Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

Deuce and a half axle questions

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Overkill, Feb 13, 2002.

  1. Overkill

    Overkill 1/2 ton status

    Joined:
    Jan 15, 2002
    Posts:
    284
    Likes Received:
    0
    Location:
    Orlando, Florida
    Anybody out there running 2 1/2 ton axles? I am getting ready to transplant a set into my '82 and was wondering about brakes and rims. The drums on these monsters are way too much. I would like to do a disk brake setup. I will probably also have a pinion brake setup, but was wondering about the legality of pinion brakes. I heard that the DOT doesn't like them, but have no proof yet. Also I was curious as to what I could do for rims for these things. I heard that I could get custom rims made for about $200 apiece, kinda pricey. Is there a common way to swap the massive military hubs for something a little more civilized and common? I was also curious as to the axle length. Right now they are 7'8" or so long (hub to hub) and I was advised to have them shortened. It would be nice to have the same size axle shaft for all 4 corners but for $300/axle, I could live with the width and having a long and short axle shaft, maybe. Don't anticipate breaking any of those. haha. I plan on lifting at least 8" (susp) and running 44's. I would like a little wider stance to offset the high CG. Mostly mud running. Any questions, comments, thoughts, ideas, or suggestions would be welcome. Just trying to formulate a game plan before I go spending a bunch of hard earned cash on useless stuff. I don't mind spending it if it's what I want, just hate doing things half ass then having to do them again, hence the deuce and a half setup, hehe. Thanks.

    Pics at <a target="_blank" href=http://community.webshots.com/user/jlblmkh>http://community.webshots.com/user/jlblmkh</a>

    (Formerly heaj1)
    Swimmin like a rock, slingin like a stock, but not for long.
     
  2. mudrunner78

    mudrunner78 1/2 ton status

    Joined:
    Sep 7, 2001
    Posts:
    366
    Likes Received:
    0
    Location:
    Rocksprings, TX
    bsmn123 sells these axles can set them up for 4 wheel steering he runs willwood 4 piston caliper on the pinions, he can also shave them to have the same clearance as a dana 44 I will have pics this weekend. rims are easy bart makes them or bsmn123 can make them.

    78 K-10 383, TH-350, NP-203, Dana 70 front, GM 14bolt Rear, 4.56 gears(underconstruction) 78 k-5 stock and rusty
     
  3. Overkill

    Overkill 1/2 ton status

    Joined:
    Jan 15, 2002
    Posts:
    284
    Likes Received:
    0
    Location:
    Orlando, Florida
    Thanks, but who is bsmn123? These are top loading pinions and to shave them sounds like trouble. Would you want to take material off the bottom "skid surface" of the pumpkin? May be a possibility, will have to check into it a little more. I looked at the user list and I see no bsmn123 on this site.

    Pics at <a target="_blank" href=http://community.webshots.com/user/jlblmkh>http://community.webshots.com/user/jlblmkh</a>

    (Formerly heaj1)
    Swimmin like a rock, slingin like a stock, but not for long.
     
  4. NoRulz

    NoRulz 1/2 ton status

    Joined:
    Feb 6, 2001
    Posts:
    388
    Likes Received:
    0
    Location:
    Mesa, AZ
    I know 2 running them so I know a little bit &amp; I'll give you what I can.

