How much caster is too much?

Brakes, Steering & Suspension

  1. Paul_G

    Paul_G Well-Known Member

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    As much as you can get is what I have read. I bought this Tenhulzen alignment system. It is a couple of plates with some stand offs to touch the wheel rim, not the tire, and it comes with a digital angle meter. I have aligned my 72 Charger before using an angle meter app on my phone with some straight edge steel. The Tenhulzen is much easier to use, and a little more accurate. https://www.wheelalignmenttools.com/product/2-wheel-alignment-system/

    On the right side there is plenty of adjustment. I have the caster at +4.8° and the Camber at -0.5°
    On the left adjustment is limited. The best I can get is caster +3 and the camber at -0.5. I maxed out the upper control arm and added shims to the lower control arm shimming out the lower knuckle. With caster maxed out now I get closer to the other side, +5.0 caster, with -1.95 camber. I know, camber way out of spec.

    No way can I get the same caster on the left side as I get on the right and still have -0.5 camber. I have a pair off off set upper control arm bushings coming for the left side.

    I set toe to 1/8" toe in and drove the car like this last night, with that much caster it drove great. No wander, precise steering and easy centering after a turn.

    Back to the question, how much caster is too much?
     
  2. Photon440

    Photon440 FBBO Gold Member FBBO Gold Member

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    Usually the only real drawback to extreme castor is that it reduces the contact patch of the tire in cornering. I doubt that our cars will allow anywhere near that amount to worry about. Sometimes you can get by with narrower bolts to increase castor, that might help the left side.
     
  3. dvw

    dvw Well-Known Member

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    Adding caster lays the tire over when it’s turned, like adding negative camber but in turns only. Think about it at 22.5* camber and caster are exactly the same. An unforeseen change in the outer tie rod is lowered. This will change bump steer. It may get better, may get worse. Just something to think about. Also remember chassis rake plays a part. For every degree of rake you loose a degree of caster. Generally speaking 2-6 degrees will be in the ball park. I’ve done thousands of alignments. With B body’s seldom do you get more than 3* with stock parts.
    Doug
     
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    • Darter6

      Darter6 FBBO Gold Member FBBO Gold Member

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      Rule of thumb is set your left side (yours has the least adjustment) to get the best camber/caster you can.
      Now the right side with more adjustment,match the specs to the left side. Mopars are notorious for this.
      As dvw stated 2-6* positive is the ball park you want to be in.Anything on the positive caster side even as little as 1* is ok as long as you match it to the other side.OR as close to it you can.
      Question, is the car mostly street driven ? I can get into stuff such as road crown and how to compensate for it.
      But that may mess with your head even more.
       
    • Paul_G

      Paul_G Well-Known Member

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      If I can get the left side closer to +4° caster with -.5° camber with the offset bushings that would not be too much. The right side can come back a little to match the left. That is what I was wondering.
       
    • Paul_G

      Paul_G Well-Known Member

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      I have done a lot of reading on alignment. If I have it right, the car will pull to the side with the least amount of caster. So we would want the left side to be a couple tenths less caster then the right side to allow for crown of the road.
       
    • Darter6

      Darter6 FBBO Gold Member FBBO Gold Member

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      Between -1/4* to max -1* of your right side setting.
      Back in the day some shops used camber to make up for road crown.
      Such as left side camber +1/2* right side 0 or close to it.
      Now remember factory specs on our old cars before radial tires were way higher + or - giving a range 1*
      Camber with new era tires tend to be 0 to - 1* .
      You may want to set as little as possible for road crown with the type/size tire you will be running.If at all.
      My old 65 specs are left +1/4* to +3/4* Caster manual steering 0 to -1* power steering +1/4* to +1 1/4*
      Today we don't even think or care to set the caster at anything negative.
      Even though alignment sounds hard to understand there really isn't much to it.
       
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      • Ron H

        Ron H FBBO Gold Member FBBO Gold Member

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        Reading the posts, I posted a thread about my Firm-Feel II install on my '63 Plymouth. What's happened is the left end rod has rubbed against the torsion bar (photo) shearing off the grease fitting and more (how I discovered the ill) and the cross link playing violin on the left TTI header (rebuilt poly). No demons detected on right side. My notes are somewhere I can't find; but recall the alignment was set pretty off OEM to gain a nice wander-less steer, have 15" radials and SSBC front disks. I've received several interesting posts on possible fixes; but I wonder if the alignment may have caused or contributed to this? Here I'm trying to recollect my notes that indicated the extent of modified alignment couldn't or shouldn't be done without some OEM parts changeout? The front is t-bar lowered around 1.75" over stock. The brake conversion didn't call for any parts change out...all bolt on. It's been some 2,000 miles on the car since all this was done. Motor mounts were replaced with the build and appear fine. I'm taking it to a shop next week (weather permitting around here) to get it back up on a lift to try to look further at what's what. Anyway, wondering about this...in case you experts have thoughts. Thanks.

        Header clearance 2 pic.jpg
         
      • dvw

        dvw Well-Known Member

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        Accounting for road crown depends on the road. Now a days the left lane is crowned the opposite direction.
        Doug
         
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        • Cranky

          Cranky Banned Staff Member FBBO Gold Member

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          I gotta come back and read all of this but what I usually did was trial and error! A lowered car with very little rake, lots of caster and camber worked well. Another thing I liked to do is use a lighter spring and a bigger sway bar so the car would ride better going straight but still corner well....
           
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          • 1 Wild R/T

            1 Wild R/T Well-Known Member

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            Back in the 80's Mercedes was running almost 20 degrees..... When the car was parked with the steering cranked to full lock it looked like there was something broken cause the wheel laid over so severely...
             
            Last edited: Nov 21, 2020
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            • Darter6

              Darter6 FBBO Gold Member FBBO Gold Member

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              Ron H, Have them look at the steering box mounting. It may require shimming.
              Ever have the frame rail looked at ? It may be that the driver side may be higher causing the K frame to be off.
              Even so if all is correct you may have to shim the K frame to frame rail to correct your problem.
              As far as the header it may be a tube that was off in the jig.Even though you have TTI's (that's all I install) and new engine mounts you may have to shim that mount.Worst case is to tweak that tube a bit.I had to on one tube that was rubbing the T bar on the driver side of my 65. Just shootin' in the dark with thoughts.
               
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