First night of Racing 1/12th scale.......................

[Blake]

I will check in with the B&G Club to see if we can get in an hour or two earlier.

Ryan, what parts do you need?  Did you break something that will keep you out of the races on Saturday?


Let me know,
Blake

[SgRddY]

I got a question about my spur gear.  As you all heard in the main my spur gear was making horible noise but knowing me, I didn't stop until the car would not move anymore.  Anyways, I went the the hobbies shop and picked up a couple of gears (64 pitch).  These are not CRC parts so they looked a little different.  Well, I put one of them on anyways, i found that I can only use some of the ball bearing.   I have 2 left over, because I could not fit anymore on the new spur gear.  On top of that, the ball bearing are sitting further outside from the center then the OEM spur gear.  This in turn, I can see half of the ball bearing sticking out of the steal diff or clutch plate (not sure what to call it).  Is this going to work for me or do I need to buy the correct spur gears?  Everything seems to be working ok but I am worry about the correct operation and performance.  Please help.

Ken

[haddow]

Guys here is a copy of some notes I keep based on posts by Frank and his team on the TeamCRC website. This is an un-edited verion I will clean it up and we can add too it during the next tutorial or test and tune and then post an edited version.

Jody...

Carpet knife Setup Tips


Front Tires:

- Start Purple front tire black for high-bite conditions
- Tire traction - 1/4 to 1/3 of the front tire, on the inside portion of surface. CRC Down Force. If your car has too much steering use less wash.

Rear Tire

- Start with Gray rear tire or white rear if slippery. Pink in extreme low grip conditions or on asphalt.
- Full rear tire traction - let soak for 20 minutes. Team CRC Down Force recommended.
-Small diameter for high-bite, large for low bite

Car width

   All CRC cars come with the rear width at ROAR maximum, which is where you'll want to leave it. ROAR rules say 172mm in the rear (about 6.75"), that would be 86mm out to the edge of each wheel from the center of the car. Im not sure about a measurement on the front end, but typically for lower grip club racing I run the car stock with unflanged bearings in the wheel and no shims on the axle (you may have to put a shim or two on the axle to get the play out). At big high grip races like Cleveland or Snowbirds I usually put a flanged bearing on the inside of the wheel, and 2 thick 1/8" shims on the axle. It helps prevent traction rolling when the grip is really high.  Sometimes depending on a tracks teching equipment, CRC cars can be a little too wide in the rear. Removing one of the rear axle shims from the left side will cure that problem.

Tire size
   typically, we always run a bigger rear tire to start out with. A) because they wear faster than fronts, & B) because more side wall usually is more side bite. As far as rake, this varies depending on the track & driver preference. It is pretty rare to have the front lower than the rear. this makes the weight transfer to the front too much and the car will be loose, especially on entry. usually you'll want the same ride height front and rear, or maybe .5 mm higher in the front. Tires are really only too small once you can't make ride height anymore, &/or the edges start flaking off the rim, whichever comes first. On high bite tracks, you may like the smaller tires better as they free up the car in the corner. However on lower bite tracks, bigger side walls will provide more grip and hold grip longer later in the run.

Springs
   
   Rear Springs

   preload on the center spring is used only for setting ride height. if you want the car stiffer or softer, you need to change the spring. a stiffer center spring usually makes the car steer more. the only place this really doesn't hold true is if the track is very bumpy. because the car is too stiff, it is chattering in the bumps and losing traction. - Center shock â€" Kit shiny silver spring for bumps. Use the optional Red (#1340) spring for increased steering response. Next is the optional Copper (#1341) for more steering on smooth tracks. The CRC SS (stiff silver) spring (1342) is stiffer yet, then the stiffest, for lots of steering on super smooth tracks with high grip, CRC SSS (super-stiff silver) spring #(1343) - 35 weight silicone oil - Adjust the center shock length so that the rear pod droops slightly below the plane of the chassis when held in the air. No more than 1mm droop. When using the, CRC SS, and SSS springs, set up the rear droop at zero. - Adjust the shock spring preload until the chassis and rear pod piece form a straight line when full loaded and race ready. Shock spring... stiffer = more mid and exit steering.


      Olive Green - 6
      Silver (vcs, not crc) - 8
      Blue - 10
      Gold - 12
      Red - 14
      Copper - 16
      CRC Stiff Silver
      CRC Super Stiff Silver


   Side Springs

   Side Springs... Stiffer equals more initial turn in, less chassis roll and more steering response (although most noticeable around center). side springs control how reactive the car is around center. a stiffer side spring will make the car twitchy around center, but not necessarily make it steer more all around. - Start with white side springs, orange + blue for more rear grip, red for more turn in, then green,
then purple. Red is good for advanced drivers wanting lots of steering. We rarely use purple. Very little preload on side springs, just enough to tweak the car flat. The side of the car with more weight will require more tension on the rear spring on that side. - Shims,....all free play shimmed out...but no pre-load on the spring.

