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I-beam vs IFS - pros/cons

Discussion in 'The Hokey Ass Message Board' started by Texas Highlander Motorsports, Apr 28, 2010.

  1. I searched to no avail. I'd like the "experts" to chime in as to what the advantages/disadvantages are between I-beam steer axles and IFS (Mustang II, etc). My 47 Dodge truck is I-beam and I am trying to eliminate any and all options for when I actully get to start on it.

    I know, I know..I-beams are the "traditional, ie HAMB" way, but I want what will give me the best ride & handling for the $$ that I'll be sinking into the truck.

    Grif
     
  2. 49ratfink
    Joined: Feb 8, 2004
    Posts: 17,510

    49ratfink
    Member
    from California

    the only advantage of an I beam is in the cool factor. that cool factor diminishes as the fenders get fatter and the car/truck in question gets newer

    47 Dodge truck?? no brainer... IFS.
     
  3. loudpedal
    Joined: Mar 23, 2004
    Posts: 2,185

    loudpedal
    Member
    from SLC Utah

    Yep, IFS it. Don't worry about the cool factor of an I-beam with that one...
     
  4. I-beam suspensions are cheap to rebuild, but not easy to lower. Alignment is easy-- 99% of the time the only adjustment is toe-in, which you can even do at home.
     
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  5. Heo
    Joined: Jan 8, 2010
    Posts: 525

    Heo
    Member

    if you want it to ride like a TRUCK go ibeam
    if you want a nice ride go ifs
     
  6. GregF
    Joined: Sep 23, 2009
    Posts: 27

    GregF
    Member

    Another vote for IFS on this vehicle.
     
  7. Von Rigg Fink
    Joined: Jun 11, 2007
    Posts: 13,428

    Von Rigg Fink
    Member
    from Garage

    ima going to be old and cranky about this..
    I beam ..pro's..it looks right, because it is..:rolleyes::D
     
  8. 55 buick
    Joined: Sep 16, 2006
    Posts: 15

    55 buick
    Member

    on a 47 dodge IFS for sure,just like 49ratfink says
     
  9. 49ratfink
    Joined: Feb 8, 2004
    Posts: 17,510

    49ratfink
    Member
    from California

    someone should be along soon to spout the virtues of a Jag front suspension. they will be followed closely by another guy who for some reason thinks the stock axle and brakes are just fine, then the mouth breathers will show up to tell you pintos are junk, so the MII suspension is also.
     
  10. Von Rigg Fink
    Joined: Jun 11, 2007
    Posts: 13,428

    Von Rigg Fink
    Member
    from Garage



    hahaha he's already here:D
     
  11. Thanks for the inputs, but I'd like to get more than opinions. My question was to get tangible reasons for one or the other - not just style opinion (although those are appreciated as well).
     
  12. oldcarfan
    Joined: Jan 7, 2010
    Posts: 315

    oldcarfan
    BANNED
    from missouri



    ride in a truck with an ibeam and then ride in a truck with IFS.

    one knocks your fillings out and the other rides like your daily driver.

    like 49rat already said teh only reason to run an ibeam suspension is to look cool because your car doesnt have fenders. since you have a big ass fendered truck it truely is a no brainer.
     
  13. bobscogin
    Joined: Feb 8, 2007
    Posts: 1,674

    bobscogin
    Member

    One of the inescapable natural laws of hot rodding states that the desirability of a solid front axle is directly proportional to it's visibility.

    Bob
     
  14. Ford-Man
    Joined: Apr 6, 2009
    Posts: 288

    Ford-Man
    Member

    My '49 Ford has a straight axle, and honestly the ride is about as smooth as my Lightning. I plan to replace the stock springs that were de-arched with a fresh set and remove a few leaves until I can afford a drop axle...and I expect an improved ride quality with the newer leaf springs. If you plan to lower it, the straight axle costs more. Look up Sid Drapel's dropped axles and see what that would run vs. a set of coil springs for a MII. Mustang setups are slightly more adjustable that way. If you want pros and cons, here is my short list I made when I was milling the same idea

    Pros to straight axle:
    "Cool" factor
    easy to align
    few parts involved
    you already have the straight axle

    Cons:
    Can provide a stiff ride depending on how it is set up
    not as easy to adjust ride height...

