14 bolt 8 lug to 5 lug conversion

[87Scotty]

I picked up a 3:73 Gov loc 14 bolt rear with intentions of converting it to 5 lug and running it in my '87 Scottsdale C10/R10. I contacted Moser today about making new axles for me. I also inquired about a disc brake kit which they do not have for a 14 bolt. They cannot make 5 lug axles for me until I have a rotor.
I want to run 15" wheels with the standard Chevy bolt pattern. Any ideas or help would be greatly appreciated. This is my first conversion so you may have to dumb it down for me.

[sweetk30]

i play with the 14 full float so my info is real limited .

did you see this kit ? https://www.tsmmfg.net/general-motor...-kit-2541.html

might be worth a phone call to them and see what they can do for you .

i know i have read a tiny bit over the years about guys doing 6 lug swap and a custom spacer with the newer 6 lug axles in the older 80's axle housings for our trucks but its been a bit and i dont recall were i read it .

good luck and hope you figure it out .

[mongocanfly]

I assume you have a semi float..?..if your gonna use 15in wheels your rotors and calipers will have to be on the small side to fit inside the wheel itself

[ACS]

Just knock 3 lugs out

For the brakes - have you seen these: https://www.ruffstuffspecialties.com/14BSRW.html

[87Scotty]

Thanks for the replies! The RUFFSTUFF brackets look promising. This is going to be an adventure in scrounging.

[kwmech]

If you have a semi-floater 14b, GM had/has a factory 5 lug that was in the 90s in the 454ss trucks. Stock replacement shafts could be found without something 'custom'. Full float 5 lug on 5.5 can be had with 'solid axle' hubs and ford rotors

[sweetk30]

Ruffstuff is for full float axle .

And if I recall 80's semi float axles are a different width than 454ss axles .

[87Scotty]

This is getting confusing...as I knew it would. I am not well schooled on the differences between rear ends i.e. Full float, semi float etc. Guess I need to do some research, which I should have done before buying this rear end. I got the hubs off yesterday which was fun since the brake shoes had welded themselves to the hub. It appears that the only thing retaining the axles to the differntial is a clip (that makes them semi-float?) I am going to pull the axles today and get a look at the differential. I found a stamping on the housing RAR G 1281 if that means anything to anybody. I would like to figure out what year this rear end is.

[kwmech]

Having to remove only 'C' clip for shaft removal indicates a 'semi-float' axle assy. As I said..that 14 bolt has a factory 5 lug axle shaft. The only issue may be getting the correct offset/length for the housing you have in relation to the brake offset and drums. Having the original shafts is a plus 'cuz you can get measurements off of them to see if the 5 lug is compatible. If it is, all you'll have to do is get the 5 lug drum, unless you are set on having rear disc

[87Scotty]

I would much prefer to go with disc brakes...but I will do what I need to do to make it work...if that means drum brakes that is what I will do. Your info has been most helpful.

[57taskforce]

I’m quite certain GM uses an AAM built (same design as the original GM) semi float 14bolt in some of the later model 1/2 ton trucks. You might be able to source at least the rotors from this application. I’m working on a full float disk brake swap using late model parts as we speak, what you might be able to do is use the backing plates, rotors, calipers, and caliper mounts from a late mode disk brake truck. That would get you a reliable oem parking brake setup as well.

Edit: this may not work as I think I remember most all of the late model trucks went back to 6 lug everything for the 1/2 tons. Ie 2wd is 6 lug like 4x4.

[87Scotty]

Well...maybe this will help those who are trying to help me! I just got in touch with the guy that I bought the rear end from. He say's that it's from a '75 Silverado. I did not think that it was that old.

[mongocanfly]

Scotty, put up some pics of the axle you have,,,like whole housing from the rear, and each end where the lugs are..
I dont think semi floats came along till mid 80s

[87Scotty]

I'm not seeing the pics...do I need to go somewhere else to pull them up?

[mongocanfly]

http://67-72chevytrucks.com/vboard/s...sting+pictures

[Irish1941]

I built more than few 14b SF 9.5 to 6 lug from 8 lug. 99% off shelf GM parts too.
Collecting parts for a current 8 to 6 lug build in fact.
5 lug is a problem. but not impossible.
9.5 is 9.5 never changed. 1981 to 2015 same same. Tube size, center section, bearings etc all same.
Axle tube length DID change but easily solved.
Question is how bad do you want to do this?
Rabbit hole can go deep $$ quick with aftermarket parts.
90-93 SS454 trucks had 9.5 14b 5 lug metric stud but gonna pay to get one.
KW nailed it pretty much.
Ten Factory makes a decent axle for 9.5.

[Mattchu60]

Not sure what custom axles cost - i assume you want the 14 bolt to handle power?

I used quick performance in Ames IA to rebuild my stock 10 bolt - put new gears, the truetrac diff, new yukon axles, new bearings in it. Said it would probably handle almost double the hp I was planning on. I just have a 5.3 with a cam upgrade so I'm around 350-375hp. I feel good knowing I'll never break it.

For this rebuild it was around $1,500. Maybe something to consider vs trying to make a 14 bolt work - the custom 14 bolt parts may cost you more than building something that naturally would fit (the 10 bolt).

[Irish1941]

If you're at $1500, just go to a 9" rear. Looked into building a 12b for the LS3 truck and it was same price as new 9".
For around $3-700 you can do a 9.5 depending what have on hand, dig up on the forums or can get from the wrecking yard.

I use 92-up k1500 heavy half 9.5 brakes. Drums are 6lug but that's what I use. Brakes all bolts on to any 9.5. Even e-brake works. I'd use the SS drums for now.
You could look at Trail Blazer SS rear brakes with different rotor.

Anywho.. here is some axle numbers for you.
92-98 K1500 9.5 axle is 33.1/4″ long - 6 lug
90-93 SS454 9.5 axle is 31 9/16″ long - 5 lug (correct pattern)
81-87 C10 10 bolt axle 31 5/16″ long - 5 lug
79-87 C20 9.5 axle 32.3/4″ long - 8 lug

So looking at those, to get to correct 5 lug width you'll need to cut housing tubes down and re-weld backing plate mount back on or use filled/drilled 6 lug axle and 1/2" spacer behind backing plate. Downside in your application on last option is rear gets wider overall by nearly 4". Great for 4WD not so much on street truck.
Hope this helps.