C7 alignment sticky???
#21
E-Ray, 3LZ, ZER, LIFT
Member Since: Sep 2007
Location: NE South Carolina
Posts: 29,498
Received 9,624 Likes
on
6,628 Posts
"Mil is a length measurement unit. Mil, also known as a thou is equal to one thousandth of an inch (0.001 inch). The mil or thou is still used in the United States to measure thickness of various materials.".
As you note, mm (millimeter) is metric or as it's called today, SI (for International Standard; Note many European's swap words, i.e Standard International!) It's about 0.040 inches.
Last edited by JerryU; 11-28-2018 at 05:29 PM.
#22
Melting Slicks
Hmm, quoting:
"Mil is a length measurement unit. Mil, also known as a thou is equal to one thousandth of an inch (0.001 inch). The mil or thou is still used in the United States to measure thickness of various materials.".
As you note, mm (millimeter) is metric or as it's called today, SI (for International Standard; Note many European's swap words, i.e Standard International!) It's about 0.040 inches.
"Mil is a length measurement unit. Mil, also known as a thou is equal to one thousandth of an inch (0.001 inch). The mil or thou is still used in the United States to measure thickness of various materials.".
As you note, mm (millimeter) is metric or as it's called today, SI (for International Standard; Note many European's swap words, i.e Standard International!) It's about 0.040 inches.
Either way, you cant convert the millimeters of toe in DSC spec to degrees using the calculator he provided. In order to convert mm or inches of toe to degrees, you need to know where the toe measurement originated from. The hub, barrel of wheel, or tire. In this car, DSC used the barrel of the wheel. (I called and asked a while back). Using a C7 Z as reference, the conversion is .056º in the front and .059º in the rear for DSC alignment specs.
Last edited by atljar; 11-28-2018 at 08:36 PM.
#23
My bad? I'll revisit my conversion from the search to convert MM to degrees.
This is another reason why the DSC spec is a bad spec as the required conversion for us, and most of us are reasonably well educated enough to understand the differences in measurements can produce different interpreted meanings. The DSC spec is not a good one to share unless it's provided with uniform measurements that are not open to conversion.
Last edited by Gnarley Z51; 11-28-2018 at 06:23 PM.
#24
I'd also like to suggest toe should be measured in degrees as the possibility to measure toe could allow the desired measurement to rotate based on a circle from the rotation of the upper and lower ball joints allowing the spindle to rotate in a circle if there was nothing attached to the spindle and allowing it unrestricted movement where it could complete a 360 degree rotation if unimpeded.
Measuring toe in millimeters would depend entirely on the location of the measurement and the larger the arc the larger the toe measurement would be!
Measuring toe in degrees is uniform whether you are 2 inches from the center of the radius or 24 inches so no matter what .5° is .5°
Do we all agree?
Measuring toe in millimeters would depend entirely on the location of the measurement and the larger the arc the larger the toe measurement would be!
Measuring toe in degrees is uniform whether you are 2 inches from the center of the radius or 24 inches so no matter what .5° is .5°
Do we all agree?
#25
Melting Slicks
Also -0.5 mm = -0.028125° https://www.inchcalculator.com/convert/mil-to-degree/
My bad? I'll revisit my conversion from the search to convert MM to degrees.
This is another reason why the DSC spec is a bad spec as the required conversion for us, and most of us are reasonably well educated enough to understand the differences in measurements can produce different interpreted meanings. The DSC spec is not a good one to share unless it's provided with uniform measurements that are not open to conversion.
This is another reason why the DSC spec is a bad spec as the required conversion for us, and most of us are reasonably well educated enough to understand the differences in measurements can produce different interpreted meanings. The DSC spec is not a good one to share unless it's provided with uniform measurements that are not open to conversion.
Last edited by atljar; 11-28-2018 at 07:07 PM.
#26
E-Ray, 3LZ, ZER, LIFT
Member Since: Sep 2007
Location: NE South Carolina
Posts: 29,498
Received 9,624 Likes
on
6,628 Posts
The link he provided was a conversion for milliradians, or Mils. Super confusing, because machinists also call a millimeter a mil as you noted. https://www.google.com/search?q=milliradians
Either way, you cant convert the millimeters of toe in DSC spec to degrees using the calculator he provided. In order to convert mm or inches of toe to degrees, you need to know where the tow measurement originated from. The hub, barrel of wheel, or tire. In this car, DSC used the barrel of the wheel. (I called and asked a while back). Using a C7 Z as reference, the conversion is .056º in the front and .059º in the rear for DSC alignment specs.
