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Yeah... I've had a few thoughts this afternoon. Maybe a small "puck" to hold a laser pointer to the disc brake surface (magnetic maybe). It could then be moved around to point at the other side. It would be nice to have the laser alignment be "hands free". Probably need to measure run out of the disc.

Like this...

If you've got a "floating" disc... that won't work! If you don't, that should be your next mod...full floating discs.
 

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Discussion Starter · #62 · (Edited)
Humm... Calibrating the Flyin' Miata hub stand toe bar on the Lotus is complicated by the fact that there is precious little hub exposed once the hub stands are bolted up. In addition the face of their hub stand provides little in the way of a place to put an alignment laser pointer. Once you have a pointer held against the hub you are hard pressed to reach down and turn the alignment knobs.



I think any solution to this needs to allow for "hands free" attachment of the laser alignment tool. After playing around a little last night I think either an additional "plate" sandwiched between the wheel hub and hub stand (like <@¿@> has suggested) or a provision for mounting another sort of laser "holder" is in order. I'm leaning toward drilling and tapping four holes in the hub stands in-between the lugs to allow for mounting a parallel plate for alignment. I like this because it will allow you to remove the plate if necessary and might facilitate a un-foreseen contingency later. It is (of course) important to make sure any bar attached in this manner is truly parallel to the back face of the hub stand.

Actually... I'll probably drill and tap the holes and make a set of plates to sandwich.





While the stands are off the car I'll cut away the material that interferes with the screw heads on the brake rotors. The washers under the hub stands are another variable I need to eliminate before putting much stock in the "numbers".

 

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I'd like to take the top part off the stand and machine (fly cut) a flat surface on the inside to mount your calibration bar.

On the other hand, why don't you just make a horizontal plate that mounts in place of your washers. Like you are thinking, just one flat piece that goes through your hub bolts. I don't like your idea because you are introducing 3 points of error (tolerance) for each material you add. For inspection, you want as few as possible.
 

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Discussion Starter · #64 ·
OK... I'm off to make Horizontal plates, tap some holes, and cut reliefs into the stands!

The closest I have on my stock rack is 1/2" thick 4" wide 1018 cold rolled, so I guess I'm off to Discount steel in the morning. They pretty much always have exactly what you want and are great to deal with.



 

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whoa, I was thinking to buy and install some Nitrons too but i didn't know you had to get all this other stuff too.
 

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whoa, I was thinking to buy and install some Nitrons too but i didn't know you had to get all this other stuff too.
You really don't need all that stuff. jimarneson is just trying to make an easy setup to get reproducible, accurate alignment measurements at home.

All you really need to align a car is jacks and stands, strings, some lengths of metal, and rulers, but it's both time consuming and difficult to do perfectly each time.

To corner balance at home you need scales, rulers, and the ability to create a very level surface - again, doable without all this gear but time consuming to do right and create reproducible measurements.

Alternately you can spend $200-$500 to have a race shop with an alignment rack (the professional way to get reproducible, accurate alignment measurements) do a ride height, corner balance, and alignment job for you, which I personally would do anyway to get a baseline setup to work off of. That gets expensive if you're tweaking all the time, but for a one-setup street/HPDE/fun driving kind of car it's probably all right.

In short all you *need* to do to get Nitrons on right is budget an extra few hundred bucks for an alignment.
 

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Jim,

Don't forget to check/correct runout of the wheel mounting surface. Torque up your plates to the hub and use a dial indicator while rotating the hub. It doesn't take much runout at all to potentially cause a significant error in setting toe -- this is especially critical if you are trying for minimal or zero toe.

When I was racing, we always made sure all hubs on all our cars were true. We almost always ended up machining the hub surfaces of the wheels also. Much of this effort was pre-CNC so a bigger issue than I would expect nowadays. BTW -- I did this as early as the late 1960s at Ford as a ride and handling engineer so that when developing alignment specs we would know what I chose as design/manufacturing specs really was directly based on what I tested. Unfortunately, tire (non)quality negated most of my efforts to be precise.
 

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Discussion Starter · #68 ·
Yikes... you can get this done for $500. I've spent almost 10 times that and the Lotus isn't aligned yet!
 

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Discussion Starter · #69 · (Edited)
As Promised... We started with breakfast at the Egg & I on Lyndale.



Made our way downtown to Discount Steel.



Got the guys outside working to cut off a piece of 1/4" x 4-1/2" steel.



