Question about alignment, or How bad would it be if ...?

[parsonsj]

I'd like to take my car to a local autocross tomorrow morning, and I spent the week trying to find a place to help get the suspension aligned. I wanted to get the corner weights and cross weights all sorted out, and then do a precision alignment.

So ... two local shops said they couldn't do it (car is too low, they say). Another local chassis builder claimed to be able to do it, but then blew me off all week.

Now it's Saturday, the autocross is tomorrow, and the best I can do is:
1. measure the wheelbase side to side (within 1/16" with my high precision tape measure, framing squares, and laser level).
2. measure the toe. It is also within 1/16" (using the same highly accurate tools, with bonus help from my 12 yr old daughter).
3. measure the camber. It is between -0.5 and -1.0 degrees using my precision analog angle finder.

The autoX is about 80 miles away or so.

Anybody got an informed opinion of the likelihood of tire damage? Think I'll be ok? Bad idea, stay home?

Any other thoughts?

thanks!

jp

[jeffandre]

I am no expert here, but I believe you can get it all close using the tools you mentioned. Precision may be off a tad but if you use a temp gun on the front tires and measure the inner, middle, and outer areas of the tire patch you can get a decent idea if you are overworking any areas of the tires. How much caster do you have?

Not sure how well the tires would heat up, but I would drive it on a local semi-twisty road to warm up the ties and start taking temp measurements. Then adjust the camber/caster a bit until you see relatively even warming of the tires. Try this on the freeway too.

Definitely find a local shop that will take care of your alignment when time there is no time pressure, and work it out where you can take it back once or twice for fine tuning depending on tire temps/wear. Good luck, and if you go to the autocross let us know how you did! Vids are even better!!!

[parsonsj]

Jeff,
I have no temp gauge. Sounds like something to pick up soon. Wonder if any of the other autoX'ers might have one.

Caster, I have no idea. Katz designed to 7 degrees, and I've put the cross-shafts in the middle of the adjustment range. Other than that, who knows?

jp

[slowcamaro]

Sounds like you'll be fine. I've been running -1.0 for a year and no noticeable odd wear. My friend ran -2.0+ daily on his last car and with tire pressures dialed in he didn't have any extreme wear either.

Toe is your biggest concern. Though 1/16th shouldn't kill you either. Especially on such a short trip. Now just get your tire pressures dialed in.

Caster doesn't affect tire wear so no real worries there.

I drove my car 40+ miles after eyeballing my front suspension rebuild. Didn't tear anything up on that drive.

Your close enough to have a little fun. Do it, and get video.

[Bow Tie 67]

John,

I think you'll be fine, and hope you did attend. Even if everything is not exactly where you want it you'll have a blast. Had you been able to get the alignment your tires will still take a beating, it's the nature of the beast.

Matt

[David Pozzi]

Sorry for the late reply, hope it worked out for you.
As long as you get the toe-in pretty close, you should be OK.
Get a smart level digital protractor at Sears and use that to measure camber, it's accurate to .1 deg.

Caster can be measured by turning the wheel in, taking a camber reading, then turning it out the same degrees and take another.
The trouble is measuring the turn angle precisely enough to have repeatability. Even with turntables it's not easy. Try some kind of protractor against the wheel.

Look here at the Smart Level tool, download the .pdf owners manual, there are charts to help you figure out caster angle.
http://www.smartracing.net/alignment.htm
David

[parsonsj]

Thanks for all the replies guys. I did go to the autoX ... in my Duramax. I'm glad I did, because I got lost going and coming home! Anyway, I met the club president and talked with the local alignment guru. The guy does lots of local racer setups, he's got a level pad, corner scales, etc. I'm going over there next week.

I hung out and watched as the locals put their cars through the paces. The course was *very* tight. Two U-turns, 2 complete circles, and a tough left-hander that was over 90 degrees. I don't know how well my pavement pounder would have done on such a course ... I'd guess the Mini Coopers would beat it!

Next action is the 2nd week of May.

jp

[silver69camaro]

John,
I always set up cars without a professional shop. If you're careful, you can get it VERY accurate. Heck, that's what we did for Art's '55 and '60 Vette, and those both did very well.