Either way, you cant convert the millimeters of toe in DSC spec to degrees using the calculator he provided. In order to convert mm or inches of toe to degrees, you need to know where the tow measurement originated from. The hub, barrel of wheel, or tire. In this car, DSC used the barrel of the wheel. (I called and asked a while back). Using a C7 Z as reference, the conversion is .056º in the front and .059º in the rear for DSC alignment specs.
Yep to measure toe given in an angle into a length measure you have to measure from the center of the wheel to wherever you are going to make the distance measure at the tire. Recall I did mine for the street rod to the same groove in a tread on both tires.
Last edited by JerryU; 11-28-2018 at 08:31 PM.
#27
Tech Contributor
Member Since: Oct 1999
Location: Charlotte, NC (formerly Endicott, NY)
Posts: 40,089
Received 8,928 Likes
on
5,333 Posts
Yep that is confusing! Angles are measured in degrees or radians so see how a milliradian can be used.
Yep to measure toe given in an angle into a length measure you have to measure from the center of the wheel to wherever you are going to make the distance measure at the tire. Recall I did mine for the street rod to the same groove in a tread on both tires.
Yep to measure toe given in an angle into a length measure you have to measure from the center of the wheel to wherever you are going to make the distance measure at the tire. Recall I did mine for the street rod to the same groove in a tread on both tires.
Bill
The following users liked this post:
Gnarley Z51 (11-28-2018)
#29
Melting Slicks
Because they are a race shop and I'm sure are doing lots of field alignments. Setting toe in the field is done with a tape measure and string. Degrees is "better" in the sense that it eliminates some potential sources of error but not something that can be easily done at the track
Last edited by atljar; 11-28-2018 at 11:20 PM.
#30
Because they are a race shop and I'm sure are doing lots of field alignments. Setting toe in the field is done with a tape measure and string. Degrees is "better" in the sense that it eliminates some potential sources of error but not something that can be easily done at the track
Last edited by Gnarley Z51; 11-29-2018 at 12:22 PM.
#31
Safety Car
Are you saying for best tire wear and spirited street driving that I should tell the Service Manager to tell the alignment tech to set the Camber to -1 (degrees?) for all 4 wheels, and the toe to 0 (degrees?) for all 4 wheels?
And then what do I tell them to set the Caster at for front? ...and Caster for the rear?
Also, do they have to have that special bracket mounting piece to align the rear? Is that a must have item to get it correct? What is that piece called or what is that item part number please?
Thank you subieworks
.
Last edited by HorsePower Junkie; 11-29-2018 at 03:41 AM.
#32
subieworx,
Are you saying for best tire wear and spirited street driving that I should tell the Service Manager to tell the alignment tech to set the Camber to -1 (degrees?) for all 4 wheels, and the toe to 0 (degrees?) for all 4 wheels?
And then what do I tell them to set the Caster at for front? ...and Caster for the rear?
Also, do they have to have that special bracket mounting piece to align the rear? Is that a must have item to get it correct? What is that piece called or what is that item part number please?
Thank you subieworks
.
Are you saying for best tire wear and spirited street driving that I should tell the Service Manager to tell the alignment tech to set the Camber to -1 (degrees?) for all 4 wheels, and the toe to 0 (degrees?) for all 4 wheels?
And then what do I tell them to set the Caster at for front? ...and Caster for the rear?
Also, do they have to have that special bracket mounting piece to align the rear? Is that a must have item to get it correct? What is that piece called or what is that item part number please?
Thank you subieworks
.
Those specs should work fine for the average user who wants the car to handle well. For caster front go wtih stock recommendations. For rear go with .7 as DCS mentions.
I have no idea if your dealer will have the tools. Not all do. You have to specifically ask if they have the tools to do it and then check that what they are telling you is accurate. I wouldn't be surprised if most dealers would immediately say yes, then back pedal when pushed on the issue.
#33
E-Ray, 3LZ, ZER, LIFT
Member Since: Sep 2007
Location: NE South Carolina
Posts: 29,498
Received 9,624 Likes
on
6,628 Posts
subieworx,
Are you saying for best tire wear and spirited street driving that I should tell the Service Manager to tell the alignment tech to set the Camber to -1 (degrees?) for all 4 wheels, and the toe to 0 (degrees?) for all 4 wheels?
And then what do I tell them to set the Caster at for front? ...and Caster for the rear?
Also, do they have to have that special bracket mounting piece to align the rear? Is that a must have item to get it correct? What is that piece called or what is that item part number please?
Thank you subieworks
.
Are you saying for best tire wear and spirited street driving that I should tell the Service Manager to tell the alignment tech to set the Camber to -1 (degrees?) for all 4 wheels, and the toe to 0 (degrees?) for all 4 wheels?
