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| Re: [GMCnet] Torque Steer??? [message #333326 is a reply to message #333323] |
Sun, 10 June 2018 22:10   |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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I guess you could describe torque steer that way. "The coach jerks to the left on hard acceleration", is kind of harsh. I find myself having to correct the steering on acceleration, when it pulls slightly to the left, but it is not really a jerking type of action. My coach steers somewhat differently due to the limited slip diff, and possibly because of the different offset front wheels (Dodge) I run on the front, but I think the torque steer is minimal.
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
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| Re: [GMCnet] Torque Steer??? [message #333335 is a reply to message #333323] |
Mon, 11 June 2018 08:33 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Senior Member |
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On a perfect coach it will be pulled to the side that has traction. If you have a loose front end or have changed the steering axis by adding wheel spacers that could upset things further.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: [GMCnet] Torque Steer??? [message #333338 is a reply to message #333335] |
Mon, 11 June 2018 08:45 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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John,
I believe that is because the spacers move the point that the steering axis intersects the center of the tire contact patch.
On the OEM steering the steering axis intersects the center of the tire contact patch, adding 4 inch spacers moves it 4 inches
outboard.
NOTE: the numbers above are a SWAG; I did not calculate it. See this drawing:
http://www.gmcmhphotos.com/photos/aa-miscellaneous-photos/p56759-steering-axis.html
Regards,
Rob M.
The Pedantic Mechanic
Sydney, Australia
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426
USA '77 Kingsley - TZE 267V100808
-----Original Message-----
From: Gmclist [mailto:gmclist-bounces@list.gmcnet.org] On Behalf Of John R. Lebetski
Sent: Monday, June 11, 2018 8:34 AM
To: gmclist@list.gmcnet.org
Subject: Re: [GMCnet] Torque Steer???
On a perfect coach it will be pulled to the side that has traction. If you have a loose front end or have changed the steering axis
by adding wheel spacers that could upset things further.
--
John Lebetski
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: [GMCnet] Torque Steer??? [message #333345 is a reply to message #333323] |
Mon, 11 June 2018 10:37 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Senior Member |
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Yes Rob that is what I am saying. What people don't understand is changing the diameter (or radius or circumference how ever you want to measure) also changes the steering axis. Because where the imaginary line intersects the pavement has now changed. This is more a problem with the "dubs" crowd than here but should be understood in concept. I can be compensated somewhat by changing wheel offset, but now you have changed bearing loading. No free lunch. The engineering behind this was truely a systems approach and changing wheel tire combos changes that.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: [GMCnet] Torque Steer??? [message #333349 is a reply to message #333323] |
Mon, 11 June 2018 13:53 |
bwevers
Messages: 597
Registered: October 2010
Location: San Jose
Karma: 5
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Senior Member |
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Yes, it seems to me that Ackerman for a GMC should
compensate for shorter turning circle of the inner wheels
compared to the outer wheels.
Bill Wevers GMC49ers, GMC Western States
1975 Glenbrook - Manny Powerdrive, OneTon
455 F Block, G heads
San Jose
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| Re: [GMCnet] Torque Steer??? [message #333351 is a reply to message #333347] |
Mon, 11 June 2018 13:55 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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Ackerman effect is the difference of angle between the inside wheel and the
outside wheel. Two different radius angles. And when you turn right vs turn
left, the effect has to be opposite.
Then, throw in independent vs straight front axles, equal vs different
length "A" arms, and about a million other factors, and you get a feel for
what the GMC engineers had to contend with, not considering corporate
stupidity and bean counters. But, the Miller Brothers made front drives
that worked, so did E.L. Cord.
Jim Hupy
On Mon, Jun 11, 2018, 11:42 AM David H. Jarvis wrote:
> Are front wheel drive vehicles affected by "Ackerman"?
>
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