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??? for Dr. Stephen

Discussion in 'OffRoad Design' started by LKJR, Feb 8, 2002.

  1. LKJR

    LKJR 1/2 ton status

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    Ok, being a college student and being exposed to all this engineering stuff my brain is going 100mph, and I can't find the brakes. Two questions at the moment and more to follow I"m sure.
    1) What are the major drawbacks of IFS other than cost, and the half shafts being a weak link? Advantages other than Ground Clearance?

    2) Any idea what kind of torque would be applied to the U-joints at the wheel end of the half shaft? Guestimating a 500 ft/lb engine. or any other torque amount you may know

    thanks

    Les

    Like em big and topless
    You call THAT...a 4x4....LMAO?
     
  2. 84_Chevy_K10

    84_Chevy_K10 Banned

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    I know I'm not Dr. Stephen, but I hate IFS enough I'm willing to post here anyway.

    1. Ground clearence isn't an advantage. As the suspension compresses, ground clearence is reduced in the center. An additional disadvantage is travel. IFS like the new Chevys have just doesn't have any travel/articulation capabilities. The Baja trucks have IFS, but just their front suspension probably costs as much as a new pickup, so you'll never see that on a new pickup.

    2. Torque applied to the CV joints at the end of the half shaft would be the engine's 500 foot pounds, multiplied by all the gearing in the trans, transfer case, and axles. If it was a stick shift, the dynamic load could be MUCH higher when you let the clutch out. Keep in mind an auto's TC can multitply power too.

    You said it yourself in your signature, "You call THAT...a 4x4....LMAO? " That's what I think of IFS.

    Tim
    '84 Chevy K10, lifted, loud, fast, and 3/4 ton axles
     
  3. DieselDan

    DieselDan 1/2 ton status

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    Just to play devil's advocate (again), lemme say that there is a ground clearance benift. Can you say Hummer/HMMWV? 18+ inches under the diff does help. But the real problem is that MOST trucks with IFS are more geared towards on-road performance than off-road. Even the HMMWV does not have the articulation of a stock K5. And the HMMWV uses offset/reduction hubs to boost the ground clearance without additional CV joint angles.

    If you wanted to get your late model IFS suspension to really work off-road design and build a offset hub for it to perform. (HMMWV axles spin backwards) I think it will only be a matter of time before someone fabricates a IFS/IRS vehicle on the level the Sniper and such; then the arguments will REALLY begin.

    Real trucks don't have spark plugs!
     
  4. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Um, I never said that IFS/IRS can't be used sucessfully. Baja trucks use it very sucessfully.

    The HMMWV costs over $70,000. That's why it has independant suspension that works.

    Tim
    '84 Chevy K10, lifted, loud, fast, and 3/4 ton axles
     
  5. LKJR

    LKJR 1/2 ton status

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    "I think it will only be a matter of time before someone fabricates a IFS/IRS vehicle on the level the Sniper and such; then the arguments will REALLY begin."

    Someone is catching onto what I"m headed toward here...... I don't have a newer body style truck with IFS I"m trying to think outside the box, and design something totally off the wall, cost is not a prohibiter in the deign phases, and hell how many of us can afford to go out a buy a humvee or a sniper, I had some major brain farts in the shower yesterday morning and I"m trying to develop them into some rational concepts here...

    Off the wall IFS design, new U-joint design, etc.

    thanks guys for the input..sat down tonight at work during some free time and tried to put some of these thoughts into paper form and it's not getting too far, but it's still stewing maybe something will come of it yet..

    Like em big and topless
    You call THAT...a 4x4....LMAO?
     
  6. Triaged

    Triaged 1/2 ton status

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    There was a jeep at TTC a few years back that had IFS and IRS I think. The inboard suspension pivots were only a few inches apart making for really long control arms. He was running at least 40" tires.

    '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>
     
  7. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Geby's Jeep. He won too. Caddy powered, IFS/IRS and it performed well. He is from Kelowna BC, only a few hours from here. It was all custom fabbed stuff though. I believe he usde standard diff center sections with flanges just outboard of the diff housing then custom half shafts from there. Wilwood aftermarket disc brakes etc etc. It looked like a spendy truck, but then almost any TTC contender is a spendy truck.

