Friday, December 31, 2010

Working on the pod....



I going to be doing some more videos eventually finishing off the car, but remember if you have any questions about anything please comment or email.  I certainly don't know everything (I actually don't know much), but I'll be able to address anything in the videos or posts and make them more interesting.  Thanks.

F104 videos continued....chassis

F104 videos continued....



F104 build videos

I made some videos of building up the rolling chassis of the F104, with the emphasis on rubber tire racing.  The ideas are the same for foam though.  Something to check out.


Wednesday, December 29, 2010

F104- the tbar mod

If you don't race Tamiya races..........
Ok, I'm going to let you in on the most important secret of all. Remove the center screw from the t bar where it attaches into the rear bulkhead. The car is WAY too stiff front to back with that screw. It will now also turn better too as the car can twist slightly.

All these guys who post about running with no shock attached, or no oil or spring or whatever baloney have an inkling of the cause of their problems, but removing the screw is the best deal. Check out a 103 and you'll see that the front to rear flex is far greater.

Myself and some other guys from our track have run this on foam tires, and it works great. It's the only way to get close to a 103 on lap time. Much more stable and steers. Still not quite as good as the 103 but easier to drive.

You will also need  a TC5 shock rebuild kit.  There are 4 foam circles in the package that are die cut.  If you pop the center out, the foam ring is a perfect cushion for the center screw in the t bar.  In fact the car will be significantly better if you glue the foam to the t bar and just remove the center screw!  This is how we ran at Trackside TCS, and how I was planning on running my car at the TCS Nationals until I found out this would be deemed illegal.

Much credit to Greg Sharpe and Jimmy Stegen, inventors of the foam "trick"

EDIT:  Details in this VIDEO -

Tuesday, December 28, 2010

Set the links on your F109

In putting this car together, I noticed that the rear link setup is pretty close to the SpeedMerchant Rev style 1/12 cars. It also requires you to go through the same setup for the links to create a smooth suspension action.

The instructions tell you to set the links at the same length. This probably won't be correct however. Most of the time, if you do this, you will feel a "clicking" or a "catch" in the side to side action. To really feel what the car is doing, you need to have the links attached to the lower pod plate with no other parts on the pod plate, and the rear bulkhead with the center pivot attached to the chassis and lower pod plate.

It's fairly easy to take 4 screws out of the lower pod plate, and remove the motor mount and axle, upper plate, etc, all in one piece. With the lower pod clean, you can cycle the plate side to side and feel if the suspension is hanging up. If it is, and it probably is, you need to start adjusting one of the links. The idea is to go shorter or longer on this one link until the suspension feels very smooth and free and does not click or hang up at all. You will know which way to go by the fact that one way will make the car start to smooth out, and the other way will make everything much worse. It may take a bit of adjustment, but it will get there.

Once the car is feeling good, you just need to reattach everything and run. If you get into a good wreck, you may have to do this again, as the car may have shifted around. I know after I built my car per the instructions, it was pretty bound up feeling. It took a little cranking, but now it feels great.

CRC side spring mod for the 3Racing F109

Go to nexus racing and get CRC #1280 side springs and 3387 molded spring retainers. You'll need 2 4-40 screws, decently long to use as tweak screws. The hole for the grub screw which secures the pin for the top deck hinge goes all the way thru, so you can use this for a tweak screw hole. You'll need to cut down the pins for the top deck, and secure them. I JB Welded them in the hole.

You'll need to dremel off part of the spring cup on the bulkhead to clear the spring retainer. Remove the spring retainer on the lower pod plate. Then screw the 4-40 screw into the bulkhead, screw on the CRC spring reatiner and attach the CRC side spring. I used red for carpet, but there is a good selection in the kit. You now have a wide variety of springs and also tweak control for the car.

Monday, December 27, 2010


Still the sweetest video ever..........

F103 front end questions

One other question.  Have you ever tried the 3Racing adjustable front suspension?  The kit comes with adjustable camber.  I also have the adjustable caster center piece, so I'll be able to adjust camber and caster.  Going to try it on the F103, the Exotek F104, and the Exotek F103 when we get it.

>>Yeah, i have run the 3Racing. I have the 3Racing F109 and I've also run it on the 103.  It has quite a bit of steering-camber is key.  I found 0-.5* is a good place to start.  I had run 1-2* when I first tried it and the car was bananas.  Caster at about 6* is a good start as well.

Also, have you tried the carbon resin version of the stock front suspension?  It is stiffer and I wondered if it would be the ticket on foams and carpet.