And then what do I tell them to set the Caster at for front? ...and Caster for the rear?
Also, do they have to have that special bracket mounting piece to align the rear? Is that a must have item to get it correct? What is that piece called or what is that item part number please?
Thank you subieworks
.
Second I would NOT have anyone mess with rear caster unless they know what they are doing. There was at least one post where the dealer tech messed it up. It is another set of adjustments. Frankly if NOT tracking not sure I would let a dealer touch rear caster. If Tracking or driving very aggressively find a shop that knows what they are doing, has done it before and understand yourself what you are achieving!
Last edited by JerryU; 11-29-2018 at 10:14 AM.
#34
FWIW, look at the allowed range that GM specifies for your suspension. The Dealer Service Manager may NOT set the suspension outside the GM range. I went just somewhat under the GM centerline specs favoring better tire wear but within the allowed range. Turned out my rear wheels on the Grand Sport were set from the factory near the max allowed camber, so it was well under that!
Second I would NOT have anyone mess with rear caster unless they know what they are doing. There was at least one post where the dealer tech messed it up. It is another set of adjustments. Frankly if NOT tracking not sure I would let a dealer touch rear caster. If Tracking or driving very aggressively find a shop that knows what they are doing, has done it before and understand yourself what you are achieving!
Second I would NOT have anyone mess with rear caster unless they know what they are doing. There was at least one post where the dealer tech messed it up. It is another set of adjustments. Frankly if NOT tracking not sure I would let a dealer touch rear caster. If Tracking or driving very aggressively find a shop that knows what they are doing, has done it before and understand yourself what you are achieving!
#35
E-Ray, 3LZ, ZER, LIFT
Member Since: Sep 2007
Location: NE South Carolina
Posts: 29,498
Received 9,624 Likes
on
6,628 Posts
I understand it's iterative, as he adjusted toe to get close to the centerline I spec'd the camber changed and visa versa. Took him ~30 minutes!
Last edited by JerryU; 11-29-2018 at 11:10 AM.
#36
Drifting
Subie is 100% correct. There are two eccentrics on each lower control arm, and two shim washers under each upper control arm dogbone bolt. When you change camber, you are going to change caster, whether front or rear. Better to be informed of the consequence of any alignment setting being off. For best street driving getting all settings on the left close to those on the right will help driveability on the road. You need some camber in these cars,setting them to 0 then getting on the interstate where nominal speeds are often 85-90, then asking the car for some more mph is courting disaster.
The beauty of the C7 is that now you can change rear caster, and for cars with big fat tires get a setting that will reduce the chance the car to go into a snap oversteer when a mistake is made in a turn. What happens with this suspension design is when torque is added to wheels (pushing on the happy pedal) the rear knuckle is twisted forward. If you have negative rear camber, the knuckle acts as a lever and increases the force on the leaf spring, increasing suspension compression. Now, when this happens, the tie rod whose axes are different, pull on the toe setting, increasing rear toe (out). Picture your outside rear tire, in a turn, the one with all the grip, now pointing further away from the vector of the car. That big *** tire with lots of grip and a vector different than the car's vector and you have throttle-steer. People experienced with track days use this as an advantage to rotate the car so they have the optimum vector of the car at the finish of a turn. People not able to take advantage of this, or stab the throttle quickly observe panoramic views (spin). The usual response of the inexperienced is to lift the throttle or worse, hit the brake. This puts the grip in the front and none in the back to a car that is just starting to spin. Then the panoramic view is just a blur.
Regarding spirited driving, well, curves in highway roads are DIFFERENT than on the track. Almost every curve on the highway has negative camber. This is because a curve in the road is there to go around an obstacle, usually a hill or a gully next to the road. The DOT logic, especially where winter temperatures go below freezing is to pitch the camber of the road so water drainage is most efficient. They expect the driver to respect wet, or icy pavement. You are at a disadvantage as a "spirited driver" in these curves, because the car is put in a situation where snap oversteer is likely and the escape choice is the ditch or hitting oncoming traffic.
If you like speed, then go autoX or HPDE and learn how to drive a car. Your need to be a spirited driver may lessen and you won't be putting yourself or other innocent drivers at increased risk. We have plenty of folks willing to put us all at risk with their friggin' cell phone use. At least a spirited driver is paying attention to his behavior and therefore better able to manage chaos. Driving today's roads is a curious combination of ballet dancing and cage-fighting.