I use David's method for caster too. All I use to get up the car is a digial protractor, turntables, corner scales, and a tape measure. Works great for me.

[parsonsj]

All I use to get up the car is a digial protractor, turntables, corner scales, and a tape measure. Works great for me.You forgot a level pad. Though even with no level pad, I agree, and I may get into that myself. The only tool that I own of those is a tape measure. Frank (ProdigyCustoms) and I have talked about splitting the cost of picking up a set, but we haven't done it yet.

Actually, that's how I expect the guy to do it when I get there. He's got a level pad and the ability to work underneath the car with it at ride height.

I'll let everyone know how it goes ...

jp

[chicane67]

So how'd the Duramax do thru the cones ... ?? ... :lmao:

As David stated... if you get the toe nailed... you should be ok. For ever and a day, I ran -1.75 with +3.5 and 0.0625 to 0.125 toe out without any real adverse wear. I have heard that it takes about 500 miles of a funked-up alignment to set wear in a tire, with normal/non performance driving.

At home alignments are quite simple with an SLA or SA/Strut suspension. At Guldstrand... we used a 10+ year old Longacre bubble camber/caster guage, a pair of 12' 2x2 aluminum I beams, two tape measures, two clothes pins and four 4x4 blocks each about 12" long. I purchased the very same components for myself and have been using them ever since... and to think, the greater majority of those cars went 200+ MPH.

If that isnt scarry enough for you... we also used a bubble tire balancer (eg. static) that he has used since the late 60's... on those very same cars.

Longacre 78260 = 129.00
2x 12' I beam = local metal supply @ 35.00
2x 25' tapes = 25.00
2x clothes pins = You should be able to con the wife out of a pair for cheap
4' for 4x4 = I am sure you have this laying around the shop somewhere

With the 78260 (http://www.longacreracing.com/catalog/item.asp?id=129&catid=5), you should be able to do a complete alignment, within 1/8 to an 1/4th of 1.0 degree, in about 20 minutes. For another $70.00... the digital 78290 (http://www.longacreracing.com/catalog/item.asp?id=1219&catid=5) unit will hold 0.1 degree with even more ease of use.

[Salt Racer]

John,

Just get the corner balance done properly, with you or simulated weight in the driver's seat.

Alignment isn't a black magic. I've been doing my own alignment for years using el-cheapo tape measures and a digital protractor - it's been good enough for 1:43 flat at Willow Springs big track in a stockish 134-hp BMW, and I didn't kill myself to boot. You won't feel a difference between backyard alignment and super-precise alignment unless your name is Michael Schumacher.

I wouldn't worry too much about tire wear. They are wear items when you do cone-dodging or track driving. It's an expensive hobby no matter how you approach. Funky wear pattern could also develop due to poor driving too, so consider the first set as throw away tires for learning. I'm not saying you are a bad driver, but you are unexperienced (as far as I know - otherwise, my apology).

The methods David and Tom described work just fine, and is the right way to do for home-brew alignment jobs. If you are not running inner fenders, you can also put a digital protractor against vertical surfaces on the knuckles or horiz surface on the steering arm to get pretty accurate caster measurement. Besides the ease of fabrication, that's why your knuckles have vertical surfaces.

For cone-dodging and tight road courses, start out with 1/8" toe-out, -2.2~2.5* camber and +7-ish caster as starting point. Once that's set, at this point, you should really concentrate more on getting comfortable with the car and improve your driving skills IMO.

Remember, a skilled welder can lay beautiful beads using a $300 flux-core wire feed machine while an $8000 equipment is only good for making abstruct art work "Wires sticking outta burnt hole" in the hands of Joe JBweld. Cars are no different - they can only be as good as the driver.

If you can't drive consistently, changes in setting won't mean much and only add confusion and variables. I'd limit the adjustment to tire pressure, and possibly anti-roll bar (only if the car has excessive under/oversteer to a point it won't respond well to throttle steer).

Have fun! Off to Pahrump NV for a track event.

