Drilling Angled Holes in the Original Slots?

[whodathunkit]

Some say to have the car set lower in the front and run with toe in on back wheels is better then running it high in the front and toe out in the rear.

With toe out in the rear wheels.. it drives the wheels into the car body and acts like breaks lots of friction plus it opens the wheels up to the wind and catches in the wheel cavity plus the under side of the car.
With toe in the rear wheels.. it drives the wheels out to the axle head.. less friction.. but the wheels still have what is called tread scrubbing of the track as it rolls forward.
So yes any thing you can do to fight off friction to gain speed is a plus.. and key to having a fast car.

Plus: yes it keeps a lot of us Pineheads up late at night.

[Loud2ns]

Some say to have the car set lower in the front and run with toe in on back wheels is better then running it high in the front and toe out in the rear.

With toe out it drives the wheels into the car body and acts like breaks lots of friction plus it opens the wheels up to the wind and catches in the wheel cavity plus the under side of the car.
With toe in it drives the wheels out to the axle head.. less friction.. but the wheels still have what is called scrubbing of the track as it rolls forward.
So yes any thing you can do to fight off friction to gain speed is a plus.. and key to having a fast car.

A little backwards....
Low nose= toe-in, which pushes wheels into the body.
High nose=toe-out, which pushes the wheel into the axle head.

I aim for a totally level car. A little toe-out will be stable, but a bit of toe-in can induce some tail wiggles.

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[Loud2ns]

Opinions? Advantages/disadvantages of each?

I think the $95 gives good value. It can do everything the $125 model can. The only advantage would be a fixed wheelbase, but that wouldn't bother me. My jig needs to be adjusted for every wheelbase, and it hasn't been a problem.

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[whodathunkit]

A little backwards....
Low nose= toe-in, which pushes wheels into the body.
High nose=toe-out, which pushes the wheel into the axle head.

I aim for a totally level car. A little toe-out will be stable, but a bit of toe-in can induce some tail wiggles.

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Thank you Loud2ns
I do tend to get things backwards and mixed up from time to time.

[philm63]

...and to add... I added an edit to my previous post to include the possibility of "rear steering" - thought I'd pull that reference forward here as I did not realize a few more responses had come in. If the rears toe-in or out to some degree, it seems that may also result in possible drift to one side or the other - not a good thing.

Does anyone compensate for this by shimming the jig to provide for a small shift in front-to-back angle when drilling the rears? A small change in the angle of the drill can add a little toe-in or out to compensate for that which may occur as a result of the car not being level in the final assembly phase.

[FatSebastian]

If it is simple enough to do, I'm all in on all of those "small things to gain every advantage".

What type of race or race kit you are competing with... BSA? Awana? Other? (Assuming BSA since you mentioned "Pack rules" in your initial post.) There is an adage that the car's performance is going to be limited by what you've done the worst (least best). That is, the big performance tasks need to be of concern and addressed before attempting the "small things", otherwise the "small things" will be in the noise and won't matter...

Using the original (unfilled?) slots is going to complicate one's ability eek out every tiny advantage, because it is more difficult to get optimal alignment. As you noted in your initial post, the axles will be loose if open slots are drilled out! And a 1/4" plank body already gets pretty thin above the slot, so the body may need to be thicker than usual, which means that the CoM placement and aerodynamics will already be sub-optimal, and so on...

Does anyone compensate for this by shimming the jig to provide for a small shift in front-to-back angle when drilling the rears?

I believe the Turbo Jigs DFW ST guide compensates for that (which was one point of the Reece Racing youtube video that Whoda referenced); it places the front axle so that the car is leveled and there is no toe on the canted rears.

A small change in the angle of the drill can add a little toe-in or out to compensate for that which may occur as a result of the car not being level in the final assembly phase.

Sleep well and don't worry about lack of leveling affecting rear toe...

We drill into pinewood, an organic material with varying density (grain), and if you fill-and-drill the slots you will also have varying materials (adhesive, etc.). And even if you do everything perfectly, a thin body can twist after a few days. These can all affect the alignment at or above the level that we are hypothesizing here. Now if it were significant, a jig could compensate for it, but I don't know that any do. Remember that jigs are also subject to manufacturing errors and may not perform absolutely perfectly out of the box, either - I say this from experience. I have access to several jigs from different manufacturers (including the Turbo Jig, and Clear Jig, and the one that Whoda would not name). Some were very expensive. Some are no longer being made (probably for good reasons). While still useful, I can't say that any of them were "perfect".

But if you use a Turbo Jig with an ST drill guide, that is intended to level the car, so the issue may be moot.

[philm63]

Pheeew. That does put me at ease, thanks.

After all this I'm thinking for next year's build - seeing as the rules are silent on slots - I'm just going to flip the block over and drill my own holes with that nifty $95 Turbo thingy, and cut it into a Hershey Bar - let my boys do their axles and wheels (I'll help them with the power tools, though), and decorate as they see fit. Maybe a Wonka Bar as one of my boys is named Charlie...

Now, how to weight such a thin block... (got some more research to do, apparently)

[Loud2ns]

1/4" tungsten cubes is the best way to weight a thin car.

