Jump to content




Photo

How-to... the tuning fork F1 (v2.0)


  • Please log in to reply
28 replies to this topic

#1 JimF

JimF

    Checkered Flag in Hand

  • Full Member
  • PipPipPipPipPipPip
  • 1,924 posts
  • Joined: 20-June 07
  • Gender:Male

Posted 11 June 2013 - 03:19 AM

This thread will be focused on the build, testing, and development of Tuning Fork F1 v2.0. The goal for this chassis will be to maintain the dramatic flex of the 1.0-1.3 versions while trying to solve the inherent weakness of that frame which led to its early demise after only a few weeks of use. I'll also intentionally reach out for heavier parts as the original was just too light (87 grams) to be very effective on a twisty flat track
 
This frame will be built at 1.625" width and will use the cut-down JK Can-Am nosepiece that I resurrected from the earlier car. This build would be legal in the west but not for the IRRA™ rules. However, the same build could be done around the fine JK F1 kit and all the steps would be same save the rail spacing and width of the forks.
 
The first step is to decide on your bracket of choice and what nosepiece to use, whether to use a pre-fab or to go scratch, and then where you want the forks to go (inside the bracket legs or outside. Then, you’ll lay out your parts and decide where you want the rails to go and what size you’ll use.
 
This shows a 3/4” Warmack bracket and the salvaged JK nosepiece. I have cut a bracket plate from .093" brass to fit inside the bracket, then drilled a 5/8" hole in the plate to clear the gear. Center the hole right under the axle.
 
64daf5f1-fb0e-4aa7-af6b-078aa7edeeb8_zps
 
Here is the bracket laid out on a flat block with the fork rails laid in place to check the spacing. This also gives you an idea of how your rails will fit. Bending the fork rails isn't as tough as I thought it would be. Just use good square pliers and you won't lose much in the bends. In this case I bothched one so I had to bend three to get two. That’s been about my average so far. These are pretty good but rear leg of the near side rail needs a little work.
 
033b60cb-f43d-4721-94f2-6676743b9d87_zps
 
Now, into the jig. This is an R-Geo jig that has some features that I really like for this build. Besides, it’s just flat and square and very precise, the way a jig should. Here, I have the nosepiece in place, the forks are in place, and the front tubes are in place. Now is the time to check for square and to make sure everything fits. Try to get the fork rails as parallel as possible and as flat as is reasonably possible. Keep in mind, the pivot tubes will hold the rails up a little so completely flat isn't possible. When you’re happy, a quick tack of the pivot tubes to the nosepiece and the rear legs of the fork to the bracket. Triple check for square and that the forward fork rails are free and not binding.
 
c53d3cdb-3ab0-492b-bccf-c204add01d65_zps
 
Next, we lay in the main rails and this is the key part of this build. The mains are .062" wire mounted in pivot tubes at the rear of the chassis. You want these rails to go straight and drop right into the slots in the nosepiece. It will take a spacer rail between the rear fork leg and the rear pivot tube to do this right. In this case .055" spacer rails provided almost perfect spacing so that the main rails were very parallel. In this pic, the rails on the right are in place and ones on the left are held so you can see how they fit. Once everything is in place front and rear, solder the spacer rails and the rear tubes in place. Don’t solder the main rails in yet.
 
b5581779-5988-4455-980e-f81d955be7c3_zps
 
This pic shows the main rails with little caps of 3/32" tubing soldered in place as retainers. Build these outside the frame so that there is no danger of soldering up the rail in the tube. Leave the front a little long so you can cut it to fit. With the caps on, slip the rails through the rear tube, slide forward as far as possible, and cut the excess off at the front. Make sure it's all free and solder the main rain rails into the nosepiece. There is a little piece of .039" wire on the outboard side of the main rail to reinforce the solder joint. At this point, you have a completed center section. Check for fore and aft slop due to the opposing hinges and tighten up as much as possible.
 
