Cubmobile Secrets

Discussions related to building cubmobiles.
Post Reply
User avatar
frontosacam311
Master Pine Head
Master Pine Head
Posts: 119
Joined: Wed Jan 23, 2008 9:53 am
Location: Pacific ,Northwest

Cubmobile Secrets

Post by frontosacam311 » Sun Jul 06, 2008 12:06 am

One thing I was curious about is the weight limits. Are there different weight classes, do you have to add weight to cars to keep the playing field level.



User avatar
sporty
Pine Head Legend
Pine Head Legend
Posts: 3355
Joined: Sun Feb 13, 2005 2:00 am
Location: rockfalls, Illinois

Re: Cubmobile Secrets

Post by sporty » Sun Jul 06, 2008 7:53 am

You have hit on one thing, that is the draw back of cubmobile.

Most do not allow weight to be added to even the playing field. A heavier driver usually has the advantage.

Soap box derby has a total weight they run. So the weight is the same.


My guess is the only reason alot of cubmobile races have not gone to this is, one the design. Two, you would need four scales to verify equal weight.

A good built cubmobile with a driver who has practiced alot, does have a really good chance of over coming the heavier driver.

Thats something that we have been very good at achieving in the past and currently.

I should further add, that in my testing. it takes about 3-4 pounds of weight to effect weight placement or balance point of the weight to the cubmobile. with about a differance of 1 inch of a balance point movement either way. Depending on the placement of the weight.

Naturally if the weight was placed in the middle, this would change the balance point very little.

So, knowing where to have that balance point is key ! alot of cubmobiles do not have a proper weight placement (seat & driver) placed right on the frame (2x4 or 2X6) "52 inches long"

Allot of people seem to have it too far forward, which would give a good initiall boost on a down hill race, but would lack the initial energy gained from the coming off the ramp.

So they usually do not maximize there potential energy off the ramp.

Remember down at the hill or at the finish line. cars do not speed up. the winner usually looses less of the energy it gained and or also maximized that potential energy off the ramp.

For every wiggle or steering correction the racer does it is usually a loss of .10 of a second on time. so 5 or 6 corrections on a 150 foot track. Is going to cause that racer to be about 1/4 car length to 1/2 a car length behind the other racer.

That racer scrubbed off alot of speed, through friction of steering adjustment. (rubber to pavement friction).



Sporty



User avatar
frontosacam311
Master Pine Head
Master Pine Head
Posts: 119
Joined: Wed Jan 23, 2008 9:53 am
Location: Pacific ,Northwest

Re: Cubmobile Secrets

Post by frontosacam311 » Sun Jul 06, 2008 10:30 am

So can a steering dampener/stabilizer be intalled to minimize steering wheel twitch. Then if the course needs corrected the results wont be as drastic. I could really have a lot of fun with this sport if the rules permitted. Imagine the year 2029- GPS Auto Pilot is used to keep steering fixed and take out the human error variable, hybrid trees are now grown that are suitable for this sport due to the fact that the molecular structure of the hybrid wood allows for almost no wind resistance. :shock: :roll: Corvid



User avatar
sporty
Pine Head Legend
Pine Head Legend
Posts: 3355
Joined: Sun Feb 13, 2005 2:00 am
Location: rockfalls, Illinois

Re: Cubmobile Secrets

Post by sporty » Sun Jul 06, 2008 10:34 am

Here our some speed secrets and tips-


pictures.


There our a few ways to mount the axle rods or bolds.

Here our two ways that I use and have used.


This 1st one, was what I used for the 1st couple of years, it still works better than between the wood or in the wood.

prevents bending and major alignment issues.
Image


This what I had made for a better alignement of axle rods or bolts.

Image

Image

Ruber used between the brake and frame and bolt, prevent that brake from falling down and dragging. a spring works also to help hold it up. Especially if they fall when coming down off a ramp.

Image


Wood is soft and after a few runs, the front steering loosens up. It is the #1 reason kids have a hard time with wiggle.

brass bushings placed in the whole (top & bottom of the board, prevent compression and the bolt loosening up so easy on race runs.

Image

Again, the center steering bolt, I have seen 97% of the time, the reason why a child is having wiggle issues. the tighter the better !!

Remember it's a strait run !

Image

notice the distance on the steering limit blocks. You do not steer much and very little is needed.



in this next diagram, taken right from the basic cubmobile diagram. Most people seem to not do this when putting together the front steering.

Image

Bearings-

You need to remove all that grease from both sides of the bearing on each wheel !! spin and spin and spin them !!

Wd-40 or lighter fluid really works well for this process.

Image


I am using this picture to show something else-

Notice the washer next to the wheel. most have them too tight. you should still be able to spin the washers on both sides of the wheels after the wheel is installed. if not, it's too tight !!

Due to the racer, little wiggles and slight steering adjustment, you want some play here and also due to low quality stock bearings. Pressure on the bearings inner race. Really seems to slow the car down.

Image


More to come-


Sporty



User avatar
sporty
Pine Head Legend
Pine Head Legend
Posts: 3355
Joined: Sun Feb 13, 2005 2:00 am
Location: rockfalls, Illinois

Re: Cubmobile Secrets

Post by sporty » Sun Jul 06, 2008 5:18 pm

Link to my manual--

http://www.mediafire.com/?godubw9nbjq

60 plus pages.

3d manual link-

http://www.mediafire.com/?bmxwnmged4m


pdf file downloads.

Enjoy and let me know what you think.

These manuals are not for posting on other websites or linked to this post. Do not share or give out. for you only !! ! One time download of each file.

copyrighted.

I also ask, please if you found the manual useful and worthy ! please donate $1.00 each person, To Derbytalk.com

It is due to this website, that this information can be brought to you.

sporty
Last edited by sporty on Mon Jul 07, 2008 3:44 pm, edited 1 time in total.



User avatar
frontosacam311
Master Pine Head
Master Pine Head
Posts: 119
Joined: Wed Jan 23, 2008 9:53 am
Location: Pacific ,Northwest

Re: Cubmobile Secrets

Post by frontosacam311 » Sun Jul 06, 2008 6:30 pm

Thanks for sharing. Those are some great tips. If I ever build one of these cubmobiles I know who to come to. Do you fiberglass your 2x4? Glassed basswood would be cool. You could really lay a sweet coat of paint. How bout grooving axles and lube? Corvid



User avatar
sporty
Pine Head Legend
Pine Head Legend
Posts: 3355
Joined: Sun Feb 13, 2005 2:00 am
Location: rockfalls, Illinois

Re: Cubmobile Secrets

Post by sporty » Sun Jul 06, 2008 7:09 pm

the lube i recommend is lightening lube from boca bearing.com


no fiberglass , just primer & prep and paint.


Sporty



Post Reply