The beauty of the C7 is that now you can change rear caster, and for cars with big fat tires get a setting that will reduce the chance the car to go into a snap oversteer when a mistake is made in a turn. What happens with this suspension design is when torque is added to wheels (pushing on the happy pedal) the rear knuckle is twisted forward. If you have negative rear camber, the knuckle acts as a lever and increases the force on the leaf spring, increasing suspension compression. Now, when this happens, the tie rod whose axes are different, pull on the toe setting, increasing rear toe (out). Picture your outside rear tire, in a turn, the one with all the grip, now pointing further away from the vector of the car. That big *** tire with lots of grip and a vector different than the car's vector and you have throttle-steer. People experienced with track days use this as an advantage to rotate the car so they have the optimum vector of the car at the finish of a turn. People not able to take advantage of this, or stab the throttle quickly observe panoramic views (spin). The usual response of the inexperienced is to lift the throttle or worse, hit the brake. This puts the grip in the front and none in the back to a car that is just starting to spin. Then the panoramic view is just a blur.
Regarding spirited driving, well, curves in highway roads are DIFFERENT than on the track. Almost every curve on the highway has negative camber. This is because a curve in the road is there to go around an obstacle, usually a hill or a gully next to the road. The DOT logic, especially where winter temperatures go below freezing is to pitch the camber of the road so water drainage is most efficient. They expect the driver to respect wet, or icy pavement. You are at a disadvantage as a "spirited driver" in these curves, because the car is put in a situation where snap oversteer is likely and the escape choice is the ditch or hitting oncoming traffic.
If you like speed, then go autoX or HPDE and learn how to drive a car. Your need to be a spirited driver may lessen and you won't be putting yourself or other innocent drivers at increased risk. We have plenty of folks willing to put us all at risk with their friggin' cell phone use. At least a spirited driver is paying attention to his behavior and therefore better able to manage chaos. Driving today's roads is a curious combination of ballet dancing and cage-fighting.
#37
E-Ray, 3LZ, ZER, LIFT
Member Since: Sep 2007
Location: NE South Carolina
Posts: 29,498
Received 9,624 Likes
on
6,628 Posts
Reminded of my '67 Corvair and it's tire pressure and rear alignment specs few followed and dealers did not understand or use!
The rear toe specs were 1/4 inch toe-in +/- 1/8 inch for some years. That is up to 3/8 inch toe-in! Crazy- no not if you are trying to counter Oversteer! As the car went very fast around a turn the outside wheel was effectively "steering" into the center of the turn to counter the rear end wanting to swing off the road! Talk about poor polar moment of inertia! The rear engine Porsches of the day were no better! Recall when Porsche decided by customer demand to retain the 911 and not replace it with the 928, water cooled front engine as planned. They advertised their NEW design (that Toyota Engineering Services helped design the manufacture so they did not continue to lose money on each car sold) had titanium rear parts to get a better weight balance. They showed the new front rear weights, However Car & Driver as I recall caught them as they also added weight to the front bumper! Good for ads but not for polar moment of inertia!
Probably the biggest issue with Corvairs was the recommended tire pressures not being followed. They were specified at only 16 psi for the front. That was to reduce front traction and promote Understeer! Most folks, gas stations etc didn't follow or understand the reason!
That gave Ralph Nader material for a book and claim to fame! In fact he quotes a “handling spring” sold by JC Whitney to “improve handling of the early swing axle Corvair” but doesn’t say a word that the same part ad showed it was usable for Porsche and VW! In fact Nader used the fact that the ‘65 and later Corvairs replaced the swing axile with a parallel rear suspension to “prove” GM knew those early Corvairs were “Unsave at Any Speed!” A BS book IMO but he made a name for himself!
The rear toe specs were 1/4 inch toe-in +/- 1/8 inch for some years. That is up to 3/8 inch toe-in! Crazy- no not if you are trying to counter Oversteer! As the car went very fast around a turn the outside wheel was effectively "steering" into the center of the turn to counter the rear end wanting to swing off the road! Talk about poor polar moment of inertia! The rear engine Porsches of the day were no better! Recall when Porsche decided by customer demand to retain the 911 and not replace it with the 928, water cooled front engine as planned. They advertised their NEW design (that Toyota Engineering Services helped design the manufacture so they did not continue to lose money on each car sold) had titanium rear parts to get a better weight balance. They showed the new front rear weights, However Car & Driver as I recall caught them as they also added weight to the front bumper! Good for ads but not for polar moment of inertia!
Probably the biggest issue with Corvairs was the recommended tire pressures not being followed. They were specified at only 16 psi for the front. That was to reduce front traction and promote Understeer! Most folks, gas stations etc didn't follow or understand the reason!
