Achieving LBW Alignment and Straightness (LBWA +S)

[Jewel]

How do you get your Pinewood Car into the condition to roll perfectly straight and have the wheels neither move into or out of the body when rolled both forward and backward?

I have read Stan Pope’s LBW (Learn to Build a Winner) book, a must for anybody who wants to roll fast and I am still having trouble getting the alignment perfect. Let me expose my car imperfections bravely so that the truths of my flaws are clear and so that I may eliminate them at the next race.

Q1: I have slightly bent axels. Must you have perfectly straight axels to achieve LBW Alignment (LBWA) and a straight rolling car (LBWA + S)? If they have to perfectly straight how do you achieve this?

Q2: The ID of the wheel (axel hole) must be perfectly perpendicular to the OD of the wheel (tread) to get LBWA + S? If you have flaws here how do you know? Well any amount of shimming help?

What did I do? I shimmed and rotated the axels and the front wheels were cambered. I found that having a slightly bent front axel allowed me to get the car to run very straight when I turned the axel witgh a pair of needlenoxe pliers. I tested the car many times and got it to roll straight enough that I saw no deviation from a thread my car followed over about a 4-foot distance. However, I failed to get the front wheel into LBWA. I have a flaw and how do I overcome it best.

Note that I used wax paper shims to move the axels into proper alignment.

Q3: If you could have straightness or LBWA perfect on all three wheels which would be better? Does perfect LBWA entail straightness?

The basic lesson here for Pinewood racers is that you must start with very straight axels, very straight axel holes, and very nice wheels round and ID to OD concentric? If you start with quality stuff you can achieve LBWA + S using wax paper shimming and use the alignment computer to help you get it right? If there is a flaw in your components it seems hard to get LBWA + S right.

Are there any other methods beside shimming and turning the axels to achieve great alignment? Turning bent axels is a flaw that you have to try and avoid but I think but it may be impossible because you can’t get the axels totally perfect.

Thanks to all for any positive imput.

[RACER X]

[Message edited by the Site Admin since the content fell under the no unsolicited advertising rule.]

[Stan Pope]

Coincident hub and tread centerlines are assumed for LBW alignment.

Wheel tread must be sufficiently cylindrical and regular that the wheel can roll alone in a straight line.

Straight rolling is the first step and an ongoing requirement. The online Java program doesn't talk about this (as I recall). The online Java program description does reference the book, however. I have no association with that Java program.

Bending and rotating the nail is a "never", or is that "NEVER"? Such an adjustment is just too coarse.

Nail straightness is needed to the extent that wheel moving in or out a total distance of less than 1/8" does not materially change its orientation. The method depends on consistent orientation and insertion depth to minimize effect of errors.

[railman]

Stan and others,

Can you provide some guidance on how to use shims with axle holes? Maybe I have drilled the holes too "tight", I can't see how I could get shims and the axles into the drilled holes. Thanks for your help on this.

[Stan Pope]

Stan and others,

Can you provide some guidance on how to use shims with axle holes? Maybe I have drilled the holes too "tight", I can't see how I could get shims and the axles into the drilled holes. Thanks for your help on this.

You are shimming only the outer end of the holes ... about 1/4". Begin by inserting the 1/8" wide shim strips into the hole to a depth of about 1/4". Get them where they need to be to accomplish the desired effect. Fold the shims back against the the side of the car. Then insert the wheel/axle to the planned depth. (I use a piece of wood with a slight, about 1/16", depression so that the wheel can sit on the wood with the axle head in the depression. Then press the body of the car down to the wheel hub. When you lift the car, the wheel has the planned amount of play.)

Does this help?

[railman]

Yes, Stan, thanks. I guess a couple of follow up questions - I think I understand you to be saying the ends of the shims would come out of the axle hole almost like flower petals, right? And these would be trimmed off with an xacto, etc once alignment is achieved?

[Stan Pope]

Yes, Stan, thanks. I guess a couple of follow up questions - I think I understand you to be saying the ends of the shims would come out of the axle hole almost like flower petals, right? And these would be trimmed off with an xacto, etc once alignment is achieved?

"Exacto-ly"

During alignment, just fold them back so that they don't interfere with your tests. Trim them off flush with the car body when alignment is dead-on.