    Brakes on the rear are pretty easy, you can adapt a number of different things on there with some machine work. As an example one friend has the older Ford superduty brakes on his, the other is running Ford 1/2 ton rotors &amp; calipers... one at each wheel and one on the pinion. The superduty stuff is plenty big enough, &amp; the other is fine with 3 rotors &amp; calipers, although a bigger master cylinder is a must with that setup. Both are still running the stock drums in the front since converting that is a bit more difficult than the rear.
    As far as DOT legality, I don't know for sure, but I hope pinion brakes are illegal. If you have any intention of street use, I really hope your not going to trust 2 rotors to stop 44" tires on a 7000lb vehicle. IMHO that's worse than front lift blocks.
    Both my friends are running/have run larger than average tires, 20", 22.5" &amp; 25" so I honestly don't know your options there. I know Boyce &amp; Stockton wheel can do the bolt patteren, but I know nothing about boyce's quality, &amp; I've heard enough horror stories about Stockton to never want to ever send anyone to them.
    Easiest way to narrow them is to cut 7" out of the long side of the axle. I assume your talking about rear steer too if you want all 4 the same length. If you shorten the long side 7", a standard short side axle will slip right in. Last I heard Boyce was getting $150ish for axleshafts, but that was quite a while ago.
    They do break, &amp; easier than you may think. It's a big, badass housing with deep gears, but your talking about axleshafts made with metalurgy (sp) from the 50s, that were never designed to have much more than a 150hp 6-cyl turning them. They were designed to carry alot of weight, not take alot of power. My buddy has broken both a front &amp; a rear shaft with a very mild 460, open diffs &amp; 50" tires.
    As far as lift, think things out &amp; measure ALOT before you decide on a height. Those pinions &amp; oil pans can get in fights if you don't think things out.
    As far as CG, I don't know about 15/16.5" wheels that are made for them, but I know with 20"+ wheels &amp; commercial tires your CG will be alot lower than you think. You'd be looking at least 300lbs per wheel/tire + the weight of the axles, it ends up being alot of weight down low. It really can make the truck more stable than it should be. I've sat in the back of my buddies Chevy crew cab sitting over 48" tires spinning doughnuts in the desert. It feels so wrong, but it never fell over.

    Hope this helps ya out a bit, just trying to share what little I know/have witnessed with you.

    My Ford has chevy parts! it's all good!
     
  5. Overkill

    Overkill 1/2 ton status

    Joined:
    Jan 15, 2002
    Posts:
    284
    Likes Received:
    0
    Location:
    Orlando, Florida
    Thanks a bunch NoRulz, that is exactly what I was looking for. I did froget to mention that both axles were fronts and four wheel steering is almost certain to find it's way into the setup, with lockout pins for the rear of course. I wasn't too sure about the pinion brakes as this will be a streetable rig. That's where Im having trouble, keeping it all street-able (legal-ish). It won't be a daily driver, but will have to get to and from the mudhole on a regular basis. I know a bunch of people who have similar setups but they trailer them everywhere. I don't have a trailer or a rig to pull one, the K5 will be it. I was trying to figure out how to use a pinion brake with regular disk or drum backup, 3 calipers/disk or drums per axle. That should stop 44's fairly easily. The pinion brake would be primary with normal setup for backup. I was also wondering if leaving them stock length would be a possibility and run a deeper back spaced rim. But a rim to cover those gigantic drums would be expensive, Im sure. If I could convert the drums/hubs to a more civilized (1 ton) hub type setup and keep more options open for rim/tire selection and shave some weight. I havn't even had a chance to really check out the axles yet as They are sitting in a friends back yard still, so I'm not sure what parts of them bolt on/off and what parts will have to stay or be torched/welded to be changed. So many questions.....sheesh. Haha.
    Again, thanks for the input.

    Jamie

    Pics at <a target="_blank" href=http://community.webshots.com/user/jlblmkh>http://community.webshots.com/user/jlblmkh</a>

    (Formerly heaj1)
    Swimmin like a rock, slingin like a stock, but not for long.
     
  6. four_by_ken

    four_by_ken 1/2 ton status

    Joined:
    Jun 9, 2001
    Posts:
    3,806
    Likes Received:
    0
    Location:
    Allenton, MI
    Look into the pinion brakes a little bit. Two little dinky pinion brakes will stop a big truck a LOT better than 4 wheel brakes. You have to take into cinsideration the gearing. You have the gearing working against you at the wheels, and for you at the pinions. Loose all four big ole drums and go with just the pinion brakes.

    Ken H.


    '86 K5 in parts
    1-ton 454 44 TSLs
     
  7. thatK30guy

    thatK30guy 1 ton status Premium Member

    Joined:
    Jan 12, 2001
    Posts:
    32,076
    Likes Received:
    55
    Location:
    .
    <blockquote><font class="small">In reply to:</font><hr>

    I really hope your not going to trust 2 rotors to stop 44" tires on a 7000lb vehicle.

