Howling At The Moon - 4.88's in 8.25" rear axle

[X E Ryder]

So I went to the trouble to have West Coast differentials install 4.88 gears for me, and they howl like nobody's business. In all the gear sets I've installed, I've never had howling like this. Is that common for 4.88's in an 8.25" or what?

Drove it 55 for 20 minutes, parked until cool. Then drove home 50-55 all the way.

Never had one I setup whine like this. Thoughts? Thx.

 

[MrAnderson]

Yikes my man! Most shops don't like putting 4.56's in a 8.25!

The (no clue) is way to small for that type of gearing

 

[whitexj98]

What brand gears? I set up 4:56s myself in my 8.25 (nitros) and they are dead quite. I would be taking it back to the shop.

 

[MrAnderson]

Really? I've always heard that 4.56 is the lowest you wanna go in a 8.25? But I don't know a whole lot

 

[XJEEPER]

Take it back and set clear expectations that the setup is unacceptable.

 

[EricsXJ]

Before you do any of that, check your pinion angle. That driveshaft is spinning a whole lot faster now and if your pinion angle is off it is common to get vibrations that are small enough that you don't feel, but loud enough to hear.

 

[NotMatt]

They shouldn't be any louder than stock gears... the problem could be any number of things, bad install, didn't get a bearing seated all the way, poor quality/defective gear set, they might quiet down after a few hundred miles, who knows.

Lucky for you, the solution is easy... take it back to the place who did the gear install and have them fix it. They might want you to wait it out for a while to see if the gear set quiets down after it gets fully broken in.

 

[kastein]

What brand? IIRC, USA Standard Gear are listed with a warning that they may be louder than other brands, it comes with the price. If they used a brand that doesn't say that, no excuses. If it's not set up right it is probably damaging the gears so they should look at it ASAP either way.

MrAnderson, I have never heard that about 8.25s, it is d30s that some don't like putting 4.88s in.

 

[xjtrailrider]

I have the 4.88 Nitro's in my 8.25 that I set-up myself 2 years ago, no noise at all and I have beat the **** out of them on the trail. I did have mine cryoed before instal by Performance Cryogenics. Cryoeing a gear set tends to make them noisier.

I think you have a bad set-up, take it back

 

[sandyeggoxj]

Take em back! I had a guy tell me that if you setup the gears with a center contact on the ring gear it can be loud. Just think in 3d and move it to the heel or toe, he said. My front 4.88 gears make a little noise but only when. In 4wd on the road. Good luck

 

[X E Ryder]

Hey XJ Brethren Thank You Much for all the replies...

What brand gears? I set up 4:56s myself in my 8.25 (nitros) and they are dead quite. I would be taking it back to the shop.

They used Sierra, but when I researched it further, that gearset seems to all go back to the same foundry, after which a dozen wholesalers put their name on.

Before you do any of that, check your pinion angle. That driveshaft is spinning a whole lot faster now and if your pinion angle is off it is common to get vibrations that are small enough that you don't feel, but loud enough to hear.

Yes, it is certainly going much faster! I have a SYE and Tom Woods shaft with CV - my rear is shimmed and I re-looked at and that yoke is looking Right at the Xfer case as spec'ed. The whine did not start until after the first hour, and now makes quite a racket under any acceleration - part throttle contact is horribly loud and harder acceleration is a tiny bit quieter. Coasting is near silent.

They shouldn't be any louder than stock gears... the problem could be any number of things, bad install, didn't get a bearing seated all the way, poor quality/defective gear set, they might quiet down after a few hundred miles, who knows.

Lucky for you, the solution is easy... take it back to the place who did the gear install and have them fix it. They might want you to wait it out for a while to see if the gear set quiets down after it gets fully broken in.

Can they quiet down after an oil change? None of those I set up myself ever made this much noise so I really don't know.

I have the 4.88 Nitro's in my 8.25 that I set-up myself 2 years ago, no noise at all and I have beat the **** out of them on the trail. I did have mine cryoed before instal by Performance Cryogenics. Cryoeing a gear set tends to make them noisier.

I think you have a bad set-up, take it back

That's what I'm leaning at - I think he set the backlash too tight - driving it heated / swelled and it just got hotter worse. I never went real tight on backlash, I just went for a good mark pattern and you can always come back and redial the lash (especially on a 8.25" with those handy spin up cap ends).

