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How to do an alignment with a string system?

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  • #16
    This is a screenshot of the spreadsheet with actual measurements (all linear measurements in mm)...

    Click image for larger version

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    Last edited by apk919; 07-29-2012, 03:29 PM.

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    • #17
      Can you please explain how the laser method works in comparison to the strings?
      W the string you measure from the string to the store bar (front and back). With the laser mounted to the toe bar (pointed parallel to the carea am guessing) what are you points of reference?
      Are you measuring to a body panel?

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      • #18
        When I tested hub stands, they produced different measurements than with the wheels. I now use scale and wheel stands that the car sits on and dont have to jack the car between every measurement and adjustment. Still need to lift the car to set spring perches.

        Setup takes time and a commitment to detail. Shops that have nice alignment gear make the job very easy. But if you are looking to do this yourself and don't own an alignment rack, it takes time. The good news is that once you get it to your baseline, small changes around that baseline don't take too much time. The biggest PITA is to get the car on the leveled wheel stands. After that, it is gorillaing the eccentric bolts so they don't move. After that, the biggest PITA is repeating every race weekend. If you really want the benefits setup provides, it is done every weekend and then modified at the track for what you are feeling. It is a commitment and a knowing that setup makes the difference. For me, making a change that improves the car is almost as rewarding as driving the car. I don't enjoy doing setup, but I do enjoy the results from putting in the effort to do it.

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        • #19
          Quick note: the stands that Emilio is using probably produce much better results than the stands I used. The difference is the flat base plate that is roughly equal to the tire width. The stands I used did not have that base plate and is the reason I suspected that i had different results than with the wheels on.

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          • #20
            Hey James and Brett, you probably remember Joey and I doing a bazillion alignments a weekend at the track. We used the string method and used ramps to put the car high enough to do the final toe adjustments. The first step is to establish a square we used the rear axle centerline and or hubcenter on wheel make sure all centers match and the front and rear have different track so be aware of that also. Once it is square we would them start the adjustment process. You can fine tune the handling with toe and tire pressure. If we need a big adjustment we would adjust the camber, but it was mostly toe and pressure at the track. It could get interesting for some tracks we would run a different tire pressure on every tire. Of course that is a spec miata where you don't have a ton of adjustment so that's what we did. The ramps made it so we could do a toe change in about 15 minutes. A camber change and realign in about 30 minutes. One trick we learned is we would measure the toe while we were adjusting with the car in the air to make it easier. For example while the car was on the ground it may have 3.0 degrees of negative camber, at full droop car in the air it may have 2.0 If we wanted to make an adjustment we would move the concentrics the same amount in the same direction and it would not screw the toe up. we would have one guy holding the gauge until it changed the correct amount as the other guy worked the concentrics. We put the car down and roll it and verify the change and then go through the alignment check, but 9 times out of 10 if we did it correctly we would not have to change the alignment. In addition we would make the adjustments with the strings all on the car to save time and check square when we dropped the car, but if your careful and don't bump the strings this can be a quick deal. Hope that helps.

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            • #21
              Joe!!!!!! Good to hear from you.

              The big take away from your email for everyone IMO is the commitment you guys had to making changes to the car at the track for what the driver was experiencing. Whatever method anyone uses, the important thing is repeatability and consistency in process. This allows you to establish a baseline that can be used every time you set the car up and give you consistency and confidence when moving away from that baseline as the track and driver demand a change.

              My go to setup adjustment at the track is rake/derake, adjusted at the rear. Has minimal impact on camber, toe, cross weight. After that, rear bar and front toe. I try hard not to use tire pressures too much to correct handling. I may be able to correct the problem for an ideal lap, but at the expense of overheating a tire on a long run. That said, tire pressures adjustments are my weak spot and I have probably settled into my method to mask that deficiency. Something I need to work on more.

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              • #22
                Originally posted by Joe jordan View Post
                Hey James and Brett, you probably remember Joey and I doing a bazillion alignments a weekend at the track. .
                Joe,

                Can you comment on what you try to achieve with a bazillion adjustments? What exactly does that mean? During practice do you say to yourself I want more top speed in T8 @WSIR because I'm in that turn a long time. So you dial in more negative camber on the left side and see if the lap time falls? If so how do you decide or prioritize goals?

