Questions from a novice on magnet free cars

[3nickel]

Hi 1/32 people, I am wondering how you like your gear clearance between pinion and spur on your sidewinders for magnet free use? The Revell Lola I have is very smooth, not tight which seems correct to me. The SCX Fiat and Fly Porsche 911 gears are noticeably tighter, making them slightly jerky on a slower plastic track like I have. The braking on them is very fast, but I prefer the Revell "feel". The Scx Fiat Spider draws over 250 ma before it starts moving at 10-12 volts! They are all great looking cars to be sure.

Also I've been adding brass weights ( no lead purchased yet) in the range of 3-4 ounces total. What range of weights are you all adding? Sorry for these super entry level questions.

[chrisguyw]

Hello 3nickel, First off, gear mesh set-up is no different for magnet or no magnet racing....the gears don't know the difference ;)

For inline, sidewinder, or, anglewinder configurations there should be just a tiny bit of "lash" free play between the pinion and crown/spur gear. As long as there is even a tiny bit of free play (all around the gear) you are good to go.

Once you have the gears installed, turn the rear tires to feel just a bit of free play between pinion/spur....spin the rear tires so the gears move a few teeth, and check again.....repeat this process checking around the complete circumference of the crown/spur. At no point should the spur "bottom out"....this will result in unnecessary friction, it will wear both your axle and motor bushings prematurely, and, will cause the motor to overheat, and potentially fail.

You may find that there is a slight difference in "lash" at different points on the gear.....this does occur, as not all spur gears are perfectly concentric, and sometimes, pinions are not installed correctly, and "runout" can occur.

You certainly can invest in much better quality pinions/spurs/crowns,....and, a good quality pinion press/puller, but, with a bit of fiddling, you can improve the mesh on stock gears.

If the gears are tight.......and I am hoping it is the gears, and that the bushings are not misaligned, rear tires are not rubbing the chassis or pinion, and that both rear bushings a correctly seated in the bushing cups.......if all the previous points check out, you can use a hobby knife or a small round file to remove a tiny bit of the plastic on the front edges of the motor pod where the motor snaps in, this will allow the motor to move just a hair forward in its housing....take a tiny bit at a time, check, and repeat until you have some gear lash at all points as the gear rotates.

If you do happen to take a bit too much off, resulting in the motor moving in its mount, you can use a drop of ShoeGoo etc. to secure the motor.....securing the motor with motor screws/ShoeGoo etc. is a very, I repeat, very, good idea regardless of how secure the motor feels in its housing.

As far as weight, there is no absolute correct answer,.....it will depend on such variables as,...motor, tires, gear ratio, track grip, track voltage, and, track layout. As a general rule, I build my cars with no weight added, and then track test. If the car pops out or deslots at the nose of the car, a couple of grams at the front,( behind the guide or at the front of the chassis sides) will help. If the car lacks traction, a bit of weight towards the rear of the car (back edge of chassis sides, or wherever there is space) will help. Weight placement can get a bit more complex, but, this is a good general starting point.

Too often folks rush to add weight to overcome handling issues without trying to discover the inherent cause of the problem.......I have seen countless cars at our local clubs', or, cars brought into the shop that are loaded with weight, but, have un trued tires (front and rear), twisted chassis, poor guide set-up, etc.etc., and once remedied, a ton of this weight can be removed......so, once everything else is sorted, use weight as a final tuning element,....not to overcome fixable issues.
A lighter well tuned car, will always be quicker than a car loaded with weight to mask inherent issues ;)

Tire truing, chassis flex, guide placement , etc, are all additional elements that will drastically affect the car,.....but,....these are different topics :D

Hope this helps, and let us know how you make out, or, if you need more info.

Cheers
Chris Walker

[RichD]

With the majority of 1/32nd RTR cars the motor is fixed in place. If the car has an inline motor the crown gear has a boss that locates the rear axle assembly and you are stuck with the mesh that you have. I prefer to replace the rear axle assembly with aftermarket parts and not use the gear boss. I use spacers to get minimal side play and put a piece of plastic film between the pinion and crown gears to get the perfect mesh before I tighten the set screw. Sidewinder gears do not always mesh perfectly, some times you can lap them to improve the mesh otherwise you might get better performance with aftermarket gears. With sidewinders and anglewinders the pinion gear is usually 6.5 mm. Scalextric and Fly used 19 mm spur gears and just about everyone else uses 18 mm spur gears. In my experience you should always get a good mesh with quality aftermarket gears. The anglewinder setup is a little different in that you can change the mesh by moving the spur gear sideways, moving it outward tightens the mesh and moving it inward loosens the mesh.
In all cases you would not want the gears to be bottomed out. If the gears are even a little too loose they will wear faster.

[waaytoomuchintothis]

This is how you know the people who come to HRW really like us. I predict at least two pages of replies on this one. Its like someone just wants to hear everyone's opinion and boy will they get it! Welcome, TripleNickel, and good luck. We have no shortage of opinions around here. Actually on this subject, I expect everything you get will be useful gold.

[mattb]

Not sure if this applies to the crown gears installed on rtr 1/32 cars, but with Cox and Parma crown gears they will usually mesh smooth in 90% of applications. Sometimes you can feel a tightness at a particular spot on a crown. A firm push with the thumb at that point will sometimes remedy this.

