K2500 Suburban Rear Axle Replacement

[Steve Addy]

Glad you were able to find the right parts, if all you're taking are the axle shaft and hub you don't need to worry about anything else.

The ratio makes no difference with just these parts. That's as long as you're taking the axle from the correct side.

Let us know when you're back on the road!!

Steve

 

[LikeABoat]

Saturday update. Picked up the rear axle from the salavage yard, pulled mine apart ( my brake shoes are 3.5" wide, does that mean my axle isn't original? ) then went to take the passenger side hub and axle out. Can get the drums off ( either side ), studs were bent. So, I tool the axle back to the yard and asked them to pull me another one and to be careful. So, now waiting till monday to hopefully pick up another axle to remove the hub and axle shaft and install on mine. Luckily this is a really simple job, once you have the right parts. To be continued...

 

[454cid]

Yeah, it sounds like you've already got the JB8 rear brakes to me. Measure your wheel cylinders if you get into the brakes that far.

 

[Steve Addy]

Saturday update. Picked up the rear axle from the salavage yard, pulled mine apart ( my brake shoes are 3.5" wide, does that mean my axle isn't original? ) then went to take the passenger side hub and axle out. Can get the drums off ( either side ), studs were bent. So, I tool the axle back to the yard and asked them to pull me another one and to be careful. So, now waiting till monday to hopefully pick up another axle to remove the hub and axle shaft and install on mine. Luckily this is a really simple job, once you have the right parts. To be continued...

TBH I suspected something wasn't original when you said, "because 1/2 ton suburbans have rear sway bars, my 2500 does not" because AFAIK all Suburbans got the rear sway bar. That's one reason the trucks don't show up as a direct donor for Suburban rear axle, because the trucks lack the rear sway bar mountings.

At any rate, it sounds now like you have the JB8 brakes since you're measuring 3.5" shoes. I kinda thought the drum you posted a pic of looked awfully familiar, the Jx7 drums are noticeably less deep.

However, it doesn't make any difference for the parts you're replacing (hub / axle), but it sounds like you bought a complete rear axle based on what you said about not being able to get it apart due to bent wheel studs?

If that's the case make sure you get hubs that are good, no one wants to have to replace wheel studs after they've purchased a used hub that should be good. For me I chose to replace studs because I knew my hub / bearings had 100k miles on them and I didn't know what the donor had on it or the maintenance of the other axle. I ended up extracting the studs from the used hub and reinstalling them in my original hub. I also like looking inside the original and seeing Timken on the bearings and I couldn't do that with the replacement from 2002.

Also be sure and post up some pics of the action! Everyone likes pics.


Steve

 

[LikeABoat]

Well, yesterday I changed the hubs and axels from both sides. No change to the vibration. Even thought the right rear wheel now spins perfectly true, that wasn’t my vibration source.next step going to take my driveshaft to a place that can spin it faster to double check balance. If it’s not that, then I’ve heard people talking about tcase vibrations or pinion bearing ( my pinion feels solid ).

one thing I did notice swapping axles shafts and hubs yesterday in 40 degree weather that after a driving 10 miles, the axles were warm at the ring gear end. Is it normal for the pumpkin to warm up ?

 

[stutaeng]

Well, yesterday I changed the hubs and axels from both sides. No change to the vibration. Even thought the right rear wheel now spins perfectly true, that wasn’t my vibration source.next step going to take my driveshaft to a place that can spin it faster to double check balance. If it’s not that, then I’ve heard people talking about tcase vibrations or pinion bearing ( my pinion feels solid ).

one thing I did notice swapping axles shafts and hubs yesterday in 40 degree weather that after a driving 10 miles, the axles were warm at the ring gear end. Is it normal for the pumpkin to warm up ?

Oh man, sorry to hear it didn't fix your problem. Can you jack the rear and let it spin? Maybe you can spot/feel/hear some anomaly. What about wheels or tires? Not uncommon to get a tire or rim damaged and cause vibration.