[silver69camaro]

Good to see you on here, Katz. :twothumbs

[TheMonkey]

i didn't see that anyone mentioned it above... how much to turn the wheels when measuring for caster, and the multiplier for the difference.

if you turn the wheels 20* to the right, take your camber measurement, then 20* to the left, take your camber measurement. most likely, they will have opposite signs (one tipping in, one tipping out). so, if you have one measurement of 1.75* in, and the other is 1.25* out, then the difference is 3*. multiply that by 1.5 to find caster.

i think 20* turns multiplied by 1.5 is normal. this gets you very close. some people use bigger turn angles with a smaller multiplier, or smaller turn angles with a bigger multiplier, but offhand, i'm not sure what angles/multipliers work. it is not a straight line relationship. it is math that i cannot do, so i have to take the numbers at face value.

[parsonsj]

Katz!!!!

It's good to hear from you. You are right about the most important variable: the driver. Me, I've no real experience, other than some drag racing such a long time ago that it embarrasses me to say when it was.

I'm really looking for confirmation that the car is built square and level, and that the thrust angles from the back wheels are reasonable. I just want to be sure that I eliminate excuses when I get out there and lose to Mini Coopers on the autoX.

One thing the car does that I'd like to understand is that it tends to push right when I get on it. It especially happens when I shift gears, as if the unloading of the rear tires causes something goofy. Pre-loaded springs might cause it.

And actually, right now the rear housing is out of the car and it and the axles are being narrowed a half inch. The rear wheels were just too close to the sheetmetal during severe body roll. I'll have it back together in a couple of days. I noticed that one of the rear ARB bushings was loose when I pulled it apart. Maybe that caused the push.

My front bar is too big (according to your spreadsheet), because the swing arms ended up shorter to accommodate the radiator. I think it will push a bit ... but I'll know soon enough.

jp

[69Nova]

John where was the autox at? Let me know next time you want to go and I'll meet you there.

[parsonsj]

Andrew,

The autoX was at Lake County Tech Center. Just about an hour from my house, assuming I don't get lost again. :) The next one is in a couple weeks. I'll let you know.

jp

[69Nova]

Cool. Also if I was you I'd try and go to the next one at the gainsville roadcourse. I liked it alot. It was basicly a roadcourse with cones set up to keep speeds down. Lots of fun.

(the red is the course I ran)
https://static1.pt-content.com/images/noimg.gif

[parsonsj]

Deal on Gainesville! That looks like fun. When is the next event? Is it SCCA? Or the Martin SCC?

jp

[Norm Peterson]

i think 20* turns multiplied by 1.5 is normal. this gets you very close. some people use bigger turn angles with a smaller multiplier, or smaller turn angles with a bigger multiplier, but offhand, i'm not sure what angles/multipliers work. it is not a straight line relationship. it is math that i cannot do, so i have to take the numbers at face value.20° with a 1.5 multiplier is probably common partly because the commercially-available bubble type caster-camber gauges use that angle. But 14.5° and 2.0 works, as does 30° and 1.0 (if you can get that much steer angle).

It's not all that difficult or expensive to fab a fairly accurate caster-camber gauge that works off the wheel flanges (and uses a dial indicator). Careful choice of some dimensions makes it (almost) direct-reading.

Good to see you drop in, Katz. I was beginning to wonder if you'd fallen off the face of the earth.


Norm

[69Nova]

Deal on Gainesville! That looks like fun. When is the next event? Is it SCCA? Or the Martin SCC?

jp

I'm going to pm you some info right now.

[Norm Peterson]

Me, I've no real experience, other than some drag racing such a long time ago that it embarrasses me to say when it was.There are literally dozens of tips, but here's a few that I think are more important.

Walk the course several times. If the club offers an instructed novice walk-through, don't miss it. Likewise, for a run, there may be the opportunity to have an instructor in the passenger seat - take full advantage of this (I don't think you'll have to twist anybody's arm very hard).

Except for Pro-Solo, there is absolutely no benefit in having the best reaction time, as the timed portion of your run does not start until you've traveled several feet past the point at which you'll stage. A good, clean launch is all that matters.

Expect to be told to "look ahead" and fight the natural tendency to look at the cones that you're just passing. If you're already at them and aren't about to run them over, they don't matter any more.

