Alignment Platforms?

[MVS]

Time to stop begging my way onto everyone else's and buy one for myself...What brands are people using, lessons learned, recommendations, etc...?

Kodiak, Bass, Trubore, MK, etc…


Thoughts?

[Mike Milner]

MK. Can't go wrong . Call Marty and let him know what you have and he will build it to fit your exact situation .Beautiful top quality product and reasonably priced . Good luck .

[Joefisherff]

I've got a Bass Brothers platform and like it - very well built. Keep in mind when ordering the type and size of scales you will be using. The other consideration is your cars wheelbase and weight.

[preform resources]

Truebore,very high quality must see to appreciate as they say.
Dave Craddock

[TimW]

Truebore,very high quality must see to appreciate as they say.
Dave Craddock

Is Jon still making platforms? I sent him an email to enquire but got no response.

[RussMcB]

I may have a platform for sale soon. Haven't thought about price yet. It's made by Elite. Was used for an Indy Lights car. I had the wheelbase and track shortened (professionally, accurately) to fit my Ralt RT-5 (recently sold).

My strong preference would be to find a buyer near Atlanta, because it would be a pain to ship. It is a little bigger and heavier than most platforms I've seen.

[Mike Scanlan]

I have a brand new platform for sale, that I was going to post on here soon, give me a call: 516-621-6280. It's located on Long Island in NY.

[James Hakewill]

At the other end of the scale (haha) from the good stuff already mentioned - you can make your own!

My old scale platform (soon to be for sale along with the scales) worked very nicely - it was made from 1 3/4" thick plywood for the tops of the pontoons, with the weight supported by steel U-shaped conduit running across the underside and either side of the scale cutouts. It sits on six adjustable feet. The scales are 0-300lb Pelouze shipping scales - with rs232 out.

The er, quality, has to be seen to be believed.. :-)

Given the effort involved to make it, and the cost of materials, I don't think I'd do it again.

James

[T.A. Treat]

James,
How did the RS-232 work out for you? Since you are so fast, I guess it works well. I am curious about how you fed them into a laptop and how you multiplexed them together.

[RoadHazard]

I see you've got Danica Patrick's brand of antifreeze there in the back.

[James Hakewill]

I see you've got Danica Patrick's brand of antifreeze there in the back.

That's just for refreshment. Greg would get very upset if I put it in the motor!

As for the RS232 ports -- I never did get around to getting it set up! A piece of wood with screws in keeps all four display boxes together -- then if I need crossweights etc then I either do it on paper in my notebook, or use a simple little excel spreadsheet.

There are only so many hours in the day after all... :-)

James

[GTmule]

How do those shipping scales work? I've been eyeing the 270 pound jobs on ebay (like 69.99) for a while. I'm on a poor FSAE team, and I've been considering this, as it's got to be better than nothing, but I just can't afford a set of L-acres or whatevers.

-Chuck

[James Hakewill]

They work great - but they are not the same as the expensive scales. The model I'm using (Pelouze 4040) has 0.5lb steps for the readout rather than the typical 0.1lb accuracy from proper race scales.

They're much cheaper than proper race scales for a reason - they don't use a load cell, but instead use metal beams with a quartet of strain guages. And no single readout for crossweights/percentages etc. And they're made from pressed steel rather than cast and machined aluminium.

Repeatability is pretty good, and they are well enough calibrated such that I can set them all up, zero them, stand on each one (I'm 157lb today) and get within +-1.0lb. Which is a much bigger difference that you'd expect from a four-way scale setup -- but the biggest error is still within a reasonable range for doing cornerweights.

The biggest factor in repeatability for cornerweight measurements has always been stiction in the suspension/shocks or sideways preloads in the tires. I use little 'squish plates' behind the scale for when the car rolls off, and that gets rid of the sideways preload. Gently bouncing the front and rear suspension followed by jiggling the roll hoop seems to give good results -- with the roll bars disconnected and the shocks backed off of course. (And turning around three times clockwise and saying 'no place like home')..

They are suprisingly tolerant of the car not being centered on the scale.

So, all in all you get what you pay for, but they've worked just fine for me.

James

[James Hakewill]

There's a good article on Longacre's website about using scales here:

http://www.longacreracing.com/articles/art.asp?ARTID=14

James

[dereklola]

Time for me to make my annual comment on corner weights.

What's all this about +-1# maybe not being accurate enough - "'good scales show 0.1#" - etc.