As for the spline end getting warm, I would guess that's completely normal. After all, you still have a lot of metal to metal spinning at high rates. Just about any part of the drivetrain gets hot when you drive.

 

[Erik the Awful]

Are you sure the rear end housing is straight? If the axle was bent, there's a decent chance the housing's bent, which could be causing a misalignment and vibration.

 

[Steve Addy]

Well, yesterday I changed the hubs and axels from both sides. No change to the vibration. Even thought the right rear wheel now spins perfectly true, that wasn’t my vibration source.next step going to take my driveshaft to a place that can spin it faster to double check balance. If it’s not that, then I’ve heard people talking about tcase vibrations or pinion bearing ( my pinion feels solid ).

one thing I did notice swapping axles shafts and hubs yesterday in 40 degree weather that after a driving 10 miles, the axles were warm at the ring gear end. Is it normal for the pumpkin to warm up ?

Well that's unfortunate, however, if it fixed the wobbly right rear wheel problem then it did some good even if the vibration didn't end up being resolved or related.

So have you had your tires balanced recently to make sure it's not related to tires?

Before proceeding you need to determine if the vibration is engine rpm based or speed based. If it's speed based then you can eliminate the engine / trans (generally) but you will still need to have the drive shaft looked at. Speed based would be anything from the back of the trans to the rear, including the center support bearing too.

If you're going down the road say at 55 and you nudge the shifter into neutral and let the engine idle while still rolling down the road and the vibration disappears then it's likely something trans or engine related. If the vibration persists while engine is idling then it's downstream of the engine / trans but could include tires and wheels, diffs etc.

Good luck and post back!

Steve

 

[LikeABoat]

Well that's unfortunate, however, if it fixed the wobbly right rear wheel problem then it did some good even if the vibration didn't end up being resolved or related.

So have you had your tires balanced recently to make sure it's not related to tires?

Before proceeding you need to determine if the vibration is engine rpm based or speed based. If it's speed based then you can eliminate the engine / trans (generally) but you will still need to have the drive shaft looked at. Speed based would be anything from the back of the trans to the rear, including the center support bearing too.

If you're going down the road say at 55 and you nudge the shifter into neutral and let the engine idle while still rolling down the road and the vibration disappears then it's likely something trans or engine related. If the vibration persists while engine is idling then it's downstream of the engine / trans but could include tires and wheels, diffs etc.

Good luck and post back!

Steve

Thanks Steve for the feedback. I've tried pushing the shifter into neutral, the vibration is still there, turning left, right ,accelerationing, breaking, ... still there. Tires are new and we rotated them around with no effect. I noticed when I took the driveshaft out that the yoke was worn enough more than I've ever seen ( however there was only a little movement in the extension shaft but not bad I think, but what do I know ). I called around to find a driveshaft shop to check the balance and all shops said after Christmas. So, I though maybe I'll just replace the yoke myself and put a new bushing in the extension housing and see what happens. There resulted in several issues 1) I can't find the bushing listed for a NP246 transfer case ( NP8 ). Finally call a trans shop that seems to know exactly what I'm trying to do and says its the same as a 400 turbo, and gives me a National PN. 2) Looking online it seems this transfer case takes special fluild only available at GM, AutoTrak2. I had to go to 3 dealerships to find it. Does it call for this , but noone uses it? seems like it isn't a common fluid. 3) Then I can't find a bushing removal tool. Parts stores have no idea what I'm talking about, summit says they have one, drive there, their out. Can't find anyone to borrow it from. ( growing up we always had this puller, I didn't realize it wasn't common ). So, the burb ( money pit ) is going to sit for a couple of weeks for the holidays. Maybe my luck will be better in 2021.

 

[LikeABoat]

Are you sure the rear end housing is straight? If the axle was bent, there's a decent chance the housing's bent, which could be causing a misalignment and vibration.

I can't be sure, but we tried to check it. And after all this work it seems that it doens't have the orginal rear end because the brakes are 3.5 inch shoes, I think it should be 2.5 inch shoes. Who knows with this thing.