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Old 11-28-2023, 02:15 AM   #1
Mini-Skoolie
 
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N175 Pinion Bearing

I hope this is okay to post here as it's in a 95 4700 flatbed not a skoolie. I have noticed a whine when going down hill and foot off the throttle over the past 5-10 thousand miles. Had crawled under and wiggled the driveshaft after I first noticed the sound and there was no play. Today when I was greasing the rear u joint I wiggled the driveshaft. Defiantly has a bad pinion bearing. What can I expect. Truck has 318,000 miles, the line setting ticket says the rear axle is an International N-175, research says it's made by Spicer. Is this something I can maybe tackle myself or best to send to a rearend shop to set the proper pre load and inspect the gear set for wear?
I haven't done any rear end work in the past, but do most all of my own work otherwise.

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Old 11-28-2023, 06:53 AM   #2
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you can do it.. I lost a pinion bearing in my Loadstar. in my case it also took out the pinion gear.. the 3rd member on these weighs a few hundred pounds.. its a floating axle so you can pull the center shafts without even taking the rear wheels off.



the pinion bearing is pressed on and since I dont have a press i sent my whole chunk out to be redone.. and since I needed to change the gear, I re-geared to the ratio i really wanted.. my carrier was capable of the ratio.. installing it was straight forward.. I put the 3rd member in.. then installed the axle shafts then installed the driveshaft. I used a transmission jack to help install it.
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Old 11-28-2023, 07:50 AM   #3
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Replacing pinion bearings on these is much simpler then doing it on a pickup. The pinion gear assembly is in it's own housing held to the pumpkin by 6 bolts. Remove the driveshaft, remove the 6 bolts, and with a whack from a dead blow, the housing should pop free.

So long as the ring and pinion gear itself is fine, there's no need to remove the carrier. If you don't have a press, bearing splitter, or the shim selection, you can take that to a truck shop and they can swap bearings pretty quickly. There are shims for preload and shims for pinion depth. The pinion depth shim shouldn't change, but the preload shims might. If you use good bearings, there's a good chance neither will change, at least that's my experience.

Any truck shop or driveline shop should be able to tackle this.
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Old 11-28-2023, 12:26 PM   #4
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I do have a press, no shim assortment on hand currently. Isn't there 2 pinion bearings? Wouldn't the carrier need to be removed to replace the inner? What do you mean by ring and pinion being "fine"? Do they need inspected for wear which could cause howling or not a concern? I can tell you they must not be broken up as there are no unusual grinding or clunking noises, just the whirring on deceleration.
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Old 11-28-2023, 01:21 PM   #5
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3 pinion bearings.

Carrier doesn't need removed. Reread the first paragraph in my prior post, as you're not understanding how it's removed. There's no need to remove the carrier/pumpkin, as you can remove the pinion gear without doing so. Pinion gear and bearings are held in their own separate housing.

Yes, the inspection is visual. Looking for chips, cracks, brinneling, etc. on gear faces. At 318k miles, there is definitely wear on the gear, and it could be causing your deceleration noise. However, that wear isn't causing your up/down side/side movement at the yoke, that's caused by looseness in the bearings themselves. That looseness is likely much more of a concern then any noise you're hearing.
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Old 11-28-2023, 01:48 PM   #6
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Understood, I found a Spicer Drive axle Service Manual ASXM-0866 with a breakdown of the pinion gear assembly. I'm not concerned with the noise really if it won't cause other problems, if it goes away with new bearings great. If not I can live with it, I put an average of 5-10 thousand miles a year on it.
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Old 11-28-2023, 07:56 PM   #7
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A little bit of gear whine is not to much to worry so long as the bearings are fine. Mine would growl from 40 kph and faster under load. Was kinda nerve racking listening to the noise.

My situation was the ring and Pinion was trashed. Ran to long with a bad bearing. Got a used member that checked out good. Has a little whine between 60-80kph but otherwise perfect. Carrier bearings checked out good on used member. Pinion bearings were fine too. The gears will develop a small cup on the tooth as they wear. As per Spicer it's perfectly acceptable.

