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914World.com _ 914World Garage _ Front Sway Bar Loads
Posted by: Matt Romanowski Aug 14 2023, 07:20 AM
I though people might find this interesting. I installed a strain gauge on a sway bar drop link and had some interesting results. It's pretty neat to see the loads that the drop link see on track.
The strain gauge on the drop link.
The forces on a whole lap on track.
Zoomed in to a corner.
Posted by: Racer Aug 14 2023, 07:45 AM
What track?
Posted by: Matt Romanowski Aug 14 2023, 09:22 AM
What track?
Club Motorsports in Tamworth, NH. I also have a 375 lb springs in the front and a custom sway bar, so I'm not sure how relevant the data is to other cars, but it gives a decent idea of the sort of load that is there. As a comparison, NASCAR cars can see close to 3,000 lbs!
Posted by: jim_hoyland Aug 14 2023, 10:30 AM
Wow ! Very cool; thanks for sharing.... 
What does the strain gauge read when the car is at rest?
Posted by: yeahmag Aug 14 2023, 11:10 AM
Assuming no sort of weird setup, the drop links should see no load at rest on level ground with the correct ballast in the car.
Posted by: Matt Romanowski Aug 14 2023, 12:45 PM
Wow ! Very cool; thanks for sharing....
What does the strain gauge read when the car is at rest?
It reads zero like pointed out. One interesting thing I learned is that you can not feel preload it the drop link heim joints. It can read 40 lbs and still feel free.
Posted by: jd74914 Aug 14 2023, 01:04 PM
It reads zero like pointed out. One interesting thing I learned is that you can not feel preload it the drop link heim joints. It can read 40 lbs and still feel free.
That's really interesting. Thanks for sharing!
What's your bar look like if you don't mind me asking? Nascar?
Posted by: gereed75 Aug 14 2023, 01:07 PM
Very cool and thanks. Timely and useful for me. I am redoing the sway bars on my Datsun race car and re-designing the rear bar using an adjustable blade that will require a new mount point at the trailing arm. Was wondering about the loads this mount point will see. This gives me a ball park data point.
I assume this is a front bar?? Is there a rear bar on the car?? Thanks again.
Posted by: Matt Romanowski Aug 14 2023, 03:05 PM
It reads zero like pointed out. One interesting thing I learned is that you can not feel preload it the drop link heim joints. It can read 40 lbs and still feel free.
That's really interesting. Thanks for sharing!
What's your bar look like if you don't mind me asking? Nascar?
It looks like a regular through body bar and uses the Tarrett ends, but it's a custom OD/ID, length, and uses monoballs to mount it instead of bushings.
NASCAR bars, or at least the ones I'm familiar with, are huge and something like 2.5 or 3" OD and probably .100" or more wall. They are really stiff.
Posted by: Matt Romanowski Aug 14 2023, 03:05 PM
Very cool and thanks. Timely and useful for me. I am redoing the sway bars on my Datsun race car and re-designing the rear bar using an adjustable blade that will require a new mount point at the trailing arm. Was wondering about the loads this mount point will see. This gives me a ball park data point.
I assume this is a front bar?? Is there a rear bar on the car?? Thanks again.
Yes, this is the front bar and I don't have a rear bar.
Posted by: windforfun Aug 14 2023, 03:43 PM
Fantastic work!!! Strain must be a big concern. I'd want to know in what part of the suspension is it worst. Is the noise on the plots from road vibration? Dumb question I suppose.
Posted by: Matt Romanowski Aug 15 2023, 05:28 AM
Fantastic work!!! Strain must be a big concern. I'd want to know in what part of the suspension is it worst. Is the noise on the plots from road vibration? Dumb question I suppose.
Probably. To be honest, I haven't zoomed in far enough to really check that part out.
Posted by: jd74914 Aug 15 2023, 08:30 AM
It reads zero like pointed out. One interesting thing I learned is that you can not feel preload it the drop link heim joints. It can read 40 lbs and still feel free.
That's really interesting. Thanks for sharing!
What's your bar look like if you don't mind me asking? Nascar?
It looks like a regular through body bar and uses the Tarrett ends, but it's a custom OD/ID, length, and uses monoballs to mount it instead of bushings.
NASCAR bars, or at least the ones I'm familiar with, are huge and something like 2.5 or 3" OD and probably .100" or more wall. They are really stiff.
Thanks for the details. I have a Nascar bar (rear) that's 1" OD (forget ID) and splined. Only reason I asked. Their front bars are absolutely massive. It's crazy.
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