010_zps159cc3dc.jpg
 
dacb1e74-43ab-4e7b-bc1b-d5b3d84d223c_zps
 
This pic shows a contingency plan. What you see pictured is an optional minor main rail. This would go as shown (more or less) and be soldered to the rear assembly and the nosepiece at the two blue arrows. This might be necessary for local rules but it also might be necessary if there is just too much movement between the fore and aft sections. This could also stiffen up the frame if it too flexible for your tastes. I suspect that I'll add this in on the first test day. My choice will probably be to make this out of .032" or .039" wire.
 
6bc2f517-1bfa-4ffe-a9c3-8cc85fa2d564_zps
 
This is the finished center section with the rear pan tabs and pans cut and ready to go in. These are all 1/4” X .093" brass (remember... I’m seeking weight) The rear tabs have to be narrowed about .012" per side but the pans make the width as is.
 
41ec2b0b-509c-4eab-a210-6da3728b7f2a_zps
 
All the shaker tubes are in place and are 3/32" square tubing. The front tubes are lifted on a piece of 1/4" X .026" brass (blue arrows); this to get the shaker tubes up above the pivot tubes and also flat on the thick pans. Note: .050" brass would have been a better fit for leveling things but I didn't have any.
 
b8c68ea9-0041-4f59-bac0-4c9f5ec4a520_zps
 
OK... home stretch now. The whole frame goes back in the R-Geo jig and is lined up for width. This jig has holes for a stop pin at any width you could possibly want. I set the pins in at 1.625" and then used pieces of oiled paper to space the pans out to the proper width. This took about .006" per side. I think this is a key feature and not all jigs have it.(Congrats to Rick for thinking out the details.)
 
All the remaining bits are laid out to see. Two pieces of pin tubing, two pieces of .047" wire for the rear stops, and a bit of .055" wire for the front shaker (this could be .047" if you want more movement).
 
7d08e0ec-470d-4747-ab95-14315578e17a_zps
 
Having the stop pins here is a godsend because holding all these bits in place and the chassis, and the iron, can be a real fiddly step. In this case, you drop the pieces in place, go around the horn and solder them all up and... you're done. Here’s the finished product, ready for a little clean-up and final check for flatness and for pivot movement.
 
aa9c53d6-71ec-4513-bf39-fb29abebd8ad_zps
 
And... ready for the track. This car hits 103 grams without body, and has almost exactly the same flex as gen 1.0 but is much stronger. There is a little bit of movement within the tubes and this may cause wheel hop. If so, I’ll have the minor rails ready to go on the first test session. This is using S7 MB motor geared 8/29, JK 8713T tires narrowed, Swiss BB front wheels, and a Parma Matra body.
 
75561f85-c72d-4727-8bc4-f09016afeb9b_zps
 
Ongoing testing reports and further developments will be reported in this thread. Development of some Can-Am prototypes or other general discussion will be continued in the exploring the tuning fork thread.
Jim Fowler




#2 Steve Deiters

Steve Deiters

    Checkered Flag in Hand

  • Full Member
  • PipPipPipPipPipPip
  • 1,880 posts
  • Joined: 28-May 07
  • Gender:Male
  • Location:Cincinnati, OH

Posted 11 June 2013 - 08:21 AM

Very interesting build.

#3 John Streisguth

John Streisguth

    Johnny VW

  • Full Member
  • PipPipPipPipPipPipPip
  • 4,770 posts
  • Joined: 20-November 08
  • Gender:Male
  • Location:Bangor, PA

Posted 11 June 2013 - 08:40 AM

What keeps the chassis from getting shorter? I see how the stops on the outside rails keep it from getting longer, but there does not seem to be anything for the opposite direction? Or did I miss that? (Wouldn't be the first time... LOL.)
"Whatever..."

#4 MSwiss

MSwiss

    Grand Champion Poster

  • Advertiser
  • PipPipPipPipPipPipPipPip
  • 19,066 posts
  • Joined: 16-April 06
  • Gender:Male

Posted 11 June 2013 - 08:49 AM

The middle tuning fork rails in the tubing.