Went inside to see the cashier and shopped around a bit in their new "retail center".



Then drove out the way we came in.



That's my 12 year old daughter who likes these Saturday morning outings and is actually willing to hang out in the garage with a wrench in her hand. Now all we have to do is teach her to drive a stick...
 

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Discussion Starter · #70 · (Edited)
I decided to take another run at calibrating the FM toe bars before starting to fabricate any spacers. I bought a Bosch line and point laser at Home Depot on our way home from Discount Steel. It has a much nicer laser spot than the cheap laser pointer and is not too big.



The front hubs have a little more exposed front face and the Bosh laser sits nicely on it. The combination of having nice flat bottom on the level and a nicer laser spot made it fairly easy to get the front toe bars lined up nicely. The spot is almost exactly 1/8" diameter which allows for a nice precise reading. I'm much more confident of these "numbers".



Front toe measurement point...


Rear toe measurement point...


For the rear hubs I held a small aluminum plate in place under the level. This made the rear calibration go nearly as well as the fronts.





Once the toe bars were lined up I took another set of alignment numbers from the fixture. This set shows 3.5mm toe out on front and 3.2mm toe in on the back.



I think I'm still going to fabricate a set of spacers even though the better laser greatly increased my confidence. I think a "hands free" system for supporting the laser would take any remaining uncertainty out of the system. The Photo-shopped image below shows what a 7-1/4" round spacer would look like under the laser. I'm going to talk with my laser cutting friends before I start making any on my own.

 

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Discussion Starter · #71 · (Edited)
I found these EZ-Mark Line Cords at Rockler in Minnetonka this afternoon. I tried them out on my alignment fixture and they'll work great.



The Rockler clips position the string closer to the surface of my scales and slide back and forth really nice.





The line is elastic and and a little smaller in diameter than the masons string I've been using. I like the bright yellow color and would like to get rid of the springs I have in the middle of my set up. Since these are all too short I'll have to find a supply of elastic string but I'm guessing that won't be too hard.

 

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Discussion Starter · #72 · (Edited)
I stopped by Handcock Fabrics last night and picked up some elastic cord. They sell it in 1/32" and 1/16" diameter. I bought a couple packages of each and plan to pry open the Rockler clamps and install the new cord.



I've been playing around with the alignment system for the last few evenings trying to get a feeling for how repeatable it is. I'm starting to think that our old friend Carl is on to something when he measures toe using the Advanced Racing Technologies Laser Toe Gauge. I'm struggling to get my toe measurements to repeat much better than 1/32". The Flyin' Miata system relies on measuring toe across the car using tape measures. The issues with repeatability are caused both by calibration difficulties and the fact that it is easy to "bump" (or slightly move) the bars as you work around the car. Implementing the ART system with the wheels off the car would (of course) require having a "surrogate" wheel in place on the hub. The Ferrari guys in the photo here seem to be doing just that.



The hub stands facilitate setting ride height and corner balance without the wheels installed but probably set a limit to how well you can measure (and set) toe. Is alignment within 1/32" an acceptable result?

 

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Your error is about 3X of what it should be. You're getting ± 0.03" and you should be able to get it down to ± 0.010". It doesn't take much "slop" in the system to get large variations at the 24" wheel diameter.

All of the F-1 teams use what is called setup wheels...that is what you are seeing the Ferrari guys using. They are machined discs that have the nominal rolling diameter at the wheel offset. So, if your front wheels have 28-mm offset, these setup wheels have that same dimension from the mounting face of the wheel to outside plane of the setup wheel.

BTW, do you have the OEM rubber wishbone bushings, or aftermarket steel bearings like Nitrons? If you still have the OEM rubber, your error will very likely be there...
 

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Discussion Starter · #74 ·
Its interesting... It is easy to read the position of the string used in the system to .010" (using the OD in this example) and only a little harder to read the laser spot on the tape measure. The trouble comes when you set out to calibrate the toe bars using the laser. Even with an improved laser... positioning it on the face of the brake hub is difficult. I've "started over" quite a few times now and will have to say the numbers are repeating to about 1/32" (.030"). It is important to remember that we're talking about not only the toe bar calibration but also the 65" gap between the right and left sides of the vehicle. A small change to the toe bar alignment (calibration) gets magnified across the system and .010" disappears pretty quickly.







I am now thinking about making a "hub spacer" that will not only provide a stable platform for the laser level but is also large enough in diameter to measure toe directly with another system like the ART laser toe gauge. Something like the Photo-Shopped image below.