Take it fairly easy on the first run and don't worry about the time at all. It's generally easier to add speed on successive runs than it is to dial it back (plus it's encouraging when you find out that your second run is several whole seconds faster than the first, you know there's still more to be had, and maybe even where to find it).



One thing the car does that I'd like to understand is that it tends to push right when I get on it. It especially happens when I shift gears, as if the unloading of the rear tires causes something goofy. Pre-loaded springs might cause it. Roll steer? If there's enough oomph to torque the chassis over with the throttle, the rear axle is steering slightly; normally this steers the axle to the left and makes things feel like the car has decided to make a right turn all by itself.


And have fun.


Norm

[chicane67]

Katz Man... whats been shakin' ??

Hey, did you hear... ??... Pahrump is going private ?? Like "Resort/racetrack" style private ??

[parsonsj]

Roll steer? If there's enough oomph to torque the chassis over with the throttle, the rear axle is steering slightly; normally this steers the axle to the left and makes things feel like the car has decided to make a right turn all by itself.Maybe ... but to be clearer: the dart to the right happens as I lift the throttle for a gear change. My steering is ultra quick (Tony Woodward forbid me to talk on a cell phone while driving ... he said answering the phone would be the same as a lane change), so maybe it is just the reach for the gear shifter?

Oh, and thanks for the a/x driving tips. I appreciate it.

jp

[David Pozzi]

i didn't see that anyone mentioned it above... how much to turn the wheels when measuring for caster, and the multiplier for the difference.

if you turn the wheels 20* to the right, take your camber measurement, then 20* to the left, take your camber measurement. most likely, they will have opposite signs (one tipping in, one tipping out). so, if you have one measurement of 1.75* in, and the other is 1.25* out, then the difference is 3*. multiply that by 1.5 to find caster.

i think 20* turns multiplied by 1.5 is normal. this gets you very close. some people use bigger turn angles with a smaller multiplier, or smaller turn angles with a bigger multiplier, but offhand, i'm not sure what angles/multipliers work. it is not a straight line relationship. it is math that i cannot do, so i have to take the numbers at face value.


Toe in turn calculations and charts here:http://www.smartracing.net/alignment.htm


Katz!
Man, I've missed you around here! :grouphug:

David

[chicane67]

Maybe ... but to be clearer: the dart to the right happens as I lift the throttle for a gear change. My steering is ultra quick (Tony Woodward forbid me to talk on a cell phone while driving ... he said answering the phone would be the same as a lane change), so maybe it is just the reach for the gear shifter?

Where is your hand placement on the steering wheel when shifting ?? If your single hand is above 9-3... this could be your culprit.

Driving ergonomics plays a factor is driving smooth and consistant... as does hand placement on the wheel, the shifter and its as important as foot work on the pedals. Looks like it might be time for a driving "Mechanics" course.

[Norm Peterson]

some people use bigger turn angles with a smaller multiplier, or smaller turn angles with a bigger multiplier, but offhand, i'm not sure what angles/multipliers work. it is not a straight line relationship. it is math that i cannot do, so i have to take the numbers at face value.I think a pretty close formula for the multiplier is

[Multiplier] = 0.5 ÷ sin(steer angle)

where steer angle is the amount you steer the front tires each way (not the total).


David - Thanks for the smartcamber link.

John - Glad to help.


Norm

[Salt Racer]

Dave, JP, Matt, Norm, and Tom,

I’m still alive. Just stopping by to help JP out. I don’t really intend to come back here regularly. My interest has shifted. No more hotrods for me, and I’m interested more in developing myself as a driver than car setups.

Besides the fact it’s more fun driving than working on cars, as I wrote in my previous post, my slow-working brain finally started to realize that having a theoretically-perfect chassis don’t mean a **** if you can’t drive well. Some of you already know I have been driving E30 BMWs these days. The cars are cheap and good platforms to learn how to drive, and don’t take much prep for track duties. Suspension kinematics are ****ty at best (McStrut/Semi-trailing arm), but the cars are pretty well-balanced even with factory springs and bars, and ergonomics is one of the best layouts I've seen on production cars for track driving (the only complaints are seats sit too high and clutch pedal a bit too high for left-foot braking). 32mpg helps tremendously with today’s outrageous gas price also.