      1295 - Side Spring- Blue - Soft
      1296 - Side Spring- White - Med
      1297 - Side Spring- Red - firm
      1298 - Side Spring- Green X-firm
      1299 - Side Spring Purple XX-Firm

   Front Springs

Softer = more steering, Harder = less steering (18 = soft 22 = harder). Softer means that there is more weight transfer as you let off the throttle and the tires can steer more with more grip. A harder spring allows less weight transfer and therefore less steering.

      1392 - .018 Front Spring-12th - (2)
      1393 - .020 Front Spring-12th (2)
      1394 - .022 Front Spring-12th
      1395 - .024 Front Spring-12th

Raising shock mount (batteries in and out smoothly)

   I usually put about 4 or 5 shims under the front ball stud (.060 - .075) and that gives just enough clearance to get a 4 cell pack in and out without popping the shock off. raising the front of the shock is suppose to reduce steering, but it must be a very small amount cause i have no trouble getting tons of steering out of my car.

Geometry changes

Camber... more will add front steering, to a point. Camber effects are very dependant on track grip.
Caster... more will add steering when the wheels are turned a substantial amount. Lots of caster usually makes the car "softer" to drive around the center point of the steering, but steer hard at full throw.
Springs...stiffer = less steering, may feel like more rear grip.
Toe... a little out = more steering and less straight line stability. Start: No Toe in, slightly toed out if at all...

Shock and Damper Tube Oil

Shock oil... not much effect here. Just heavy enough to damp the shock over the bumps. If very smooth, run a heavier shock oil. If too heavy on a bumpy track, the shock will not respond quickly enough. 20-40 weight should work

Tubes... must be tested on the track. Sometimes heavy is more traction and easier to drive, other times it is less traction and twitchier. - - refill every 3 races. Thicker oil is twitchier usually, thinner is less twitchy. Side spring and damper fluid changes have similar effects. Whatever you udo make sure there is fluid in the tubes. Frank suggests a change every 3 heats..

Differential Building

Lets start fresh to show the true potential of a great diff...
*** 3 new CRC 1/4 x 3/8 flanged bearings (must be CRC bearings, try others back to back, you will see why)
*** 2 new CRC 1/4 x 3/8 flanged bearings (again, use ours)
*** 2 new Large "D" rings (ours, IRS, Associated)
*** 1 pack of our cheap 1/8" diff balls (we have a good deal on a bag of 100)
*** 1 new spur gear (our gear is better for a free diff and stock racing, Kimbrough is better for mod racing, slightly less free)
Use the left wheel hub/wheel combination as a holder for the assembly. Put the axle in the left diff hub with the "D" ring seat face up. Place 1 new D ring on the seat and set it in the machined pocket.
Load the outer ring of holes with the 1/8" balls. Pop them in. Place 1 small "dot" of white Associated diff lube (NOT STEALTH!) on each ball. Just a little dab while do. Now, put a new unflanged bearing in the inner and a new flanged bearing in the outer part of the diff hub. Use another couple of dabs of diff grease to hold the D ring to the diff hub as you put it on the assembly. Slide the diff hub/ring on, making sure the ring stays seated in its machined area on the hub.
Now, put a small shim over the axle. Then the aluminum spacer/collar. Then the spring washer with the cone pointing out (or at you). Then the lock nut. Tighten the lock nut SLOWLY... especially as the assembly begins to tighten and the rings are being pressed to the diff balls. Overtightening here will ruin the outer bearing in the hub. As you tighten the diff nut, check it by holding the left wheel in your left hand, hold the right wheel in your right hand. Push the gear with your right thumb, if it "slips" it's too loose.  Once it's tightened to the point of no slipping (AND NO FURTHER), install the axle in the car and apply 2 volts to the motor. Hold the left wheel for a minute or so, then release and hold the right wheel as the motors spins and the diff breaks in.  Check to see if you can now slip the spur gear with your right thumb and tighten until you you can not do so (And NO FURTHER). Now your diff is ready to use and should last for a number of race meetings.
Good luck.

Thanks for choosing CRC.


Frank Calandra
Tom Firsching
John Firsching

[haddow]

Ken

Your diff will be fine with less balls, some spur gears have a different configuration. As long as the ball isnt riding on th edge (balls must be rolling on the flat surface obviuosly)  of the diff ring you should be ok.

Jody

[Blake]

You're probably fine Ken.  I think it's quite common to be able to see about a third of each diff ball extending outside the circumference of the diff ring.  Just be sure that the diff balls are definitely running against the surface of the metal diff rings.

Sometimes the spur gear will have two sets of holes: an inner set and an outer set.  Correspondingly, there are two sizes of diff rings: small and large.  Use the inner holes in the spur gear for the small diff rings, and the outer holes for the large diff rings.

As for the number of diff balls... different gears have different numbers of holes.  Six and eight holes are the most common.  It doesn't really matter - just fill up the entire inner set, or the entire outer set with diff balls.


Blake

[Tom]

I got a question about my spur gear.  As you all heard in the main my spur gear was making horible noise but knowing me, I didn't stop until the car would not move anymore.  Anyways, I went the the hobbies shop and picked up a couple of gears (64 pitch).  These are not CRC parts so they looked a little different.

