Front Wheel Interaction with the Center rail

[Jewel]

Would it be better to camber the front wheels of the car so that wheels are angled about 5 degrees and the inner edges of the wheels are raised so that you get a single point of contact with the center rail?

This allows the car to roll when it touchs the center rail as oppose to scrape when the wheel is angled vertically.

I won an adult highly competitive race using angled front wheels, and neutral aligned wheels in back using the Stan Pope method of alignment.

I also found that making the car go straight was really much easier with the front wheel cambered. Our track is bout 48 feet long, so you really need to glide a long way and avoid losing speed to the inner rail.

[RACER X]

There are several chains of thought on this topic. First, i still believe that if the wheel is square to the car and aligned properly it will float back and forth between the axle head and the body, this would be your point of least friction. Second, the inside edge of the wheel needs to be true. if it is not, it will cause the car to kick side to side as it hits a high spot on the edge against the guide strip. I know this set-up can be a bit tougher to align, but we have been very successful with it.

[MaxV]

With axles cambered as described, the wheel hubs will constantly rub against the body of the car. Also, the distance between the wheels may be reduced slightly, resulting in more contact with the guide rail.

Cambering wheels the other way also has its share of problems. So all things considered, I believe that flat is better.

[Stan Pope]

A small bit of anecdotal evidence:

For the 2002 Prairielands Council Race season, I assisted my Son-in-Law, Grandson and Granddaughter to build cars.
Grandson: Rail design with level axles, one front wheel up.
Granddaughter: Rail design with axles canted up.
Son-in-Law: Rear axles canted up, front axles canted down.

Body design for all: Rail
Weight distribution of rall: 80% on rear axles.
Wheels for all: fresh from Hugh plus coned hubs.
Axles for all: kit, polished, coned heads.
Wheel alignment for all: "looks okay"

My grandson lives about an hour and a half away, and we were unable to get together a second session to align wheels prior to pack race. They went with "looks okay" alignment.

Following the Pack races (which Grandson swept), these cars raced head to head on a 4'X32' track with substantially dead heats.

Son-in-Law and Grandson came back for a wheel alignment session. Preliminary look said "Yech! Lots of room for improvement!"

With guidance from Grandpa, Son-in-Law and Grandson align wheels per procedure in LBW. Grandson sweeps 130 car Council Races including 8 consecutive alternating lane wins over 2nd place car. (Race format: Cars divided into four groups for preliminaries. Double elimination preliminary where each "heat" is best 2 out of 3 runs on alternating lanes. Top two cars from each of four preliminaries meet in 8-car double elim finals using same definition of "heat". 2nd place car was in grandson's preliminary, losing there only to Grandson (4 times) and then losing 4 more times to grandson in final. The kid felt "snake bit," I think. He had arrived with high hopes of 1st place trophy.)

[Jewel]

Very interesting feedback, empirical evidence overturns slippery issues of theory. However, here a few more details about my car.

Body design: Rail
CG. 1.7 inches from rear of car
Wheels polished, hubs straight no tapering is allowed.
Axles for all: kit, polished, perpendicular heads. no coned heads allowed.
Wheel alignment in rear per LBW, front cambered down 7 degrees
Body Bearings. .050 steel ball bearings directly below each axel.
Track: 48 feet with about a 6 foot drop, 28 feet of flat with a 6 inch rise on the flat. The guide rail of the track is 1/4 inch plywood about 1.5 inches wide and is moderately smooth.

Discussion:

The frictional losses from cambered wheels in the front only may have been minimized by the use of a small ball bearings. I checked with race management and they were legal to use. Do you think the ball bearing glued onto the body of the car were an advantage? With this new evidence would you be tempted to camber the wheels to improve the rolling of the car with the long track against an imperfect guide rail. Does the 1 oz. xg downward force on the front wheel indicate lower the friction on the front wheels to make cambering in the front only a good tradeoff?

It seems that from Stan's response that the choice is clear. The races won show that cambering is a flaw period. I must reveal a weakness in my building technique that also influenced my decision to camber the front. Achieving excellent alignment per LBW and excellent straightness of the car has eluded me. I found that I could get good rear wheel alignment and good straightness, but not for all three wheels at once.

In tuning the straightness of the car I found that having a slightly bent front axel and then turning it will a set of needlenoze pliers allowed me to get the car to run very very straight with good LBW alignment in the rear. With this additional discussion I would like to be further convinced that I have a flaw in the design of my car, relative to the track I race on. I want to seize opportunities for improvement since this is a yearly race at our company.

Thanks for your insights and I am leaning toward keeping it all straight.

[Jewel]

I am still concerned about this element of front wheel camber choice. The rear wheels I don't think hit the center rail often and they have twice the weight on them and thus twice the friction. My advice would be to keep the rear wheels neutral with LBW alignment. But I think the front wheels do hit the center rail and when they do the breaking torque is high because it hits at the max wheel radius. Avoiding the high braking torque might make this a potential trade off against classic LBW alignment.

[RACER X]

I believe that it would be a trade off between braking torgue on the guide strip vs. riding on the axle head, you would have to make a decision which one you prefer.

our alighnment was incrediable this past season, so thats a concideration, but after reviewing the video from our pack raced, the car touched the guide strip lightly on average 3 times momentarly. It was like it tapped it and cleared away, never hugged.

