12 replies to this topic

[JimF]

I realize that this is not a super popular subject, but these are fun to build and play with. In NorCali, we run these five-six times a year in our regular rotation and we use a fairly liberal interpretation of the Pro Slot "big dog" motor. We require that the arm be a "Big Dog" or less (Puppy for example) but we allow bearings, shunts if you want, and usage of the JK Hawk set-up. We run these with coupe bodies, (Lola T70 coupe for example) and typically run them on our faster tracks although we have occasionally run them on flat tracks as well. These cars are generally 3-5 tenths faster than our Can-Ams.

 

This one is built to accommodate the Pro Slot motor and the Falcon (etc.) motors.

 

Starting point is an R-Geo nosepiece (.040) and guide tongue. The rest is .047" wire

The axle tube is 1.100" wide, spacing between rails in the front is 1.250" matching the nosepiece.

You'll note three indexing marks along the length of the frame. This enables me to keep centered.

 

 

A key element is to build around the gears that you think you'll use. This FK is set up with a 12/40 combo.

• I like to use the largest diameter gears that I can because the bigger gears allow a flatter motor angle.
• This gear is a Fass 40t (long obsolete) and I have a stash of Fass 43s that I love to use when I can.
• Figure this out in advance because an 11/37 (same ratio) will need a higher angle to your rear end.
• I use 64 pitch gears because they are much larger in diameter than 72 pitch and thus easier to build around.
• With this setup, I have a 13 degree motor angle and can comfortably fit the most useful ratios that I'll use.
• Also note that the center of mass of the motor crosses over the centerline of the chassis.
• Another key element of this build is that the gear side frame rails have two .047" half rails that fit inside the main rails. This is one element that allows the motor to be more centered.

 

This view shows the axle tube supports and bracing.

• Gear side, you have the two .047" half rail uprights at the rear of the axle tube, and a forward brace of .047".
• Opposite side, you have the two inner frame rails that run to the back, and an .062" in the front.
• Far rear, you have two transverse .047" braces that tie left and right main rails together.
• Motor brace on top of the tube is .078" wire. This facilitates motor installation.
• Forward perimeter of the motor box is defined by a pair of .047" cross rails.

 

This is just a different angle of the points covered above.

 

 

Hopefully, this will de-mystify to some extent the considerations in building an anglewinder. From here on, the build is normal but as I finish it up today, I'll show some further progress as there will be some weight tuning features planned for this.

[Tom Eatherly]

Jim,

 

Do wish we ran more than twice a year down here, but, that'll have to do. We (SCRRA) only run them on the flat track, the Checkpoint and SWC. The way these anglewinders handle, it kind of surprises me we do not run them more. Flat track or King would be neat, but, I can live with it. You gonna make it down for the SWC? More A/W coupes the better.

 

BTW, nice looking build you have going on there. Can't wait to see finished chassis.

[Arne Saknussem]

A very nice piece of work, Jim. I must have built and rebuilt dozens of those guys back in the day. None were as nicely done, of course, but I was never one for looks (or structural integrity, as it turned out too often).

 

Looking at yours makes me want to build another.

[Bill from NH]

Jim,

 

Back in 2008, you were building anglewinders for Falcons using .078" main rails. What were the positive and negative aspects of these chassis, and in what areas does your new design hopefully improve their performance?

[JimF]

You gonna make it down for the SWC? More A/W coupes the better.

Tom:
 
Turns out that this year, I'm probably free on the SWC weekend. The problem is that I'm not very fond of the motor dependancy (and all that entails) in the King track races. I do plan to come down on the 11th. I'll have this one done and I do have another AW that will fit a Falcon/RH motor. I've also built a king track car... .
 
I think what I'll do is buy maybe four Retro Hawks and break 'em in and try my hand at the King. If it turns out that I'm under the bus with all four, that tells me what I need to know about racing on the King and I won't bother with the SWC. OTH... if there is at least a B-C Main kind of motor in this batch, then I'd be inclined to come for the SWC. I'm just not at all into buying 20 motors at a time for a race.

