Regearing 8.25 Pattern Advice and Help

Qban

New member
This is my first time regearing solo and was hoping to get some help on the pattern. This is on a 8.25 with 4.56. I'm setting backlash with a dial indicator according the FSM process of torquing and everything I'm arriving at .005-.006 consistently with that process so I'm happy about that.

This is initial using the old pinion depth shim. The pattern on the drive side looked too high (crown) and I thought it should be a little closer to the toe.




So I added 0.010 to the original shim but that still didn't allow me to see any yellow between the crown and the contact pattern. So I then used 0.025 + original shim which looked like too much.

These next pictures are drive and coast of 0.019 + original shim.







I also have pictures of the 0.025 and 0.010 setups if that would help. I just didn't want to flood the thread with too many. Right now I'm using my old bearings on the pinion which got grinded for setup bearings.

Any advice would be appreciated. Thanks!
 

Qban

New member
So I'm reading a little more and looking at the pics with a fresh set of eyes today. My thoughts are that the last 2 pics with the 0.019 shim is in the right direction but that I need to increase the backlash a hair, right now I'm at 0.005-0.006 BL. I'm thinking of increasing BL by 0.002 and checking the pattern again. Depending on how that looks, I can also subtract the Pinion depth by 0.002, taking me from original shim + 0.019 to original shim + 0.017.

Let me know if you guys think I'm on the right track. Thanks
 

Keekleberrys

New member
You're too deep on the pinion now. Your first drive pattern looks very close. You might not get better. Id go back to your starting pic and then try maybe a few thousandths deeper. Smallest adjustment you can make and see if it improves
 

Qban

New member
You're too deep on the pinion now. Your first drive pattern looks very close. You might not get better. Id go back to your starting pic and then try maybe a few thousandths deeper. Smallest adjustment you can make and see if it improves
Thanks Keekleberry,

So I already had done Pinion Depth Original Shim + 0.010 and had pictures so let me post them. At least so I can bracket what my best pattern should be between.

BL 0.005-0.006, Pinion Depth Original Shim + 0.010
Drive Side


Coast Side


After I ran this pattern I really thought that this pattern was too high and that I needed to get it further away from the crown and closer to the root by increasing the pinion depth. I guess that's why I'm posting images, so I can learn that I'm wrong =)
 

Keekleberrys

New member
Thanks Keekleberry,

So I already had done Pinion Depth Original Shim + 0.010 and had pictures so let me post them. At least so I can bracket what my best pattern should be between.

BL 0.005-0.006, Pinion Depth Original Shim + 0.010
Drive Side


Coast Side


After I ran this pattern I really thought that this pattern was too high and that I needed to get it further away from the crown and closer to the root by increasing the pinion depth. I guess that's why I'm posting images, so I can learn that I'm wrong =)

I don't think it's too high. See the line forming at the root of the tooth on the coast side? If anything that's an indication that you're getting deep, it also looks like you're starting to lose resolution of the pattern on the coast side.

I would worry less about seeing the yellow strip at the top of the tooth and worry more that the overall majority of the pattern is centered from face to flank(top and bottom) on the tooth WITH diffuse edges. The edges look like they are getting harsher in the last pic.

.010 is a pretty gross adjustment you got any shims in between the two? I think your ideal number is somewhere in between the two. Honestly I would have no problem running the first pattern
 

Qban

New member
Ok, I'm starting to see and get what your saying, good call on the harsh line at the root and the diffuse edges. Unfortunately the smallest shim I have is 0.010

That being said would it be ok to NOT use the original shim from the old setup? That's the shim with the little ears/tabs on the inner part of the shim. I can measure the original and probably make another pack with a few extra thousandths.

Thanks again!
 

Digger87xj

New member
Honestly I would have no problem running the first pattern
This
The first pattern looked like all it needed more backlash.

Increase it to between .008 and .010" backlash and the stock shim under the pinion and I'll bet you come in with a perfect pattern.

Ignore the backlash specs in the FSM as you are using aftermarket gears.

I've had to set backlash to .012" on a set of aftermarkets to get a good pattern before.
 

Qban

New member
This
The first pattern looked like all it needed more backlash.