    <hr></blockquote>
    Well, not quite... how do you explain monster trucks using the same brakes and stopping 66" tires and a 15,000 lbs. truck? [​IMG]



    <font color=red>Only real men drive K30's!!!</font color=red> [​IMG]

    <a target="_blank" href=http://coloradok5.com/gallery/thatK30guy>The K30 Collection</a>
     
  8. DieselDan

    DieselDan 1/2 ton status

    Joined:
    Jan 27, 2001
    Posts:
    1,056
    Likes Received:
    0
    Location:
    Vermont
    Ha, Ha, Ha You're worried about two high performance pinion mounted brakes? Have you ever dealt with stock Duece brake sytem? The last of the M35A2's rolled off the assembly line around 1967. Are you familiar with SINGLE CIRCUIT brakes? They do use a "hydravac" compressed air power boost, but the old master cylinder is often neglected by virtue of being open vented, mounted under the floor, needing a wrench to open the resevior. The wheel cylinders are hardly any better, I suspect many (most) of them have been rebuilt (read: honed) so many times they won't hold their seals. Ask one of my mechanics who lost two wheel cylinders after the hydravac dragged. Then lost ANOTHER three wheel cylinders (two of which were "new") trying to power bleed the system. Watch for flying wrenches!l

    I lost track of how many times I had a brake failure in a Duece, doesn't even phase me anymore. They started rebuilding Dueces around ten years ago, as M35A3s. Now the master is under the hood, contains dual circuits, BUT also dual hydravacs. Better pump up that spindly little leg, you girlie man

    Real trucks don't have spark plugs!
     
  9. pcorssmit

    pcorssmit 1/2 ton status

    Joined:
    Jan 2, 2001
    Posts:
    1,346
    Likes Received:
    0
    Location:
    Denver, CO
    I asked this a while ago on a different thread, but didn't get any replies. I understand how two smaller rotors can stop a big truck due to the gearing. But what about heat dissipation? You still have the same amount of energy to dissipate, but you're doing it with 1/4 the amount of metal as an equivalant 4 wheel disk system on 1 ton axles (if you use a caravan or similar sized rotor as was suggested on the other post, if a 1 ton roter, then 1/2 the metal).

    Pete

    '83 K5, 350 TBI (ex 6.2), 700R4, NP208, Dana 60/14 bolt, 4.56s, Detroits, 3" lift, 15-39.5x15 TSLs
    '97 Dodge 2500 4x4 CC LB Sport, Cummins 5 spd
     
  10. BadDog

    BadDog SOL Staff Member Super Moderator Author

    Joined:
    Feb 24, 2001
    Posts:
    7,777
    Likes Received:
    11
    Location:
    Phoenix, AZ
    Seems to me you have a 6.7?:1 reduction in energy to dissipate by virtue of the gearing compared to wheel brakes at 1:1. If you went the other way, and the brakes were forced to work against the gearing (effectively making the brake weaker instead of stronger) you would have more energy to dissipate thru friction/heat.

    Russ

    85 K30 CUCV, 350 TBI, TH400, 205, D60/C14, 4.56 Locked, 4" lift, 42" tires
    Some day: massive cutting, shorter wb and rear overhang.
     
  11. Triaged

    Triaged 1/2 ton status

    Joined:
    Feb 21, 2001
    Posts:
    3,808
    Likes Received:
    0
    Location:
    CA (LA/OC area)
    Energy can NEVER be created or destroyed! You just convert it from one form to another. In the case of brakes you are converting kinetic energy (energy of motion) into heat (just another form of energy). Stopping a heavy truck w/ 2 pinion brakes would have to convert the same amount of energy into heat but would have much less heat dissipation capability. It would be about like trying to stop a truck with only the rear drums working but having a long lever to push on the brake peddle.

    '71 Blazer CST w/ a 400sbc, 4" lift, 36" Supper Swampers, and alot of rust
    <a target="_blank" href=http://community.webshots.com/user/triaged>See it Here </a>
     
  12. BadDog

    BadDog SOL Staff Member Super Moderator Author

    Joined:
    Feb 24, 2001
    Posts:
    7,777
    Likes Received:
    11
    Location:
    Phoenix, AZ
    Yes I agree and I know about conservation of energy, mass etc. However, I don't see how a brake operating at the pinion behind almost 7:1 gearing could possible build as much heat as the same brake, slowing the same mass, at the same rate, with 1:1.

