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Suspension/Sway Bar help, please

Discussion in 'The Hokey Ass Message Board' started by 35PontiacCoupe, Apr 5, 2009.

  1. 35PontiacCoupe
    Joined: Jun 7, 2008
    Posts: 232

    35PontiacCoupe
    Member
    from COS

    I'm looking into putting sway bars on my car, but I'm wondering why is it that rodders seem to push rear sway bars so much? I know most production cars usually run just the front, or have a much smaller one in the rear. Why do so many people say that rear sway bars are so much more important than fronts?

    I have a MII IFS front and parallel leafs in the rear if that makes a difference...
     
  2. phat rat
    Joined: Mar 18, 2001
    Posts: 4,482

    phat rat
    Member

    You can run a front sway bar only but you don't run a rear sway bar only. Heavier bar is in front.
     
  3. 35PontiacCoupe
    Joined: Jun 7, 2008
    Posts: 232

    35PontiacCoupe
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    from COS

    I've seen several people say rear only.. Including fatman which is who made my ifs
     
  4. 35PontiacCoupe
    Joined: Jun 7, 2008
    Posts: 232

    35PontiacCoupe
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    from COS


  5. Pontiac35
    Joined: Aug 27, 2005
    Posts: 52

    Pontiac35
    Member
    from Wisconsin

    I put the front one in first, came from Chassis Engineering and was the one Fat man mentions in his instruction sheet. I ran with just the front for a few years and then finally put a rear one in. CE# SB-1037R. a world of difference, now because I am changing from a GM rear end to a 9" I hope the darn thing will fit. How have you been?
     
  6. 35PontiacCoupe
    Joined: Jun 7, 2008
    Posts: 232

    35PontiacCoupe
    Member
    from COS

    Obviously I didn't build it to be a rally car, and I'm not punching it through corners. I know the reasoning behind sway bars and why they work, I just don't understand why some people push the rear as being so important... I guess I'll go ahead and just do the front and see how that goes then think about a rear later on down the road if it gets squirrely on me.

    Pont35- are you gonna be down here for any cruises or shows this year? We need to meet up and check out our cars! Do you notice a difference in anything besides pushing it into corners? Or is it that it's more able to hook coming out of a corner?
     
  7. phat rat
    Joined: Mar 18, 2001
    Posts: 4,482

    phat rat
    Member

    Some build a car to look and handle good and some build only for looks. Can't think of any other way to explain it as you seem to have your mind made up that they aren't necessary
     
  8. 35PontiacCoupe
    Joined: Jun 7, 2008
    Posts: 232

    35PontiacCoupe
    Member
    from COS

    No, I'm not saying that I don't want my car to handle good, I'm just saying that I don't understand why some say that rear is more important than front or that it should be thicker than the front. It just seems to be out of the norm compared to what OEM's do. That's all. I'm open and willing to learn!

    I see that your car stops level and straight, but how much of that is the rear bar? What purpose does the rear bar serve in that scenario? Would the rear have kicked out otherwise?
     
  9. phat rat
    Joined: Mar 18, 2001
    Posts: 4,482

    phat rat
    Member

    I have to agree on not understanding why someone would say heavy on the rear or that the rear was most important. I've never seen an application where the rear was heavier or rear bar only. As far as the rear kicking out that one time I don't know. But as you saw it was pretty darn level. My wife about needed to change her pants on a trip one time. We were running down the xway at around 70-75 when a semi just ahead hit and kicked up a large piece of 2 X 4 it was headed right at us about windshield level but I was able to crank the wheel over and back and miss it. What really got her was the concrete barrier we were running alongside of at the time. It all happened so fast that it was instinctive reaction only. Had I tried that with a car that didn't handle as good as my cpe who knows what could have happened. Just another reason why I want my car to handle the very best it can
     
  10. 35PontiacCoupe
    Joined: Jun 7, 2008
    Posts: 232

    35PontiacCoupe
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    from COS

    I can definitely understand wanting it to handle the best possible. I would have wanted to avoid that 2x4 as well!

