborn when it comes to trying to do something correctly.


Thanks for this suggestion!

I got one of those and it worked well for me, especially now that I may have a few more attempts and have to drive on it to know if it's set up properly.

I also found a nice trick for pulling the pinion bearing off. I'm using a bearing separator with the shop press pressing on the threaded side of the pinion, but on the sides of the separator I put some long bolts to pull the two sides of the separator to the underside of the press table and keeps the separator from deflecting upwards and binding on the bearing cage. I'll post a picture next time so hopefully it helps anyone.

That is optimal speed for ujoint noise to manifest. Because of the phasing the noises usually come and go at 30 & 60'sh mph, and because your driveshaft is spinning faster it could be making it even worse. Not saying that's what it is, but you're in the right speed zone for it to be happening.

Regardless of what people will say aftermarket gears are much more likely to make noise, I have a perfect pattern on my dana 30 and it still howls. It will probably be something you will just have to live with, because it sounds like you've already got some miles on the gears. My front makes a little bit of noise at lowspeed and it's gonna a little bit better but I don't think it will ever go away.

 

[IH392]

After some driving with the extra shims maybe it will get quieter. Also, did you put enough preload on the carrier bearing when you installed it the final time. I have always read that there should be .015 extra shim added to the carrier bearings for preload (I'll put .008 one one bearing and .006 on another bearing). To make things easier I always put the carrier in the freezer to make it shrink and make it easier to install. Maybe you already knew this. I also still think that it could be the driveshaft, especially since it's spinning so much faster now, like what others have said. Just make sure your angles are right.

 

[Qban]

After some driving with the extra shims maybe it will get quieter. Also, did you put enough preload on the carrier bearing when you installed it the final time. I have always read that there should be .015 extra shim added to the carrier bearings for preload (I'll put .008 one one bearing and .006 on another bearing). To make things easier I always put the carrier in the freezer to make it shrink and make it easier to install. Maybe you already knew this. I also still think that it could be the driveshaft, especially since it's spinning so much faster now, like what others have said. Just make sure your angles are right.

It's a 8.25 Chrysler, it has screw adjusters instead of shims on the carrier. If you follow the fsm process it's impossible to get the carrier preload wrong. I would also love to believe its the driveshaft but the noise changed a little bit on the second setup. Also if it was driveshaft wouldn't there be a little vibration associated with it? This is a howling/whirling sound only. Thanks for the ideas though, I appreciate it.

 

[Digger87xj]

What brand of gears? Some just howl. some more than others.

Also, 100 miles is not broken in. they may quiet down after 500.

 

[Qban]

What brand of gears? Some just howl. some more than others.

Also, 100 miles is not broken in. they may quiet down after 500.

Yukon brand 4.56 and I got the version that is supposed to be quiet =) As I was told by someone with way more experience than me, Chrysler 8.25 is an odd cut and Yukon is really the only ones that do it correctly. It's possible that this is just how they are, I just have a tendency to blame the installer (myself) before just blaming it on the gears =)

I guess I'll just play around with it some more. I did have one idea today though, One thing I've noticed was common to almost all the patterns I've run is that near the root it is rather sharp and not as feathered as the top. This is true regardless off the pinion depths I've tried. Similarly I haven't tried a greater backlash, as in greater than 0.008.

Maybe I should take the current pinion depth and increase the backlash to 0.012 which is easy and see how the pattern changes and if I get more feathering in the root of the tooth then I can move the pinion depth taking into account that I'm trying to achieve an "acceptable" pattern while maintaining a BL of in greater range around 0.010.

I'm just trying to think logically while being a little outside the box.

 

[Qban]

So I increased the backlash to about 0.011 which I know is high but I wanted to make a large change to see if it affected the gear howling. The pattern still looked reasonable to run so I gave it a shot. The howling pretty much continued about the same...

So last night I got some longer bolts and a bunch of washers and increased the Tcase drop from 3/4inch to about 1.5inch. Guess what! the howling went away by about 80% You can still hear it, but not nearly as much as before.

Grrr... I know, everyone suggested that. Congrats, you were all right! and I was too stuborn to try an easier test first =(. It also didn't help that I had the mechanic at my work go for a test drive and he said "oh... without a doubt that's your gears". So right now I'm stuck with a sub optimal pattern on my gears and an obnoxiously large tcase drop =)

So I went ahead and did the right thing last night. I ordered an NP242 TomWoods SYE with driveshaft from 4x4 groupbuy which I had been eyeing for a while and now I need to go measure everything and also get some pinion angle shims. I don't see any point in touching the gears again until I get the driveshaft angles resolved and then I will re-setup the gears to the original pattern which looked stronger than what I have now.

I'll concentrate on the good news though:
- I get an SYE which I've been needing to get
- More importantly the tcase drop can disappear which is ghetto and lets me get some clearance back.
- At least now I can setup the front gears with more confidence