There's nothing special about any particular brand of spur gear for these cars; the spur gears are a pretty standard part.

There are two styles of diff; old-school (originally on the first R/C 10, which came out about 20 years ago), and stealth, based on a better transmission for the R/C 10 that came out around 15 years ago.

The old-school uses the same diff ball radius as the original R/C 10, and the stealth uses the same diff ball radius as the Stealth transmission interal diff, which was based on the diameter of spur gear mounting holes, which was in turn based on the mounting holes for 1/12 scale wheels.

Robinson, Kimbrough, Paragon, Associated, Trinity, and many other R/C car parts manufacturers make standard gears that will fit most R/C cars out there; most cars have interchangable spur gears, but a few kinds require special gears.

Well, I put one of them on anyways, i found that I can only use some of the ball bearing.   I have 2 left over, because I could not fit anymore on the new spur gear.

The number of diff balls doesn't really matter all that much.  You need at least 3.  Many people will run a diff with lots of empty holes; other people will fill every hole they can.

On top of that, the ball bearing are sitting further outside from the center then the OEM spur gear.  This in turn, I can see half of the ball bearing sticking out of the steal diff or clutch plate (not sure what to call it).  Is this going to work for me or do I need to buy the correct spur gears?

What matters is if the diff balls are running on the surface of the diff ring.  If they are running on the edge of the diff rings, that won't work.  Also, if they are running over a notch in the diff ring (in case you are using a stealth diff with D-rings), you'll have to try a different arrangement.  Many spur gears will have 2 sets of holes; the inner holes are for the Stealth style diff, and the outer holes are for the old-school diff.  The correct spur gear is one that is the right size, and that has the right set of holes for your style diff.  Some spur gears will have a slightly different hole radius than others; this allows you to re-use worn-out diff rings, since the balls will be running in a new groove.

Everything seems to be working ok but I am worry about the correct operation and performance.  Please help.

If everything seems to be working ok, then don't worry about it.  Like I said in a previous post, 1/12 scale cars tend to have many interchangable parts with other brands of cars, and tend to be qute standardized.  Most 1/12 scale cars (including all models of the Carpet Knife) will work perfectly fine with any standard spur gear made in the last 20 years.

[jamminjim]

Hey Jody,  That's more like what I'm looking for. Good stuff!!

[Blake]

I checked with the Boys and Girls Club today to see if we can get into the gym any earlier than 4PM.  Unfortunately there is group of wheelchair basketball players that have the gym reserved until 3:30PM every Saturday afternoon.

So, the best we can do is show up at 3:30PM, and hopefully have the track built by 4:30PM.  That would give an hour and a half for a testing/tuning.

Oh, and they're going to check into the possibility of setting the alarm for 11:30PM instead of 11:00PM.


See ya all Saturday,
Blake

[Grinder]

Why don't we get the alarm set for 12:00 instead of 11:30.  If we are going to ask to have it changed we may as well make it worth our while....

[RYY]

Blake,
Has there been any discussion on making an earlier say 3:30 offical start time rather than running later?
RYY

[haddow]

Ryan we cant start too early as some people work Saturday. But we could get setup and practice for longer.

[RYY]

Jody,
I would agree with that, if it were at all possible and if it were of interest by a majority of the club.  I would hate to see just you and I doing all of the set up!!!HAHAHa However with my track record of helping set up in the summer series I am sure a few folks would like to see me set up and tear down by myself once in a while.  
For those who are legitimately working on saturdays it would be nice to have everything set up and we race as soon as they arrive.  A question to ask would be; How many poeple are working on saturdays and what time could they arrive?

RYY

[Blake]

Hey all,


I asked about the alarm but unfortunately it cannot be changed.  This means that we're going to have to keep to our schedule during the night.  It sucks to run only two qualifiers instead of three so let's have everyone make an effort to be ready to run (and marshal) when they're supposed to.

Ideal schedule:

3:30PM Arrive
3:45PM Start track setup
4:30PM Track is open for practice
5:45PM First round of qualifying
6:45PM Second round of qualifying
7:45PM Third round of qualifying
9:00PM Main events
10:15PM Cleanup
10:45PM Prizes
10:50PM Out the door


Blake

[Grinder]

Did we get any feedback about noise levels/garbage/cart in the hallway?

[Blake]

Hehe, no, we didn't get any negative feedback which is great!  I went in there this morning and the cart was just where we left it.  And I guess the neighbours weren't too bothered by the noise.  I didn't notice any garbage problems on Saturday.  It seemed like we cleaned up pretty well.

That said, this weekend I think we should make a conscious effort to keep the gym doors closed.  If you're out there smoking then just leave the door open a tiny crack.  Gross smoke smells were coming into the gym last Saturday apparently.

Oh, and I think we definitely need to be a little quieter at the end of the night when leaving.  Maybe save your exciting race stories for BP, or at least for when you're down at street level.


Thanks all!
Blake