6 lug conversion (dead horse?)

[super10brss]

I have a 1989 Chevy 1500 that I am getting ready to LS swap in the next few months, and seen some stuff about 6 lug conversions. I have a 10 bolt disc brake 3:42 now that I like, but it is a open diff rear axle. I know a LS will eAt one tire all up! The front is "easy" I guess (cut and dry would be a better term) swap spindles and order new rotors (because my truck is 1989 I have the light duty brakes) Got It!

The 1" thick 5 lug rotors on 88-91 are for regular cab C1500's that are not equipped with heavy duty brakes. If they were extended cab they'd come with 1.25". From 92-up all C1500's got the 1.25" rotors regardless of regular/extended cab.

Now on to the 2500 6-lug (7200lb GVWR) trucks; regardless of year, if it's a 2500 6-lug it's got the 1.25" rotors. Those trucks came with HD brakes either way because of the rest of the equipment package to achieve the 7200lb GVWR. Look 'em up... RPO C5Z = 7200lb GVWR which is what a 6-lug 2500 is by design.

SO...if you're converting an 88-91 REGULAR cab C1500 that did not come with HD brakes (and typically they did not), to use 2500 6-lug rotors, you gotta change spindles too.

Richard

The rear end is where I am STUCK! Like I said I have a 3:42 disc brake rear (swapped out to the 3:42 from 2:08's couple years ago with the disc brake conversion, Impala ss based setup from several years back) Why can't I use a 99-2006 GMT800 rear that already has disc brakes and "maybe" a G80. Seems the 99-06 lots of them had G80's. I have SEARCHED and searched the ol interweb's and found:

The GMT 400 style 14 bolt 9.5 from 88-98 6 lug is. (same as 1/2 ton 10 bolt?))

67.5 WMS-WMS

That's 33.250 in. for the shafts + 1" pin


Rear is 68 1/2 WMS to WMS on GMT800 trucks.

Some guys say to find a semi float 14 bolt from a 2wd 2500 to get the right width for my half ton (those are getting harder to find in a local salvage yard and non disc brake). If my numbers are correct the GMT800 being 1.5 inches wider wouldn't be much of a issue since the stagger would be ok.

Then 6 lug conversion: some guys say bolt a 99-06 6 lug wheel up and roll, some say they have to use spacers? I'm not trying to reinvent the wheel here! I know guys on this forum have been there and done this, just looking for some cliff notes! Thanks guys

 

[someotherguy]

On your last sentence: your wheel choice is going to be the key here. Many modern 6 lug wheels are designed for the 1999-up hubs which have an inboard bearing, totally different hub than the 1988-1998 2WD trucks. Some simply will not fit the hub for one or both reasons: hub bore size, hub bore depth before center cap. So, easiest solution to picking a wheel that won't require you to run a spacer? I've said it before: go to the parts house and get a 6 lug C2500LD rotor, get a bearing dust cap for it, then go drop it into a wheel you'd like to use. You'll know right away.

Richard

 

[super10brss]

4 Wheeler magazine! http://www.fourwheeler.com/how-to/t...129-1003-gm-95-14-bolt-axle-gears-and-locker/

However, most people are not aware of the less common six-lug, semi-floating version of the 14-bolt axle. GM called it the "9.5" 14-bolt (after its ring-gear diameter) and offered it exclusively in light-duty 3/4-ton pickups built between 1986 and '93. While not as strong as its eight-lug cousin, the semi-floating 14-bolt rearend does sport some noteworthy attributes. For instance, the all-important width measurement from wheel mounting surface to wheel mounting surface is 67 inches-perfect for most 1/2-ton pickups. Generally, you wouldn't even need to change mounting brackets to bolt this housing right into the rear of a 1/2-ton GM pickup because the leaf spring architecture is identical. We like the fact that the ring gear measures out at a healthy 9 1/2-inch diameter, and the 33-spline axleshafts have a 1.370-inch diameter-a sure improvement in strength over the typical 1/2-ton shafts. This less grown-up version of the 14-bolt may not have the extra pinion support bearing of its eight-lug cousin, but it's rated to handle 5,000 lb-ft of torque, so it's no lightweight either. Moreover, aftermarket suppliers such as Randy's Ring and Pinion offer all the upgrade goodies you need to make this rear end survive with up to 37-inch-tall rubber. As a result, owners of virtually any GM 1/2-ton pickup offered with six-lug wheels can benefit greatly from a semi-float 14-bolt axle upgrade.