11 replies to this topic

[JimF]

The first thing I've built in many months and this took me almost a month of stealing a few minutes at a time for the bench. Building that way is really inefficient but was all I could do. So.....what's up wit dis???

 

Of course the pros all know this and do this but quite a few not-so-pro builders may not. The first point is to know what you're going to do and why, before you start. A lot of guys are going to just "build something and go try it out" Instead, this is a very strictly planned variant of an existing chassis that I've had that is successful.

 

• Original is 4.05 WB with .875 Guide Lead.
• Original chassis is 6 rails of .039 fully soldered and 110 gr all up.
• The 6X.039 makes a lot of bite. More for ex. than the more common 4X .047
• Original was fast off and a race winner but occasionally a little "bitey" on tight flat tracks.

 

What I wanted was the same speed off but a little easier to drive in high bite situations. So.........

 

• New one is still 6X .039 but with a longer WB (4.125) and longer Guide Lead (.925)
• There is a little cutout on the nosepiece about 3/4" inch from the very front.
• This is a solder stop that keeps 1/2" of the rails from soldering to the nosepiece.
• With that 1/2" of rail not soldered to the nose, the flex is even greater than the original.
• I hope the longer W/B compensates but if not, I can stiffen it up immediately by just soldering it up.
• This chassis also has three sets of body mounting tubes rather than the more common two.
• The front will be a constant but the middle and rear ones will be tested independently to determine any diff.

 

So....I planned the build, now I'm planning the testing.

•  
• The Parma Matra body and 8-29 gears always work on flat tracks so initially those will be constants.
• Occasionally, I'll test 8-28 or 8-30 but just always seem to start with a 29 on our Mini Brutes.
• I've already planned my weight tuning. 2 gr/side right at the rear by the bracket will be tried first.
• I'll also test 4-5 gr additional on the center weight and maybe that plus the rear weights.
• That nifty little tire organizer holds my initial tire test runs.
• I'll start with my usual narrow (.250) fronts and JK 8703 natural (narrowed)
• I'll follow with Alpha reg full naturals and then the JK premium in small hub.
• I'll run the same sequence with full width if conditions dictate.
• Finally I'll take the best tire/weight combo and test with the wide (.400) fronts.

 

 

Hopefully building and testing with a plan similar to this will help eliminate some of the randomness that some builders experience.

 

[NY Nick]

And it shows, neat and clean. Thanks for posting your work.

[Tim Neja]

Geez---with all that organization---we might "learn" us something!!!     Very nice Jim!! 

[Gary Pershall]

Glad to see you back posting Jim... Love looking at your builds... I credit you for giving me ideas on most of my chassis builds since I started back building and racing this year. I need to take heed to your organized testing since it is almost a 4 hr drive to where I race and I need to maximize time spent at the track.

[JimF]

Glad to see you back posting Jim... Love looking at your builds... I credit you for giving me ideas on most of my chassis builds since I started back building and racing this year. I need to take heed to your organized testing since it is almost a 4 hr drive to where I race and I need to maximize time spent at the track.

 

Thanks to all. and specifically to Gary..............

 

The organized testing is key. If you go out and spend 30 min on black, without making changes, you're practicing not testing. Practice is great. That's when you find out what your pace is, find out any lane weirdness to be aware of, and learn the sight-lines. Testing is when you run 10-15 laps with a tire, weight, body, gear configuration and then change to see if you can improve. 

 

Of course it helps to know what to do when you are trying to correct something specific. That will come with time, developing consistency, and knowing what your goal is. IOW if you end a 30 min track time session with the idea that I need "to be faster".........then you haven't learned anything. OTH if you end a session with the idea that "I need to come off the corner faster without tipping" or I need to in "further without plowing out" then you've learned something specific to work on. Without some type of analysis, and organization, you end up throwing stuff against the wall to see if it works. That's way too random to be effective on a repeatable basis.

[JimF]

Ready for the first track test..........Yippee!!

 

This'll be the first non race day testing I've been able to do since early November and even this is kind of a fluke. I have an appointment to do my taxes in Sacto today so I'm going to head out a little early and sneak in some test time on the "Yellow Dragon" flat track at Fast Track Hobbies.

 

I have much of the prep work done including cutting the different weights that I'll use and of course the tire variations that I think I'll need both for FTH and more importantly for our next race on the little Korkscrew at Motown.

 

Here's what I think will happen..............

• The tires shown on the car will probably end up as the best choice. (JK 8703PP narrowed)
• If it's slick, I think the best might turn out to be the Alpha Pirhana regular full hub.
• The weight options are 5 gr for the center, 2 gr/side or 3.2 gr /side at the rear next to the bracket.
• I think I'll end up with the 5 gr center weight and the 2 gr/side rear weights.
• If the motor turns out to be a beast (relatively speaking... ) I may end up with a 30t crown.
• I have no clue if the different body pinning positions will have any effect at all.....(I suspect not)
• So......I gots me a plan. Dunno if it'll work but, that what testing is about.

Car, ready to go with no added weight = 111 gr.

 

 

The Yellow Dragon at FTH...........

 

 

 

 

 

[Gary Pershall]

 Waiting..... Waiting.... for the results.

[JimF]

 Waiting..... Waiting.... for the results.

 

OK.......a little inconclusive b/c my tax appointment was bumped ahead an hour so I didn't get as much time as I thought I would. Also the track wasn't great. For the first 20 laps or so, my tires came back looking like cotton balls. After about 100 laps, the track came in enough that times were within .10 - .15 sec of optimal.

 

First take..............this was the fastest car in my box on the right side of the track. Particularly in the downhill/fallaway esses going under the bridge and then in the uphill donut (with the bonus 'dip' in the middle). I could go at this section much harder than I thought I could and faster than any other car I have. Surprisingly, it didn't feel like it needed weight. I usually run 120gr or more on this track but this car was just fine @ 111gr. Given the shorter test session, I concentrated on tires and found as I sorta guessed that the narrowed 8703PP was just fine. Given the rather slick conditions, I switched over to the reg full hub Alphas, and it got a little better but by the time the lane came in, it didn't matter.

 

The conclusions may be different when I get the car on a stuck track which should be next weekend at our race at Motown. Early on however, I'd say this hit my target.

[Jay Guard]

Hey Jim:

Is the Yellow Dragon the flat track that Fred Hood had down in Fresno?

[JimF]

Hi Jay

 

Yes it was in Frez. It was stretched in a couple of spots and very heavily reworked by Cruzin' Bob Scott. It is a very nice flat track and in great shape.

[Bill from NH]

Jim, is the "Yellow Dragon" at FTH the same Monty Ohren built flat track that used to be at Uncle Kal's in Monrovia?

[JimF]

Jim, is the "Yellow Dragon" at FTH the same Monty Ohren built flat track that used to be at Uncle Kal's in Monrovia?

 

Bill:

 

Sorry I missed this question for so long. No, the YD is not the old Monty Track from Kals. However, we do have that track in  Nor Cal. It is in Motown Raceway in Modesto and is a regular stop on both our retro tour and the popular NCSCRA "scale" tour. This is one of my favorite tracks ever (I just like small tracks)