Post by Andrew Rowland on Mar 26, 2016 3:21:33 GMT -5
Hmm David I thought that the case. Problem is i've just realised that maybe those motors won't fit in this body.... Anyone know what those motors measure? Plus they certainly won't fit my gearbox which probably means me bowing out of this '50's class.
Oh dear! Was kinda looking forward to carve and race this....
Post by Chris Wright on Mar 26, 2016 10:20:16 GMT -5
Argentine Grand Prix, January 19, 1958: The race was won by Stirling Moss in Rob Walker's privately entered Cooper T43. It was the first World Drivers Championship race win for a rear-engined car and also first win for a privateer team in Formula One and the first by a chassis built by the Cooper Car Company. Moss took his seventh Grand Prix victory by 2.7 seconds over Italian driver Luigi Musso (Ferrari Dino 246).
Post by Phil Kalbfell on Mar 26, 2016 15:20:54 GMT -5
With the motor configured as endbell drive about 1.5 to 2 mm of the motor will project below the car body..I cannot see anything in the rules that prevent the motor being below the body provided ground clearsnce is maintained. I have built several cars like this and either paint the parts below the body black to hide them or extend the body sides with some black painted styrene to hide the motor.
"...But it is a car really for the slimline type motor..."
I agree. I doubt that a FC-130 motor would fit at all.
By the way, Andi, regarding your desire to use your Policar gearbox as part of an entry for the VRAA.... I should tell you that years of experience with these low-power motors in light cars has taught us that the optimum gear ratio is somewhere between 2.3-2.5:1. I know there are presently 3 choices of rear axle/gear, but are there alternative pinions or idler gears available that could, used in combination, results in such a gear ratio?
Post by Andrew Rowland on Mar 27, 2016 14:12:32 GMT -5
Hmm fascinating tip there Stewart, thanks for that! Well it certainly puts a different spin on it doesn't it
It sets my brain in a slot like.....
If my gearbox was designed to compensate for the usual solution for braking with slimline of motors of running very large crown gears to make as much as 1:4 ratios and I managed to get a similar performance with the step down and 1:2.8 or whatever mine actually is..... Then it might be reasonable to assume that if 1:2.3 is the way to go for normal crown/pinion set up then mine might be able to operate as high as 1:2?
Which would theoretically give an advantage on the straights.....
Anyone got any 11t 64 pitch pinions?
11:25 gives 1:2.27 Then 17:18 gives 1.059
In combination therefore 1:2.14
I think i'm doing that right?
Might have to give it a go..... Of course it might just be that with these low power motors there is absolutely no advantage to be gained by my step down set up! We'll have to wait and see won't we.
The trick with the FF-050 motors is the limited torque. With a high-revving motor this may be mitigated with higher numerical gear ratio, at the cost of some ultimate top speed. With the low-revving 14K motors we use in the VRAA, it becomes a balancing act between top speed and enough oomph to accelerate smartly out of the corners. Light cars and minimizing friction losses become important factors in how low numerically one can go with the gear ratio. It is reasonable to assume that there would be more friction losses in the Policar gearbox than in a straightforward pinion/crown gear setup due to twice the number of gear meshing surfaces and axle/bushing surfaces. Whether this is a significant factor or not, I have no idea.
Andi, Will Policar be making any variations on the intermediate crown gear part? The present one is 25/16, I believe. A 23/16, 22/16 or 24/18 would be useful when combined with the 16T axle gear.
Post by Andrew Rowland on Mar 29, 2016 2:22:21 GMT -5
Hi Stewart More interesting food for thought. I'm going to try to set up some tests with ratios once i get my hands on one of these motors.... I personally think the answer to the ratios in the Policar gearbox will be in increasing the teeth in the pinion rather than reducing the crown. The crown itself took over a year to develop and test so building more is unlikely to be attractive..... Especially as most customers are likely to be using higher revving motors.
Once I get some pieces together and do the testing i'll give feedback. Don't hold your breath anyone!!!
I personally think the answer to the ratios in the Policar gearbox will be in increasing the teeth in the pinion rather than reducing the crown. The crown itself took over a year to develop and test so building more is unlikely to be attractive.....
Hello Andi, unquestionably, a different pinion is the easiest and most cost effective way to vary the ratios in the Policar gearbox, but, how much lateral room do you have to reposition the crown/contrate, which you will no doubt need to do when fitting a larger dia. pinion.
Andy Brown at ABSlotsport has 64P (true pitch) pinions in a variety of sizes incl. 10/11/12/13........if for any reason he is out of stock, please let me know and I will be happy to send you one........all of these 64P pinions are however a 2.0mm bore, so they will have to be sleeved, but, as luck would have it, AB also carries these sleeves.
I do not know of any 1.5 bore 64P pinions in a 10/12 tooth count that are used/sold by slot folks.......however, it certainly does not mean that they don't exist.
As others have stated, you will be looking at achieving a final ratio of 2.3/2.4 to 1........numerically higher and you will suffer on the straights, and any lower....well, these poor little motors just won't pull it.