Mike Swiss
 
IRRA® Components Committee Chairman
Five-time USRA National Champion (two G7, one G27, two G7 Senior)
Two-time G7 World Champion (1988, 1990)
Eight-time G7 King track single lap world record holder
17B West Ogden AveWestmont, IL 60559, ( 708) 203-8003
mikeswiss86@hotmail.com (also my PayPal address) 
Note: Send all USPS packages and mail to: 5858 Chase Ave., Downers Grove, IL 60516
Make checks out to Chicagoland Woodworking, Inc.


#5 SlotStox#53

SlotStox#53

    Posting Leader

  • Subscriber
  • PipPipPipPipPipPipPip
  • 3,937 posts
  • Joined: 13-March 13
  • Gender:Male
  • Location:TX

Posted 11 June 2013 - 09:29 AM

Really neat new F1 forker with the lessons you learned from the last ones taco experience!

Such a great build and detail of what and why you did things ,really gives inspiration to others to have a go. :)

#6 Greg VanPeenen

Greg VanPeenen

    Race Leader

  • Full Member
  • PipPipPipPipPip
  • 944 posts
  • Joined: 26-March 10
  • Gender:Male
  • Location:MI

Posted 11 June 2013 - 10:30 AM

Jim,
 
Tuning fork chassis are already proven winners. I have been building them for over three years. The Retro East Championship was won by Matt Bruce running Tuning Fork Chassis.

I really like the direction you are going with your new build build and hope it works well for you. I have built several Can-Am Chassis with the tuning fork rails running into tubing at the front. First outing was the Retro East flat track race a few weeks ago. That resulted in a TQ, fastest race lap, and a win. I have a couple of F1 chassis almost ready to go. Early testing shows improvement over the standard tuning fork F1's we have been running.
 
Best of luck with yours, Jim. You do a great job of showing you chassis builds.
 
One hint: I tried running the main rails floating at the rear like your new build a couple years ago. I found that the car rear steered badly and was very unpredictable. As soon as I soldered them solid the car was great.
 
Regards,

Greg VanPeenen
Team Black Sheep Racing

#7 John Streisguth

John Streisguth

    Johnny VW

  • Full Member
  • PipPipPipPipPipPipPip
  • 4,770 posts
  • Joined: 20-November 08
  • Gender:Male
  • Location:Bangor, PA

Posted 11 June 2013 - 11:28 AM

The middle tuning fork rails in the tubing.

 

Maybe if they bump up against the nosepiece... otherwise they float freely.


"Whatever..."

#8 SlowBeas

SlowBeas

    Troublesome De-slotter

  • Subscriber
  • PipPipPipPipPip
  • 819 posts
  • Joined: 15-January 07
  • Gender:Male
  • Location:Lost in South Carolina, USA

Posted 11 June 2013 - 11:45 AM

I seem to be missing the rationale behind one significant step...

 

Why do you place the ends of the fork into tubing, instead of merely soldering to the nosepiece?


Jim Beasley
South Carolina, USA

"Assuming either the Left Wing or the Right Wing gained control of the country, it would probably fly around in circles."
- Pat Paulsen, 1968
"I drive way too fast to worry about cholesterol."
- Steven Wright ca. 1983

#9 MSwiss

MSwiss

    Grand Champion Poster

  • Advertiser
  • PipPipPipPipPipPipPipPip
  • 19,066 posts
  • Joined: 16-April 06
  • Gender:Male

Posted 11 June 2013 - 11:56 AM

Maybe if they bump up against the nosepiece... otherwise they float freely

 

I think it's a given they extend up all the way to the nose pc.

 

If you look closely in the pic with the blue arrows, you can see the wire peeking out of the tube on the right.

 

Also, note near the end of the article, Jim mentioned:

 

"There is a little bit of movement within the tubes and this may cause wheel hop."  

 

I'm not surprised. It would be pretty tough to eliminate the movement totally in this kind of design.


