sweetk30

picked this up from a friend few days ago .

1973 12 bolt truck rear 3.73 gears and in real good shape for rust belt axle. but it spent most of its life out west before it arrived here. good pattern / wear and no major play .

$100 bucks scored this for the truck since the 2.73 or 3.08 rear 10 bolt I had now was junk anyways .

will be swaping over the brakes from newer to older axle . gets me from 11x2 upgraded to 11 5/8 x 2 3/4 . bigger is better .

going to send it out for some light media blasting so I can make it match the clean rest of the truck when I paint it.

also going to swap out the open diff for a nice new eaton / Detroit true trac posi unit . gears no clutches to wear out.

Ian Johnston

Good pickup by the sounds of it. I have a 12 bolt 3.08 I picked up cheap. Pay to check the axles where the wheel bearing runs, hardening has worn on one of mine.
Also, mine has the dual wheel pattern axles(car, and pickup) Is this common? Just knock out the wheel studs, and refit in other holes. Brake drums match as well. Not up with these that much.

sweetk30

scored me a detroit trutrac posi unit new still in the box shipped for $90.00 bucks off reg every day price on ebay . no clutches to wear out in this style unit . and drives like open diff untill needed to bias power. and no its not a gov-lock unit .

also got me a TA rear diff cover girdle unit with preload bolts for the main caps . its got rear fill/drain ports and aluminum with bracing in it. holds little more fluid and will look cool under there for sure. got thsat for $155.00 shipped.

pic 1 stock file pic from eaton .

pic 2 act unit from ebay

pic 3 stock pic from TA covers.

gofastwclass

iTrader: (2)

I think you will like the Detroit TruTrac. I put one in one of my cars and it is nearly invisible until you stand on it and see a pair of elevens in your rear view.

I have noticed that mine will chatter the inside tire in a tight turn, especially on less than ideal surfaces. This is nowhere near a complaint, just an observation. I like it enough that I'll buy one for the next car I build over a clutch or cone style posi any day.

sweetk30

good info / feedback man thanks

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got the 12 bolt torn down this weekend .

needed 2 new carrier bearings/races ( set36 timkin ) the originals had some water damage from sitting for years in 1 place. the races had some spots were the finish was poping up . pinion bearings and races looked great .

got the seals for the pinion / axles and yoke off the old 10 bolt and found a chewed up seal surface. every place in town over $35.00 my cost and order in for the repair sleave for the yoke . rock auto to the rescue $15.50 shipped to the door

also found the cross pin bolt was broken on the 12 bolt open diff. common every day on this style . ( if you need to remove and save try this place http://www.fabbriassociates.com/index.html ) mine was broken past the threads but with magnet and wiggle jiggle still wouldn't come out . so I got heavy metal on it with a punch & 4lb hammer and drove the cross pin out sheering the broken pin off since I was installing a posi unit in the open diffs place anyway .

also beefed up the carrier bearing caps with ARP main studs . had to grind down the tops a tiny bit for the washers to sit flat. but anyone who has installed a ARB unit will have to have done the same on some model axles for the retainer plate on some models .

test fit of the new BIG THICK BEEFY diff cover

then I was going to swap over to the 11 5/8" x 2 3/4" brakes off 1 of my other 10 bolt junk rears till I found out all 3 sets of brakes from 12 bolt and 2 10 bolts were the small 11" x 2" so I posted up a wanted ad in the sale section for brake parts on my home forum . and a guy poped up with what I needed.

also ordered 2 new leaf spring perches for the 12 bolt to beef it up more over stock . http://www.ruffstuffspecialties.com/.../25-PERCH.html and top plates http://www.ruffstuffspecialties.com/...25GM-UPLT.html I had left over from ford 9" idea I was going to drop in before I found it was not the correct deal I was told and got my money back .

even tho its 2wd got to pimp some hd beefy stuff. I already have www.diy4x.com hd usdr 5" shackles on the rear for 1/2" more drop over stock hight .

oh well on to other projects till all the parts show up .

sweetk30

that's it I am tired if this solid axle stuff .

I am going I.R.S

no not realy . but it would be so cool and I sure wouldn't use german stuff . full rear suspension from a car I was working on .

real easy 6 bolts for c/v drive shaft head. 2 ebrake cables . 2 calipers . and 2 abs wires and 1 headlight aiming switch for load on the suspension . then 4 big bolts and its out.

