Something didn't smell right. What do you think?

[PineNut]

The pack race was held this past weekend. 2 cars walked away with the win...both brothers. I'll admit that the competition in the pack has increased dramatically in the last few years with the addition of a 4 lane aluminum track, timer and software...but these two cars could not be touched. They were running anywhere from .02 to .05 faster than the next top cars (beating them by a car length - which is a lot - considering the competition). I did not have a car in this years race, but can tell you from the past years, the other cars in the pack are good, well, better than good in that the district winner normally comes from our pack (33 packs in district).

Something just didn't seem right. The times ranged from 3.116 to 3.183. This is on a Piatedosi Oar, 4 lane Alum, Micro wizard timer, with micro switch at 40 feet (used 8 track sections). To give you an idea, the best time on the same track was the previous year at 3.194 - and this car won overall district beating 145 other cars.

Our rules are super strict. We check weight, length, must use grooves, axles must be visible from underside, can't be embedded higher up in car, no major wheel mods allowed, must be able to see tread, you name it, we got it covered.

Best part is, dad claimed boys built the cars all by themselves! Yeah, and last year's winner was built right out of the box with no mods! Ha Ha!

Question to all: What in the world is going on here? What possible design feature could provide such a huge advantage to the rest of an already extremely competitive pack? I am thinking grooved axles (which are illegal, but no way to check, but after reading posts, don't seem to provide much advantage anyway). Any thoughts?

Pinenut

[davem]

Possibly lube.

What track was used?
Reason I ask - I have seen .06 time difference on a track with 3 ft. vertical drop (not as large as most modern tracks).
The graphite (Hob-E-Lube) cars kicked butt over Krytox...however - the cars were within .005 on a 42 foot aluminum track.

[PineNut]

Piatodosi Oar Track (I think Micro Wizard purchased the rights), but its the smooth curve track - does not have the pre curved piece.
40 foot, 2 years old, anodized, smooth, smooth, smooth.

Could be a lube - but I'll be honest, doubt that's it. Our track looks like a graphite construction zone at the end of the race. EVERYONE uses lube. Most use the Hob-E-Lube but many use customized lubes from internet (Hodges Hobby House, etc.).

These cars had the jump at the gate and continued to speed it up through the finish. The one car length win was against the next top cars during the "Finals" phase of the race. During elimination phase, if the cars were up against mediocre cars, the win was a blow out by 4-5 car lengths.

[ohiofitter]

Pinenut it sound like maybe thay had on lighter wheels or 1 gram wheels.........I have read enough here that the lighter wheels will get the jump at off the line....This year we had a dad race and my car had the 1 grammys on it and the car seemed to be half way down the hill by the time the other cars started.............I was really impressed by the wheels.

[davem]

A "jump at the gate" sounds like lightened wheels may be present to me as well. We are allowed to run lightened wheels - and doing a frame by frame analysis of video shows the light wheels have a clear advantage at the start.

Was there any serious wheel inspection at check in?
One of my pet peeves is when un-informed people are doing check in inspections.

[PineNut]

My son was a Webelo 2 last year and now in scouts. I was there to help out for setup, early morning and cleanup. I did not inspect the cars. And yes, our rules are looking for the nubs on the outside, but I would spot the thinner inner tread in a heartbeat, but I did not run inspections and normally don't anyway since I am normally running the race. We will see the cars at district.

Lighter wheels - they are illegal in our race. What am I looking for? Thinner tread or do they take the weight out of the inside hubcap area? Or both? Any way to tell?

[priority]

Lighter wheels - they are illegal in our race. What am I looking for? Thinner tread or do they take the weight out of the inside hubcap area? Or both? Any way to tell?

I agree with the others that lighter wheels are the most likely source, assuming something nefarious has gone on.

MaxV's website has pictures that compare different wheels. http://www.maximum-velocity.com/prostoc ... saxles.htm

Scroll down a bit and you will see the insides of the wheels. The 2.1g wheels are easy to miss without a knowledgeable inspector because all the interior markings are still intact.

Also, I ran a simulation for these wheels versus a stock wheel and found the difference in time to be ~0.035 seconds...

Also, just to add another option: are you checking for magnets in the nose of the car? I am not familiar with the start gate on an Al Piantedosi, but if it is metal like on a BestTrack...

[gpraceman]

Also, just to add another option: are you checking for magnets in the nose of the car? I am not familiar with the start gate on an Al Piantedosi, but if it is metal like on a BestTrack...