Mike Swiss
 
IRRA® Components Committee Chairman
Five-time USRA National Champion (two G7, one G27, two G7 Senior)
Two-time G7 World Champion (1988, 1990)
Eight-time G7 King track single lap world record holder
17B West Ogden AveWestmont, IL 60559, ( 708) 203-8003
mikeswiss86@hotmail.com (also my PayPal address) 
Note: Send all USPS packages and mail to: 5858 Chase Ave., Downers Grove, IL 60516
Make checks out to Chicagoland Woodworking, Inc.


#10 MSwiss

MSwiss

    Grand Champion Poster

  • Advertiser
  • PipPipPipPipPipPipPipPip
  • 19,066 posts
  • Joined: 16-April 06
  • Gender:Male

Posted 11 June 2013 - 12:05 PM

Jim,

 

Great job as always on the chassis and article.

 

I really like the .093" thick bracket brace with the round hole,

especially with the nice chamfer*.

 

It's nice to see something a little different.

 

* I find it semi-amusing my spell check doesn't recognize chamfer as a real word.


Mike Swiss
 
IRRA® Components Committee Chairman
Five-time USRA National Champion (two G7, one G27, two G7 Senior)
Two-time G7 World Champion (1988, 1990)
Eight-time G7 King track single lap world record holder
17B West Ogden AveWestmont, IL 60559, ( 708) 203-8003
mikeswiss86@hotmail.com (also my PayPal address) 
Note: Send all USPS packages and mail to: 5858 Chase Ave., Downers Grove, IL 60516
Make checks out to Chicagoland Woodworking, Inc.


#11 Tim Neja

Tim Neja

    Grand Champion Poster

  • Full Member
  • PipPipPipPipPipPipPipPip
  • 5,516 posts
  • Joined: 11-June 07
  • Gender:Male
  • Location:Orange County

Posted 11 June 2013 - 12:06 PM

I seem to be missing the rationale behind one significant step...

 

Why do you place the ends of the fork into tubing, instead of merely soldering to the nose piece?

 

The tubing at BOTH ends allows very smooth flex in the length of the chassis. Otherwise you'd be twisting the wires to get the flex.  


She's real fine, my 409!!!

#12 Steve Deiters

Steve Deiters

    Checkered Flag in Hand

  • Full Member
  • PipPipPipPipPipPip
  • 1,880 posts
  • Joined: 28-May 07
  • Gender:Male
  • Location:Cincinnati, OH

Posted 11 June 2013 - 12:08 PM

Mike,

Do you see this chassis as definitely not IRRA™ legal?



#13 Tim Neja

Tim Neja

    Grand Champion Poster

  • Full Member
  • PipPipPipPipPipPipPipPip
  • 5,516 posts
  • Joined: 11-June 07
  • Gender:Male
  • Location:Orange County

Posted 11 June 2013 - 12:08 PM

Geez, Jim - I love your builds and explanation/documentation you've done! Thank you!!! I'll definitely build another one of these babies soon like yours to try at the Cave and the BPR flat track!!

 

Keep up the great work!! Always good to see the "Fossil" building and racing!!! :) :)


She's real fine, my 409!!!

#14 MSwiss

MSwiss

    Grand Champion Poster

  • Advertiser
  • PipPipPipPipPipPipPipPip
  • 19,066 posts
  • Joined: 16-April 06
  • Gender:Male

Posted 11 June 2013 - 12:08 PM

 One hint I tried running the main rails floating at the rear like your new build a couple years ago. I found that the car rear steered badly and was very unpredictable as soon as I soldered them solid the car was great.

 

Good point.

 

I wonder if it will be less of issue for Jim, using the slower (which I think is fine) S7 motor.


Mike Swiss
 
IRRA® Components Committee Chairman
Five-time USRA National Champion (two G7, one G27, two G7 Senior)
Two-time G7 World Champion (1988, 1990)
Eight-time G7 King track single lap world record holder
17B West Ogden AveWestmont, IL 60559, ( 708) 203-8003
mikeswiss86@hotmail.com (also my PayPal address) 
Note: Send all USPS packages and mail to: 5858 Chase Ave., Downers Grove, IL 60516
Make checks out to Chicagoland Woodworking, Inc.


