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Any way to ID 28 or 30 spline without tearing down?

aandpman

aandpman

1/2 ton status
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My K5 is an 88, and in all the references vary from 87-89 being the year that rear 10 bolt 8.5" changed from 28 to 30 spline.

Mine has begun to go, and I need to order some rebuild parts.

Yes I know, why not change to 14bff or 14bsf, I have stuff built later when I retire and don't have to use it for a daily driver. I also don't want to lift yet etc.

Currently I just want to do a rebuild, in my driveway, quickly.

So, is there any way, short of tearing it down, to determine if the spline count is 28 or 30....i.e. rpo code, axle tag, stamping on the flange end of the shaft etc.?

I haven't found anything using RPO codes, and I've been doing repairs on the wife's Town Car so I can get to/from work, so I haven't had time to tear it down.

Thanks for any info.
 
Are you in a hurry? Or can it wait a little bit?
What gears are you running?

I ask this because I'm getting ready to swap out my rear axle for a 2004 one. Which means my good to go axle will be available. I'm about 45 minutes north of Austin.
 
Currently the K5 has 3.08's, but I'm looking to go to 3.73's. The diff is open. I've been in a bit of a hurry, to get it done, but it seems like it's taking me longer to decide WHAT to do than to actually do it.

In the mean time I've had to do a complete front-end rebuild on the wife's town car and about to put tires on it...

...and I JUST got finished doing the steering box, ORD tie rod & tie rod ends, steering pump and hoses on the K5. I have a steering box brace yet to go in.

How much time till you are going to do YOUR swap, and is the 2004 going to be a 14bsf?
Just curious, since I've been exploring that option too.

My limitations are that
I don't have a trailer to haul axles around with...
I have a crackerbox welder, but don't have a 20amp circuit in the house I'm in...
I have a pretty sloped driveway, so I have to be very careful putting anything up on stands...
 
No, I'm going completely different.
I've already converted my front 10 bolt to Hummer H3 4 piston calipers with slip over disks and 14mm lugs. I'm swapping my 10 bolt rear to a 2004 8.6 10 bolt with disks also.

jrLrEl.jpg


My axles are 3.73 and I think the rear is a G80 Gov lock. I'm not sure of the time frame. The axle is on the way. Right now I'm confirming exactly what needs done. I'll need some new spring mounts, but hopefully everything else is straight forward. I suspect it will be for the most part.
 
That's a sweet setup you're doing there. Do you still have the old front with the 3.73's in it too? Also, what year model is your K5 (just curious what the spline count might be)
 
1989 was the first year for 30 spline axles, but who knows if someone prior to you swapped axles at some point.
 
Oh wait - you said you converted the front existing axle with h3 outer parts...gotcha...
I'm in SW Austin - what area are you in?
 
Up near Ft Hood.

Unlike a bunch of people, I will NOT be switching to 8 lug. I'm going a MAX of 33" tires and it's not a dedicated off road rig. I'm really about improving the suburban and trying to use "factory" parts to keep repairs and future parts access easy.
I even used factory fit brake hoses for the front. As I build the truck, any part from another vehicle is listed and any changes noted. I keep a small notebook with me for reference.
 
At this point, I'm kinda the same way. It's my daily driver - I drive from SW Austin to Giddings and back to work every day so I'm putting at least 130 mi/day on her.

Right now I have 31" BFG's for tires on stock steel rallye wheels. I just like the sleeper look :-), so I'm not going 8 lug any time soon.

Like you, I LIKE stock off the shelf parts when possible. I guess its part of my Airframe/Powerplant training. You never know when some clown will make a really good aftermarket gizmo, only to later croak or go out of business. Then you're stuck with a really nice gizmo, with no way to get bearings/seals/bushings/etc. to rebuild it.

I have absolutely QUIT buying VatoZone DuraCrap chinese parts, since they fail. I try to track down US made bearings/seals/balljoints/tre's from Moog/Spicer/etc and pay more for them. at least I'm not repairing it again in a year.