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                • #23
                  Originally posted by fatbillybob View Post
                  Joe,

                  Can you comment on what you try to achieve with a bazillion adjustments? What exactly does that mean? During practice do you say to yourself I want more top speed in T8 @WSIR because I'm in that turn a long time. So you dial in more negative camber on the left side and see if the lap time falls? If so how do you decide or prioritize goals?
                  It is very track dependent, but we usually talk about the most important corners of the track before the weekend and dial in the car to those corners, I am an old tire guy so I am very comfortable messing with the tires, I use contact patch as a key tuning element and also consider the tire a spring IE the lower the pressure the softer the spring, higher pressure the higher the spring. We always ran higher tire pressures than almost everyone else except at lower grip surfaces like Mazda raceway Laguna Seca.

                  In regards to the bazillion adjustments, this was on test days, we would always start by making one adjustment at a time, so we would literally align the car 5-10 times a day on a test day, people thought we were crazy most of the time... We would dial in the most important corner on the track, for example at Willow springs we would say turn 9 because it connected the two longest straightaways. and try not to give away anything in other parts of the track, we would then dial in the second most important corner on the track without giving up anything for the most important and so on. I felt rake and cross weight were bigger adjustments than toe and tire pressures, Once we got to know a track like Willow springs and or MRLS we would run asymmetrical setups with less camber on one side of the car than the other to help it go through left handers at MRLS and Right handers at Willow Springs.

                  We very rarely worried about top speed except at Cal Speedway and or Road America or someplace with really long straightaways, spec miatas were all so close we did not get hung up on that and chose to focus on corner entry minimum speeds as we learned that exit speeds were all very similar but how you got to them was different, in many cases when you watched our car race it appeared that the car gave up under braking, but actually he was transitioning to the throttle before most to gain the time between braking and full throttle if that makes sense.

                  Hope that helps

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                  • #24
                    James,

                    We all have our strengths and weakness areas! I have a longtime tire background so I am very comfortable with them. In regards to rake we changed it very little and actually used camber mostly in the rear to tune the car for specific corners, as you may remember Joey liked a car that turned in quick and that was very loose, so many of our adjustments were standing up rear tires and tire pressures. Rake and or cross weight were too big an adjustment usually for Joey. He was looking for small changes, we knew the car so well from racing them from 94-99 in the Speedvision cup (now continental series, one time I knew how many racing miles we had in miatas in those years and it was something like 72,000 race miles!!! Several 24 hour races and all endurance racing) Will Rodgers like the car a touch tighter but not much, but some would say the car was undrivable lol.....so everyone has their own way and the key is to not be afraid to try anything.

                    I don't think we ever made a sway bar adjustment after the first few events and did do some testing with no bars to see if we could improve grip... To help you with tires, think of tires like a spring rate, they actually do have a rate that Toyo or Hoosier can provide and it does change with pressure. We ran most of the time as close to 50.0 cross as we could. Every time I dialed in some cross that I thought would work he would complain the car was not consistent and it made him hesitant to go all out like he wante, he wanted a car balanced in what it felt like in every corner and the small changes to air pressure and camber and toe would give him enough to go fast with confidence.

                    I was open to sharing any of our setup with anyone that asked, i'd tell them what we did and most did not believe the toe settings and tire pressures we ran, they thought I was lying, but I wasn't it just worked for us!

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                    • #25
                      Great info guys. So I invested in some hub-stands and made a string rig along with having a camber gauge.
                      I understand that in order to get the toe of a wheel I need to take a measurement from the string to know point on the rear and front of the wheel ? The goal is to have the toe amount equal on both side of the car.
                      I came up with a spread sheet just to understand this better. Can someone please confirm I am on the right track?

                      I also read above that hub-stands gave a different measurement that with the wheels on ? That makes sense, but its not a bad thing is it?

                      Last edited by FoxSTI; 05-10-2017, 07:40 PM.

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                      • #26
                        Another question, when you guys add or subtract camber or toe (most importantly) at what increments do you do this?
                        I remember when racing 8th scale nitro RC cars we would work on 1/2 degree increments.

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                        • #27
                          Originally posted by Joe jordan View Post
                          I was open to sharing any of our setup with anyone that asked, i'd tell them what we did and most did not believe the toe settings and tire pressures we ran, they thought I was lying, but I wasn't it just worked for us!
                          1st sorry for the side-bar but this is really interesting stuff. Joe, are you basically tuning with akerman creating more over steer torque to get turn-in and corner entry and seeing what your data says is faster? If so how much of that is really driver dependant? If a guy is not a trail braker you need more akerman. If a guy trail brakes you need less because trailing improves turn-in. What about tire pressures now? I think of tire pressures to achieve max lateral grip. But I suppose you can use tire pressure to alter loads and thereby induce more yaw under braking to improve turn-in for one direction like the entry of turn3 at ACS. Is this the kind of tuning you are getting at with toe and tire pressure?