That gave Ralph Nader material for a book and claim to fame! In fact he quotes a “handling spring” sold by JC Whitney to “improve handling of the early swing axle Corvair” but doesn’t say a word that the same part ad showed it was usable for Porsche and VW! In fact Nader used the fact that the ‘65 and later Corvairs replaced the swing axile with a parallel rear suspension to “prove” GM knew those early Corvairs were “Unsave at Any Speed!” A BS book IMO but he made a name for himself!
Last edited by JerryU; 11-29-2018 at 12:41 PM.
#38
Reminded of my '67 Corvair and it's tire pressure and rear alignment specs few followed and dealers did not understand or use!
The rear toe specs were 1/4 inch toe-in +/- 1/8 inch for some years. That is up to 3/8 inch toe-in! Crazy- no not if you are trying to counter Oversteer! As the car went very fast around a turn the outside wheel was effectively "steering" into the center of the turn to counter the rear end wanting to swing off the road! Talk about poor polar moment of inertia! The rear engine Porsches of the day were no better! Recall when Porsche decided by customer demand to retain the 911 and not replace it with the 928, water cooled front engine as planned. They advertised their NEW design (that Toyota Engineering Services helped design the manufacture so they did not continue to lose money on each car sold) had titanium rear parts to get a better weight balance. They showed the new front rear weights, However Car & Driver as I recall caught them as they also added weight to the front bumper! Good for ads but not for polar moment of inertia!
Probably the biggest issue with Corvairs was the recommended tire pressures not being followed. They were specified at only 16 psi for the front. That was to reduce front traction and promote Understeer! Most folks, gas stations etc didn't follow or understand the reason!
The rear toe specs were 1/4 inch toe-in +/- 1/8 inch for some years. That is up to 3/8 inch toe-in! Crazy- no not if you are trying to counter Oversteer! As the car went very fast around a turn the outside wheel was effectively "steering" into the center of the turn to counter the rear end wanting to swing off the road! Talk about poor polar moment of inertia! The rear engine Porsches of the day were no better! Recall when Porsche decided by customer demand to retain the 911 and not replace it with the 928, water cooled front engine as planned. They advertised their NEW design (that Toyota Engineering Services helped design the manufacture so they did not continue to lose money on each car sold) had titanium rear parts to get a better weight balance. They showed the new front rear weights, However Car & Driver as I recall caught them as they also added weight to the front bumper! Good for ads but not for polar moment of inertia!
Probably the biggest issue with Corvairs was the recommended tire pressures not being followed. They were specified at only 16 psi for the front. That was to reduce front traction and promote Understeer! Most folks, gas stations etc didn't follow or understand the reason!
Now there's a term I've heard few drivers or pretty much anyone else ever mention... "polar moment of inertia"! I remember when I was a young greenhorn trying to understand stockcar chassis setups and flew from the west coast to Indiana for a Ray Dillon stock car chassis school put on for 3 days and I learned that term and others. I also had the honor of closing the bar on one of my nights there with Dick Trickle, those are great memories.
#39
E-Ray, 3LZ, ZER, LIFT
Member Since: Sep 2007
Location: NE South Carolina
Posts: 29,498
Received 9,624 Likes
on
6,628 Posts
^^^
Yep, we were sponsors to the Petty Team toward the end of his driving career. More apt to hear "Plowing" and Lose" versus Over and Understeer from the NASCAR crowd! They understand what is was and during a race used tire pressure or the rear spring load jacking adjustment and "give me a full crank" on the right rear from a knowledgeable driver on the communication system - like Richard!
Yep, we were sponsors to the Petty Team toward the end of his driving career. More apt to hear "Plowing" and Lose" versus Over and Understeer from the NASCAR crowd! They understand what is was and during a race used tire pressure or the rear spring load jacking adjustment and "give me a full crank" on the right rear from a knowledgeable driver on the communication system - like Richard!
Last edited by JerryU; 11-29-2018 at 01:10 PM.
#40
Tech Contributor
Member Since: Oct 1999
Location: Charlotte, NC (formerly Endicott, NY)
Posts: 40,089
Received 8,928 Likes
on
5,333 Posts
After my track incident and subsequent repair which required replacement the entire right rear suspension parts except the spring the body shop did a realignment on my car and I noticed their Hunter machine was set up to read toe in degrees. The mechanic said it might be possible to choose displaying the settings in inches or millimeters but wasn't sure.
When doing this in your own garage the only way to get close to 0.5 mm measurement is by accident. The measurement tools, parallax error and the human eye aren't sufficient to get a measurement less than 1/32 of an inch. The thickness of the string is part of the problem.
Bill
Last edited by Bill Dearborn; 11-29-2018 at 02:13 PM.
The following users liked this post:
Gnarley Z51 (11-29-2018)