Take em back! I had a guy tell me that if you setup the gears with a center contact on the ring gear it can be loud. Just think in 3d and move it to the heel or toe, he said. My front 4.88 gears make a little noise but only when. In 4wd on the road. Good luck

Funny that the first failed setup I have ever owned is one I paid someone else to do. If I wasn't having a ton of other stuff done I would have done them myself. I was a little short on time - so much for saving myself time right? While they were in there I replaced all the front axles/ U's with 760x and spline upgrades in the D30, the 8.25" has a Auburn pro series limited slip. I had all the bearings everywhere swapped, blah blah.

I really appreciate the input guys, I'll let you know what I find! :us:

 

[kastein]

I bet they either got the lash wrong or the pinion preload wrong, maybe the crush sleeve didn't start crushing properly, now it has, and the pinion is loose and flopping around causing a screwy contact pattern.

Either way, they have a problem to fix.

 

[jeeperjohn]

Definitely take it back to be checked. It sounds like a bearing cup may not have been seated and now it is making the preload on the pinion nonexistent. This can go south in a hurry. When they fix it and put the cover back on make sure they put a super strong magnet on the inside of the cover to catch wear material.

 

[Mtb Jak]

We just had a good time with USA standard 4.88s in my 8.25 diff this weekend The pinion cut was not deep enough. Noisy and tight when set to spec. They are loud. After break in we are gonna check everything again and measure it again, not a happy camper, spent a good 4+ hours trying to get it right with a gear expert and all the specialty tools! The 8.25 was supposed to be the easy one haha. Just bit the bullet and ran it cause I was away at a shop doing the install.

 

[XJEEPER]

I've run Sierra gears in 2 rigs at 4:88 ratio and never had a noise issue. D44 and AMC Metric Tonne 20.

 

[RWKHausSupply]

The brand on the box mean very little when it comes to a 4.88 C8.25 gear set. Theres box sets by many that use one company supplied gears, and then theres the higher end, which cost more. Basically 2 tiers.

I have installed MORE 4.88 C8.25 gears then any other ratio (in the C8.25). I have had one that was beyond noisy. I took it back in and tried setting backlash tighter and it did get better, but never went away and so I replaced the gear set with a new set, that solved it. Besides that one set, I have never had an issue with the 4.88's that were in a USA Standard box. And I would venture to bet they are the same as the Sierra boxed set.

If they are that loud then they likely were setup incorrectly and by you said about it getting worst after some miles, I would bet the gear set is toast now. I would bet that the backlash was way to loose and now the whole gear set is worn and needs replacing.

Take it back and let us know what they do for you.

 

[Mtb Jak]

Mine have gotten a lot quieter! When I do my rear disc brake swap at the 500 mile diff service they are going to check and make sure everything is in spec and the pattern looks good! Boy did the diff get hot on the first 50 miles on the highway though, I stopped like 3 times and let it cool off!

 

[jeeperjohn]

Boy did the diff get hot on the first 50 miles on the highway though, I stopped like 3 times and let it cool off!

This indicates to me the bearing preload was excessive or the pinion was set too deep. Could also be too little backlash. I don't think there are many good reasons to set up a gearset "tight", at least not on a rig driven on the street.

 

[xjtrailrider]

This indicates to me the bearing preload was excessive or the pinion was set too deep. Could also be too little backlash. I don't think there are many good reasons to set up a gearset "tight", at least not on a rig driven on the street.

I agree, sounds like the pinion bearing preload is too tight.

I will add that I have found on the 8.25, the carrier bearings really can't be over pre-loaded(with in reason)

Running the pinion too deep or too little BL is bad for any street set-up that will be seeing high speed.

 

[X E Ryder]

Wednesday

Well on Wednesday I go back in to see WTH happened in there - the shop was horrified and said they will take care of everything.

They said in 20 years they have had about a dozen sets that did this and they are less concerned with what happened - they will just swap them out with new ones and get me on my way with no hassles.

I may go ahead and step back to 4.56's too - I regret to say I think I went a little deep this time. I drive a 17% grade and while it did help alot, I shortened my legs so much I can barely drive the highway without winding way out. My driveshaft spins fast enough to open a door to another dimension. :attom:I'll pick up a pinion tooth that way too, and with how tiny the pinions on these sets are, I wouldn't mind.