                          What does this level of precision net you in regards to lap time? Are we talking this improves 10ths or a is there a whole second to be found there or even more???

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                          • #28
                            FOX STI, yes I believe you are on the correct path. I don't think it matters if it's different at the wheels, but you need to understand the differences. For example I love hubstands for scaling the car and initial setup, but feel it takes to long at the track to set them up so I get down and dirty to achieve speed in changes at the track.

                            Most guys that I see don't spend a ton of time tuning their alignments at the track they use rake and or cross to tune the car.

                            JJ
                            Last edited by Joe jordan; 05-11-2017, 12:12 PM.

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                            • #29
                              Originally posted by fatbillybob View Post
                              1st sorry for the side-bar but this is really interesting stuff. Joe, are you basically tuning with akerman creating more over steer torque to get turn-in and corner entry and seeing what your data says is faster? If so how much of that is really driver dependant? If a guy is not a trail braker you need more akerman. If a guy trail brakes you need less because trailing improves turn-in. What about tire pressures now? I think of tire pressures to achieve max lateral grip. But I suppose you can use tire pressure to alter loads and thereby induce more yaw under braking to improve turn-in for one direction like the entry of turn3 at ACS. Is this the kind of tuning you are getting at with toe and tire pressure?

                              I have not thought of it in the way you describe, but after talking to many guys I respect who coach and are top drivers themselves they consistently told me the speed between a fast guy and pretty fast guy was all before the apex of the corner. So speed was gained with higher minimum speeds and getting on the gas just slightly sooner. Exit speeds were always very similar. The gap between a slow guy and fast guy were much more pronounced. This philosophy is why we focused on turn in (toe ackerman) and to the apex with our tuning and didn't really focus on much else other than balance. We also went with some radical to most set ups like asymmetrical camber, different camber on every corner on some tracks and whacky tire pressures, most also though we ran way to much toe out in the front! We also ran a lot of toe out in the rear of a FWD car....

                              In regards to tire pressures, I think speed is created through driver confidence so the consistency of the contact patch is the most important especially to a newer driver, as the driver develops they can handle a changing contact patch. Higher pressures create a more consistent contact patch even if sometimes it's smaller contact patch than low pressures.

                              In regards to trail braking, my driver my kid did do a fair amount of trail braking, but what he was most concerned with is the initial turn in, after turn in he has very quick hands and if you watch his in car he is always correcting not the classic slow hands smooth approach, many have commented about this in his videos which I find funny, because most of the ones negatively commenting about that aren't driving at the absolute limit. Also the different tire pressures were used to get the car through a specific corner for example at willow springs mostly right handers the car may have a slight push in turn 1 so we would raise the RR tire pressure to compensate for that, the car most likely had a degree less negative camber in the right side than the left to get through the left handers faster.... the slightly higher tire pressure would stiffen up the car for that specific corner without negatively affecting the speed through the other corners. Does that make sense?

                              Here is a video for your entertainment. This was a borrowed car as we hurt our car in qualifying, so it's not completely our normal setup but you can see his hand movement.

                              Watch This Spec Miata Driver Go From Last to First in Just One Lap


                              One other note, the Norcal crew tend to run lower tire pressure as they run on low grip tracks like MRLS and Sears Point frequently, my opinion is the more squirm in the tire, lower pressure helps create heat in the tires and thus grip at those tracks, so we would run lower than normal pressures for us. Sears Point especially is a track that local knowledge is king, we would always do pretty well there but not as well as we did at Thunderhill that has more grip and our higher pressures seamed to work better and most did not change pressures depending on the track. I think this is also why some spec miata guys say some tracks like old tires and some like new tires, they just arrive at their findings differently.


                              What does this level of precision net you in regards to lap time? Are we talking this improves 10ths or a is there a whole second to be found there or even more???
                              When we first started and he was developing as a driver the times gained were significant 1 second or more as he become more refined and a better driver less time was gained. We see anywhere from a .1 to .5 per lap from the the first session (baseline) settings to the last after many changes or a few depending on the track. In spec miata that is a big swing. I think James and Brett can attest to that.
                              Last edited by Joe jordan; 05-11-2017, 08:13 AM.

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                              • #30
                                I have no clue how I answered the above in a quote sorry about that. I tried to highlight it in bold with edit feature, I can set up a car, but I'm an idiot on the forum

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