The axles were level on this car.

[RacerRusty]

LBW = Load Bearing Wheels?

I checked the encyclopedia and LBW was not list.

[Go Bubba Go]

Rusty:

LBW - Learn to Build a Winner - a reference to Stan's On-Line book of the same name (see link below).

http://members.aol.com/standcmr/lbw_apl.html

I occasionally have some trouble linking there directly and have to open another browser, start at Stan's home page ( www.stanpope.net ) and use his link. Don't know why.

The section on wheel alignment is under IV. Workshop 101 section 5. Wheel Alignment Techniques.

I have enjoyed watching you "blow the dust off" some of the old postings... Started out that way myself about 6 months ago

Lots of good stuff here.

Regards, Bubba.

[RacerRusty]

Rusty:

LBW - Learn to Build a Winner - a reference to Stan's On-Line book of the same name (see link below).

(Slaps forehead)

Bubba,

Thanks. Have you ever asked, what you thought to be a completely reasonable question at the time, but when someone answers it you realize the answer was so blindingly obvious that you wish you hadn't asked?

I am VERY familiar with Stan's web page. I have been all over it. It's at the top of My favorites list under the "PWD" heading. Admittedly I have not read Stan's book, I'm trying to read all the threads on the board first, but it IS on the top of my list (yes I actually have a Notepad document on my desktop with a list of things from this board to get back to). I have not checked yet, was Stan's book ever actually published? For some things I just prefer hard bound. Links are wonderful but sometimes nothing beats being able to dog ear a page. Know what I mean?

I have enjoyed watching you "blow the dust off" some of the old postings... Started out that way myself about 6 months ago

Thanks. Honestly I was a bit worried about irritating people by dragging up old topics.

Thanks again, Rusty

[Stan Pope]

I have not checked yet, was Stan's book ever actually published? For some things I just prefer hard bound. Links are wonderful but sometimes nothing beats being able to dog ear a page. Know what I mean?

Rusty,

Thank you for asking! The answer is that it was "published online" but not "in print."

There was thought early on to do so, but I looked at the logistics and the population and decided that the council would get more out of it this way. One major consideration is that I didn't want to get in the way of the flow of $, and any tax and accounting repercussions that might follow. The council, on the other hand, was already set up to track and make any necessary reportings.

[Go Bubba Go]

Bubba,

Thanks. Have you ever asked, what you thought to be a completely reasonable question at the time, but when someone answers it you realize the answer was so blindingly obvious that you wish you hadn't asked?

You mean, like proposing a Split Front End that would allow for independent front suspension but wouldn't trigger the finish line laser? LOL

Never, not me... Well, OK, usually once before Lunch and twice before bedtime.

I am VERY familiar with Stan's web page. I have been all over it. It's at the top of My favorites list under the "PWD" heading. Admittedly I have not read Stan's book, I'm trying to read all the threads on the board first, but it IS on the top of my list (yes I actually have a Notepad document on my desktop with a list of things from this board to get back to). I have not checked yet, was Stan's book ever actually published? For some things I just prefer hard bound. Links are wonderful but sometimes nothing beats being able to dog ear a page. Know what I mean?

Understand your affinity for "dog ears", I printed out a copy and put it in a 3 ring binder with index tabs . Just add highlighter, pencil/pen, reading lamp and a comfortable chair and you ought to be good. I recommend you consider reading through his book once right away so that you have a mental reference point against which to compare the various viewpoints you will find on DT. Every 6 months or so you might want to sit down and read through LBW again. One of the authors I respect most (Eli Goldratt) once made a comment about one of his books along the lines of this "If you only read the book "The Goal" once, you don't know how to read".

I have enjoyed watching you "blow the dust off" some of the old postings... Started out that way myself about 6 months ago

Thanks. Honestly I was a bit worried about irritating people by dragging up old topics.
Thanks again, Rusty

Personally I much prefer "pulling the string" a little farther on an existing thread than creating an entirely new one. A user is certainly free to skip over the "old stuff" and go straight to the latest reply, but IMO they risk skipping over some material that might be new to them or at least in need of a refresh.

[RacerRusty]

Stan,

You are most welcome. That was not the answer I wanted to hear of course but it does eliminate my nightmare "Worst case scenario". I had this vision of ending up on E-bay in a bidding war with Bubba, MaxV, RacerX and a dozen or so others over an original printing copy.

And the way people around here bird dog E-Bay for completed cars and other things, there was 0% chance of a copy slipping thru unnoticed.


Bubba,

Understand your affinity for "dog ears", I printed out a copy and put it in a 3 ring binder with index tabs . Just add highlighter, pencil/pen, reading lamp and a comfortable chair and you ought to be good.

The best option left.

I recommend you consider reading through his book once right away so that you have a mental reference point against which to compare the various viewpoints you will find on DT.

Yea, I was already getting that impression. Your good advice backing up the gut feeling I was already getting. Good sign I should follow thru. I guess I'm off to read Stan's book now.

Thanks again,
Rusty