Fellers - no track is perfectly level, we're not going to the moon and we never turn left and right at the same time. Forget this extreme accuracy - none of us can detect 1% or 2% variation on the track. Forget it. Get over it. Just because your scales can to it and you heard Jean Todt say it does mean that we need it. Same applies to suspension settings. I'm not saying don't be diligent and careful - just not to these extreme accuracies.

End of annual rant.

[Brian]

I have a set of Pelouze PEL 4040's which are 400 pound shipping scales, I like them a lot for what they cost me (Thanks, Derek!). No platform - garage floor is level enough (within 0.1 degrees of level does it for me, using a Mitutoyo digital level, as of last weekend, needs some shims in the spring If I had a heavier car, there would be an issue, or course.

Brian

[Jim Garry]

Ditto Brian's post.

Jim

[R. Pare]

.1 degree slope from scale to scale comes out to about a .101" height difference. For a modern car with fairly stiff wheel rates, this could mean as much as a 60# crossweight change!

Can you feel that? Damned right you can!

Can your tires notice a 10# crossweight difference? Damned right they can over a session!

Guess how fussy you get depends on whether or not you want to maximize your tire $$$ useage, never mind have a chance to win.

[dereklola]

Richard

I value your opinion but my point is that trying to measure corner weights to 1# [or by implication 1/10#] is nonsense if only because no track is that smooth and, my favorite comment, 'we never turn left and right at the same time' by which I mean we end up adjusting left and right sides separately depending on how the car handles left and right. I hope you agree with this. If not I'mstill willing to learn.

Another question for you, Richard or anyone else, after a race do you ever end up with the car perfectly 'square' - exactly equal left and right?

I agree with you over 1/10" diff between scales being too much with stiff springs.

Derek

[R. Pare]

True - trying to adjust these cars to 1# accuracy is hard, if not impossible, but can be done with a bit of forethought. If you are really trying to understand your car, and get the most out of it, you need to think in terms of repeatability and consistancy.

For instance : Each track you visit will treat the tires slightly differently, and as a consequence, affect the tire growth every session. Assuming that the car is set up and driven the same each time out, the growth changes can be mapped and compensated for in the setup so as to make the car come to square at the end of the session or race (generally the faster setup), rather than go away from you (denoting a slower setup).

To achieve this, the car will want to be set up unsquare to start. However, if your alignment platform cannot be set up exactly the same each time, and then compounded by the inability of not being able (or willing) to set corner weights repeatably accurately (a 5# change in crossweight at the front can dramaticaly affect tire growth), then you do not have a chance in heck of getting the most out of the car at any time, never mind consistently.

And yes, cars can, and have been on a regualr basis, been set up to have the corner weights come out even at the end of the race.

[Scott Hanba]

This is maybe getting a little off track, but how soon after a session does the tire circumference start to shrink back down from its hot condition. Does it follow with pressure or temp? Pressures seem to stay up longer than temps do. I would like to keep records of this, but its is hard to do on pit lane w/o a jack, and by the time you drive back to the paddock spot, you've pick-ed up so much junk it is pointless to check then.

[R. Pare]

Once the tires grow, they stay there unless you bleed out the air before the tire cools down.

[SteveG]

...(within 0.1 degrees of level does it for me, using a Mitutoyo digital level, as of last weekend...
Brian

Check the accuracy of your level, most are +- 0.1 degrees at the temprature at which they were calibrated. So your "within 0.1 degrees..." is more like "within 0.2 degrees" at best. In my experience (reinforced by Mr. Pare's chassis class and Neil Porter's proper setup of my car) Digital levels are not accurate enough for chassis set up save setting camber. I purchased a machinist bubble level with, I believe, 10 second vial graduation accuracy. I compared my cool digital level to the new bubble level and, well, no wonder my car handled like sh!t... The digital level was off by up to 0.5 degrees no matter how many times I calibrated it.

If you'd like to find out more about digital level accuracy, just google "digital inclinometer" and read up on the accuracy (not resolution) of the electrolytic and MEMS sensors which all digital levels are based on. You'll be suprised at how inaccurate these sensors are.

Steve

P.S. Sorry, didn't mean to hijack your thread.

[Brian]

Steve, you definitely got me thinking about the accuracy of the level. So I got out my machinists grade level (prior to this used only to level the lathe until I learned how to set up a lathe without worrying about dead level) and checked the Mitutoyo. It was as accurate as the machinist's level but as you point out, that could change based on various factors. But it was accurate to it's level of granularity, it seems extremely repeatable, and it has the great advantage of telling me what any angle is, not just zero.