    As for the rear only bar, fatman says in their instructions and catalogs that they don't believe in fronts for early rods. Ok, I actually just went and looked at fatmans site, which I haven't done in a long time, and it now explains it better. Here's what it says:

    The general rule is to add a sway bar to the end that is misbehaving, so an understeering car would want a front sway bar. Since most pre-’48 cars have such favorable front to rear weight distribution, they seldom suffer from that problem. In fact, their high rear center of gravity generally causes oversteer, so rear sway bars are recommended. We add a front bar with larger engines, top heavy cars like panels and woodies, and the ’49 and later cars. Those later cars have the engines much further forward in the chassis and bring us back to nose heavy induced understeer.

    Any thoughts on that? Or is that pretty much the logic behind it that I missed out on? :cool:
     
    Last edited: Apr 5, 2009
  11. 40streetrod
    Joined: Nov 11, 2007
    Posts: 477

    40streetrod
    Member
    from nj

    I have a Fatman's MII IFS front with a Chassis Engineering sway bar and Posies parallel leafs in the rear with no sway bar, in a 40 ford pick-up and it handles like a slot car. the only one who had a problem with it was NSRA safety team but they still gave me the safety pin and that was many years and miles ago, with NO problems
     
  12. 35PontiacCoupe
    Joined: Jun 7, 2008
    Posts: 232

    35PontiacCoupe
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    from COS

    I have the same setup, fatman front and posies rear leafs. Why did the safety team have a problem with the setup? What do those guys usually look for? I haven't had the chance to see them in action...
     
  13. phat rat
    Joined: Mar 18, 2001
    Posts: 4,482

    phat rat
    Member

    Well my cpe is 52-48 front to rear if I remember correctly. But it is a big motored car, 454. In regards to their statement that you start with a rear bar. I would question why the factory put front sway bars on all and rear bars only on the performance version of some models. Even some of the 40's cars had a front bar stock. I've had newer Suburbans that had a rear bar added at the factory when all came with a front bar. On one I added it myself and it made a world of difference in the trucks handling

    That was apparently a new or uninformed safety team. I'm sure that nowhere in the book is there anything about the need for a rear sway bar or for that matter a front bar
     
  14. 35PontiacCoupe
    Joined: Jun 7, 2008
    Posts: 232

    35PontiacCoupe
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    from COS

    Right, my buddy's explorer, which certainly would fall under the "topheavy" category has a huge bar up front and a little tiny guy in the back...

    Phat- do you think I should just go with the rear bar, or start with the front and see how she does?
     
  15. 40streetrod
    Joined: Nov 11, 2007
    Posts: 477

    40streetrod
    Member
    from nj

    well it went like this

    something about the bolts going thru the sway bar bushings / lower a-frame breaking and the sway bar hitting the brake line. but after the bullshit I found out that I was not the only one they told that too. talked to a vender and they said " are they starting that bullshit again" believe me when I say the truck is safe, I have no problem driving it 2700 miles in 9 days or leave NJ on fri nite coffee run to louisville nats and be back in NJ sunday morning @ 10 am.
    but on another note, I don't get along with NSRA very well either. once drove all nite to louisvlle stopped and got my paper work @ papa's john, then drove thru the gate just to be yelled at because my sticker wasn't on the windshield right. (Chopped truck -I take it off when I leave the fair grounds) NSRA didn't like that, but hey I need to see out of my window. then rent a cop told me he was going to rip up my paper work. well after that the shit hit the fan, people with video camera's had a field day with me jumping up and down and a little out of control. and then after we all cooled down the rent a cop just had to say -" he's from NJ and they all have an attitude"
    well needless to say round 2 was underway
    sorry to hijack the thread
    anybody here got the video?
     
  16. phat rat
    Joined: Mar 18, 2001
    Posts: 4,482

    phat rat
    Member


    I don't have personal experience with M11. Regular suspension no question I'd do front first. I've never driven mine without frt and rear so I have no idea what difference it would make on this car with one bar only. But as I said before I have driven a vehicle that had only front bar an then added rear bar for a real improvement. In my past experience your buddies Explorer is the normal application of bar size
     
  17. 40streetrod
    Joined: Nov 11, 2007
    Posts: 477

    40streetrod
    Member
    from nj

    let me ask you this,
    how come years ago new cars came with front sway bars and no rear sway bars?
    did you ever see the factory put only a rear bar on with out the front?
    always the front or both, never the rear only
    yes - no?
     
