[Top Down]

On an approx. 3m sq. 22m lap length routed and fairly tight technical circuit how should I be gearing the car, just as a guide? Start nearer the 2:1 or 4:1 end of the scale. 

Currently the car has the standard Slot.it gear ratio of 11:28 (2.54:1).

[BAracer]

I'm no expert, but in these type of situations, I've been told "the car will tell you what it needs". 

Do you have access to the track?

[Nonfractal]

I would say that the gearing you have is a good starting point.

However, you don't say which motor you are using  or whether you are using magnetraction in the car.

If the car is sluggish in the infield and is still accelerating halfway down the straight, raise the ratio (bigger spur gear an/or smaller pinion)

If the car darts through the infield but is slow on the main straight, lower the ratio.

There is a post on slotracer where I go through the detail (if you feel inclined to dive down that rabbit hole)
I'll put the link in to this post later.

Alan
Here is the link.
Happy reading 

https://slotracer.online/community/showt...=Explained

[Albion]

Also What’s the motor spec

[Top Down]

Thanks for all the feedback. Really helpful.

Basically the track runs in a U-shape around the outside of the area but has quite a technical infield entered through a hairpin, into esses, a second hairpin and a smaller U-shape back to the start. So I'd say no straight is longer than 7' and generally 4'-ish.

It uses magnetic braid and the particular car (Slot.it Nissan R390 GT1) has stock Slot.it traction magnets. (They also run magless cars at times - but that's for another time.)

The motor is possibly a Slot.it V12/4 23000 rpm? (I'm the 'second user').

Pic' attached.

   

And yes, I had spotted the guide isn't connected to the motor.   

An Oxigen 'C' chip is going to plug the gap 

[chrisguyw]

On an approx. 3m sq. 22m lap length routed and fairly tight technical circuit how should I be gearing the car, just as a guide? Start nearer the 2:1 or 4:1 end of the scale. 

Currently the car has the standard Slot.it gear ratio of 11:28 (2.54:1).

I think that you will find that the "standard" ratio on Slot-it inlines is 9:28 (3.1 to 1)......that is the ratio on the car you pictured.

With the stock "orange" endbell motor, 9:28 works well with both the motor and most tracks........longer more flowing tracks may well benefit from a slightly lower numeric ratio, while tight twisty tracks may favour a higher numeric ratio.

It is important to keep the characteristics of the motor in mind when selecting ratios, as the motor will affect the ratio choice as much as the track.

Cheers
Chris Walker

[Top Down]

After a physical count you're right of course. 9:28. 

(I hadn't actually counted the teeth before, just took the info from Pendle's tech' spec' page.)

A higher numeric ratio being? 9:29, 9:30, or whatever?

[chrisguyw]

After a physical count you're right of course. 9:28. 

(I hadn't actually counted the teeth before, just took the info from Pendle's tech' spec' page.)

A higher numeric ratio being? 9:29, 9:30, or whatever?

All Slot-it inline configuration FC-130 motored cars have been geared 9:28 since the beginning of time, and all Slot-it sidewinders have been geared 11:32,.....so perhaps Pendle is referring to something else.

As far as ratio designations,......you are correct !!.......9:29, 9:30 are higher numeric ratios, than the standard 9:28,...........and 9:27 etc. is a lower numeric ratio.

For a given motor, higher numeric ratios will give increased responsiveness (quicker acceleration), and better brakes, while reducing the top end,......lower numeric ratios, will give a more relaxed response (less acceleration), and less braking, while adding a bit to the top end. So, a lot depends on the motor you are using, and the track you are running on.

It is important to keep in mind that high (er) RPM motors with less torque (FC-130's), will favour higher numeric ratios, while lower revving/higher torque motors (FK-180's) will be more at home with lower numeric ratios. 30K FC-130 motors will be very happy geared in the 3.5 to 1 range, where the high torque comparatively slower revving FK-180's will be happy at the 2.5 to 1 (ish) range,....with minor variations depending on your track configuration.

Also, the diameter of your rear tyres will have an effect on the overall ratio (and handling, which is a very important consideration)........smaller dia. rear tyres will have the effect of increasing the numeric ratio, while taller rear tyres will have the opposite effect.

While the math is fairly straightforward, lap times, are the major consideration,...so, experimentation is highly advised.

Cheers
Chris Walker

PS..Additionally, car weight will have a factor in determining the "ideal" ratio, but,...that is for another thread.

[Top Down]

As it turns out, at the moment I only have one option, a 30t crown., so I'll give that a try.

I did. It's academic, as it doesn't fit.

[chrisguyw]

As it turns out, at the moment I only have one option, a 30t crown., so I'll give that a try.

I did. It's academic, as it doesn't fit.

As your track is twisty with shortish straights, trying the 30T Crown is very worthwhile.............especially with magnets, as the motor will spin up more readily and therefore run a touch cooler,...both good things !!

I am assuming that the increased dia. of the 30T Crown, interferes/rubs on the inside of the rear cowling or interior tray of you Nissan ???.........given that the 30T is not a ton larger than the 28T, you should be able to grind/file/sand a bit away to provide clearance.

Before you do this, it may be worthwhile to insert a thin spacer between the rear chassis plate and body post to achieve clearance.........this will let you know if the gear change makes a positive difference, before you start filing/sanding.

Cheers
Chris Walker

PS If you do like the difference that the gear change makes,.....and do not wish to do any body filing, you could always go to an 8T pinion (5.5mm dia.) and use your 28T Crown. This will give a a slight increase in numeric value vs your 9T x 30T (3.5 vs. 3.3), but, for your track. I do not think this will be problematic by any stretch.



Cheers
Chris Walker