Whine after regearing

[ScoobyCarolanNC]

Hey y’all! Got spicer 4.88s installed in my Mojave yesterday. The shop is extremely well known and I paid a premium for their expertise. On pickup the tech came out and said the backend is whining at 50mph. He reviewed the setup twice and thinks it was just how that set was cut. It had a good pattern and the backlash was in spec. I drove 45-55 the whole way home with a bunch of red lights and stop signs and yeah it’s pretty bad. They’re going to replace the rears on Monday, but I’m wondering if this is at all normal? Anyone else get spicer gears that did this? They’re owning it and being 100% by me so I’m not upset, just wondering why or how?

 

[WJCO]

Hey y’all! Got spicer 4.88s installed in my Mojave yesterday. The shop is extremely well known and I paid a premium for their expertise. On pickup the tech came out and said the backend is whining at 50mph. He reviewed the setup twice and thinks it was just how that set was cut. It had a good pattern and the backlash was in spec. I drove 45-55 the whole way home with a bunch of red lights and stop signs and yeah it’s pretty bad. They’re going to replace the rears on Monday, but I’m wondering if this is at all normal? Anyone else get spicer gears that did this? They’re owning it and being 100% by me so I’m not upset, just wondering why or how?

Either a part or labor issue but glad they're taking care of it. If they truly feel confident in their measurements, maybe just a bad set. Does it do it on accel, decel, both, or just all the time when moving?

 

[ScoobyCarolanNC]

Hey bud! Only when I’m on the gas. I’m I take my foot off and coast it goes away. He was confident it’s a bad set and said something I didn’t really understand about the the way the gears were cut and how they meshed. All that aside, I was stoked to see 8th gear and be getting 16mpg again! I’d forgotten how nice it was. Seemed like I had more pickup too when I thought I’d be loosing some acceleration.

 

[WJCO]

Hey bud! Only when I’m on the gas. I’m I take my foot off and coast it goes away. He was confident it’s a bad set and said something I didn’t really understand about the the way the gears were cut and how they meshed. All that aside, I was stoked to see 8th gear and be getting 16mpg again! I’d forgotten how nice it was. Seemed like I had more pickup too when I thought I’d be loosing some acceleration.

Any time a whine occurs on accel or decel, it's a gear issue. Could be bad set or could be something not set up right. At least they're correcting it.

 

[wayoflife]

Any time a whine occurs on accel or decel, it's a gear issue. Could be bad set or could be something not set up right. At least they're correcting it.

This ^^^ and I would say it's typically a setup issue. But, glad to hear they're standing by their work and fixing it for you. Also, I have NOT heard of other issues with Spicer gears.

 

[ScoobyCarolanNC]

Right on. They’re fitting me in first thing Monday and promised to have me out in a couple of hours. On a separate note he said my 4.10s were in perfect condition considering all the mud & sand wheeling with 20,000 road miles on 37s.

 

[Disciple Off Road]

I also have to agree something is off from setup. Spicer is one of the better brands out there and if the gear was off/bad cut, good chance it would have been visible when running a pattern. I’m assuming they log all the setup specs and take pictures of the pattern, can’t hurt to get a copy for your records. Glad they are taking care of it

 

[ScoobyCarolanNC]

Yeah they gave me the numbers from the frontend (PS-.050, PPL-15, BL-6 ?) but said since their scraping the backend there was no reason to (which makes me think the mistake would have been apparent).

Here's a real question I just realized though; they gave me standard break-in instructions. But since I have a FAD aren't the front gears not fully engaged? Should I do anything to burn them in?

 

[CalSgt]

When I did mine I would pull it into 4hi for the long straight sections of highway on my way to and from work. I would bump it back into 2hi for any turns or curves. I would accelerate from 35-40 to 55-60 and decelerate back down repeatedly the whole way, about a 20 minute drive. I did that for about a month.

Not sure if that’s the right way to do it but it seemed to work fine. I’m also running Spicer 4.88’s but I set them up myself, no whining.

 

[WJCO]

Yeah they gave me the numbers from the frontend (PS-.050, PPL-15, BL-6 ?) but said since their scraping the backend there was no reason to (which makes me think the mistake would have been apparent).

Here's a real question I just realized though; they gave me standard break-in instructions. But since I have a FAD aren't the front gears not fully engaged? Should I do anything to burn them in?

I haven't re-geared a JL or JT but would think back and front would be different.
0.050 is likely the pinion depth shim.
PPL is pinion bearing preload (rotational inch pound reading).
BL backlash .006.