#15 MSwiss

MSwiss

    Grand Champion Poster

  • Advertiser
  • PipPipPipPipPipPipPipPip
  • 19,066 posts
  • Joined: 16-April 06
  • Gender:Male

Posted 11 June 2013 - 12:15 PM

Do you see this chassis as definitely not IRRA™ legal?


As is, it isn't IRRA™ legal.
 
Adding the additional rails, he talking about possibly doing, or soldering the wires solid in the tubes, on either end, and it's IRRA™ legal. (Of course, sans the wide nosepiece.)

Mike Swiss
 
IRRA® Components Committee Chairman
Five-time USRA National Champion (two G7, one G27, two G7 Senior)
Two-time G7 World Champion (1988, 1990)
Eight-time G7 King track single lap world record holder
17B West Ogden AveWestmont, IL 60559, ( 708) 203-8003
mikeswiss86@hotmail.com (also my PayPal address) 
Note: Send all USPS packages and mail to: 5858 Chase Ave., Downers Grove, IL 60516
Make checks out to Chicagoland Woodworking, Inc.


#16 John Streisguth

John Streisguth

    Johnny VW

  • Full Member
  • PipPipPipPipPipPipPip
  • 4,770 posts
  • Joined: 20-November 08
  • Gender:Male
  • Location:Bangor, PA

Posted 11 June 2013 - 01:46 PM

Could you expand on that?  Besides the nosepiece, I don't see what would make it not legal.


"Whatever..."

#17 MSwiss

MSwiss

    Grand Champion Poster

  • Advertiser
  • PipPipPipPipPipPipPipPip
  • 19,066 posts
  • Joined: 16-April 06
  • Gender:Male

Posted 11 June 2013 - 02:32 PM

    
This pic shows a contingency plan. What you see pictured is an optional minor main rail. This would go as shown (more or less) and be soldered to the rear assembly and the nosepiece at the two blue arrows. This might be necessary for local rules but it also might be necessary if there is just too much movement between the fore and aft sections.  
 

 

 

Could you expand on that?  Besides the nosepiece, I don't see what would make it not legal.

John,

I was incorrect that it would be illegal for F1.

 

I was thrown off by Jim's above quoted line "This might be necessary for local rules"

 

 It's not necessary for IRRA ™ F1 rules. 

 

It would be necessary for a Can-Am chassis where the rule reads:

3i. Wire or tubing rails must connect the front 

and rear sections of the chassis
 
While the same rule is in the current F1 rule set, that was a cut-n-paste error that was clarified in the IRRA's Latest News section of their website.

Mike Swiss
 
IRRA® Components Committee Chairman
Five-time USRA National Champion (two G7, one G27, two G7 Senior)
Two-time G7 World Champion (1988, 1990)
Eight-time G7 King track single lap world record holder
17B West Ogden AveWestmont, IL 60559, ( 708) 203-8003
mikeswiss86@hotmail.com (also my PayPal address) 
Note: Send all USPS packages and mail to: 5858 Chase Ave., Downers Grove, IL 60516
Make checks out to Chicagoland Woodworking, Inc.


#18 JimF

JimF

    Checkered Flag in Hand

  • Full Member
  • PipPipPipPipPipPip
  • 1,924 posts
  • Joined: 20-June 07
  • Gender:Male

Posted 11 June 2013 - 03:13 PM

Wow....thanks for all the commentary and especially to Mr Swiss for 'splainin most of what's going on here. Here are a few specific answers...........

 

  • John: The forward aspect of the fork passes through the tubing and the leading edge of the nosepiece provides the positive front stop.
  • Greg and MS: You guys have read between the lines and are spot on. The accumulated tolerances of the opposing pivots are just too difficult to completely eliminate. I don't have much, maybe .005 total but I'm thinking it'll be too much.
  • MS: You read my mind on the minor rail deal. Personally, I'm too dumb to be able to decipher the rules completely. However, that rules possibility and also the accumulated movement in the pivots caused me to think of the "minor rail solution" that covers both bases.
  • Jim B: The reason for tubing at both ends is to preserve the really soft overall torsion. Tim N. pointed this out and he saw the original run both before (and....uhhh....after) the "big one"
  • Timmy: You're reading it right (as usual) all I'm really trying to do here is duplicate the car you saw in a.....ummm....."survivable" form.