Mine was a N190. Pretty much the same but spline count on the spiders were different.
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Old 11-28-2023, 11:49 PM   #8
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I may have gotten off easy this time. I went to take the pinion gear assembly out and the nut that holds the yoke on was loose. I tightened that nut up and the play is gone. I will run it a while and see what happens.
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Old 11-29-2023, 05:44 AM   #9
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Quote:
Originally Posted by aawil View Post
I may have gotten off easy this time. I went to take the pinion gear assembly out and the nut that holds the yoke on was loose. I tightened that nut up and the play is gone. I will run it a while and see what happens.
What did you tighten that Pinion nut too? They also don't generally back off.
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Old 11-29-2023, 07:11 AM   #10
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Quote:
Originally Posted by Booyah45828 View Post
3 pinion bearings.

Carrier doesn't need removed. Reread the first paragraph in my prior post, as you're not understanding how it's removed. There's no need to remove the carrier/pumpkin, as you can remove the pinion gear without doing so. Pinion gear and bearings are held in their own separate housing.

Yes, the inspection is visual. Looking for chips, cracks, brinneling, etc. on gear faces. At 318k miles, there is definitely wear on the gear, and it could be causing your deceleration noise. However, that wear isn't causing your up/down side/side movement at the yoke, that's caused by looseness in the bearings themselves. That looseness is likely much more of a concern then any noise you're hearing.

mine was frozen in .. I couldnt even get it out with a slide hammer.. hopefully his is not!
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Old 11-29-2023, 07:35 AM   #11
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Yeah, the nut was loose because the bearings are loose and lost the preload. The nut on my ra39 has a cotter key to hold them, or they'll use threadlocker, or an interference nut. They shouldn't loosen up through operation, unless something happened inside that caused them to loosen.

You might get by with what you did, I wouldn't count on it.
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Old 11-29-2023, 11:51 AM   #12
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I found a service manual from Spicer but it didn't have anything on the N series Differential. It was J&W. It says that nut should be torqued to 900-1200 lbft. I tightened it as much as I could with a breaker bar. My largest torque wrench stops at 150lbft. I do have a torque multiplier but to throw that on there and crank it down I would just be guessing, maybe asking for trouble.
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Old 11-30-2023, 04:18 AM   #13
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Originally Posted by aawil View Post
I found a service manual from Spicer but it didn't have anything on the N series Differential. It was J&W. It says that nut should be torqued to 900-1200 lbft. I tightened it as much as I could with a breaker bar. My largest torque wrench stops at 150lbft. I do have a torque multiplier but to throw that on there and crank it down I would just be guessing, maybe asking for trouble.
That's the reason I asked.

Budget a rebuild. Keep a close eye on it. It's is crazy high torque on that nut. As mentioned your buying time. You don't want it to go to long with it loose. Can ruin your gear set. Then cost jumps quick.
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Old 11-30-2023, 11:17 AM   #14
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The reason you have noise when you de-accelerate is there is too much play in your ring and pinion and when you back off it pulls the pinion deeper into the ring gear and you get a gear whine, not good, your front bearing behind your yoke is probably bad which is usually evident by the leak and also by the loose nut. If you still have that whine after tightening that nut then it tear it down immediately or you'll be replacing the whole rear end out on the road and paying a premium price.
I put a complete used rearend out of a semi in my bus and had some noise so I pulled the pumpkin and the carrier bearings had spalling, must have had a million miles on it and the ring gear was so sharp you could shave with it (which is not necessarily bad) replaced all the bearings and everything went right back where it was as far as adjustments, put some dye on it and had a great pattern, so blessed! This may be the time to change your ratio if you want.
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Old 12-01-2023, 12:31 AM   #15
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I'll keep an eye on it. I had thought about re gearing, according to the axle tag I have a 4.44 ratio now, with a 6 plus transmission. 55mph is about 2100rpm. Speed drops quick when loaded and pulling much of a hill, it would be nice to lower the rpms at highway speed but would I seriously be lacking power then?
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Old 12-01-2023, 07:47 AM   #16
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That's right lower numbers will steal power to climb hills. I don't understand how you can have the same driveline as me and yet your RPMs are so high. I have DT466 with a 6 speed Allison and 4.33 rearend with 42 inch tires and I am turning @1600 RPM at 70 MPH, something is different, I don't think you have the rearend ratio you think you have, sounds more like 6:1. See if the ratio is stamped on the front of the pinion, mine is.
How about filling in your personal information so we know where you are coming from.
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