    Hmmm, I think I see my mistake. I was just thinking of the force multiplication due to leverage and I couldn't reconcile my intuition with the conservation laws. That is why I said “seems to me” rather than making a statement of fact. Unfortunately, I wasn't thinking of the extra rotational velocity due to the 7:1 gears. That’s what happened to the kinetic energy after going through the gears, and the reason my intuition was arguing with my education.

    Sorry for the noise, it's been a long day. [​IMG][​IMG] When I’m as brain dead exhausted as I am today, I really shouldn’t post answers to anything more complex than “can I run 15 inch rims on an C14 rear?”. [​IMG]

    Russ

    85 K30 CUCV, 350 TBI, TH400, 205, D60/C14, 4.56 Locked, 4" lift, 42" tires
    Some day: massive cutting, shorter wb and rear overhang.
     
  13. mudrunner78

    mudrunner78 1/2 ton status

    Joined:
    Sep 7, 2001
    Posts:
    366
    Likes Received:
    0
    Location:
    Rocksprings, TX
    pinion breaks work great, I am not going to get into physics or try to explain myself other than that I have seen them stop a 5800lb mud racer, setup with 48 inch tires and a built 468. They always have stopped the vehicle no problem. now I know this setup wasn't used on the street with alot of heat build up, but as far as braking energy, theres no problem, call the willwood service reps, they can really help you out when it comes to brakes./

    78 K-10 383, TH-350, NP-203, Dana 70 front, GM 14bolt Rear, 4.56 gears(underconstruction) 78 k-5 stock and rusty
     
  14. Overkill

    Overkill 1/2 ton status

    Joined:
    Jan 15, 2002
    Posts:
    284
    Likes Received:
    0
    Location:
    Orlando, Florida
    Thanks everybody for the input. I see how pinion brakes could be confusing. You only have 6.7:1 of the torque to stop but also you have 6.7:1 more velocity than at the wheels. The worst thing i was thinking about the pinion setup was the fact that if the diff was open you could have one wheel lock up, or actually reverse while the other did little in the way of stopping. Guess I'll have to lock 'em, hehe, for safety you know. The wife should buy that...Right? I guess I will have to get ahold of someone who does this kind of thing for a living and see what they suggest.
    I still haven't heard any opinions or options about axle length though. I would like to not have to shorten them if possible. If the original drum brakes and hubs can be swapped for something smaller (ie. shorter) that might eliminate most of the issues in one shot. If I could do 4 wheel disk (1 at each wheel) with pinion brakes on a proportioning setup I would think it should be fairly safe. I don't plan on any long road trips or daily driving but would like the security of knowing I could, should I decide to. Never know when I might feel the need to head for Moab, haha.
    Again, thanks for all the input and feel free to keep the suggestions, options, and opinion rolling. I don't think anyone could ever be too well informed. That's kinda like being too wealthy, hehe.

    Pics at <a target="_blank" href=http://community.webshots.com/user/jlblmkh>http://community.webshots.com/user/jlblmkh</a>

    (Formerly heaj1)
    Swimmin like a rock, slingin like a stock, but not for long.
     
  15. four_by_ken

    four_by_ken 1/2 ton status

    Joined:
    Jun 9, 2001
    Posts:
    3,806
    Likes Received:
    0
    Location:
    Allenton, MI
    There wont be as much heat since the brakes will not be working as hard in the first place. There is a lot less work for the brakes to do at the pinion that at the wheels.

    Ken H.


    '86 K5 in parts
    1-ton 454 44 TSLs
     
  16. NoRulz

    NoRulz 1/2 ton status

    Joined:
    Feb 6, 2001
    Posts:
    388
    Likes Received:
    0
    Location:
    Mesa, AZ
    <blockquote><font class="small">In reply to:</font><hr>

    Well, not quite... how do you explain monster trucks using the same brakes and stopping 66" tires and a 15,000 lbs. truck?