 

Probably important to note.....This frame design is way softer in twist flex than any other TF designs that I have seen. I mean waaaaaaaaay softer. I didn't think it would work but it did and even on a technical track like the "Cave" in So-Cal.

 

Thanks again to all for the commentary and critique.


Jim Fowler

#19 Gator Bob

Gator Bob

    Grand Champion Poster

  • Banned
  • PipPipPipPipPipPipPipPip
  • 13,350 posts
  • Joined: 12-April 11
  • Gender:Not Telling
  • Location:.

Posted 11 June 2013 - 05:22 PM

I seem to be missing the rationale behind one significant step...

 

Why do you place the ends of the fork into tubing, instead of merely soldering to the nosepiece?

 

:laugh2:  Good question, right there...


Posted Image
                            Bob Israelite

#20 Greg VanPeenen

Greg VanPeenen

    Race Leader

  • Full Member
  • PipPipPipPipPip
  • 944 posts
  • Joined: 26-March 10
  • Gender:Male
  • Location:MI

Posted 11 June 2013 - 06:16 PM

Here is the answer.

 

In my normal simple tuning fork the main rails are .063 and the tuning fork is .055 wire this combination is very simple to build and works well on most tracks. When I build the (lets call it a center hinge) tuning fork I use .063 wire for both the main rails and the tuning fork. This combination gives you a stiffer chassis ( up and down flex) but also gives you more and smoother chassis twist with the tuning fork rails free to rotate in the tubes at the front. This helps the rear tires follow the track surface even better then the standard tuning fork. When done correctly you will get even rear tire wear on both sides on almost any track. With both tires working evenly a properly built tuning fork chassis will be a rocket off the corner. If anyone out there has a tire pyrometer you can check the tire temps just like on a real race car. A stiffer Chassis with the proper suspension set up (Chassis twist) is always faster and easier to drive, Just like the real thing. This type of chassis also has the advantage of not soaking up the motors power and putting what you have to the ground to move the car forward. Running any rails at the rear of the chassis unsecured through tubing causes uncontrolled rear steer and many free trips to walleworld.

 

I hope this info is of use to all.

 

Greg VanPeenen

BSR 



#21 Duffy

Duffy

    a dearly-missed departed member

  • Member at Peace
  • PipPipPipPipPipPipPip
  • 3,791 posts
  • Joined: 25-January 09
  • Gender:Male
  • Location:Geographically Brooklyn, Politically Berkeley

Posted 11 June 2013 - 06:20 PM


* I find it semi-amusing my spell check doesn't recognize chamfer as a real word.

 

Your spell check clearly was born sometime after tech & engineering classes lost out to "Core Curriculum" funding practice. Kinda makes us proud to be Republicans, huh?


Michael J. Heinrich
1950-2016
Requiescat in Pace
 
And I am awaiting
perpetually and forever
a renaissance of wonder

#22 MSwiss

MSwiss

    Grand Champion Poster

  • Advertiser
  • PipPipPipPipPipPipPipPip
  • 19,066 posts
  • Joined: 16-April 06
  • Gender:Male

Posted 11 June 2013 - 06:26 PM

On Google Chrome at home, it doesn't recognize "analytical" either.

 

Here at the raceway, on Firefox, it does.

 

Chamfer is no-go on either browser.


Mike Swiss
 
IRRA® Components Committee Chairman
Five-time USRA National Champion (two G7, one G27, two G7 Senior)
Two-time G7 World Champion (1988, 1990)
Eight-time G7 King track single lap world record holder
17B West Ogden AveWestmont, IL 60559, ( 708) 203-8003
mikeswiss86@hotmail.com (also my PayPal address) 
Note: Send all USPS packages and mail to: 5858 Chase Ave., Downers Grove, IL 60516
Make checks out to Chicagoland Woodworking, Inc.