    Must. II Pros:
    Parts are cheap and easy to find
    ride height is easily adjustable
    can be dialed in for better handling, or smooth driving
    everyone makes a kit for pretty much any application

    Cons:
    Not "old school"
    It takes a little work to change everything over
    More parts involved

    Just my .02
     
  15. Stu55
    Joined: Mar 30, 2009
    Posts: 82

    Stu55
    Member
    from Dallas Tx

    If you've ever driven an I beam suspension down a washboard road you'll know why IFS is much better. Forget the I beam unless you enjoy the cool factor and the crappy ride on crummy roads.
     
  16. That's what I was looking for...Thanks!!!
     
  17. KIRK!
    Joined: Feb 20, 2002
    Posts: 12,032

    KIRK!
    Member

    There's a reason cars don't have beam axles any more.

    There's a reason why guys without IFS are cool.

    Either way you lose.
     
  18. 392_hemi
    Joined: Jun 16, 2004
    Posts: 1,737

    392_hemi
    Member

    If you want to follow that logic, why not make it a unibody and front wheel drive while you're at it? Lots of vehicles still have I-beams.
     
  19. KIRK!
    Joined: Feb 20, 2002
    Posts: 12,032

    KIRK!
    Member

    Passenger cars and light trucks?
     
  20. Ned Ludd
    Joined: May 15, 2009
    Posts: 3,878

    Ned Ludd
    Member

    Yes, but it isn't the one it's generally believed to be.

    Thing is, we're not really comparing I-beam as such with IFS as such. The I-beam set-up in the Dodge truck was designed for toughness and ease of maintenance, not for ride, never mind handling. It rides hard because the spring base:track ratio (probably about 0.6:1) means you need a lot of spring stiffness to provide adequate roll stiffness. With IFS the SB:track ratio is necessarily 1:1, so you get the same roll stiffness with much softer springs.

    Every solid-axle set-up I've ever seen has a SB:track ratio of less than 1:1. That's not to say that it's impossible to devise a set-up with a SB:track ratio of 1:1. I think I've figured out how to get a straight axle to have a SB:track ratio of greater than 1:1, something that's not possible with an IFS without sacrificing some independence e.g. by using an anti-roll bar.

    The problem with anti-roll bars is that they're undamped. With a light bar you won't notice it; once you start wanting to add lots of roll stiffness you run out of shock absorber. And of course you can run an anti-roll bar on a softly-sprung I-beam: same problem.

    I believe the solid axle has unexplored potential. For starters there's nothing like it for controlling camber. You'll be told that independent systems are designed to gain negative camber in roll, but every IFS you're likely to encounter outside a road-race circuit is going to gain positive camber through most of its useful travel. On real vehicles on real roads, the I-beam is going to give you better camber. In fact, combined with low front roll stiffness it's going to give you such good camber that oversteer will be a problem!

    But exploring that unexplored potential isn't an off-the-shelf exercise. I think, in practice, you're probably going to be better off with IFS.
     
  21. Dick Dake
    Joined: Sep 14, 2006
    Posts: 788

    Dick Dake
    Member

    How much do you have to spend? How are your mechanical skills? Is there anything wrong with the current setup? How are you using the truck? Who is going to do the work if you are not? What other modifications are you going to make while you are at it?
     
  22. 49ratfink
    Joined: Feb 8, 2004
    Posts: 17,510

    49ratfink
    Member
    from California


    please explain the difference between a tangible reason and an opinion.


    if you can't see the benifits of IFS then we can't really help you.
     
  23. KIRK!
    Joined: Feb 20, 2002
    Posts: 12,032

    KIRK!
    Member

    All of that said, why wouldn't F1 guys use them? They use what is the best of the best. Serious question.
     
