posted on December 03, 2010 20:36
The Ultimate Guide to Suspension and Handling: Part Six, Adding Negative Camber
By Mike Kojima
In the first 5 parts of this series you learned some basic steps to improving your car’s handling. The first four steps involved the use of basic performance suspension parts available for most cars, the parts that most people with an interest in handling obtain. Been there, done that? Then it's time to head for more advanced suspension tuning, involving the alignment, chassis stiffness and suspension geometry.
Step Six: Add Negative Camber
Adding negative camber the MotoIQ way should be done methodically to enhance cornering power and road holding. Getting a lot of camber so you can be Hella Flush and have stance is sorta dumb to us. Sometimes when seeing those pictures from the "all about stance" crowd with credit cards in the fender gap, I want to roll my eyes. At least that's my opinion, for all of the Stance Nation out there, do what you like and all the more power to you, just don't think your car is going to grip or drift better because of it!
To read the rest of this series click here!
|Negative camber is shown on the left when the tops of the tire tilt inward. Positive camber is on the right where the tops of the tires point outward. Dynamically, negative camber improves grip in a corner unless it is over done.
For a tire to grip well it must use its entire contact patch. Thanks to problems like tire distortion and production car compromised suspension geometry this rarely happens. When a tire is subjected to side load its sidewalls flex, digging the outside tread into the ground and lifting the inside. If you drive hard, you have probably noticed that the outside edge of your tires gets chewed up much faster than the rest of the tread.
|This picture really shows why negative camber helps grip. Look at the heavily loaded outside front wheel of this Sentra. The tire is so distorted, it is practically rolling over and the rim is almost hitting the ground. The tire's outside shoulder is loaded heavily and the inside of the tread is lifting off the ground. Effectively only about half of the tire's contact patch is being used. The result, a big loss of grip and grinding understeer.
Thursday, December 02, 2010 9:08 AM
You know, I majored in Electrical Engineering because understanding complex mechanical systems (like suspension) was completely lost on me. But after reading all 6 parts of this series (in one sitting, I might add), I finally feel like I understand how suspension on cars works.
Thursday, December 02, 2010 9:12 AM
I am the opposite, ME was a lot easier, I barely past the electrical part of physics and had to drop an elective electronic circuits class.
Thursday, December 02, 2010 9:14 AM
My statics/dynamics course was pure hell for me!
Thursday, December 02, 2010 9:15 AM
I'm the go-to guy in my car club for all electrical work, though. I'd rather rewire the whole dash than change a headgasket.
Thursday, December 02, 2010 9:43 AM
Mike, I'm glad to know I'm not the only one who struggled with Electrical stuff. I too barely passed the Electrical/Magnetism part of Physics (didn't help I took it in Summer) and I had to retake Electrical Engineering, barely passing the second time around.
But Statics and Dynamics, Fluids, Thermo, etc all make sense to me without a ton of effort.
Thursday, December 02, 2010 10:05 AM
Exactly. I guess its how our brains work. To this day I hate electrical work. I can do it if I have to but I prefer not to.
Thursday, December 02, 2010 11:15 AM
Great series; suspension and brakes are my favorite parts of a car! So are there any overall suspension geometry differences when adding negative camber via the drill/slot method on the bottom strut mounts, as opposed to adjusting the angle of the entire strut assembly from the top? As it seems the former method adjusts just the hub assembly. Thinking along the lines of calculating roll center, etc, earlier in the series.
Thursday, December 02, 2010 11:17 AM
p.s. I'm no engineer like some of you, but electrical is also my Achilles heel. *shudder*
Thursday, December 02, 2010 11:33 AM
Lol, I'm the same way as well. Electrical power systems are a PITA. I'm a Thermo/Fluids/Heat Transfer guy myself, but I still grasp the machine design/dynamics stuff just fine. lol
Thursday, December 02, 2010 11:54 AM
We are going to get more into suspension geometry later in this series.
Thursday, December 02, 2010 12:47 PM
Loving this series. I am learning a lot. Keep it coming!