    Rene

    <font color=green>Dyslexics of the world...UNTIE!</font color=green>
    <a target="_blank" href=http://coloradok5.com/gallery/project_T2> tRusty pics...</a>
     
  8. LKJR

    LKJR 1/2 ton status

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    Ya'll got a pic or a web link of this machine?

    Like em big and topless
    You call THAT...a 4x4....LMAO?
     
  9. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    I'd have to search my magazine archives...[​IMG]

    I'll see if i can find it. I'm pretty sure it was TTC 98 or maybe 97.

    Rene

    <font color=green>Dyslexics of the world...UNTIE!</font color=green>
    <a target="_blank" href=http://coloradok5.com/gallery/project_T2> tRusty pics...</a>
     
  10. Big_B_Murphy

    Big_B_Murphy 1/2 ton status

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    If I remember correctly, that Jeep used Gamma Goat axles.
    If you don't know what a Gamma Goat is, It was a Military vehicle that was a predecessor to the Hummve. It pivoted in the middle.
    Funky looking thing.

    <font color=red> It is just as much fun to build it as it is to bash it</font color=red>
     
  11. morphed86k10

    morphed86k10 1/2 ton status

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    to clarify (or muddy) the ground clearance issue...

    Sitting in the driveway an IFS vehicle often has more center clearance than a straight axle of comparable tire size. BUT....when the weight of the vehicle comes down, i.e. a bump, it can be much much less, while the straight axle clearance will not change unless the "road" surface is really soft.

    To illistrate what I mean, my roommate had a 95 tahoe with 9 inches of lift and some 35in BGF's, while flying through the desert he udderly destroyed the IFS (hit the right side lower A-arm) when he hit a rock in the bottom of a rise. The rock was only about 5 inches out of the ground, but the suspension was completely bottomed out, which is to say nearly on the ground. One front wheel was pointing straight while one was pointing off towards the side of the road. This was not a problem for my straight axle.
     
  12. Stephen

    Stephen 1/2 ton status Moderator Vendor

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    " I think it will only be a matter of time before someone fabricates a IFS/IRS vehicle on the level the Sniper and such; then the arguments will REALLY begin."

    I know where one is sitting right now, it's looking good so far, 22" or so of clearance under the belly from front to rear, hidden driveshafts, tubular control arms with Hummer outers, centered diffs, swayaways at all 4 corners, etc. We'll see what happens. I think it will shake stuff up a bit.

    IFS can hold up pretty well if it's built really beefy. Durability isn't a problem given extra work put into the construction. On a production vehicle there's no doubt a solid axle holds up better to hard use. But with strong arms and pivots the IFS won't fall off the truck the first time you use it.

    Biggest problems I've seen are joints. It's hard to get a strong joint in a compact package that will operate through the range of travel. So you grenade half shafts. The Toy at TTC was a good example of that, they wasted a lot of IFS parts in places I've seen straight axle truck with Toy fronts work easily. The arms were strong enough, just not enough torque strength.

    4WD Corr trucks run really wide stances and center the diff and don't have radical wheel travel, all of which contribute to making 4wd IFS live. Plus there's a lot of custom machine work there.

    Torque at the tire is not to hard to measure just by looking at the parts that break. A 297 joint is good for about 4000 ft-lbs of torque, I've seen specs on the D60 joint that indicate about 10K ft-lb to break them. So we generally run somewhere in that range. Obviously the tires don't hook up enough to transmit all the engine torque because at a 100:1 gear ratio you would only need about 90 ft-lbs from the motor to break both front axle shafts. Most of our motors will do 3 times that amount but the front shafts don't simultaneously grenade that often. I've done it once but only once.

    Making the world better, one truck at a time.
    SW-ORD
    <a target="_blank" href=http://www.offroaddesign.com>www.offroaddesign.com</a>
     
  13. LKJR

    LKJR 1/2 ton status

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    Thanks guys........

    Like em big and topless
    You call THAT...a 4x4....LMAO?
     
  14. 84_Chevy_K10

    84_Chevy_K10 Banned

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    I definitely see your point, but I don't see that happening for a while. It's just too easy and cheap to bolt in a Dana 60 front axle and be done with breakage. Even in all your insane things you've done, you've only managed to break one shaft.