[JimF]

Bill:

 

I'm not sure that I can properly define the differences but here's a stab. A single .078", whether inline or anglewinder is a very good general purpose chassis design. It's a fair bet that it'll work just about anywhere, anytime. However, I (think) that multi rails of smaller wire give the builder more finite control over the torsional flex that is the primary contributor to cornering speed. There is also a rather theoretical argument that the smaller wire lowers the center of mass but I really think that is mostly unprovable as to effect.

 

I think that a single .078" can be gotten to saaaaay... 97% of the theoretical optimum almost 100% of the time, and the tuning in order to get to that point is often not that complex. OTH, I think that given the knowledge and patience to tune them, multi rails may get closer to that optimum but at some cost of just not being all that good sometimes. I also think that some multi rails can be more susceptible to changing track conditions.

 

At least... I think... that's what I think.

[JimF]

OK... hot off the jig and ready for cleanup. This frame will build up at 89 grams or so with all running gear and no body. Figure about 95-96 all up. This includes the small brass weights that are in place at the rear that add about 2.3 grams each.

 

This may still be somewhat too light for our speedway tracks and WAY too light for a flat track. I made two large add-on weights at 4.8 grams each that will either go on the inside of the pans or inboard between the frame rails. These two weights will get the all up weight to about 105-106 and that will be a good start for a flat track. I suspect I'll want to make two more of those trapezoid shaped weights that will go 2.5-3.0 grams each for the first test so that I'll have an easy 101-102 gram option.

 

 

[Tom Eatherly]

Looking good, Jim. I'll try and make it for the 11th for some testing. Want to chat with ya on a couple of things.

 

Not much of a King track racer myself. Prefer the flatster.

[JimF]

Here is the first on track update for the new frame shown in this article. The test venue was the flat track at Buena Park Raceway in So. Cali. I was there for the coupe race on the 11th of July. I tested back and forth between the new car (left) and an older car (right). Both were very very good and in fact, the new car was faster and turned the fastest laps of any car I saw over the weekend. However, the older car was fast too and was easier to drive so I chose that one to race. I finished third with it behind two exceptionally fast guys and might have done a little better had the motor not laid down badly for a couple heats.

 

As you can see from the pics, these cars are roughly similar. The new car was a little 'snappy' on turn exit and despite it being somewhat faster as far as practice lap times, that's the reason I chose the other one.

 

The differences:

 

• Older car is 4 rails of .047 and in fact, the fourth rail was added on after initial testing.
• Older car has a 1/8" longer axle to guide length.
• Older car was 106 gr. as shown here in race trim.
• Older car has center weight pan floating rather than fixed.
• Older car ran best with JK 8713 Treated and narrowed.

 

• New car is 5 rails of .047. so it is stiffer.
• New car is shorter in OAL although the guide leads are the same.
• New car was 114 gr. in race trim.
• Center weights are fixed which contributes somewhat to a stiffer structure as well.
• New car ran best with JK 8703 untreated (and was still a touch loose)

Conclusion is that the new car being stiffer did not lay down the power as well on the flat track. Also, the shorter wheelbase made the car less forgiving. So........a new one is in the works that will combine the features of both of these.

 

 

[Tim Neja]

Beautiful builds Jim as always!! 

 

I think your "floating" weight also helped make more Bite as evidenced by the treated tires!  I've got to build a new angle winder coupe!! I LOVE those cars!! Their so fun to drive and a smooth as glass!! Of course, Duran managed to look good with his Can Am / Coupe!!

[Dennis David]

Jim, 

 

Sometimes I think you like testing better than racing. ;-) Keep up your extremely valuable testing reports. Nobody does them better or make them so interesting.

[JimF]

Jim, 

 

Sometimes I think you like testing better than racing. ;-) Keep up you extremely valuable testing reports. Nobody does them better or make them so interesting.

 

I'm going to steal a line from a fine builder whom I like and respect. He says......."I race so that I can build"............I feel the same way.

[JimF]

Beautiful builds Jim as always!! 

 

I think your "floating" weight also helped make more Bite as evidenced by the treated tires!  I've got to build a new angle winder coupe!! I LOVE those cars!! Their so fun to drive and a smooth as glass!! Of course, Duran managed to look good with his Can Am / Coupe!!

 

 

 

I just finished the next AW frame which is a blend of these two cars. You guessed it. It has a floating center weight. The four rail vs. five rail thing is part of the equation as well.