286 replies to this topic

[Pablo]

Thanks Steve. I'm going to leave it as is for now and see how she feels on the track ...... may handle just fine with a small amount of flag rotation. I can always trim it at the track and make a new stop for it later.

[Tex]

Having the guide flag swivel until it hits the body and possibly popping the car out of the slot might be preferable to allowing the guide flag to swivel further and getting so far sideways that the car (1) is unable to straighten up and move forward, and (2) it is now a target sitting sideways for another car to hit.

[Pablo]

Track test # 1 results:

The car itself is a tilting pile.  I'm tired tonight, don't know what I'm going to do about it until I sleep on it......I may try to stiffen the chassis and add weight, or I may scrap it and start over with brass rod.  I'm done with round tubing, I'll tell you that much. My first experience was not good.

 

The motor, however, is a super performer, great acceleration, great brakes, very smooth and lots of power.  Runs absolutely stone cold temperature - wise at 12 V.  I ended up using an Okeefe arm in my setup, as the pablo arm had a nick across the windings and a possible short.  The Okeefe is absolutely a home run armature !!      

 

It needs a heavier, stiffer chassis I think.  I'll be working on it soon......

[Bill from NH]

 Too much horsepower for the chassis? Did you also test this car at Talladega?

[havlicek]

Hey Pablo...maybe too much tire?  Cars of the period were typically light relative to their power, but too much grip will really screw things up.

 

-john

[SlotStox#53]

John's got a point, maybe too much tire? Needed the edge of the tires rounded off somewhat,narrower tires?

Sorry it was such a naff track test

[Pablo]

I have considered the "too much grip" theory. It is possible, I agree.

Next track test: 4 January.

For now, the M2B lives in temporary quarantine housing ( a Tupperware container) before being allowed into the display box

[Steve Okeefe]

Pablo,

 

I remember the days when we couldn't get enough traction no matter what we did...  But that was then and this is now.

 

I went back and looked at post 169, and I see (or I think I see) modern black tires.  John may be right; you've got too much traction (and too much power) for the light-weight chassis.

 

Something you could do as a quick-fix is to narrow the rubber (there is no requirement that the tires be a full 1/2" wide), or save the wheels as they are for a heavier car and substitute with wheels made with rubber known to have a bit less traction.  Maybe even German Graupners.

 

Given the motor has good power and brakes, and does not run hot (my biggest concern), you may want to save it for a heavier car (maybe a fifth race coupe or sixth race F1, or maybe even a 1967 car).

 

I'm beginning to think 29 gauge is as heavy as you want to go on a light-weight car like this. 

 

Do you think possibly the confined (cannot swivel very far) guide might also have something to do with the chassis' squirrely behavior? 

[dc-65x]

Hi Pablo,

 

Based on the dozen or so R&C cars I've built and tested you've got too much motor and too much traction. If you had less traction you could still use the motor you've got as it will light up the tires all the way down the straight.      Personally, I don't really enjoy that so a milder motor would be a good thing.

 

I've tried the modern tires on the narrow width Russkit rear wheels (.350" wide) and it didn't really help.

German's might be pretty squirrely.

Fresh period VC's or Tiny's tires work great but are hard to come by.

 

Hmmmmm...........I've got a pile of fresh Riggen orange donuts. I know the color is wrong but they might just work. They don't match the traction of a modern tire for sure.

 

Pablo, did I ever send you any orange donuts?

 

[Pablo]

Steve,

"Do you think possibly the confined (cannot swivel very far) guide might also have something to do with the chassis' squirrely behavior? "  No. It's not a cornering issue. It is absolutely spooky jumpy going down the straights. Not planted at all. I launched it twice. Full force into the bank wall. The mirrors and driver are still perfectly intact     Crash test, excellent

 

Rick, I have one more pair of orange Hershman donuts. Based on y'all's input, I may leave the car as is and switch to a less grippy donut. That would be an easy conservative change.

[dc-65x]

Hi Pablo,

 

Don't give up on your cool chassis. I really think trying a less grippy tire is the way to go. Putting that mother honk'n 28 gauge motor in a heavier sports car would help too

[Pablo]

I hear you.

[havlicek]

Yikes Pablo.  Re-reading some of the posts above, it seems that Steve wound you a #28?  That's a lot of oomph for that car alright, although I pray at the altar of the horsepower gods myself  Still, horsepower doesn't make a car tippy, it just means you need to drive carefully.  I'm sure you'll "figger" it all out though.

 

-john

[SlotStox#53]

Maybe a slab 'O lead perhaps?

[Pablo]

Maybe. Maybe a combination of things. You guys have given me plenty of ideas to chew on

Right now I'm working on my race cars. Once I get that out of my system, I'll sit down and take a hard look at it.

[Pablo]

M2B decision time:

- Okeefe motor is way too powerful for this car. I'm taking it out and saving it for a different build.  It is really amazing how powerful this motor is, given the old style brush holders, small brushes, small springs, no post protectors, etc.

-Gear ratio is wrong. I'll change the pinion to a 7 vice the 8.

-The rear wheels need to be rounded at the edges more.

[Bill from NH]

Epoxy & balance a stock Chinese 16D arm (70T of 30 ga.), stick it in a Mabuchi can with French, Hemi, or Mabuchi magnets. Advance the timing to 25-30 degrees, if you wish.  .

[endbelldrive]

I'm coming in late to the discussion and haven't read all of the previous posts with a fine tooth comb but (from past experiences...some from way back in the day) here goes.  How does it run without the body?  We used to butcher the nose and cut a large crescent shaped chunk out if the bottom edge of the body in order to clear a Cox quick change low profile guide flag.  An inverted horseshoe or "V" piece soldered to the guide flag bearing is good enough to use as a guide stop and period correct. 

 

Like others have said earlier, 1/2" rims with modern rubber is way too much traction for these lightweights.  A little too much power and traction overpowers the mainrails and turns these early designs into rolling, chattering piles.  Get it just right and you can punch these old F1s.  They used to be quickest class before anglewinders.

[Pablo]

Yes Bob, I will be trimming the body up front to clear the flag and make a new stop also.

But if you read my track test post # 138, as I said, it's not just a cornering issue; it's spooky jumpy on the straightaway.

I will be fixing the tire issue also.

Thanks for the info.  I'll be working on it

[endbelldrive]

Spooky jumping?  The old two railers would hop because the mainrails were like a leafspring when you punched it.  Lack of rigidity in the motor/gear area seems to be the culprit in these old designs.  

[endbelldrive]

By the way, the car looks great!!

[Pablo]

Thanks Bob   I may be able to squeeze in one more main rail on the outside.......

[Pablo]

Steve, you achieved your goal, you built a cool running arm that runs like a Jaguar

I kept the Okeefe arm right where it's happy, in the blue can setup. It's as fast as a modern 16D, and will be used in a future build.  For this car, I need something tamer.

 

I found an (endbell drive) arm that has slightly smaller wire and less turns.  16D mags fit perfectly in a Mabuchi can once you flatten them and grind the nasty notches flat on the inside. Hole is .560 and the arm is .518.  Experience has shown a big airgap works well with these motors. Mags are held in place with circlips and CA.  Bushing housing is soldered in with a 5mm BB.  Endbell will be a Mabuchi FT-16D with stock bushing, hardware, brushes, and springs.

 

 

[Steve Okeefe]

 

[SlotStox#53]

Once more into the realm of BIG 16D builds .... Go Pablo