  18. 35PontiacCoupe
    Joined: Jun 7, 2008
    Posts: 232

    35PontiacCoupe
    Member
    from COS

    Yes, that's pretty much what I've always seen and known- front only or front and rear. That's why I was all confused at why people have been saying to start with the rear or make the rear thicker... Common sense says that's silly! We'll see, i guess!
     
  19. WOW is there some mis information here. First a couple of definitions;
    Understeer - The front tires don't want to turn the car, but rather have a high slip angle and want to continue straight. Racers call this Push or Tight.
    Oversteer - The rear tires want to break loose, especially on corner exit. Think of the rear end trying to pass the front end. Or watch Drifting. Racers call this Loose.

    Now how do Anti Roll Bar (or sway bars) affect this? In general anti roll bars do as the name suggest, control roll from the body during cornering. In the simplest of terms, which are appropriate for Street Rods, adding more front bar will create more understeer. Because of weight biases and suspension designs it is very common for a car with IFS to have a small front bar and no rear and have reasonable body roll and fairly neutral handling. Adding more front bar will flatten the car and add some understeer tendencies. This is safer on street cars, If you go into a corner a little too fast the car will push, not wanting to turn and you will let off, going about your merry way. If you add a bunch of front bar diameter or the car has too much understeer, then you start adding rear bar to continue to flatten the roll while getting back to neutral handling.
    In MOST cases a car with a rear bar only will have heavy oversteer and you will head into a corner, the rear will start to break loose and when your natural instinct to let off happens, the rear will completely come around. Ask any early Porsche 911 owner. Or as the NASCAR boys like to say - you will hit the wall with the rear end.
    In the case of the OP's Pontiac I would add a medium sized front bar, drive it a bunch and then decide if it needs a rear bar or not.
     
  20. tltony
    Joined: Jan 11, 2009
    Posts: 294

    tltony
    Member
    from El Cajon

    As a sway bar does it's job, it is actually lifting the inside tire off the pavement an a turn, reducing grip. The lightest sway bars/s you can get away with to control body roll, the better, if you really want to corner well. And yes, a rear bar will make the car "loose" increasing oversteer. As hotroddin said, not the safest handling characteristics for a street car. Almost all OEM's come from the factory with factory induced understeer, meaning the car will push, as delivered.
     
    Last edited: Apr 5, 2009
  21. 40streetrod
    Joined: Nov 11, 2007
    Posts: 477

    40streetrod
    Member
    from nj

    ok front first.
    now both Chassis Engineering and Posies rear parallel spring kits have the spings mounted not parallel to one another. let's just use the measurement 48 in wide(side to side) the front eye of the spring is say 47 in wide and the back eye on the spring is at 48. so now with the springs offset does this help to act like a sway bar?
     
  22. NO, not at all.
     
  23. 40streetrod
    Joined: Nov 11, 2007
    Posts: 477

    40streetrod
    Member
    from nj

    doesn't matter that there not parallel?
     
  24. tltony
    Joined: Jan 11, 2009
    Posts: 294

    tltony
    Member
    from El Cajon

    No on the non-parallel leaf springs. However, on the front (or rear) if you have split wishbones or hair pins, they will cause the axle to act as a sway bar
     
  25. I don't know that it matters but I also don't think it serves a purpose either. It does make it harder to mount the rear end to the leafs because of conflicting angles and it is harder for the U Bolts to hold the leafs tight to the rear end.
     
  26. Not sure I understand your answer here. How would you have slightly non parallel leaf springs (as proposed by the OP) with a split wishbone or hairpins? I have never seen parallel (or slightly angles) leafs and wishbones on the same end of the car. :confused:
     
  27. 35PontiacCoupe
    Joined: Jun 7, 2008
    Posts: 232

    35PontiacCoupe
    Member
    from COS

    Hmm I guess I didn't check the widths of the springs. I'll have to look into that to see If they're truely parallel..
     
    Last edited: Apr 6, 2009
  28. tltony
    Joined: Jan 11, 2009
    Posts: 294

    tltony
    Member
    from El Cajon

    I was referring to a car with a cross spring or coil overs and split bones or hair pins, not paralell leafs. It was just an FYI statement as to why some of the builders might be saying that a front (or rear) swaybar is not required.
     
  29. Ahhh ;)
     

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