I've only done 12 track events so far at six different tracks (Streets of Willow, Big Willow, Laguna, Buttonwillow, Vegas outside course, and Pahrump). Still a lot to learn, but I’m already running a few seconds faster than I ever did in my Buick in an old 4-cylinder BMW that costs a fraction of what I've spent on Buick.

These days, I'm more about laptime per dollar than building and cruising in a badass-looking muscle car.


...I'm really looking for confirmation that the car is built square and level, and that the thrust angles from the back wheels are reasonable...

That’s understandable.


...I just want to be sure that I eliminate excuses when I get out there and lose to Mini Coopers on the autoX...
It’s better to have as many excuses as possible, actually… But seriously, don't be so hard on yourself if you get beaten by Mini's, Miatas, CRXs, and the likes.


...One thing the car does that I'd like to understand is that it tends to push right when I get on it. It especially happens when I shift gears, as if the unloading of the rear tires causes something goofy...

I’m thinking it’s a combination of stuff mentioned by you and others, compounded by the locking differential (I thought you went with Detroit locker). My experience driving locked vehicles is limited to my old rockcrawler and another 4x4, which I obviously never cared to check corner weight, axle steer geometry, etc. But I do recall them doing something similar to what you’re describing when axles transitioned from unlocked to locked or vice versa.

How about just backing off the throttle with clutch still engaged? Would that still cause the car to move around? If not, try backing off the gas AND step on the clutch as if you’re going to shift, but keep both hands on the wheel and see what happens.

I thought of roll steer as Norm did, which would have made sense if the car darts to right when you get on the throttle as I built in slight roll understeer. It seems to be the other way around, but it still could be a possibility. Try changing PHB height and see if that has any effect.


...My front bar is too big (according to your spreadsheet), because the swing arms ended up shorter to accommodate the radiator. I think it will push a bit...

I wouldn’t worry about that for now. Once you get the alignment and corner-weighting done, I'd just try cone-dodging and/or track events as is. Only then, you’ll be able to make meaningful assessment of car’s handling nature. Goofing around on street won’t tell you anything.

Just have fun driving and get to know the car well. Your preference of car's handling will change anyway as your driving skills progress. There's no sense spending time and money trying to dial in the car spot-on, knowing you'll have to mess with it later anyway. Me for example, I used to be very comfortable driving a slightly understeering car and I probably would have scared myself if I got in a neutral car. Now with the same understeering car, I get frustrated as hell.

Speaking of corner balancing, be sure to disconnect the bar links. Once the weight is balanced, adjust the link length so there’s no preload with you (or simulated weight) behind the wheel.


Dave
I owe you and Mary a dinner. Not sure if I’ll be back to drive at Laguna anytime soon. Maybe when we see each other at Buttonwillow or something. Any interest in running Big Willow with SV in June/July? I’m dying to try Big Willow again as I think I can dip below 1:40 with better line and new suspension bits.

Tom
I read about SMMR on CC.com a while ago. I suppose membership feature and 22 days/month track access are very nice if you are one of wealthy people who can afford such luxury. Mortal track day participants and organizers seem to be concerned about those wealthy members barging in during track events.

Like this past weekend, for example, there were two 911s, a flat nose and a Targa, running in my run group (advanced intermediate). The median lap time for the group was 3:25-ish and those two were running around 3:50~4:0x!! And they wouldn’t point people by, until they got their hands slapped by the event officials. My buddy Brian, who copied my idea and got himself an E30, was running 3:48 in the beginner group. I can totally see more of this happening.

I have no problem with people with nice cars with not-too-impressive driving skills, so long as they’re honest about what they're capable of. Unfortunately it seems too many of them think they are entitled to be in the faster groups just because they have fast cars. Honestly I think everyone would have had more fun if those two stepped down to the beginner group. P-car drivers would have been able to concentrate more on driving instead constantly watching mirrors for overtaking cars, and we would have had more clear laps.