    Tim
    '84 Chevy K10, lifted, loud, fast, and 3/4 ton axles
     
  15. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    Stephen,

    ______________________________________________________________________

    "...the front shafts don't simultaneously grenade that often. I've done it once
    but only once."

    ______________________________________________________________________


    and I'll bet THAT was loud!!!!! [​IMG]




    -Greg72

    '72 K5 Blazer - 427BB/TH350/NP205/6" Lift/35x12.50's
    <font color=blue>See it here: </font color=blue><a target="_blank" href=http://coloradok5.com/gallery/albun38>http://coloradok5.com/gallery/albun38</a>
     
  16. Ryeguy

    Ryeguy 1/2 ton status

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    Just about everyone around here with a D60 front has broken at least one part on it. That's why I didn't go that route.

    Geby's CJ (if you can call it that) is running Gama Goat diff's. Magnesium center sections mounted in a custom cage with custom A-arms. 4 wheel steer. Inboard disk brakes (Wilwood). Modified spindle assemblies for the different rim pattern. He runs something like 16 or 18 inch travel racing shocks. Air over hydraulic suspension, totally customizable suspension height and rate. Caddy 500. Very impressive. Last time I talked to him, he was making noises about building another one for himself. The truck is definitely in a class by itself. If it had lockers (he's working on it), it would be competitive against things like the Sniper in the rocks. As it is, trucks like the Sniper won't hold a candle to it in its element (snow). Don't think he's ever broke any axle component. And he plays hard with it.

    But...it wasn't a cheap truck for him to build. I almost followed his lead, but went Mog axles instead. Now, I have far more clearance, but a taller truck without an adjustable suspension. And arguably stronger parts. And not as fat (his track width is very wide).

    --Rob
     
  17. Stephen

    Stephen 1/2 ton status Moderator Vendor

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    I bet if he left his line lock on it would break.......:-)

    Actually the simultaneous breakage on the front wasn't ujoints for me it was fusible clutchrings. I'm not sure if it was exactly the same time but it was all on the same bounce. Lots of other noises were happening too, motor noise, flying rocks noise, bumper hitting rocks noise, etc. I took it easier after that though.

    Making the world better, one truck at a time.
    SW-ORD
    <a target="_blank" href=http://www.offroaddesign.com>www.offroaddesign.com</a>
     
  18. Ryeguy

    Ryeguy 1/2 ton status

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    *grin*

    Breakage...

    D60's: seen stubs, front inners, rear shafts, and hubs blow up on different occasions. Usually the driver was doing something IMHO stupid, but then again, nobody has accused me of being sane either. :)

    Geby doesn't have a line lock. He's got controls to adjust the hydraulic and air levels in his suspension rams. And steering F&amp;R. (Rear is hydraulic and can lock it for the steet). Geby has broken parts - tie rod ends, etc. And flipped his CJ on occasions (usually endoing it, I'm told). And he has seen the axles fail (when a guy who bought his first Gama-Goat creation jumped it and landed into rocks). He himself hasn't had any failures, though.

    *Everything* breaks.

    --Rob
     
  19. Stephen

    Stephen 1/2 ton status Moderator Vendor

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    The reason for the line lock comment was my only D60 breakage so far was from accidentally leaving my front brake lock on then gassing it with full right steering. The ujoint moved on to greener pastures!

    The simultaneous break was with the 10 bolt and 37's on the Rockpile.

    I guess the moral of the story here is IFS/IRS can work very well, it just takes some major fab work and uncommon parts to make it happen.

    Making the world better, one truck at a time.
    SW-ORD
    <a target="_blank" href=http://www.offroaddesign.com>www.offroaddesign.com</a>
     
  20. 84_Chevy_K10

    84_Chevy_K10 Banned

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    "IFS/IRS can work very well, it just takes some major fab work and uncommon parts to make it happen. "

    You forgot money. Lots of money. Probably twice as much as a solid axle setup.

    It might end up working better though.

    Tim
    '84 Chevy K10, lifted, loud, fast, and 3/4 ton axles
     

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