Thursday, December 02, 2010 1:29 PM
Thank you, I love this series!
2 quick questions though:
1) Do many of the coilover kits, depending on the suspension design, have an added negative camber affect inherently?
2) I was watching Top Gear America on my DVR last night and found myself asking, "isn't Mike Kojima supposed to be making an appearance on one of these episodes?" I swear you guys mentioned it a month or two ago!?
Thursday, December 02, 2010 2:04 PM
1. Not many coilovers have the slotted hole but its not hard to modify yours to have it.
2. I am in the audience with Dave Coleman in the segment where Michele Rodriguez is the star in a small car.
Thursday, December 02, 2010 4:55 PM
Mike, page 3
"The following table provides a rough guideline on how much camber" -- the table lists positive numbers, so that should read "The following table provides a rough guideline on how much negative camber"
Or put a negative in front of all of the numbers in the table.
Thursday, December 02, 2010 5:03 PM
Also, something obviously not worth fixing IMO, but your graphic at the top of page 5 says "Part V" and should say "Part VI".
Nice addition to the series. The fine details of grip are one of my weak spots.
Thursday, December 02, 2010 9:25 PM
Thursday, December 02, 2010 10:41 PM
With IR thermometers available for ~$75 at home improvement stores, is there really a good reason not to adjust camber based on tire temps?
Thursday, December 02, 2010 10:50 PM
IR thermometers are not used for taking tire temps because they are not accurate as the tread temp falls a lot within seconds. Bead probe pyrometers are as they take the temp several mm's inside the tread.
I take temps all the time, especially when developing a new chassis. On a car that I am used to I don't usually bother though unless we have some sort of problem. You might see me in the staging lanes of a Formula D practice with an IR thermometer though but that's because practice time is short and the cars turn over so fast.
Friday, December 03, 2010 10:17 PM
Good quick read.
If you typically don't look to tire temps when adjusting camber settings, what do you go by? I'm primarily interested in auto-x where tire temps probably aren't even close to stable? I would think the tire core temperature doesn't get all that high like it would in sustained loading of road racing so it probably drops very rapidly after a run.
I haven't spent a ton of time testing yet and getting a tire probe thermometer setup was on my tools list this winter. If it's not going to help though, no point in spending the money on it.
EE vs ME, isn't it a wash? Vibrations, controls, fluids, heat transfer...you can model any of them with basic electrical circuits. Although, most EEs can't build anything to save their life where MEs are just kind of "jack of all trades, master of none." ;)
Saturday, December 04, 2010 1:27 AM
If you can do real time logging with the IR temp sensors, I say go for it. You can see how they heat up during the run.
But Mike is 100% correct about the probe vs IRs from a hardware store, but he already said that!
We even have IR TPMS sensors that measure carcass temperature from the inside with and IR element.
Sunday, December 05, 2010 10:10 AM
I take a lot of tire temps, listen to driver feedback and look at split times and lap times when developing a chassis. Once i am used to a certain car in its development cycle, I usualy don't take temps unless something weird is going on.
In autocross you usualy see pretty decent tire temps actualy.
Monday, December 06, 2010 10:44 AM
I like taking tire temps. 3 places across the tire, with a probe, nearly every time the car is on track. It gives you another data point. Data is king. By having a routine, and always doing it, we can see if we have any odd issues. Strut type suspension with the crash bolts, bolts slipping. We see it in the tire temps before we ever get a gauge on the car.
Had a tire going flat, and saw it in the temps. I had to do a double take in the pits on the temps. The driver did not notice it, but we saw it in the temps (leaking valve stem). It was obvious once we did the temps and pressures, but when I saw the temps I knew something was wrong.
Monday, December 06, 2010 10:50 AM
If you work for a anal rententive guy who takes years to devlop a simple car.
Monday, December 06, 2010 4:43 PM
Damn, nice writeup Mike!
Still struggling to understand it. :(
Why did i do a Bachelor in Business!?! :)
Is double wishbone considered unequal A-arms?
Sunday, December 12, 2010 9:00 PM
If they are unequal in length.
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