The best I did was 3:28.2. I did that in the morning with some traffic. Unfortunately by the time I got used to the track, it was getting hot and I started to lose my tires and brakes. I’m a little disappointed with the time. I’ll be back in November event with better brakes and try to do 3:23-ish. You Vegas dudes should come out.

EDIT: Just so my time doesn't look super slow, we ran on new 3.5-mile layout. Good drivers in fast cars (Z06, S2000, Elise, etc) run 3:00~3:10 range.

[CarlC]

To get a level pad in my garage I use a laser level and target the center of the wheel hubs. Working my way around the car I'll place plywood under each tire until all four are at the same level.

Buying your own equipment is the way to go. After doing it a few times you'll be glad you invested in the tools.

[parsonsj]

It's done. It took 4 hours, but the car is aligned and corner weighted.

Numbers: 48% front, 52% back. (exactly as Katz predicted)
Corners are 50/50.

Total weight (less driver, 1/2 tank of fuel): 3305 lbs. Driver weight: too much (to coin a phrase). Loaded weight with driver: 3503. My race diet begins today. :)

The car arrived with 1/4" toe out, -1.4* camber on the left side, and -0.8* camber on the right. Caster was 4* on both sides. I was pretty happy that the car came in level and pretty well set up considering my crude construction methods (tape measure, framing square, 48" construction level on a non-level floor)

Katz designed the car for dual mode, and the UCA is bolted into the street setting now. The street setting has less camber gain and side scrub. We couldn't get more than -0.8* camber on the passenger side, so we put the driver's side there as well. 6 degrees caster. 1/8" toe out. Centered the wheel.

We also set up the thrust angle using a tape measure, and the wheelbase was 1/8" longer on the right side, so we fixed that.

The rear sway bar was left home in the garage, and we disconnected the front bar during the set up. The driver's side bar link had to be lengthened an 1/8" or so to connect back up.

With those changes and no rear bar, the car drove straight, felt much more balanced, still a bit darty, and exhibited no tendency to turn right on gear shifts. I'll have to watch the rear bar to make sure it doesn't induce pre-load when I put it back in.

All that for only $227! Carl, you're right: it seems the tools will pay for themselves pretty quickly!

jp

[parsonsj]

The guy that did the set up is a driving instructor at Sebring. He's my new friend, and he'll be doing some co-pilot work with me. That will be fun.

jp

[nbecker]

Please post a video when you track it,I would love to see that car in action!

[Salt Racer]

My estimate of weight was a bit too optimistic. Carpet, insulation, A/C, big full-length exhaust pipes, etc, add up quite a bit. You may have to bump up spring rate a little WHEN you start pushing the car hard.

I guess we’re paying the price of designing the whole thing via e-mail/fax/phone calls. You should have been able to get more than –2.0* camber easily. Moving the UCA mounts to lower holes should give you some more camber, but not by much. Try backing off the caster and see if that will let you have more camber next time you align the car. Making new UCA cross shafts (with some offset) is probably the easiest permanent solution.

Did you use heim ends for rear bar links, or did you use poly bushings? If you have OE-like poly & tube end links, you need to trim the tube (or sleeve) to dial out preload. Converting them to heim joints is the best thing to do IMO, if possible.

Good thing you have an instructor friend. He can probably help you establish a good baseline setup for your current driving ability. Be sure to go for a ride when he drives, whether in your car or his car.

[parsonsj]

Oh, I can get more camber. A lot more. Remember, we put the UCA frame bracket on the inside of the frame rail. The design of the suspension places the UCA cross-shaft on the outside of the rail. I have 1.75 inches of spacer there. The problem is that I need a spacer about 1.5" thick so I can shim. It's an easy problem to solve ... it's just that I couldn't solve it there, 30 miles from my shop.

As far as weight goes, I was hoping for something a few hundred pounds less. The car is dyna-matted on the floor, doors, and rear wheel wells. Fully carpeted, hidden stereo (with a sub), console, back seat. (no A/C though). I guess it was to be expected.

My rear bar is OEM poly style, so trimming the sleeve is what I need to do. No big deal, but it will take careful setup of the car to get it level with the suspension loaded so I can figure that out.

jp