DFW wheel and axel "slot" rubbing

[viowes]

Hey all....quick question, and perhaps a silly one...but according to our rules locally, the axel must sit in the slots on the block. I have no problem drilling holes on top or thru them or using the awesome block from DD4H that is precut with slots in them....but the question is....

for the 3 or 4 wheel, rail running, canted wheels, the DFW is canted to run toward the body (in addition to steering)...so the inner wheel hub will run against the body of the car at some point for the DFW, and if anything the most rubbing would likely be between the inner hub and the side of the car udner the axel (based on the cant), rather than above the axel. Im assuming if you now had slots (either already there or cut after the drilled holes) that the inner hub is now rubbing against the open slot on the side of the car under the axel....which means two edges, front and back...rather than a solid piece of wood (as it is with just axel holes....). Is that going to slow the car down any or would that be relatively insignificant as far as friction goes....

If it might be slower...then would it be better to say put some test axels in and then put putty or filler in the axel slot (just where the wheel would contact), let it dry, pull out the axel and then sand it down smooth and then do whatever your preference is (nail polish, graphite rub, that model airplane wrap material etc) so that now if you look from the side, it just looks like a drilled hole and not slot....that way the inner hub (bottom) is now rubbing on a flat surface rather than possible two edges....

Of course I guess one could just sand the edges around the slot under the axel smooth and rub graphite on it and even a little into the slot as well...or all this may be very miniscule so it may be a mute point....

opinions?

W

 

[Crash Enburn]

Hmm. I can picture what you're asking about... It seems to me, that you might want to take a scrap wheel and manually push (and turn) it against the body to dull those sharp edges and perhaps burnish the wood there.

I'd put graphite on the hub and on the body, and burnish it in. And repeat many times.

Also, since you have to run the slots, I'd lop off the back of the block (that part which is further back than the wheels) and glue it to the front. That way, you're running the wheels as far back as possible, and still keeping in the official slots.

 

[DerbyDad4Hire]

I have thought the same thing. i think it might have a slight slow down effect on the car because it rubs on 2 spots instead of one. Not sure exactly how much slower but not a lot. I am not sure it is worth the work of filling it in or not.

 

[ljo]

So the positive cant will drive the hub to the body, but steering into the rail will push the wheel back towards the nail head. So I dont think it's really an issue. DD feel free to correct me if Im wrong.

 

[DerbyDad4Hire]

It will not push it back. It might bounce back and forth. That is why you want it tight.

 

[viowes]

given that its still awhile before the next den race (one year lol) ill fool around and see how much work it is to put something in the slot....putty, a toothpick, then sand smooth and put something like nail polish to fill in any holes and then rub graphite all around and feel if it is solid....but id gather ur all right that the speed loss is likely pretty minimal compared to other things.

 

[Rocket car]

I have found that if you make the car thin enough you can put the slots on the top of the car. Then the wheel will rub just fine. Hmmmmmm

 

[pony express]

If you fill in the slot area at the wheel contact point, you'll need something solid like epoxy. The usual body filler won't hold up. Sometimes I''ll drill above the slot and sand down the bottom till I'm back at 5/32 above bottom. You're still in the slots or just above. the back axle will come down into the slot following the cant path. The back wheels will not touch the slot this way.
The fronts are pretty good as well depending how high you drill the hole and how much of the bottom you have to sand off to get back to your 4/32. You end up with a slot with half the depth.

 

[savageone]

DD4H states..."It will not push it back. It might bounce back and forth. That is why you want it tight. " Hey DD4H when you say tight clearance on the DFW,what clearance range would you use for a scout car on three wheels? 5kidsracing what clearance do you use on the kids cars?

 

[5KidsRacing]

On a scout car, on an unknown track I would run half of the gap guage that is out there... I think the gauges are around .040" so i would run around .020". On my cars for league racing I run whatever makes my car the fastest... Sometimes that is more gap, sometimes that kills me, sometimes I do well...

 

[savageone]

Thanks 5kids. I remember an older post that DD4H said one of the biggest problems with cars sent to his shop is wheel gaps that are too big. We won pack and district last year running .032-.035 on all wheels, but we are always looking to improve. This year we have decided to go from 3/4" COM to 5/8" which has me a little concerned because we have no way of knowing what type of track (wood or alum) that we will be racing on if we make it to districts.