#23 SlowBeas

SlowBeas

    Troublesome De-slotter

  • Subscriber
  • PipPipPipPipPip
  • 819 posts
  • Joined: 15-January 07
  • Gender:Male
  • Location:Lost in South Carolina, USA

Posted 23 June 2013 - 08:16 AM

 

The tubing at BOTH ends allows very smooth flex in the length of the chassis. Otherwise you'd be twisting the wires to get the flex.  

 

 

Jim B: The reason for tubing at both ends is to preserve the really soft overall torsion. Tim N. pointed this out and he saw the original run both before (and....uhhh....after) the "big one"

 

Thanks for the explanations, guys. I was wondering about the rationale behind your builds. Before receiving these responses, I had built my tuning fork with only the .063 fork up the middle of the chassis, soldered to both the motor bracket and nose piece, and my pans hinged to both, also. I made a few minor adjustments to free the pans a bit more to allow a little bit of movement.

 

Together with Don Weaver yesterday, I tested it again at Slots of Fun's tri-oval and, frankly, it handles pretty well. It's able to handle the tight curve, even on the lowest lanes, and I only blip at the kink near the drivers' station. All in all, it's a pretty good car, despite my soldering mistake!

 

More dumb questions: What effect do you think will result from twisting the wires as they're currently configured? And, do you think the chassis is more likely to withstand the test of time if I un-solder the wires in favor of tubing?

 

Thanks again for all the guidance. It's threads like this one that make me really enjoy reading the blog.

jb


Jim Beasley
South Carolina, USA

"Assuming either the Left Wing or the Right Wing gained control of the country, it would probably fly around in circles."
- Pat Paulsen, 1968
"I drive way too fast to worry about cholesterol."
- Steven Wright ca. 1983

#24 JimF

JimF

    Checkered Flag in Hand

  • Full Member
  • PipPipPipPipPipPip
  • 1,924 posts
  • Joined: 20-June 07
  • Gender:Male

Posted 23 June 2013 - 10:47 AM

IMO.....today.......@ 8:45 AM is that soldering up the forward ends of the fork is not a good thing or a bad thing, it's just a different thing. That will have some of the same effect of the free twisting forks, just to a lesser degree. I may be racing two of my fork frames today (or not, depending on conditions) and I've been working on them a little every week. All my opinions are subject to change, and maybe as early as tonight.................. :crazy:

 

Edit for an additional thought..............This concept and others are.......ATEOTD, all about managing flex in both directions (longitudinal and torsion). I think that the center spine concept has a lot of merit in this goal. Whether it turns out to be hinged forks, soild forks or no fork at all but a solid rear box with a spine morphing out of that.........for me, the jury is still out on all of it.


  • endbelldrive likes this
Jim Fowler

#25 Tim Neja

Tim Neja

    Grand Champion Poster

  • Full Member
  • PipPipPipPipPipPipPipPip
  • 5,516 posts
  • Joined: 11-June 07
  • Gender:Male
  • Location:Orange County

Posted 23 June 2013 - 02:23 PM

Here is the answer.

 

In my normal simple tuning fork the main rails are .063 and the tuning fork is .055 wire this combination is very simple to build and works well on most tracks. When I build the (lets call it a center hinge) tuning fork I use .063 wire for both the main rails and the tuning fork. This combination gives you a stiffer chassis ( up and down flex) but also gives you more and smoother chassis twist with the tuning fork rails free to rotate in the tubes at the front. This helps the rear tires follow the track surface even better then the standard tuning fork. When done correctly you will get even rear tire wear on both sides on almost any track. With both tires working evenly a properly built tuning fork chassis will be a rocket off the corner. If anyone out there has a tire pyrometer you can check the tire temps just like on a real race car. A stiffer Chassis with the proper suspension set up (Chassis twist) is always faster and easier to drive, Just like the real thing. This type of chassis also has the advantage of not soaking up the motors power and putting what you have to the ground to move the car forward. Running any rails at the rear of the chassis unsecured through tubing causes uncontrolled rear steer and many free trips to walleworld.