>>The carbon front end comes on the 15th anniversary car, and it's mostly what I have used.  That being said, I have run the plastic front end too, and I don't know if there is much difference.  I never really tested this though, but it's not night -and-day where you know something is up right away.  The 3Racing front end is actually pretty soft, which may be why it develops a lot of grip.

Foam tire setips for F103 and Exotek/103 front end

**************Clarification questions in red
Black front spring
60K-100K diff oil on kingpins
regular front end w/caster shim to add kick up  What size shim and what thickness?  Goes under front Wing screw correct?<< 1mm wheel hex shim, correct under wing
stock steering arms Need to use the shaved arms due to ride height?<<Maybe, I think when the tires get under 51mm you may start having problems and need to shave arms
HBR Med Tamiya tire or Magenta  What tire diameter range should I true to?<<<If I remember, 53.4mm produces 4mm ride height on stock arms
4mm ride ht
black o ring on top deck screws-where top deck meets servo mount (2 total)
0 toe

bridge shock mount
35 wt oil center shock
1 o ring inside shock
set shock length so shock end covers almost all threads- you should have a little droop. How much preload? <<Just try to get the main chassis behind the battery @ 4mm
3 hole piston

yellow or blue spring from florescent mini car set
damper disc-I usually go with a heavy fluid, like 20-30K, but I have been thinking a lot about this, and I think it may make the car too twitchy.
start with 10-15K...
Stock T bar ----  front screw ---.5mm shim   rear screw ---2x .030" nylon washers.  Nylon?  Why?  Where do I find them? <<Associated sells them in packages to space hubs on offroad cars and other stuff.  They are stiffer than an o ring, but still let the t bar move.

 If that is too stiff for the amount of traction, replace 1 washer with black o ring

Start t bar tension so that it has side to side movement but, only a bit.  Don't crank it too hard, and don't let it be loose.  Adjust to taste.
4mm ride height or a bit of rake so front is lower.  Usually the 0 axle adjuster works.
space axle each side 1-1.5mm.  More spacers = more reactive
Tamiya pre mount or equivilant (ask Cuda)  or Magenta

front=same as 103, unless you want to run the 3 racing front end.  I would run 0 or .5 camber.  Caster, start w/6* and adjust to the track
What body/wings are you using F104 or F60?  <<F60 cuz it's cool!!!  Plus the cow catcher on the front is a full width bumper
45 or 50 wt oil center shock (I'm not sure yet:>)
3 hole piston
40 or 45 in side shock
2-3mm droop
CRC red or white side spring, or AE blue or gold--this is something you will have to decide on. 
Let side spring touch side link at rest.  Some guys say don't let the spring touch, but I think the car is lazy like that.

3.5 mm offset steering block vs. standard


Do you use the 3.5 offset front steering or the stock ?  What are the steering dynamics of both?  Sorry for all of the questions, with all of the testing you've done, no sense duplicating what knowledge is already available!
I have run the 3.5 arms, and if the track is small or has a lot of 180's, it's not going to steer enough.  I tried it last winter at a couple tracks, after a friend started running it.  The deal is if you are a good driver, you will want the steering from the regular arms.  The car is calmed down, but mid corner out there is nothing.  On a 103, the twichiness can be relieved with a slightly tilted t bar (like anti squat, front screw, .5mm spacer, rear oring + a spacer, or just a couple .030 nylon washers for hi traction), and 2 orings where the upper deck hits the servo mounts.  However, see below for the best idea.

The stock arms with the regular front end will be twitchy, generally.  The biggest thing you can do to make it easier to drive would be to add either a .5 or 1mm shim to the front end on the forward mounting bolt, so that the whole front end gets a bit more kickup/caster.  I take the front bolt out and loosen the rear a bit, and slide the shim between the top of the wing and the bottom of the front end, in the "wing slot" part.   Instantly more driveable, and a bit more useable steering as well.  Before this, my car would do the "F1 shuffle", where the rear end breaks loose a little bit mid corner.  Now it rolls through the corner at speed. 
This is all foam tire stuff though. 


Emails on the F104 and F103


How do you adjust droop?  Shock length?  How do you measure?  With a straight axle rear end, the only up travel is at the center of the car where chassis meets rear pod.  I guess I'm having a bit of a problem getting my head around the dynamics of this concept compared to a traditional chassis.  Please explain if you would.

You adjust the droop by shock length.  Take the car at ride height, and looking at it from the side, lift it until the rear tires leave the table.  The difference between ride height and where the tires lift is your droop.  Measure at the rear of the main chassis.  Just think of the pod like a suspension arm flopping down.