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I am going to clean up the housing a bit tho and also swap on some BEEFY and longer leaf spring perches for better control of axle wrap . then send it to my buddy to blast it up so I can paint it along with the leaf springs .

and I got the repair sleave and installed it on the stock 10 bolt yoke that will be swaped on inplace of the older od size 12 bolt yoke.

then I poped out the original hose nipple and tapped it to 1/8 pipe and got a nice 1/8 pipe to 3/8 hose barb and installed that . as the stockers are just pressed in tin units .

still working on it slow and some what steady but she will get done .

sweetk30

well took some time today and beefed up the 12 bolt truck rear a little more .

pic 1-2 = stock angle as the axle sits on its backing plate flanges on some 2"x4" square tube off the 1" thick plate steal work bench . as you can see there .4* off left to right . but the left side perch was a little deformed just a tiny bit . so it could be abuse or factory play in 1972 when the axle was built for the 1973 truck year.

pic 3 = spring perch center to outside edge of backing plate flange as a backing plate would sit on it. and this spec is for 1/2 and 3/4 ton 42" width .

pic 4-5 = general idea of how much more the ruffstuff specialty products perches have over stock . and just about or slight over 1/4 " taller over stock also .

sweetk30

pics 1 - 5 = then we got the old ones off / cleaned up the tubes / burned the new ones in place . and as you can see nice welds for a non school learned person and also great fitment to the tubes and good heat all the way threw both perch and tube for a great weld.

pic 6-7 = once cooled down and checked I was shooting for 9.4* - 9.5* to be in the middle of the original range . but I got 9.1* and 9.2* I don't think it will matter that much on a 2wd build . and the .1* is a lot closer than original difference.

pic 8-10 = then I made a few plugs out of washers and electrical tape to act as a gasket and sealed off the pinion area and axle ends and used threaded rod for all the hardware. also poped on the diff cover to seal that up also .

then on lunch I droped the empty / sealed housing and both rear leaf spring packs off at the blaster to get striped and ready for me to paint up black yo match the rest of the rolling frame.

I also have the new top plates from ruffstuff specialty to match the rest of the leaf spring clamping needs. http://www.ruffstuffspecialties.com/catalog/

then its time to toss it all back together and bolt it in the truck .

sweetk30

bed mods today to clear the longer shackle swing .

marked it before box removed .

dropped down 1" from flat bottom of rail .

then used section of 2" exhaust pipe for a thick wall and radius .

then filler panel for ends .

as you can see the pieces welded in great .

I drilled a drain hole on each end in the middle section since there was no real way for it to drain out now if need be .

and last was old cut out section next to modified section now.

Ian Johnston

Thanks for that. Looks neat, and no doubt works. I dont plan on pulling my bed off yet, but its given me ideas.

sweetk30

got a big package of brake parts .

drums qty 2 = 11" x 2 & 5/32" big brake option for 1/2 ton .
reman shoe's 11" x 2 5/32" also
hardware / hold down kit
left & right adjuster kit's
wheel cylinders qty 2
all ebrake cables cab down to axle
already had axle seals

got the used backing plates and brake bars from ( gonicgm member here ) and blasted them up in the shop cabinet and then welded up the shoe wear pads that were worn down a bit he already told me about.

so the ebrake cables arms look the same from small to big brake option . and I had both shoes in hand and tried them both with no noticeable difference.

next is to prep them and paint them black to match the rest of the under parts of the truck .

pic 1 = parts in the tool cart top/bottom

pic 2 = new wide shoe on bottom and old narrow shoe on top . for a difference comp view

forgot to get pics yet of the backing plates all blasted up .

few other pics of the 1973 12 bolt rear all cleaned up and lookin real good over any I have seen this clean up here in the rust belt. you can even read the casting #'s on the diff section .

also leafs all blasted up ready for paint. I have new pinch bolts / nuts / tubes with 4 new anti squeake pads also to put back in the #2 leafs just like factory had .

then the ruffstuff top plates to match the beefy spring perches you seen me install before blasting . just need to hit the local shop up for some ubolts when I am ready .

sweetk30

few pics of the rest of the parts blasted .

and repair welds ground down from groves in backing plates were shoes ride.


then its all nice now .

small parts painted and also leaf springs .

and the drum's / axle housing / stock cove ( not sure what to do with it ) and hardware for backing plates to axle housing / wheel cylinder's to backing plates / centerpin's / ubolts.

darn 11 5/32" x 2 3/4" drums are heavy !!! but that's compared to the baby drums I took off.