Brian

[Bob Ramberg]

Richard - what do the pro's use to set caster and camber?

Brian - what Mitutoyo instrument are you referring to?

I have a Smart caster/camber gage and I am looking for a machinist level. What is the best size to get - 6", 8" 12"?

Thanks,

[SteveG]

Brian,

I use my digital level all the time, just not for setting up the setup pad.

Bob,
Don't know what Brian has, but last time I checked Mitutoyo makes a couple of different digital levels, one under $200 and one well over $300 with the primary difference being accuracy, 0.1 degree vs. 0.05 degree.

Steve

[Brian]

is the level I have been using, actually belongs to my partner. http://www.mitutoyo.com/catalog/pdf/S-03.pdf

I take your point about the granularity, hadn't followed through to the result of .1 degrees over say 5 feet of track width. But taking an average of .05 degrees of error, from what Richard said that's about 50 thou. over a typical car track width. I can live with that, I just graduated from setting ride height with a tape measure.

http://www.kbctools.com/usa/Navigati...m?PDFPage=0687

Has several accurate levels. I guess you would really need the Starret Master Precision level, to get the accuracy of half a thou. per foot that is what 10 seconds translates to. At that level of precision I think the big challenge will be keeping the car at the 68 degrees F. or whatever temp you setup the car at - push-rods change length quite a bit with temperature change, you know...

Brian

[carnut169]

When we set up our platform 2x3 machinists blocks are placed on top of the scale pads and a screed goes on top of the blocks (after we have it close w/ a regular level). We check front to back, side to side and cross for being level with a Starrett Master Precision level #199 (.0005 per ft), although the Starrett 98 is probably good enough (.001 per ft). A tiny adjustment will move the bubble in both levels- the 199 just takes a little longer to react.

Too much? Probably.

Just be sure to always put the platform together the same way, and use the level the same (I've marked ours and the marked end always points to the front or the right).


The longer the level, the better.

[R. Pare]

A steel pushrod of 20 inch length will change by .0012" for a 10 degree F temp change. Not really worth worrying about, even if you discount the fact that the a-arms and frame will grow at the same rate, thereby cancelling out the pushrod change.

However, that .05 inch slope will still give a 15 pound inaccuracy with a 300 pound corner rate.

[Bob Ramberg]

Richard - How do the pros do it?

[TimW]

[size=1]I'm not sure how the F1 guys do it, but normal practice on a CART paddock was a surveyor's sight and 8 'targets' which had metal rules embedded in them, manufactured so the rules sat accurately the same level above the bottom of the targers. Essentially, the resolution of the rules was 0.010, so each corner was within that and the back & front pads were also within 0.010. Some also used a contractors laser level against similar targets, which seemed to go a bit quicker & require fewer people.[/size]

[R. Pare]

Actually, when using the surveyors sight and scales, you can get the resolution even finer than the .010 by remembering that the crosshair (which if I remember right are actually finer than .001" wide) can be set at either edge of the lines on the scales, as well as in the middle of the line. Getting the platforms level within .005" is pretty easy with this method, and preferred by most top teams.

The biggest problem with the laser is that the resolution is hard to get finer than the diameter of the laser point, which quite often is up around .020" and even larger.

[Bob Ramberg]

Once set up, what do they use to measure caster and camber?

[TimW]

I recall castor was always measured before going on the pad, once the front end was together and still on high stands. The upright was supported at a position where the pin heights were at a ride height position. Bump steer was measured at about the same point during assembly. Camber was measured on the pad. Both mesurements were made with digital inclinometers, but usually the Mititoyo unit. Wings were measured with same device, but with an adapter that allowed the inclinometer to span the chord repeatedly.

[R. Pare]

The caster is set up via careful measuring and setting of the arm lengths before installation. Once the measurements/caster produced are verified at the start of the season, there usually is no need to re-verify it every time new arms are put on the cars, though the really concientous mechanics still double check.

Camber is usually checked using a set of dedicated wheels with precision machined surfaces where a special bar is clamped for a precision digital inclineometer.

Toe is checked with a mirror setup similar to the Dunlop Gauges.

Of course, each team chief engineer has his own preferred ways of doing things, so the exact shape of the equipment can vary a lot, but it still usually boils down to the use of inclinometers.