  24. Ned Ludd
    Joined: May 15, 2009
    Posts: 3,878

    Ned Ludd
    Member

    Because they're dealing with tiny suspension travel, and that allows them to set up for serious negative camber gain.
     
  25. metalshapes
    Joined: Nov 18, 2002
    Posts: 10,737

    metalshapes
    Tech Editor

    Lotus experimented with a version as late as the ( mid to late ) '60s, and Ferrari had a F1 test mule with a DeDion in the late '70s ( not a front I beam, I lnow, but geometry wise its also a beam...)


    What they use right now in F1 has very little travel at all, and I bet they are more concerned with unsprung weight and packaging, which would both be problems with a Beam type suspension.

    Unsprung weight will always be the worst drawback of a Beam.

    Geometry wise, I'm absolutely convinced that a Eccellent I Beam ( there are very few of those ) is superior to a badly designed IFS ( there are a lot of those )


    All that said...
    My Truck has IFS.

    For ease of installation, features ( power disks & steering ), good geometry ( Camaro clip, and Camaro's still win at the Oval Tracks ), and parts availabillity.
     
  26. Ford-Man
    Joined: Apr 6, 2009
    Posts: 288

    Ford-Man
    Member

    Ah....F1...not F-1...I am a dumbass! Ignore my oversight that follows!

    Serious answer...I rather enjoy a straight axle. (If I read your post correct, you want to know why F-1 guys use IFS?:confused:) It has been my experiance that people shooting for a show truck/car have a harder time bagging a straight axle, whereas a MII has a bolt on kit. Hell, some places already have the bags installed, all you do is run lines and call it a day.

    My F-1 gets 4 wheel drum brakes :eek:...as opposed to the discs that are becoming more common too. It all comes down to what you want.

    I guess it depends on how much of your vehicle you want "old" and how much you want to update. There is nothing wrong either way. I just personally choose to have an old, outdated suspension and braking system.:D At the end of the day, build it how you want, and as someone said already...ride or drive something with a straight axle and something old with IFS. Get a feel for both and make your mind up based on feel.
     
  27. Ned Ludd
    Joined: May 15, 2009
    Posts: 3,878

    Ned Ludd
    Member

    Very well stated!

    And a lot of IFSes in production have a lot of surplus unsprung mass. The typical McPherson strut IFS out there has no less unsprung mass than a half-decent solid axle.
     
  28. KIRK!
    Joined: Feb 20, 2002
    Posts: 12,032

    KIRK!
    Member

    Cool info. Thanks guys!!!
     
  29. Not what the OP wanted I'm sure. Radial tires made the beam obsolete.

    Hard carcass bias ply tires don't need camber loading, same reason why IFS suspensions up to the late 70s had little camber gain designed into them. On the flip side, radial tires are soft carcass and really benefit well from positive gain camber profiles.

    The following is for the OP:

    Here in the real world it will take nearly the same dollar and labor investment to do either an IFS or properly set up beam axle. What the whole thing boils down to is what you expect out of your ride.

    A proper set of shocks and well matched springs on a beam will ride very nice. Handling can be dialed in with an anti-roll bar and some thoughtful suspension tuning. Brakes are always adaptable to what ever your needs are, same goes for steering. The biggest disadvantage I see is ride height, if you want it low you will loose suspension travel and have to deal with a harsher ride.

    IFS conversions come in all sizes, I highly suggest you research before you make a decision. Consider track width, weight of the vehicle, wheel sizes, aftermarket support, spring choices and ease of installation.
     
  30. Diavolo
    Joined: Apr 1, 2009
    Posts: 807

    Diavolo
    Member

    I vote I-beam.

    Assuming it's already in there, you are going with a pretty much stock build and just want good handling and driveability. Also, assuming you don't plan on canyon carving or street racing with corvettes.

    It's a truck. Everything is already under your frame, I guess and it's all designed to work together. I'd rather rebuild the front, maybe take a leaf or get the springs worked, get some really good shocks and call it a day. Then I could spend even more money on loud pedal goodies.
     

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