8.5/8.625 Series run questions

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BigBlockMan
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8.5/8.625 Series run questions

Postby BigBlockMan » Tue Nov 10, 2009 3:00 pm

Let me start with what I think I know...
Only 2 carriers, 2.56 and down and 2.73 up?
From 71-89 all 8.5' used the same 28 spline axles (some bolt in some C-cliped)
90 to 00 had 30 spline axles with the same carrier bearings as 71-89 (all c-clip)
00 to current had 30 spline axles with bigger carrier bearings that the others (all c-clip)
At some point (90ish) the ring was changed to 8.625, but the whole run of this rear end will interchange ring and pinion.

Now the questions..
In 90 when the spline count went up did the axle diameter also increase....and if so to what?
If the axle diameter increased did the bore of the carrier change leaving a thinner "hub" for the bearing?
If so what i sthe inner diameter of the hub?
In 00 when the bearing set needed changed was this to reticfy the thinner (read weaker) bearing hub on the carrier or was this when they increased the axle diameter?
Will internal parts (side and spider gears) interchange between the different carriers?
Will a 90-00 or 00-current carrier fit in a 71-89 housing (with proper bearings of course)?

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monzaz
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Re: 8.5/8.625 Series run questions

Postby monzaz » Wed Nov 11, 2009 12:41 am

YES.... ha ha lol. Just kidding...

OK the 1970-1989 8.5 were 28 spline. BUT I am thinking the WAGON actually had some 1987 1988 1989 models with 30 spline axles.


When they did increase the axle spline from 28 -30 Yes the axle spline diameter increased also ...It is now the same as the oldd 12 bolt chevy car and truck axles spline was.

Now in 1990 -1998 & 99 the carrier inner diameter was ONLY enlarged. Now the bearing hub was too thin to handle towing and heavy load application ...but I am sure they only found that out too late and years went by and in 1999 the trucks were corrected and increased the bearing hub again to the same outer and inner diameter as the 12 bolt chevy carrier bearing hub dimensions.

Yes the NEWER carrier from 1990 -1998 are a direct replacement with the older 1970-1989 28 spline units all you need are the 30 spline axles.
The 1999-2009 open and posi (limited slip) units will fit with a conversion bearing modification with part number 102949 bearing and 102911 race. and of course the 30 spline axles again.

1999 -2009 are considered the 8.6 diffs and yes the spider gears were redesigned to create a more equal size between the side gears and the pinion gears so that more torque can be delivered though the whole assembly. So NO they can not be interchanged from carrier unit case to case.

I hope I covered everything...I will double check. Jim
J D Race

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Re: 8.5/8.625 Series run questions

Postby BigBlockMan » Wed Nov 11, 2009 5:19 pm

Jim you nailed most of it...now I just need some numbers...What I'm trying to do it build a frankentube...
I want to use a 8.5" ring and pinion (due to ease of finding gears) with a 31 spline axle from the odd ball Olds/Pontiac stuff I have. I'm not too worried about the internal gears fitting correctly because the side gears will just get welded to the carrier anyway.

So I the only thing left to ask are for the inner diameter of the bearing hubs on the 30 spline carriers, and (just for my knowledge) the diameter of the 30 spline axles at the splines? I can't find a definate number on the web.

The inner diameter on the oddball big axle stuff is 1.345 compared to the 1.235 on a 28 spline 8.5". The axle diameter is 1.315......am I finally in luck?

Also in your opinion would I need the 99 and newer carrier or will the 90-99 version work? Average of 5000lbs car, 472 Cadillac engine, not so much for the towing part but far from just a putt into town type operation. I have twisted off 8.5" axles at the splines twice, twisted a tube out of the housing and broken a 8.5" axle right in the middle. I haven't hurt a carrier yet but am somewhat worried about the thinner hub.

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monzaz
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Re: 8.5/8.625 Series run questions

Postby monzaz » Thu Nov 12, 2009 5:14 pm

I would really try to find the 99 -2009 open carrier if you can not find one I can get them new...Which I am sure defets the whole purpose...lol.

I will get those numbers this evening for you. Ok? JiM
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Re: 8.5/8.625 Series run questions

Postby BigBlockMan » Thu Nov 12, 2009 7:58 pm

Jim,

Numbers when you get a chance would be perfect.

Just out of sheer curiosity how much is a new open carrier? I'm sure it is out of range for what I want to do but.... Do you ever get any in used?

Thanks again,

Chris Vaughn

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Re: 8.5/8.625 Series run questions

Postby monzaz » Fri Nov 13, 2009 1:27 pm

Chris here are the measurement to the best of my measuring and the inconsistency of any mass produced part.

30 spline axle from its most peak spline to the other side maximum diameter is 1.282

30 spline 10 bolt 8.5 maximum inner diameter axle access hole is 1.305

I tried to get the 31 spline axle into the 30 spline axle carrier axle access hole and it just misses. You can just open it up with a brake hone or grinder I am sure with any problem to fit thew 31 spline axle.

30 spline NEW 99-2009 carrier is : 89.00 plus shipping....They are out of stock anyway. My other supplier might have it in stock I can call. Best to hit the local pick apart to get one. Next time I am in the yard I will look for a 99-2009 truck 2wd for a carrier for you. Ok? Jim
J D Race

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Re: 8.5/8.625 Series run questions

Postby BigBlockMan » Sat Nov 14, 2009 10:18 pm

Yeah I don't think .040 would hurt too bad...better than the .110 that I would have to open up an older 8.5". I suppose I wouldn't even have to go that far as the 31 spline axles are only 1.315..so maybe .020 or so..

I will have to ponder on that newer carrier thing...we have no such thing as a pick-a-part...would be nice. If ya come across something let me know...

Would you be interested at all in one or both of these 10/12 posi's I have? I really don't have a use for them and don't see the sense in ruining one by trying to weld on it.

Let me know.

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Re: 8.5/8.625 Series run questions

Postby monzaz » Sun Nov 15, 2009 10:22 am

Wow, Did not see you were all the way in Montana. That is where my Monte Carlo was original sold. Billings, Frontier Chevrolet.... lol.

I can always use posi units...But the shipping and probably the price would not make it feasible or cost effective.

I just do not sell enough of these posi unit and or LARGE car rear to make it a super wanted item.

Lets see if we can locate a open 99 and newer open unit for you and will go from there. How does that sound? Trading parts is fine. But we still have the shipping...lol.

I do have that open 2.93 carrier in the 66 pontiac rear I need to swap that open unit to a posi. So there is that option of course and I can get that done pretty quickly. Jim
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