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[Vitamin K]

My go-to for filling in axle slots is a toothpick or two (sanded thin if need be) plus epoxy. Sometimes I will mix the epoxy with fine sawdust to volumize it and provide more of a "woody" look to to it. I don't know if it matters or not.

BTW, I corresponded with the maker of the clear jigs a few months ago, and I think he will still make the clear jigs if people contact him and ask for them.

[whodathunkit]

Pheeew. That does put me at ease, thanks.

After all this I'm thinking for next year's build - seeing as the rules are silent on slots - I'm just going to flip the block over and drill my own holes with that nifty $95 Turbo thingy, and cut it into a Hershey Bar - let my boys do their axles and wheels (I'll help them with the power tools, though), and decorate as they see fit. Maybe a Wonka Bar as one of my boys is named Charlie...

Yeah FS, has a way with words.. to put you at ease.. apparently not one of my talents on derby talk.

I also have a son who is named Charlie by the way.
One more tip I'll pass your way about these new c channel type jigs is.. if you have one there is no need for a straight edge or the 123 blocks or pen gauges to check the rear drill alignment.

Once your holes are drilled for the rears.. just slide the car body back past the end of jig and insert two drill bits the same size as your drilled axle holes.
( sticking the smooth end of the drill bit in your drilled axle holes )
Then slide the car back up to the butt end of the c channel jig so the drill bits touch.. and use the drill bits and butt end of the jig to check for gaps in your drill.
Plus side is : now your not out the cost of 123 blocks or the pin gauges.. Just the cost of a 2nd drill bit.

[whodathunkit]

My go-to for filling in axle slots is a toothpick or two (sanded thin if need be) plus epoxy. Sometimes I will mix the epoxy with fine sawdust to volumize it and provide more of a "woody" look to to it. I don't know if it matters or not.

Hi VK, good to see you chime in.
like you my go to for filling in slots are the Diamond brand 41190 square center toothpicks.

But if the axles have to be viewed in the axle slots .. per say the BSA rule at inspection... well i guess its time for a hacksaw and the derbyworx axle slot tool.

[philm63]

Seems that rule dictating that the slots must be used and also must be visible for inspection during check-in is to allow the inspector to confirm what axles are being used. Some pack rules do not allow "Speed Axles" (I'll assume they mean those that can be purchased online - Stainless Steel with coned head where the side of the wheel touches, and grooved where the hub rides, slot in the head for tuning...)

Our pack rules just say the nails that came in the kit must be utilized but so long as the head looks like any other BSA nail from the outside, the sky's the limit regarding what the rest of the nail looks like. I do believe there are modified (corrected) BSA nails available online, no?

Oh, and we did our weigh-in tonight - race is tomorrow morning - and I asked the race coordinator about the rules, mentioning the fact that they were silent on the slots needing to be utilized. I exclaimed that from time to time I'd seen blocks with "less than square" slots and inquired as to whether or not I could just flip the block over and drill my own holes and he said sure, no problem. I'm already designing my car for next year...

[exoray]

Seems that rule dictating that the slots must be used and also must be visible for inspection during check-in is to allow the inspector to confirm what axles are being used.

The first time I filled in the slots (since the rules said the slot must be used and the included nails must be used) I took a 1/4" fosterer bit and made two shallow peek holes on the bottom of the car so the ends of the nails could still be seen... I only did that the first year until I got clarification that they had no issue with me plugging in the slots, as the rule was more so to prevent extended wheelbase, not so they could see the nails used...

[philm63]

Good stuff - thanks for the input. Extended wheelbase - I hadn't thought of that one. I know it's a thing, but didn't know inspectors would target the practice. Currently limited to pack racing and our rules seem pretty consistent year to year, and thankfully they do not even mention the slots and I just last night received clearance from the pack leader that drilled holes are acceptable, just no bending the nails. Our rules also do not mention the wheelbase at all so I may explore modified wheelbases for next year's design.

Not to derail this thread - I did witness a bunch of test runs last night during check-in - a lot of cars were fishtailing, some pretty severely. I chose to not test run our boy's cars opting instead for the confidence route knowing we prepped the parts the best we could, and assembled with care, lubed well with graphite, weighed, and turned them in. If we observe this same issue with our cars, I'm hoping next year's builds, having used a good drill jig, canted the rears, raised one front wheel, applied steering, possibly extended the wheelbase and adjusted CoG accordingly, etc., will certainly NOT experience any wobble. Seems to be a serious issue and one I hope to keep in control.

I'll probably start a new thread to address the whole wobble thing - I see bits and pieces on this forum but nothing very recent, and I'm sure there are lots of fresh ideas and techniques out there for me to discover.

[FatSebastian]

I'm hoping next year's builds, having used a good drill jig, canted the rears, raised one front wheel, applied steering, possibly extended the wheelbase and adjusted CoG accordingly, etc., will certainly NOT experience any wobble.

Yes, a "rail riding" set-up addresses the wobbling. If your unit isn't allowed to bend an axle, then participants must drill at a precise angle to accomplish this, and this is hard to do without special tools. Hence everyone wobbles...

Perhaps the intent of forbidding bent nails is to keep axle orientations straight (maybe in an attempt to "level the playing field")? If so, the reaction could be interesting next year when your family, and possibly others, show up with axles drilled at precise angles.