 

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Bottom line; you are way over complicating things and over thinking this... I can't keep up with you.

Look, every time you add a piece to your system, you are adding complexity and introducing error. Look at the F-1 guys. They put on a setup wheel. you are putting on these funky stands that have; the top piece that mounts to your hubs, a pin to the stand, a stand the measure bar and I will guess 4 rollers with axles...let's see...that is 12!!!!!!! You are introducing an order of magnitude increase in error! Each piece part of your system will wear with use and always be off.

You are essentially building a Rube Goldberg machine here out of a chassis setup stand...

Step back. Have a beer. And think... You are working way too hard here... work smart, not hard.
 

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Just an observation here so if it's wrong then my apologies upfront.

With Exige/Elise cars we don't have thrust angle because we actually have no solid axle (1 piece from the left to right hubs) in the rear, we actually have a front suspension set up in the rear so we have front end and rear end toe measurements.

Also the way you are measuring "thrust angle" is flawed because the measuring string is hooked to your hub stands that move instead of being a stationary measurement from the center of your vehicle as in the Ferrari photo you posted and also I think Jim Clayton had a thread showing a good way of setting up the strings with aluminum angle pieces, padding, and string so that nothing actually touches the wheels and or hubs for measurement.

If you had it set up that way then your measuring string can not move when the hub stand, wheel, and or vehicle moves.

I may be wrong but looking at your photos this is how it appears to me and please don't take it insulting just pointing out what I see. Plus I am getting ready to start mines next week and you are saving me a ton of trial and error with the hub stands lol.




Sent from AutoGuide.com App
 

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Discussion Starter · #77 ·
For... <@¿@>

What ???

Carefully Thinking this through is exactly what I set out to do here. The Flyin' Miata (FM) hub stands provide a (relatively) inexpensive way to place a vehicle on top of corner scales with the suspension properly loaded. The Ball Transfers and pivot allow the assembly to move freely on the scales while the stand restrains the hub. In fact the pivots and Ball Transfers cleverly provide the freedom to move while introducing very little "error". The biggest issue with these sorts of fixtures is friction. The ball transfers are built using ball bearing sockets and are wonderfully friction free. While the pivot is a simple "shaft in a hole" it is a also a very low friction device. The Flyin' Miata hub stands are pretty much the opposite of a "Rube Goldberg Machine"... They are a simple, purpose built fixture designed to artfully solve a real world problem.



Adding a spacer between the hub and stand to provide a better mounting surface for the calibration laser is an unfortunate circumstance caused (here) by the fact that our Lotus vehicles have less exposed brake hub "real estate" available. The numerous advantages to the hub stand approach to setting ride height, corner balance, and alignment requires that the wheels be removed. I believe that the Flyin' Miata hub stands (using "calibrated" toe bars) will prove more than adequate to the task and I am fabricating the "spacers" to help prove it. Making larger (diameter) than necessary spacers will provide an opportunity to confirm the FM toe measurement using a completely independent system like the Advanced Racing Technologies Laser Toe Gauge.

After thinking for a long time about how to respond to your ( <@¿@> ) comments in a constructive manner here goes...

Step away from the keyboard... Put down your beer... Watch and Learn!
 

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Discussion Starter · #78 · (Edited)
For billsaidso...

I want to be as gentle as possible here. You are suffering from the very same misconceptions I had at the beginning of this effort. I studied the string methods in these pages carefully before setting out to adjust ride height, corner balance and alignment on my Lotus. I became aware of Carl Schulhof's system for measuring and adjusting these important elements while watching the videos on the topic available the Sector 111 website (see it here... Sector111 Alignment Tech Seminar Part 1 - YouTube). He uses strings only to measure thrust angle and an independent gauge to measure toe. In the videos he demonstrates a cool Old School "caliper" as well as a laser toe gauge from Advanced Racing Technologies. He points out that accurately measuring toe from strings is difficult and promotes his system as being both more direct and easier. His somewhat unintuitive method is exactly that!

Our cars have thrust angle. This is complicated by the fact that the "Toe" of the rear wheels is adjustable. This is specifically why it is so important to measure and set it accurately.
 

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This thread needs more photos

Bottom line; you are way over complicating things and over thinking this... I can't keep up with you.

Look, every time you add a piece to your system, you are adding complexity and introducing error.
:panic:
 

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