center pins are allen socket bolts and 2 nuts . will show why later when I assemble stuff.

sweetk30

rear leaf pack rebuild today .

all layed out in order

then new anti squeaker pads clipped in place.

pack assembled all tight .

pair of extra nuts rounded off to fit in the center of the top plate nice n tight for less movement.

then i installed the energy suspension bushings in the eye ends of the main leaf.

also I took a thick washer and extra nut for centerpin and sandwiched the top plate on in place . made for fast / easy install .

and then both packs got bolted in to the trucks hangers and 1" longer diy4x hd shackles for that extra 1/2" drop I talked about before.

sweetk30

and then it was time to install the ratech solid pinion spacer and shim as needed for preload. this unit eliminates the crush sleave .

empty case clean and ready for parts to be reinstalled.

pinion is in and spec was 10-15 inch pounds turning force used bearings I got just about 14-15 range then with the seal I got about 2 more as normal seal drag is 2-3 .

so I droped in the used 3.73 ring on the brand new Detroit true trac unit. got here in and clamped tight with 60 ft lbs on the main cap's . and don't forget I used arp. main studs for a ford 8" diff rear same application placement. neet trick to do .

then I got the backing plates bolted on and slid in the shafts and droped the c-clips on and plopped the center wedge in and little blue locktight and 20 ft lb as per directions for center bolt. and I will say there is hardly no play in the axle end play now with this setup .

some more fun was had .

yes that's a broken tap in the cover bolt hole.

found the T/A cover bolts to be 2 threads short of full tight to hold the cover down . so I had to finish with a bottom out tap the factory holes that just didn't get done all the way .

and then bolt #1 as I started it must have been a worn / weak tap as hardle any pressure it poped .

but I was lucky it broke under no load and was able to hammer/punch walk it out to the point of vise grips . thank the auto god's
now the T/A cover is on tight / load bolts @ 5ft lbs and jam nuts tight . also I added Teflon paste to the load bolts to help from any gear oil leaking I hope.

and the cover is BEEFY for sure.

sweetk30

I wont go into the brakes as we seen them done lots of times .

but as you seen above we have basicly 90% all new parts ex backing plates and brake bar's .

yes I skipped painting the ends of the axles. I can get them later .

and here she is in all her reman glory ready to roll over on go-jacks to be installed in her new home . from a 73 c-10 long bed to a pickup trailer for years and now back in service with some goodys inside and back under a whole truck again .


just a few glory shots of her back on 4 wheels again

sweetk30

she is still live .

over the past month I have gotten a few more parts for it here and there .

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junk yard score today .

89-91 front filler panel .

best part gm original replacement on back side . not jap .

I had one but it was a bit messed up . but for 7.50 cash I couldn't fix mine that cheep.

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got the trail blazer SS cover cleaned up and removed the 6.0 emblem someone glued on with cheep glue thankfully .

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also grabbed a new pcm computer bracket at the dealer . also few bucks more there was a pcm cover . so figured why not

sweetk30

major jump this last 48 hr's

got my buddy to swing over and lend a hand since he owed me a few favors .

got the cab off / scuffed / scraped / wiped down / and rust convertor spray to neutralize any left over surface rust for now . then we coated the whole bottom good

first cab pic gray floor was ORIGNAL not blasted . just wiped down with cleaner then scuffed for under coating

sweetk30

next we took and cleaned / blew off / sucked out all the junk / dirt and grime from the bottom side of the bed . then did the same prep work as the cab floor .

also just to be sure before finale coat we test fitted the bed and the 2 clearance notches I installed to clear the shackle swing work like a glove .

next was the same full spray on the under side .

we used transtar quick dry rubberized under coating .

and the bed floor is also that clean . hard to tell in bright sun light pics tho . but blue floor all the way till covered.

sweetk30

hope in the next few weeks to get COLOR on it finaly .

sweetk30

sorry long time between updates but she is getting there

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little more done . got the cab flipped back up and on the roll around cart . also did up the seam sealer in the cowl box area that was dryed out and all gone . next was clean up and coat the fire wall.

then we flipped the box back over and started a little filler work on it also .

nost of the bed filler work is from welded shut trim holes or on the top rails 13 yes 13 holes from tool box's and ladder racks . and the rf lower section was a small dent/gouge we hammered & dollyed out and the small repair panel job I had done from the rust hole . looks worse than it realy is as I had sanded off all the old burnt / dryed out / flacking off paint .