Help understanding why my cars are so slow

Last night was our 3rd year of Awana Grand Prix. The first year car has been the fastest car Ive ever made, it did 2.85, which would have won 1st last night also, out car last night did 2.98's... one 3rd place and three 4ths...

I polished the axles, weighted and balanced the car to 3/4-1" in front of the rear axle, angled the axles, bought Krytox 100 for the wheels, had it running on 3 wheels, pretty aerodynamic shape....

New issue for this year, was the car wobbled side to side down the track, never had that problem before, did I have too much space between the wheels and body? CG too far back? Sorry no video, sat in a bad spot and every time I tried people were in the way. Car did ok coming downhill, but on the flat lost its steam... My 8yr old cried.

 

It’s hard to say exactly, but if you bent your axles that would be the first thing to me. For scout axles the best way to do it is drill at 3 degrees and twist and tune from there because the axles themselves are bent. If you cant drill a 3 degree hole then I would just drill with a straight block from Amazon and twist the axles to see if you can’t get them in a position that cant’s the rear wheels.

Second thing I’d look as is wheel and axle prep. Are the wheels and axles polished? Bores? Hubs? Contact edges.

For weight, I can’t tell what you used, but the car isn’t extremely aerodynamic, so I’m assuming the weights aren’t in the correct spot. Make sure 5he rear wheels are close to equal and put roughly 0.5-0.6 oz on the DFW. The way to measure is by using three scales or by having a wheel on a scale with the car being level all around if you only have one scale.

Hope that helps!

 

Thanks, I didnt see a rail on the track, it just has lanes with borders. I tried to have all 3 the same tilt out at the bottom. I pushed it down my wood floored hallway, and it tracked very well, but on the course it sucked. Its a year until the next one, but I may have to build a test track in the meantime

 

I put the rear axles in at angle, the front one that touches I did bend, so I could steer it as it was hooking left really bad initially.

I polished the axles with fine sandpaper and compound then polishing. The wheel hubs I didnt have a way to do them on the short time frame I had.

The weights are put in from the rear, you can see the hot glue covering them. Its lead weights, and the car balances 3/4"-1" in front of the rear axles.

Less aerodynamic cars had better times, so its not a wind issue. I had something else very wrong.

 

Front and rear of the car is the same.

I dont have a jig for drilling, so I just put the axles in the slot at an angle on the rears. Ill get a jig for next year.

Everyone here is using oil, probably 80% dont prep anything and slap it together. And they were beating this thing, which is why Im so curious as to how I could have made it so slow. I do have graphite, maybe Ill try that next year instead.. Not sure,

 

If you can race oil, race oil. Graphite is going to be slower for sure. I think Derbydad4hire is right in that your alignment is off. I understand that cars that probably didn’t have a care in the world about alignment are blaster, but if your rear axles are angled incorrectly or you have massive amounts of toe in or toe out then that will slow your car down a lot. If you get a 3 degree drilling jig and drill a new car with the same wheels, axles, and weight configuration, it should be faster by a mile.

 

Ill get a jig for next year for sure, some of the cars had a stretched wheelbase, but not too many.

I guess the pre drilled slots could have been off, I didnt bend the rear axles at all, the front I did only to steer, and adjusted it during the race with no improvements. Im still kind of baffled as to why so slow. Im guessing the biggest factor was because it was swerving and scrubbing speed.

 

The more the car wiggles the slower it will be without a doubt! Even a little wiggle will tank a car, so if you can get the alignment correct and keep from wiggling, your car will be faster for sure.

 

Right, I dont see how the alignment would be off, I used the predrilled slots in the block. Never had an issue until this year for some reason. Im guessing it has to be too much gap between the body and the wheels?

 

Looking at the rear wheels, the alignment is definitely off. The slots on the blocks is often out of square with the block.
You may also have a lower quality bore in your new car's wheels. You may want to take the wheels and axels off your previous car and see how they run on the new care. A good set of wheels and axles are hard to find. Awana wheels are known to be slower than the typical BSA wheels.

 

Thank you

 

John is definitely giving good advice on the alignment issues. The stock Awana wheelbase makes for a terrible handling car. You definitely need to get those rears pushed to the rear for next year.

About 3 yrs ago Awana switched suppliers for their wheels and kits. That alone could account for your issues. Perhaps 3 yrs ago you still had an old set of wheels which were better quality than the new ones. You can tell the difference by looking for a mold number on the inside of the wheel. If it has one it's 99% chance it's an old wheel, the new ones don't have mold numbers on them. The new wheels have atrocious hubs. You need to find a way to at least square up the inner hub. The quality of the blocks also went down. The wood and the slots.

John is right when he says Awana wheels are slower than bsa. So far I've been able to get within .025 of bsa. I think I can get it closer, but it will take meticulous effort!

 

I’ve never used Awana wheels or their blocks, so I don’t know, but how far from the rear are the slots?

 

1 9/16" from each end. Wheelbase is
4 11/16".

 

The rules say you must use the awana kits wheels and axles... So I best learn how to polish better this year, and true up the wheels. Wish I could talk to the winners and see what they did

 

I really appreciate that! I actually bought some machined ones before I read the rules all the way through, and I probably would have run them, but they have a different finish to them, so it would be too obvious...