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sm 465 exploded!

Discussion in 'Chevy Trucks' started by jholley, Aug 18, 2006.

  1. jholley

    jholley Junior Member
    Messages: 6

    new guy to the boards here.been reading the boards for some time.
    i was hoping someone could shed some lite on this.

    i was under the impression the sm 465 was a tough tranny.last winter i did a frame up rebuild on a stretched one ton dually frame and made 5 trucks into one using the best parts and added a 11 foot flatbed dump.its hard to give it a year.74 frame 84 cab etc

    i put a rebuilt 350 in it and a known low mile sm 465.i've been using it to haul asphalt for cut and patches in parking lots a few times and hauling shingles from time to time and its been an awesome truck.getting ready to look for a plow and salter for it in the off season trying to get a deal.
    but on the way home today on the interstate running about 75 mph the damn thing exploded.i mean pieces flying from under the truck all over the place.it snapped the rearend yoke clean off,took out he Carrier bearing,tossed the rear drive shaft out on the interstate.
    it wrapped the front drive-shaft around the exhaust pipe taking that out to,slammed the clutch petal to the floor and we watched the springs from the pressure plate slide down the road as i coasted to a stop.on top of all that the drive shaft took out the new elc over hyd pump.
    now the engine shakes when you rev it,hoping its just the clutch out of balance.

    it was like the tranny just jammed itself to a dead stop going 75 and took the rest of the truck apart with it.
    anyways,has anyone even heard of this happening before?i thought i was building a pretty bullet proof truck with this combo.

    any suggestion on which way to go with it now?i was thinking of going with a th 350 or if was just a freak thing putting another sm 465 or ?????
    another question is can i use any full floating 14 bolt rear housing under a cab and chassis truck?will a single wheel axle work if you swap the outer crap over?i think it messed the rearend up pretty good to.

    what a day!!!!!

    jason holley
  2. derekbroerse

    derekbroerse 2000 Club Member
    Messages: 2,377

    I've never heard of an SM465 blowing up, ever. They ARE supposed to be pretty much bulletproof. Both my trucks run them, and while they are notchy and worn they have never broken.

    You'll need to measure spring pad widths and overall widths to confirm what axle will fit directly. There are a lot of different 14 bolts out there if you include C&C's, pickups, and vans.
  3. crete5245

    crete5245 Member
    Messages: 61

    There are 2 differnet 14 bolt rear dually axles. One is for a cab and chassis and the other is for a dually pick -up. The difference is the width of the axle. The one for the cab and chassis is narrow and your bed might hit the tire if there is a load on the truck. The only good thing is that you can run a 7'6 plow and cover your tracks with no problem. You do not need a 8' plow.
  4. derekbroerse

    derekbroerse 2000 Club Member
    Messages: 2,377

    There are more than two 14 bolt rear ends out there. The dually pickup did not use a 14 bolt, they used a Dana 70HD. The single wheel and dually C&C used 14 bolts of two different lengths.

    Besides our body style trucks, be careful of loose rear ends because 14 bolts were used in vans, cube/box trucks, and other year trucks. The differences are in the perches, shock mounts, widths, and hubs. Also watch for the smaller 9.5" semi-floater 14 bolt.
  5. jholley

    jholley Junior Member
    Messages: 6


    thanks for the info.the truck is a flat bed dump,so i really dont care about the width of the axle.it has a cab and chassis 14 bolt in it now.i had a chance to look at it better today and the pinion wiggles all over the place.even the bellhousing is split apart.
    the engine still runs,but like crap and smokes water like crazy now.the shock must have cracked the block somewhere.i tell ya, whan it rains it pours.

    if i didnt just spend so much time and money restoring the truck last winter i would just go buy another one.i spent a lot of time setting the truck up just the way i wanted it and restoring the body and interior ect.
    what i was wondering is if the single wheel axle housing was the same width and if it possible to swap over the backing plate, drums ect.they seem easier to find.i just put new brakes and bearings and races in the old axle not to long ago and want to use them anyways.

    thanks jason
  6. derekbroerse

    derekbroerse 2000 Club Member
    Messages: 2,377

    The single wheel 14 bolt is longer than the C&C version by a few inches, but depending on the width of your flatbed it may not really matter to you. Just make sure the spring perches are exactly in the same place as your current axle and you'll be fine. I remember reading somewhere that there were different perch center distances but I have never confirmed this at all, thats why I caution you on that. And of course, if its 4wd, remember to match the gear ratio's. A lot of C&C trucks were 4.10 and 4.56 as they were used for HD purposes, while more of the single wheelers would be 3.73 and 4.10.

    The tranny and rear end are really a dime a dozen, tons of 'em around. I have several of each laying around here for example, they are literally everywhere. 350 Engines, too, if yours was nothing special. I'd be very curious what happened to it. I could see a catastrophic transmission failure bending a crank possibly (remembering that it is inserted in the rear pilot bushing)--could it bend it enough to crack a block? Stranger things have happened.

    Truth is, thats one of the great things about a Chevy/GMC truck--parts are common and cheap--just try and repair an import with a failure like this!