If I understand you correctly, you mean the rear arms near the back of the servo, right.

 You want me to put spacers under the ball studs to angle the rear of the front arm up.
How much?
  Start with 1mm, you may be able to get 1.5 on with the stock screw.  More would probably need a longer screw.  You can also change the ball stud on the front of the arm to a shorter one to get a similar effect, or add even more in combination with the rear spaced up.
Is this kinda like antidive? What I don't understand is how raising the arms here does anything with the pivot ball at the top of the
This is the same as the front end of a 12L with the dynamic caster setup.  The upper arm moves forward on compression, reducing caster. There is a slight caster increase at ride height, but it's not much.  You're just pulling the upper arm back a little, but the big effect is the caster change in compression.  You'll see it if you work the suspension.

What about front caster?  Not adjustable?  Spacer under front screw like F103?

You could do the spacer,but you might not have as big of an effect due to the geometry of the arms

What about the steering blocks?  Right now the car has the 3.5 mm offsets on it.  We tried both styles on the F103 and found that the car was 2-3 tenths faster with the offsets.

I'm surprised to hear you were faster with offset blocks.  They kill a lot of steering for me.  L--- might drive different than me (i.e. better).  You may want to try the regular blocks, just because I feel they steer more off center/off power. 


Speaking of F103,  do you use the pivot ball suspension or the O ring?  I'm sure you tried both... advantages/disadvantages?  What would you use for rubber tire?  I just bought the pivot ball suspension, but before I tried it, I thought I'd ask you for your opinion.  Any special tricks/tweaks you do to them to make them work better?

I did a lot of work with the pivot suspension.  Having raced 1/12 quite a bit, I liked that you could add tweak screws and tweak the car like a 1/12.  It also was a lot of trouble for nothing, as an o ring setup was the exact same speed without all the tweak headaches.  I have watched a lot of guys out here run the pivot setup with no tweak screws, and it seems good outdoors, and at least ok on carpet. I feel that the o ring is a little better for foam, at least, as you can adjust the screw tension, as well as use different orings and tilt the t bar as well.

What I had been doing was using the stock t bar, with an .5mm aluminum shim on the forward screw.  The rear screw was either a black oring (lower traction) or an .060" nylon spacer for higher traction.  I would start with the o ring for rubber, but you may want to add a .5mm or .030" shim as well.  I was trying to achieve a slight angle to the back of the car, sort of like anti squat.  This will make the car not get on the nose so hard off power, making it easier to drive.  You may also want to look into a soft t bar as well, or even an o ring on both screws depending on traction.

The tension on the t bar affects how much it can twist, and I feel this affects  the rotation of the car.  More twist = more rotation, but there are diminishing returns here.  For a good example, the 104 with the middle screw out rotates a lot more since the t bar can twist much more freely.  Too much and it will park in the sweepers or hang a wheel in the air.  It may not be as big of as hazard with rubbers though.

Right know, with Ride A front tires and the Tamiya A's the car is hooked up pretty well.  Rear tires are "chirping" a bit a on sharp turns.  Can't seem to get the car to rotate through the corners as well as I'd like it to.  Any suggestions on getting the car to roll through the corners better? 

Tried stiffer shock spring, but started with  the silver one that has a ton on coils in it, fairly soft and all the way up to a yellow.  Just lost overall speed with not any real improvement. Tried more tension on the puck set screw, heavier grease, not saucing the rears all of which made the car slower.

Got the stock black O ring in the middle hole with the stock black T plate. The middle T plate screw is medium light on the tightness. Using the 3Racing front suspension with the caster setting at about 5 degrees.  Tried the stock front F103 front end and it again was slower than the link type front.

You may actually be a bit faster with the pivot ball, from what you are saying.  You're sliding the rears to get the chirp.  All the things you tried bound up the rear end more, so the car just wants to slide.  The pivot setup will just cycle side to side as fast as the puck lets it, so the car should rotate better.  Otherwise I would go with o rings on both screws, maybe even red orings to be a bit softer.

I think the link front end probably is the way to go, as it seems to have more traction and you can add camber as well.  I know with foams it had too much steering generally.

You might want to widen the rear a little bit as well.

This was a 15th anniversary car??  If not, and you are running the short fiberglass top deck, it will feel like it has no steering.  What is the chassis setup- graphite? fiberglass?  long or short top deck?  A graphite car can also feel like garbage on a low traction track.