Increase it to between .008 and .010" backlash and the stock shim under the pinion and I'll bet you come in with a perfect pattern.

Ignore the backlash specs in the FSM as you are using aftermarket gears.

I've had to set backlash to .012" on a set of aftermarkets to get a good pattern before.
That's good to know =) Since everything is going in the direction of the first pattern, let me post the coast picture

Coast (For Drive Side check 1st Post), BL:0.005, Pinion Depth: Original Shim Only


When I get home from work, I try the factory shim with more backlash like your recommending and we'll see how it comes out =) Thanks!
 

Digger87xj

New member
actually, now seeing both first run pics.. they were perfect. if you can nail it in that .005 to .007 window again, run with it. Id even leave it at .008" if that's where it fell.
 

Qban

New member
actually, now seeing both first run pics.. they were perfect. if you can nail it in that .005 to .007 window again, run with it. Id even leave it at .008" if that's where it fell.
Thanks, I went ahead and tried the original shim with a 0.008 backlash and here's what I got.

Drive - Factory Shim Only, Backlash 0.008


Coast - Factory Shim Only, Backlash 0.008


Staying with the factory shim only and going from a backlash of 0.005 to 0.008 looks like it made a large difference versus my first post.

Should I go ahead and try the same thing as before (factory shim with 0.005 Backlash) and see if I can get the same pattern as my first post?
 

Qban

New member
aww man, tonight was full of fail. I over torqued the crush sleeve and went too far on the pinion preload. luckily I have a another crush sleeve but what sucks is having to hit the crap out of the back of the pinion to get out the rear pressed on bearing. Hopefully my bearings aren't shot after this. Any advice or words of comfort? =)
 

MoparManiac

New member
Crush sleeves for these are cheap, I usually get one or two extra.

Your bearings are fine. I smash the pinion in/out with a plastic mallet right on the threads with no concern and have never had an issue. Getting an original pinion out sometimes needs a steel head hammer and threading the nut back on a few so you don't booger up the threads.

First pattern I would have run without concern. Don't worry too much about heel/toe as most times you can't really correct for that (at least from my experience). Top/root is all that matters.
 

Qban

New member
Thanks everyone, so I got the rear finished up on Saturday with the same pattern in the first post and a BL of 0.005 - 0.006 and have been driving lightly to break it in. Everything felt pretty good but I did notice a LITTLE bit of a low frequency howl and what felt like a slight amount of vibration at higher speeds like around 60mph. I removed the front driveshaft since I haven't regeared the front (it felt like the nice thing to do for my tcase) I'm wondering if the noise has something to do with the rear driveshaft, though I don't know what you can do wrong bolting that thing back in.
 

Qban

New member
Ratech makes a spacer replacement for the crush sleeve. PN 4114
That's cool. Initially doing my homework I thought a crushsleeve was going to be way better than shims. My only experience beforehand was regearing a dana30 with a friend. However after doing a crushsleeve by hand with a pipe wrench and a socket, BOTH with cheater bars I think both pinion preload methods equally suck =) It just depends on what kind of mood your in
 

Qban

New member
So I'm pretty sure my new gear setup is now howling. It's a low frequency growl/howling noise that only occurs at highway speeds of about 50-60mph and only while accelerating, if I let off of the gas the noise disappears which tells me it's not driveshaft or anything else, I also took out the front driveshaft to rule out any issues from the front. So I opened up the rear diff and checked backlash in 4 spots and ran another pattern to see whats causing this noise.

Backlash of 4 spots
.0075
.007
.007
.008

It seems to me like my backlashed opened up a little from my original setup. This is after about 100miles of breaking in the first setup. Here's the pattern.



Any thoughts on what to change to alleviate the howling noise?
Thanks everyone
 

IH392

New member
I'm not sure how to read patterns with gears that have been used, it definitely looks different than the pattern before the axle got broken in. But I've done a few gear sets now and I thought the pattern with the original shim plus .010 shim looked better. When I looked at post #10, I felt the pattern looked too shallow and having a deeper pinion would make it look better, because .008 backlash is definitely with in spec. It should have more of an oval pattern like in post #4.
 

IH392

New member
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.
 
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