Ford-Ferrari Wars - the Cars and the Builds

[Retro Racer 44]

Sweeeeet!

[urbanwarrior]

My cars pulled out today....should be there by Saturday.

[Audi1]

I'm seeing some really nice looking builds!

Will be home Saturday, so looking forward to getting a few more in-house, photo'd and track tested.

Allan

[F1Fan]

[waaytoomuchintothis]

Looks like I am definitely out of the race. Our cat jumped up on the track at the end of the straight, was surprised by the car at full speed a foot away, and hopped straight up, like cats do. Unfortunately, the car was caught by a paw ascending... It landed on the concrete floor at speed from 4 feet or so up, and busted the chassis and the body. I can fix it, but it won't ever be a racer again. That is, if I can find the rest of the pieces.

Anyway, I'm out. I'll post this on the other thread, too.

[Audi1]

Sorry to hear that, waay.

It's a long series, if you'd like to rebuild the car, or do a new one, then I'll make sure that it catches up with the others at whatever track they happen to be at. If not, then I certainly understand.

Allan

[gascarnut]

Chris,

Thanks for the info - I did not know about Zero Paints. The car is painted already though, so I will probably leave it now. It is a little on the light side, but not as bad as the Racer version.

I used a coat of Model Masters Competition Orange covered with a coat of Tamiya Bright Orange, it's close.

The Gulf Mirage is also painted, and that blue is a little dark for the original, as it was a very light powder blue, lighter than the later Gulf 917s. Again I did not get an exact match, but what I have will have to do for now.

[gascarnut]

Here's the frame now for the Mirage. It looks a lot like the Ferrari, just a somewhat bigger angle for the motor, to clear the same width tires under a narrower body:





Next up is getting the interiors done and then decals and details.

I might still make it...!

[gascarnut]

Lots of work this weekend, and some progress.

The Mirage is done all the way to just before decals and clearcoat:







The Ferrari has its paint, but not much more, although the interior is halfway done. The light was going by the time I took the photos, so it looks more yellow than it is.





No more work now till I get home from San Francisco Thursday night. hopefully I will just make the deadline!

[Audi1]

They both look great, Dennis. The Mirage is coming out very nicely and the Ferrari definitely says "P4" in it's appearance; particularly at the rear.

One question. It looks like you use the same gearing for both cars. Does the difference in the AW angle between the two cause any problems with gear mesh between the pinion and the spur?

You'll make it! Trust me........................ ;)

Allan

[gascarnut]

The Ferrari has 8 degrees of angle, using a straight pinion and a 16 degree gear, so it meshes a bit more on the large diameter of the teeth than on the smaller diameter.

The Mirage is 20 degrees, so it meshes a bit more on the small diameter than on the large one.

In both cases the gear mesh is very smooth and quiet, one of the advantages of 64DP gears.

[Audi1]

What is a 64DP gear? What would the standard Slot.It AW gears be, compared to 64DP?



Allan

[gascarnut]

Gears are specified in alternate ways:

Diametral pitch (DP): Diametral pitch is an imperial unit of measurement of a gear, and is the number of teeth that would fit on a pitch circle of 1" diameter. So, if you had a 64 DP gear with 64 teeth, it would be 1" diameter at the point where the teeth mesh with their mating gear/pinion. The bigger the number, the smaller the teeth.

The second method is Module: This is a metric measurement system. The Module of a gear is the number of millimeters of pitch circle diameter per tooth. Here the smaller the number, the finer the teeth.

The Slot.it gears will be made in terms of module rather than DP, and they are I think 0.5 module, meaning that a 34 tooth gear would have a pitch circle diameter of 17mm. This equates to roughly 50DP in the Imperial measurement

Remember that the PCD is the diameter at which the gears mesh, not the outer diameter of the gear.

There are exceptions to all of this. For example, Slot.it make their sidewinder gears in both 18 and 19mm outer diameters, and the outer diameter is constant despite different numbers of teeth. They achieve this by mucking with the tooth shape, and that's why some combinations of gears have better mesh than others.

Here ends the engineering lesson for today!

[Audi1]

Thanks Dennis.

So, why then would it be advantageous to use 64DP gears when one wants to be able to vary an AW gearing angle between, say 8 degrees and 20 degrees? Why would 64DP be better suited to do that than 50 DP?

Also, you refer more than once to the angle at the point of contact between the gear and the pinion. I was under the impression that the angle from the maximum diameter face of the spur to the minimum diameter face of the spur was constant. If that's not true, then are the gears on spurs actually crowned? If they are, then I could understand why the angle at the point of gear mesh would be different from the angle at either the maximum or minimum gear face diameter. Alternatively, if the pinions are crowned, the I could understand it, too.

I'm taking in that 64DP gears are more useful in AW configurations than 50DP gears, but I don't understand why, yet. :think:

Allan

[gascarnut]

The 64DP gears are easily available for me at the local Commercial raceway, and I have lots of them for my 1/24 scale racing. I dug into my parts box for these cars.

At times I have used Slot.it sidewinder gears for anglewinder applications very successfully, but in this case, I did not have the pinions I needed. That drove my decision as much as anything else.

There's no link between the module or DP of the gears and the angle of the motor.

What happens when a straight pinion meshes at an angle with a straight-cut gear is that the pinion tooth has full contact at one side of the gear tooth and less at the other. the same thing happens with an angled gear when the motor angle is different to the gear angle, as happened in my builds. So, for the 8-degree car, the pinion meshes at full depth on the large diameter side of the gear and less than that on the small diameter side, and vice-versa for the 20-degree car. If I had built the cars at a 16 degree motor angle the pinion tooth would have meshed at the same depth across the whole gear.