They come with stainless steel screws for the start pins, which are non-magnetic.

[mbb]

lightened wheels may or may not get a jump at the start, bore polish affects that a lot, and how quickly it goes to the rail. They will accelerate out of the transition and and pass up cars that beat them to the bottom though.

You said it yourself, you have strict rules and checked for everything. Lightened wheels would be obvious.

How about great alignment and superb bores and axles?

Kids can build a fast car as well as an adult, IF they are coached and told what to do every step of the way. Thats how we do it.

Having a kid build a car DOES NOT mean that the dad keeps his mouth closed and doesnt tell him exactly what to do and watch over him every step of the way. My son lathes his own wheels once I have it set up for him, no problem.

I tell him what to do, hold things for him while he drills them, etc, and help him, but he does everything, and he does well at council.

[priority]

Also, just to add another option: are you checking for magnets in the nose of the car? I am not familiar with the start gate on an Al Piantedosi, but if it is metal like on a BestTrack...

They come with stainless steel screws for the start pins, which are non-magnetic.

gp-
I had not even thought to check before your comment. The start pins are non-magnetic on a BestTrack as well.

[ScoutAndDadTeam]

I cannot speak for older Besttrack pins -- but I checked our new track that was just delivered last week.....The pins are non-magnetic.

[mbb]

Austenitic Stainless steel may not be "non-magnetic". It can depend on the cold worked state of the metal. While a normal ferritic magnet might not be attracted to some pieces, rare earth magnets (samarium cobalt or neodymium) might be.

We use rare earth magnets in process machinery to pick up tramp metal or such all the time. Never found a bit of stainless steel that they missed because it was "non magnetic"

[priority]

Stainless steel is not "non-magnetic". While a normal ferritic magnet is not attracted to some types, rare earth magnets (samarium cobalt or neodymium) may strongly attract to it.

Technically speaking, stainless steel as term is nondescript wrt magnetic properties. Austenitic stainless steel has nickel (in addition to chrome) added which alters the physical structure of the steel and renders it non-magnetic. Martensitic stainless steel does not have nickel and is magnetic.

I did test a BestTrack with a neodymium magnet and could not detect any attraction with my "finely" calibrated fingers.

[SubnetZero]

I'm still kinda new to all this (just second year)...

Last year we ran mediocre, this year I did lots of research and me and my son applied our new found knowledge..

At this years race, our car won most all our "heats" by multiple car lengths.. Some races we were at the finish and the rest of the cars still had a whole section of the track to run..

I didn't do anything "secret" that hasn't been discussed many a time here on this forum(Correct COG, Polished Axels, MaxV graphite, deburred wheels, Decent Alignment, etc etc)..

A few races were closer, we won by 1/2 to 1 car length. I noticed on the flat coming off the ramp that our car "seemed" to speed up and really pull away...
Maybe they just found the "sweet" spots on their setups??

[mbb]

Stainless steel is not "non-magnetic". While a normal ferritic magnet is not attracted to some types, rare earth magnets (samarium cobalt or neodymium) may strongly attract to it.

Technically speaking, stainless steel as term is nondescript wrt magnetic properties. Austenitic stainless steel has nickel (in addition to chrome) added which alters the physical structure of the steel and renders it non-magnetic. Martensitic stainless steel does not have nickel and is magnetic.

I did test a BestTrack with a neodymium magnet and could not detect any attraction with my "finely" calibrated fingers.

Hey, no fair. While I was clarifying my statement you grabbed it.
Like I said,even although wrought austenitic stainless steels are non-magnetic in the fully annealed condition they will become magnetic when cold worked. Cold work can transform some austenite to martensite, and rare earth magnets are strong enough to attract small amts of it.

In reality, fully annealed 304 or 316ss is hard to come by. Plate alloy has been cold worked, wire has been drawn and cold worked, the surface of anything machined gets hardened (cold worked), etc. Bolts threads are made by rolling (cold work). Unless you intentionally anneal parts, it will have trace magnetic properties. Thats why even though much processing equipement is 300 series stainless, we dont worry about magnets missing it, they get every bit of it, as well as corrosion product from it, even pieces that have cracked off (300 series will stress crack under right conditions, but if annealed would have no residual stresses so it wouldnt. ) I have cleaned 316SS pieces off of many magnets, and it was stuck tight.

If I was making a track I would make sure the start pins are truly non magnetic, and I suspect the track mfgs do exactly that.