Hopefully Discipline chimes in if those are decent specs. Regardless, your shop is taking care of you.

Your front gears won't do shit unless you're in 4wd regardless of the FAD. The gears have to be driven/loaded to break in.

 

[Disciple Off Road]

I haven't re-geared a JL or JT but would think back and front would be different.
0.050 is likely the pinion depth shim.
PPL is pinion bearing preload (rotational inch pound reading).
BL backlash .006.

Hopefully Discipline chimes in if those are decent specs. Regardless, your shop is taking care of you.

Your front gears won't do shit unless you're in 4wd regardless of the FAD. The gears have to be driven/loaded to break in.

Specs are what we normally see +/- and could really be anything causing the noise.

I don’t wanna Monday night quarterback an install I can’t see and sounds like they are taking care of it which is awesome.

And as WJCO stated, the front gears won’t see any break in unless you have solid front/1-piece axle shaft or have done a ton of 4wd. Other than that, the rear is the main one to break in and service.

 

[jeeeep]

When I did mine I would pull it into 4hi for the long straight sections of highway on my way to and from work. I would bump it back into 2hi for any turns or curves. I would accelerate from 35-40 to 55-60 and decelerate back down repeatedly the whole way, about a 20 minute drive. I did that for about a month.

Not sure if that’s the right way to do it but it seemed to work fine. I’m also running Spicer 4.88’s but I set them up myself, no whining.

This^
When I had my gears done, the shop recommended I shift into 4H on the straights to break them in along with the rears.
Same routine to heat/cool them.
Also Spicer 4.88 gears no whine.

Does the Mojave require an additive and would not having it make gears whine?

 

[ScoobyCarolanNC]

Thanks everyone! I'm sure they'll be dialed in on Monday. This is new territory for me which is why I picked ECGS instead of a local hero. I knew these guys were legit. Thanks for the crash course in re-gearing. This is like a Wayalife All-Star Thread!

 

[ScoobyCarolanNC]

Well, that did not go as planned. They pulled a new set of gears with a very different build date. Different tech did the install and the shop foreman verified everything every step of the way and it’s still whining. Slightly different, so I can tell they didn’t just have me sitting in the waiting room. He was at a total loss. They’re 100% standing behind the work and offered to switch brands or ratios if I wanted. Could the gear change have flushed out some other issue like bad wheel bearings or the carrier bearing on my driveshaft? I don’t want to bother going through all of this again to have it just be the same.

 

[Disciple Off Road]

Well, that did not go as planned. They pulled a new set of gears with a very different build date. Different tech did the install and the shop foreman verified everything every step of the way and it’s still whining. Slightly different, so I can tell they didn’t just have me sitting in the waiting room. He was at a total loss. They’re 100% standing behind the work and offered to switch brands or ratios if I wanted. Could the gear change have flushed out some other issue like bad wheel bearings or the carrier bearing on my driveshaft? I don’t want to bother going through all of this again to have it just be the same.

Did they install a master install kit meaning all new bearings? I know some shops don't do this and will reuse the old bearings. Just curious.

 

[ScoobyCarolanNC]

Did they install a master install kit meaning all new bearings? I know some shops don't do this and will reuse the old bearings. Just curious.

Yup, front & rear master overhaul kits are on my invoice.

 

[Disciple Off Road]

Yup, front & rear master overhaul kits are on my invoice.

I'd be curious to see with the pattern looks like. When adding the new ring/pinion, did they recheck pattern/specs or just thrown them in assuming they would be the same? 2 for 2 tells me something is off on setup.

 

[ScoobyCarolanNC]

He said they did, but I didn't see anything. Are these gears trashed now if I try a different shop? I just don't know what to do. This is a very well known and reputable axle shop here with decades in business. I'm really having trouble with the idea that I got 2 identically bad setups and I hate to assume they would lie to me. I’m going down a rabbit hole on drag forum’s about “driveline resonance” and some of these guys just admit it’s a thing and they’ve got tens of thousands of miles on noisy diffs that they live with because nothing can be done.

 

[WJCO]

Yup, front & rear master overhaul kits are on my invoice.

Both times or just the first time?

Also, how long were you in the waiting room?

 

[ScoobyCarolanNC]

I'm not sure what they did today. My original invoice has the master kits on it but today felt more like a repair. I was in the waiting room for about four hours. These guys build axles for a living, and he looked me right in the eyes, I gotta be honest I did not detect a lie. He said they pulled a whole new gear with different dates so I'd assume that they'd have to pull full rebuild kit too because wouldn't the bearings and everything get trashed getting removed?