The better solution and to really smooth out mesh is to set the chassis on a power track/test stand or a piece of track. Lift the rear wheels and run at full speed. Use a butane torch to heat the outside back edge of the crown while it is running. It will suddenly take on a smoother sound and higher rpm. Quit heating and run it a few more seconds to cool and you will have a perfectly smooth mesh. Not sure if this can be done on the cars you guys run. You can really tell when it gets right.

[3nickel]

Thanks for the responses guys, much appreciated. Crisguyw, I like the idea of shaving the motor mount. I've got to open up the tightest car to see how the motors mounted. What is this shoeGoo? It looks like a type of flexible adhesive. Is it a stronger adhesive than regular caulk? I bought a parma pinion puller in January (which I can't seem to locate right now) that I haven't used yet on anything. I can't believe how big a difference just sanding he tires makes. I used a slightly rougher grade of paper last night and the Lola really sticks to the track better now.

Hi Richd, Ive only seen pictures of an angle winder setup. The pinions look typical, but some photos seems to show a slightly angled bevel gear on the axle, and some appear to be a standard spur gear? I guess you can get away with a larger motor / smaller spur gear in this setup.

mattb, are you heating metal gears or plastic? not for the faint hearted.

Hello waaytoomuchintothis ! thats a good handle

I meant to respond to you guys last night but I fell asleep !

[chrisguyw]

[mattb]

I heat the old Parma, Cox and newer H&R gears. t's not really very risky. You keep the flame above the gear teeth, pointed away from the motor. You only get some heat on the edge of the gear, no flame. As soon as it smooths out you can hear the difference. You stop the heat and let it run a few seconds to cool off with the new "set" in the gear. This especially helps if your pinion is not in the true axis of the rear axle. You may be off center slightly and the heating helps your crown gear teeth adjust to the pinion being slightly out of line,

[waaytoomuchintothis]

Not to worry... People fall asleep reading us all the time. Its compensated by our falling asleep while typing this stuff. (don't even think of denying it guys)

I used to "cheat" gears to a good mesh in 1/24th with a small torch, years ago. In 1/32nd, its easier and safer to use coarse polishing compound (Tamiya) with a touch of oil, and stress the mesh by letting the tires drag a bit. This is particularly important when the pinion gear is also plastic or Delrin. I have an ancient roller jig from Dynamic in 1966 that makes a nice drag for polishing, or "running in" gears. Its so old I had to replace the platform with scrap Corian countertop material.

[chappyman66]

Running in gears makes a difference. Once you break in the motor (about 5 min at low voltage, then max voltage) you can run in the gears. Use polishing compound, or some load on the tires/wheels. You will hear the difference in the motor revs as the gears break in.

The Slot.it/Sideways/NSR/Thunderslot cars are really smooth and quiet out of the box. Fly/Ninco/SCX cars - stock gears are almost always loud but they run OK...so go figure. Scalextric depends on age....newer cars are quieter, older cars are louder. If you put Slot.it or other gears into the other cars, they quiet down....but then you have the cost of a new rear end and I am too cheap to do that until something breaks.

[RichD]

With respect to the spur gears in anglewinder setups special angled spur gears are made, however conventional straight cut spur gears will work if the mesh is adjusted properly. When I was racing 1/24th scale commercial track type cars they were all anglewinders and most of them used straight spur gears. If you do use an angled spur gear be sure that it is turned the right way! The angled gears can have the set screw side of the hub on either side.
With 1/32nd scale cars the anglewinder setup allows for using longer motors. I am not a big fan of the anglewinder setup because it often results in chatter and hop. Those problems can be overcome by gluing in the motor and adding extra chassis bracing however. Even commercial raceway cars with metal chassis could have chatter and hop. I always soldered the motor to the chassis and also added a wire brace across the axle carriers if necessary.

[3nickel]

Great info guys, I appreciate the help.

Mattb the heating the gears makes sense to me now. I may try it on the my old Revell plastic crown - its definitely rough.

RichD, interesting about the stock spurs being used sometimes for angle winders as long a the motor mount is adjustable. I plan on making my brass chassis car very adjustable to try out different gearings. I'd like to try some miniature cogged timing belts I have from "Stock Drive" from an old work prototype.

Hi Chappyman66, it seems lots of you guys use lapping powder. I may get some eventually.

Waytoomuchintothis, take a photo of your roller jig - I like to see peoples hardware.

Chrisguyw, I found a new tube of E6000 at work I bought a few years ago to test out for a job. I forgot about it completely. Ha Ha, I must have known I was building a slot track!

I think part of the issue is the motors themselves. I snapped out the rear axle on the SCX and the motor has such strong magnets, that when rotating it by hand, the motor poles are very distinct. I think I'm used to much weaker motors from smaller cars in my youth. Don't know why the Revell Lola feels so smooth when turning the rear wheels by hand, its a very fast car. Just a different motor style I guess.

I am now enjoying the incredible braking that the SCX and Fly have...it totally changes the dynamics of driving it. I read old reviews on the Lola Revell from a few years back, and lots of folks complain about the lack of braking it has due to motor and gearing.

I added another ounce to the Lola up front, and it helps a lot with the front end bouncing and de-slotting. That makes 5 ounces added to that car so far.

:teasing-blah: