Front fender vs no fender trade-off

[HillBillyRacing]

Hello Everyone,

My first post here...been lurking on this site for years. Im making and extended wheelbase graphite awana car with child. We need help deciding if a front fender with better areodynamics is more advantages than the stability without the fender. We usually have the wheelbase spread out as much as possible with aggressive cog on a ladder car/3 wheel rail rider. Our second race track , i think, is at least a 42' aluminium best track and its impossible for us to test.. Any comments would be welcomed.

Thanks

 

[Jimmy & his 2 Kids]

I do know this... while I have no personal comparison I run typical wheelbase with carefully prepped wheels, axles. Block drilled with rear wheels at rear and if memory serves from 4.5 to 4.75 wheel base. Fenders with front fender. My kids only loose heats to each other. There’s another thread speaking about this so be on the lookout but I believe there was a guru or 2 that mentioned the added stability from that long wheelbase doesn’t speed the car up as much as the set up I mentioned as long as the car is set up correctly, ie...Good tight wheel gaps, no toe in the rear axles. In other words, no slop and good alignment and wheel and axle PREP PREP PREP.
Hope that helps. Let’s see if some pros chime in but yeah, another thread recently is a good read about this.
Jimmy

 

[HillBillyRacing]

I do know this... while I have no personal comparison I run typical wheelbase with carefully prepped wheels, axles. Block drilled with rear wheels at rear and if memory serves from 4.5 to 4.75 wheel base. Fenders with front fender. My kids only loose heats to each other. There’s another thread speaking about this so be on the lookout but I believe there was a guru or 2 that mentioned the added stability from that long wheelbase doesn’t speed the car up as much as the set up I mentioned as long as the car is set up correctly, ie...Good tight wheel gaps, no toe in the rear axles. In other words, no slop and good alignment and wheel and axle PREP PREP PREP.
Hope that helps. Let’s see if some pros chime in but yeah, another thread recently is a good read about this.
Jimmy

Thanks for the input Jimmy! Our wheel base is just shy of 5 5/8". Our com has gotten so aggrisive after 9 years we might have slowed down at the last regional as we only took second place in speed. We have a local and then a regional race only. I must say after almost ten years, the number of racers is way down. However, the builders seem to be getting faster as they chase our tail. I'm almost happy we took 2nd last year....almost. I will tram in the drill press with a dial gauge this year. We have never checked our drill job other than steer. This year is over the top baby! we will employ full knowledge this year! Cheers!

 

[Mojo Racing]

5-5/8" is an awful long wheel base.

With the cubs I coach, if they don't have to run a standard 4-3/8" wheel base, we run 4-3/4" - 5" wheelbase. This allows your weight to stay on the hill longer before entering the transition. Once your car enters the transition, you don't have the same amount of energy applied to your car for the speed that you have if your car is on the hill for that extra 5/8" - 1-1/8" if your front wheels were brought back.

Plus, you can put a front fender on your car.

 

[HillBillyRacing]

Yes, the slope time before the transition makes sense. I guess that's another reason to move the fronts back. We've gone from one extreme to the next with our cog so I've always kept the fronts out there like a dragster and crossed our fingers tight. Thanks!

 

[Charles Studer]

Yeah shorter the wheel base all the way back more motor, but you have to be able to tune it.

 

[Kurtis Long]

So basically we look for the sweet spot of longer wheel base = less steer( 2” over 4’)and worse COG but less drag of the DFW on the track as compared to short wheel base = more steer, better COG but more drag on DFW to get the car to handle (4”-6” over 4’) ? Am I thinking right about it?

 

[Pinewood Outlaw]

If your block is drilled with good alignment you can run a shorter wheelbase. I normally run 4.75" wheelbase which is just a slight step up from the standard 4 3/8". My current car has about 1/2" or slightly less COG with 4 oz of tungsten cubes. Car rides down the rail like a dream with no wiggle at all.

 

[Mojo Racing]

So basically we look for the sweet spot of longer wheel base = less steer( 2” over 4’)and worse COG but less drag of the DFW on the track as compared to short wheel base = more steer, better COG but more drag on DFW to get the car to handle (4”-6” over 4’) ? Am I thinking right about it?

You are.

You have to weigh the pros and cons to both and find the best option for you.

But in short, yes, you have to find the sweet spot.

If you have the ability to test, start aggressive and work toward the safer options. You will find the faster times a lot quicker.

 

[xjarcher]

Interesting. I'm a 20 year Awana racer. Our tracks are all 30'. I've seen most of the shorter wheelbase cars struggle to keep up with the longer ones. Obviously a tuning issue as short= finicky. If our regional wasn't this Saturday I'd shorten my WB a bit and see what happens. I do have time to play with Kurtis idea of less steer for a long WB though. I've stayed at 3-4 and had good results. My granddaughter's car was 4" and ran quite well but maybe I'll take a little out of mine and see what happens.

 

[HillBillyRacing]

Thanks everyone! We are planning to shorten the wheel base for sure. Also, this site has a great active and expert community. Its been a lot of help over the years. I especially thank those who explained the same concepts over and over to the noobs over the years.

 

[xjarcher]

5-5/8" is an awful long wheel base.

With the cubs I coach, if they don't have to run a standard 4-3/8" wheel base, we run 4-3/4" - 5" wheelbase. This allows your weight to stay on the hill longer before entering the transition. Once your car enters the transition, you don't have the same amount of energy applied to your car for the speed that you have if your car is on the hill for that extra 5/8" - 1-1/8" if your front wheels were brought back.

Plus, you can put a front fender on your car.

Just a thought, If you happen to run on a Microwizard (which we have), might the really long wheelbase be helpful? Much longer incline as opposed to the Best.

 

[Mojo Racing]

shorter wheelbase still stays "on the hill" longer.

 

[HillBillyRacing]

 

[HillBillyRacing]

Well, here is the end result. I wanted to go 4 3/4" but I was worried about the nose bottoming out. We got first. Now we wait until next race in the fall. Thanks again all!