| 1 Ton Front End Measurement Needed [message #255894] |
Sat, 19 July 2014 18:40  |
djeffers
Messages: 219
Registered: June 2004
Karma: 2
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I need a simple measurement off a 1 ton front end. A tape measure quality measurement will do.
Measure from the center of the driver's side A-arm front pivot out to the center of the tire with the tape perpendicular to the chassis.
A little eyeball calibration might be needed to get the tape perpendicular.
I have made some first approximation calculations for the relative loads our three different front ends input to the torsion bars: (1) OEM, (2) OEM + 2 inch wheel spacers and (3) the 1 ton front end with 3-1/2 inch spacers.
I measured our OEM front end with Alcoa wheels and Michelin tires and got ~16 inches.
The numbers I am using for the lever arms are: (1) 16 inches for OEM, (2) 18 inches for OEM +
2 inch spacers and (3) 19-1/2 inches for the 1 ton front end.
It is highly unlikely the 1 ton spacer mounting surface is the same distance from the a-arm pivot as OEM, so I would like a more accurate measurement.
All help and corrections appreciated.
Don & Susan Jeffers
78 Eleganza II
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| Re: 1 Ton Front End Measurement Needed [message #255912 is a reply to message #255901] |
Sat, 19 July 2014 22:00  |
djeffers
Messages: 219
Registered: June 2004
Karma: 2
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Senior Member |
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RF_Burns wrote on Sat, 19 July 2014 21:12OK, I'll bite. I just went out and measured my 1 ton JimK front end.
Drivers side 19.75"
Passenger side 20"
So my front wheels are not perfectly straight ahead, so I'm guessing split the difference at 19 7/8".
I have Eagle wheels with Toyo tires. I'm not sure if there is any difference in the offset between Eagles and Alcoa.
I can tell you the 1 ton is a softer ride (read: wider stance gives more mechanical advantage against the torsion bars)
I also have my front ride height set so the axles are level, which means my ride height is about 1" lower than the book at 12 1/8". The lower control arm also appears pretty much level too (eyeballed with the axle).
Thanks, Bruce.
I've used this dimension to calculate the effect of Peter Huber's torsion bars on three of our GMC front ends:
1. OEM
2. OEM with 2 inch spacers
3. Estimated 1 ton front end with 3-1/2 inch spacers
All with Alcoas.
I will add a fourth:
4. 1 ton with Eagles
I've also calculated the required diameter torsion bar to restore the 1 ton front end stiffness to OEM stiffness + 10%.
It was very good of you to measure both sides and average. Your 19-7/8" average is only +3/8" from my estimated 1 ton with Alcoas.
If anyone knows the difference in offset between the Eagles and the Alcoas, if any, I can use that dimension until I get an actual measurement for the 1 ton / Alcoas.
My first cut measurement was on the driver's side front only. I will refine that with both sides front and rear and average.
An error of 1/4" is a little more than 1% over the length of the lever arm; 1/8" is about 0.6%. The effect of variations or errors in these dimensions on the torsion bar calculations is linear, so careful tape measure dimensions are very useful.
I will post all the torsion bar numbers once I have more accurate dimensions.
I welcome any measurements. Tell me your front end set-up (OEM? 1 ton? Wheels? Offset if you know it? etc.)
Don & Susan Jeffers
78 Eleganza II
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