    <hr></blockquote>

    They don't drive down the freeway... there's a big damn difference between stopping 10 times vs. stopping 100+

    My Ford has chevy parts! it's all good!
     
  17. NoRulz

    NoRulz 1/2 ton status

    Joined:
    Feb 6, 2001
    Posts:
    388
    Likes Received:
    0
    Location:
    Mesa, AZ
    DieselDan, actually, no I havn't ever dealt with a M35 brake system, but I hear you. I know how technology in the 50s was as far as automotive, &amp; some of the stuff I've seen on cars scares me enough. All I can say is that the systems I've seen adapted to light trucks have worked good for years running stock drums in front, &amp; converted disks in the rear.

    My Ford has chevy parts! it's all good!
     
  18. four_by_ken

    four_by_ken 1/2 ton status

    Joined:
    Jun 9, 2001
    Posts:
    3,806
    Likes Received:
    0
    Location:
    Allenton, MI
    One question...

    Who the hell woudl drive 2.5 tons on the highway!!??!!

    If you are still drviing in the highway, at highway speeds... you dont need Rockwells.

    You have to give up something everytime you upgrade. Upgrading one place almost always takes away from another. Almost.

    And 44s on the highway with any axles are not going to stop good. But, I would much rather have pinion brakes to stop me.

    Ken H.


    '86 K5 in parts
    1-ton 454 44 TSLs
     
  19. Overkill

    Overkill 1/2 ton status

    Joined:
    Jan 15, 2002
    Posts:
    284
    Likes Received:
    0
    Location:
    Orlando, Florida
    Ken, to answer you question "Who the hell woudl drive 2.5 tons on the highway!!??!! ". I would If I were on my way to a large gathering of fellow K5ers and/or mud slingers. I have no trailer or vehicle with the ability to tow what started out as my K5. I am trying to formulate a game plan of just how I can build my rig once and build it right - to fit my needs/desires. Unfortunately, at this time, I don't have the means to have a tow vehicle and trailer. I want to build my truck to be street (almost) legal,... well, enough to not get harrassed by every police officer, sherrif, and state trooper I come across, and also be bad enough to get me where I WANT to go, relatively safely. I refuse to build a rig (at this point in my life) that will absorb many thousands of dollars and literally years of my life, and not be able to drive it to the store to get a gallon of milk or loaf of bread if I needed to, for whatever reason! This game plan is the reason I am posting questions in this forum. I want to be informed and not go making half baked decisions and wasting time and $$$ or risking injury. I realize that the finished product will not be the ideal grocery getter or the best daily commuter, but if the need arose it will function in that manner (for a short period hopefully). Please don't take this explanation as me being upset, or ruffled. I am simply trying to offer as much information as I possibly can so that anybody wanting to offer advice could understand where I'm coming from. I think the pinion brake &lt;debate&gt; is at it's end. I have seen a few guys around town running rockwells and pinion brake setups on the streets and mudholes, and will hopefully get a chance to strike up a dialog with one or more of them to get some real world insight from their experience. I still haven't heard much about axle length yet. can we go there next? Anyone? haha. Thanks a bunch for all the input, it is appreciated! Is "wider" really "better"?

    Jamie

    Pics at <a target="_blank" href=http://community.webshots.com/user/jlblmkh>http://community.webshots.com/user/jlblmkh</a>

    (Formerly heaj1)
    Swimmin like a rock, slingin like a stock, but not for long.
     
  20. DieselDan

    DieselDan 1/2 ton status

    Joined:
    Jan 27, 2001
    Posts:
    1,056
    Likes Received:
    0
    Location:
    Vermont
    Ya when they work, they work pretty good (the stock drums). But I've experienced way too many failures per road mile (or road hour for Dueces, LOL). And this stuff is well maintained, we pull a service (remove &amp; replace all the hubs) on it every year and it may have only rolled 50 miles in between. The good thing is they're not that fast, manual trans, and have a lot of resistance/drag. They'll drop speed pretty quick if you let of the accelerator.

    Real trucks don't have spark plugs!
     

Share This Page