Question for 142 Guy about IPD Rear Sway Mounts
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    1. #1
      Junior Member
      Join Date
      Jul 2014
      Location
      St. Louis, MO
      Posts
      83

      Question for 142 Guy about IPD Rear Sway Mounts

      142 Guy,
      In your build thread, you have a photo on the 1st page that shows your rear sway bar mounts welded to the floor.
      Do you know what gauge steel that you used for this?
      The reason I ask is that I bought my sway bars used and they didn't come with the original IPD plates. The guy threw a couple of pieces of 3/16" - 1/4" steel plate in the box when he shipped them.
      Now, I'm not much of a welder, but I can get by. But, trying to emulate what you have done, with plates as thick as what I have, that is a recipe for some destroyed floor pans!
      Let me know when you have a chance.
      Thanks,
      Steve

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    3. #2
      Member
      Join Date
      May 2013
      Location
      Saskatchewan, Canada
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      2,178
      The reenforcement plates are definitely not 1/4" plate. From memory I would estimate 1/8" or perhaps 3/32". Probably about 6" square. You don't need to run a complete weld seam around the plates when you do the installation. Four good tacks should suffice just to stop the plate from moving around. In a previous century IPD initially offered the rear sway bars without the reenforcements and they had some cases of the mounts pulling through the floor, hence the reenforcements. In a pinch, really, really large diameter galvanized flat washers might do just fine.

      You may not want to hear this; but, I am considering ditching my IPD bars. Anti roll bars only reduce body roll resulting from the compression of the springs on the outside wheels caused by weight transfer going around a corner. Suspension systems are set up to have camber change as the suspension moves. The sway bar reduces the negative camber change on compression of the outside wheels; but, also reduces the positive camber change on the inside wheel during unweighting. As a result, increasing front roll stiffness with an anti roll bar generally reduces front grip and increases under steer.

      Rear solid axle suspension systems like on the 140 articulate when going around corners because of the intentional flex in the axle mounting points. This creates desirable negative camber change on the outside wheel and positive camber change on the inside wheel. Putting an anti roll bar on the rear has the similar effect of reducing the camber change on both the inside and outside rear wheels. The loss of camber change does not help traction which is why increasing rear roll stiffness with a rear anti sway bar tends to increase over steer. In the mid '70s, IPD used to sell the front and rear sway bars separately and they sold 7/8" and 1" front bars with the recommendation that the larger bar should be matched with a rear bar (presumably to correct the significant increase in under steer with the larger bar and rebalance the handling).

      If you install stiffer springs (particularly the Lesjofors) on a 140 the higher spring rate is going to reduce the roll caused by compression of the suspension caused by weight transfer. If the springs are shorter that is also going to reduce the perception of body roll. If you are doing a spring replacement with stiffer and shorter springs, I always recommend that you do the spring change first and try out the car. If you think you need more roll stiffness then you can try the larger anti roll bars. The anti roll bars will definitely reduce the body roll associated with suspension compression and some people really like that. However, the loss of camber change does not necessarily increase the total grip when cornering. The larger anti roll bars will also introduce noise and harshness over bumps and pot holes where the left and right wheels encounter different deflections. That said, if you are going auto crossing additional rear roll stiffness with a small front roll bar might be a hot ticket if you are looking to introduce more over steer to help you get around some tight corners.

      I did the IPD bar install in part because the OEM front bar went missing when the car was disassembled (stuff goes missing when projects get extended over years). If you do the anti roll bar replacement and you still have your original front bar and mounting hardware, I might be interested in acquiring it from you if you don't want to keep it. My anti roll bar delete experiment is pending finding a replacement OEM front bar. I have started looking locally for a front replacement bar; but, salvage 140s are in pretty short supply around here.
      Last edited by 142 Guy; 04-23-2019 at 01:13 PM.
      A 142 of course. What do you expect? I'm the 142 guy. / 1971 142 E 102 color

    4. #3
      Junior Member
      Join Date
      Jul 2014
      Location
      St. Louis, MO
      Posts
      83
      Thanks for responding.
      I honestly haven't decided if I am installing it yet, or not. I have an IPD front bar installed, but don't know if I saved the old one when I moved from Everett, WA back to St. Louis.
      I had also read where the rear bar is not really needed. I figured while I have the car apart, I could weld in some plates. That way it would be ready if I were to install the rear bar.
      Thanks,
      Steve

    5. #4
      Junior Member
      Join Date
      Apr 2016
      Posts
      305
      Steve;

      I installed front and rear bars on my 144, and combined with gas shocks, original springs, and 70 series rubber, absolutely loved the night-and-day improvement in roadholding. This was early on, before I believe ipd included reinforcing plates for the back (or maybe I just didn't install them initially, I don't recall...), but I had so much fun tossing the car around with the improved handling, that it wasn't very long before I ripped out a big hole around the mounts at the rear floor (which in the area is just a single thickness of floor, and they ripped out in a downwards direction, looking like someone shot a 50cal bullet through there...)...then, need and reason for reinforcement became quite clear...after repairing and reflattening the entrance wound, I used a 4" X 4" plate of 1/8" or so...it needed to be formed a bit to accommodate fit into the non-flat location, but once contoured, I simply held it at the corners with bolts and big washers...the point is to spread the forces and bolts will do that as well as welding...I enjoyed the improved handling for a long time after that and the reinforcements never showed any signs of movement or fatigue...

      I have seen a lot of discussion on single bigger front ASB vs adding one on the back also...after doing some research, I installed front and back ipd bars on the 140, and have the same on 122 and 1800...always with OE springs but gas shocks and 70 series rubber...I love and prefer and recommend this combination as it gives a virtually unchanged ride behavior on the highway going straight, but I found it to be a massive improvement (in confidence and fun!) in the twisties (or when an instant lane-change is called for on the highway!).

      Cheers

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