20140904_092903%5B1%5D.jpg
 
Oh - this is one enhancement I have never regretted - they came from Whitegauges.net. It's a set of decals to re-do your inst panel...
DSC_8247.JPG
 
There is nothing spline specific in a rear end rebuild. No one changes spider gears when freshening up a rear. Throw new bearings on it with the same shims and gears as long as nothing is wrong with the gear set, maybe tighten the backlash up a tad, and reseal it.

Which brings me to my next thought.

Have you ever re-done a rear?
 
The 10 bolt carries take the same bearing whether it is a 30 spline or 28 spline.

The 30 spline carrier just has a bigger bore on the id of the carrier to fit bigger shafts.
 
I've built a 14Bff with Detroit locker, a D44 front with a trac-lok and a ford 9in with Detroit. It's been more than 10yrs though. This will be my first GM 10 bolt. I wasn't sure on these if the carrier bearings were the same on the on the 28 & 30 spline models, based on the info I was seeing on sites like Randy's R&P. You guys have helped out with that info.

With the drive shaft removed, I can grab the pinion yoke and turn it and it has a lot of rotational slop in it. Also, while turning it back & forth, I'm getting some in-out play. I'm also hearing some suspect vibrational noises if I try to drive it.

I have probably rolled the odometer over nearly twice myself, and I don't know how many actual miles the p.o. really had on it. If I pull it down, I'd really rather put new spiders in for the peace of mind, or install something like a true trac. I also kinda expect to see the axle bearings/bearing surfaces be pretty worn, as it's been a bit noisy for a while. I was really hoping to drop the 3.08's to 3.73's at the same time I rebuild it.

I'd love to find one of the CK5'ers that has a 14bsf 6lug already built to buy one off of. I don't have a lot of time to go boneyard hopping, what with raising my teen grand daughter, looking after a health-challenged wife, and working full time.
 
I guess the other thing that had me confused on Randy's RP site, is there is a GM 8.5 and a GM 8.5HD listed, but now I see that the HD's are simply for folks that have put in AFTERMARKET Posi units that use a larger bearing inner journal size....
 
aandpman said:
I've built a 14Bff with Detroit locker, a D44 front with a trac-lok and a ford 9in with Detroit. It's been more than 10yrs though. This will be my first GM 10 bolt. I wasn't sure on these if the carrier bearings were the same on the on the 28 & 30 spline models, based on the info I was seeing on sites like Randy's R&P. You guys have helped out with that info.

With the drive shaft removed, I can grab the pinion yoke and turn it and it has a lot of rotational slop in it. Also, while turning it back & forth, I'm getting some in-out play. I'm also hearing some suspect vibrational noises if I try to drive it.

I have probably rolled the odometer over nearly twice myself, and I don't know how many actual miles the p.o. really had on it. If I pull it down, I'd really rather put new spiders in for the peace of mind, or install something like a true trac. I also kinda expect to see the axle bearings/bearing surfaces be pretty worn, as it's been a bit noisy for a while. I was really hoping to drop the 3.08's to 3.73's at the same time I rebuild it.

I'd love to find one of the CK5'ers that has a 14bsf 6lug already built to buy one off of. I don't have a lot of time to go boneyard hopping, what with raising my teen grand daughter, looking after a health-challenged wife, and working full time.
Click to expand...

Some play in backlash can be expected. Sure it does get worse with time and gets unacceptable. In and out is just flat out unacceptable, and probably means the gears are bad.







aandpman said:
I guess the other thing that had me confused on Randy's RP site, is there is a GM 8.5 and a GM 8.5HD listed, but now I see that the HD's are simply for folks that have put in AFTERMARKET Posi units that use a larger bearing inner journal size....
Click to expand...

Yes you're correct. My tru-trac in my shortbed street truck was like this. It took a special install kit. Its not that the posi manufacturers did something goofy its just that when the 8.625 10 bolt came out the carrier bearing size changed. In order to make the posis backwards compatible from there on out they made a special conversion bearing.
 
Ha, ha!!! My new axle is here. Time to start measuring and order some spring pads. Looks like I just need to remove the bump stop pads to weld on the new spring pads.

2URpXP.jpg
 
I was wondering what they had changed from 8.5 to 8.6" carrier bearings...did they actually bore a larger diameter journal in the axle housing (the journal that includes the bearing caps, that is line-bored)? That would explain the special bearing having to be a hybrid.
 
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