 

I hope this info is of use to all.

 

Greg VanPeenen

BSR 

Greg---did you capture the outer rails with a cap at the end so there is no movement for or aft in the outer rails?  When we do this--it seems to take the "rear steer" out of the car!! When I had a "TINY" gap there--it DID rear steer and created a LOT of problems--but when tightened to no gap--it cleared up!! 


She's real fine, my 409!!!

#26 endbelldrive

endbelldrive

    Checkered Flag in Hand

  • Subscriber
  • PipPipPipPipPipPip
  • 1,739 posts
  • Joined: 16-February 06
  • Location:Witless Protection Program

Posted 23 June 2013 - 03:32 PM

Hi Jim,

I was wondering if you tune by decreasing rear tire width too. :scratch_one-s_head:


Bob Suzuki

#27 Tim Neja

Tim Neja

    Grand Champion Poster

  • Full Member
  • PipPipPipPipPipPipPipPip
  • 5,516 posts
  • Joined: 11-June 07
  • Gender:Male
  • Location:Orange County

Posted 23 June 2013 - 04:59 PM

Hi Jim,

I was wondering if you tune by decreasing rear tire width too. :scratch_one-s_head:

Yes I know he does.


She's real fine, my 409!!!

#28 JimF

JimF

    Checkered Flag in Hand

  • Full Member
  • PipPipPipPipPipPip
  • 1,924 posts
  • Joined: 20-June 07
  • Gender:Male

Posted 23 June 2013 - 11:15 PM

Hi Jim,

I was wondering if you tune by decreasing rear tire width too. :scratch_one-s_head:

 

As Tim says.......absolutely. In fact, I'd say I narrow down tires much more often than I don't. Today @ Modesto I ran narrow tires on two of the three cars that I raced and those two ran narrowed wonders. The F-1 pictured in this thread ran treated @ full width but the flat track was a little loose.

 

I have enough data now to update both "fork" threads but it'll be a day or two to organize it take some more pics. The V 2.0 F-1 was a winner today as was an anglewinder coupe that I haven't pictured yet. I didn't race the tuning fork Can Am today b/c one of my other cars was faster.


  • endbelldrive likes this
Jim Fowler

#29 JimF

JimF

    Checkered Flag in Hand

  • Full Member
  • PipPipPipPipPipPip
  • 1,924 posts
  • Joined: 20-June 07
  • Gender:Male

Posted 25 June 2013 - 01:55 AM

OK.....first performance/racing update for V-2.0.

 

I raced the 2.0 yesterday @ Modesto on the famous Korkscrew road course. The car was a runaway winner but given that a couple of the regular flat track aces were not there, that alone is not a proper barometer. However, the track was a little loose yet the lap total for a 31 min main was on par with a normal 32 min main. That is a good indication of how the car ran. This was the easiest driving F-1 I've had on this track. It was so easy to drive that I could run fast and didn't deslot on my own for the whole race.

 

The car as raced is about as shown in the initial build. The exception is the "minor rails" shown below. (blue arrows) This is a piece of .032 wire soldered to the nosepiece and to the rear bracket/rail block (red arrows). This minor rail tightened up the cumulative slop from the opposing hinges without having any notable effect on the crucial torsional flex. In addition, there is a 4gr lead weight on the nosepiece and there were two additional brass weights tacked to the inner fork rails just forward of the bend. These were dropped off for clarity while the frame is stripped down for a minor repair. Tire choice for the loose track was a JK treated 8713 run full width. Race weight was 108 gr w/out body.

 

c9698e71-0ec3-466a-b428-772a2e0156e6_zps

 

4f2388a6-41e8-4453-b41c-a60980a9ecc1_zps


Jim Fowler





Electric Dreams Online Shop