B44.2 bashing and motor cooling

[Hesketh racing]

Hi

I've recently purchased a Team associated b44.2. I intend to take it club racing down to my local club (Bury Metro) at some point, but also want to use it for bashing.

I'm currently running with a 21T pinion, a 81 turn spur gear, an 8.5 t Turnigy trackstar motor, a 120A Turnigy trackstar turbo esc (have not tried the programming box yet) and some Turnigy nano tech 5100 mAh 65-130 C discharge Lipos.

I took it out for its maiden run, and have since tightened the slipper clutch.

The second run was around 10 - 15 minutes or so. The ESC was hot, and the motor incredibly hot - even after cooling down for 5-10 minutes was still too hot to touch.

Ideally I would like to run a fully charged battery, and bash my heart out!

I'm assuming that running a motor at these high temperatures is a sure fire way to kill it?

If any one could give any advice on the following questions (and save me lots of £££'s in trial and error) then it would be greatly appreciated - especially if you're able to answer multiple questions.

1) I'm aware that I can drop the pinion size to aid motor cooling - but how low should I go?

2) I'm also unsure if my slipper is too tight or not, and what impact this may have on motor cooling. Any advice would be really useful.

3) The spur gear is already showing signs of wear, and I don't think it'll last much longer, Is this to do with the high motor temps making the plastic more malleable, or the slipper clutch being too tight?

4) Would a higher turn motor work better for 15-20 minute bashing runs? If so what turn motor/pinion/spur?

Any advice/additional advice that anyone could give would be greatly appreciated.

Many thanks

Dan

[AfroP]

The Kit standard spur gear for a B44.2 is an 81T is there any reason why your running a 71T? or was that a typo?

if it is a 71T I would highly recommend going back to the standard 81T

It also depends on what surface your running, if your on lengthy grass this is obvs putting more strain on the motor, and causing it to get hot.

an additional motor heatsink and fan may be a good purchase.

Motors will generally run quite hot over 5 mins on a track
I run a 6.5 motor on a 20 pinion with kit 81spur and that gets hot after a 5min run.

[Hesketh racing]

Thanks Afrop

You're right it was the kit 81T spur.
Many thanks

[Big G]

I run a 19T pinion on a 7.0 motor and find temps at 55oC after 5 mins of racing on grass.

I think I'm probably under geared, but the car has ample top speed and picks it feet up out of the corners nicely.

[andy110m]

I'd advise you have a chat with any of the many helpful people at the Bury track. Someone will be able to check the temp of your motor after a run and you may find its not as hot as you think.

Also, as mentioned, racing on a track where you're accelerating or braking, all the time, on high traction does get the temps up much quicker than just bashing around.

The only things I'd suggest you check as your concerned are,

1. Is the mesh to tight?
2. If you take the pinion off does the transmission turn over freely by hand. If it doesn't the diffs could be shimmed too tight or a bearing somewhere could have seized.

If you check out all that and its nice and free I'm sure you won't have any issues.

Hope that helps.

[Lee24h]

Can i ask why you want to go bashing with a b44.2?

[Noob]

I would go with a 81t spur and 19 or 21 pinion on an 8.5.
Make sure the gear mesh isnt tight up against each other and check brake and drag on esc isnt too high, refer to manual setup for diff and slipper setting and start from there, the slipper should go before the diff.
And running for ten to fifteen minutes is gonna produce heat on anything when these cars are typically run in 5 minutes heats

[Big G]

my motor and esc felt very hot, but when I temp checked them both they came to 55oC give or take. nothing like the 75oC I see from racing on polished wood indoors.

[Noob]

Yeah its mostly the stop starting that murders the temp i meant in any car not surface if thats what you mean ?
I have noticed a lot of heat but the oC is actually not as bad as it feels.
I ran a 6.5 and went back to a 7.5 as it felt more comfortable, it still runs hot as hell but definetly cooler than before.

[Hesketh racing]

Thanks for all your responses, they've all been really helpful, and will give me something to work with. I wasn't aware that motor temps could comfortably run 55-75 C.

Does anyone know what the maximum safe running temp of a motor is (preferably 8.5 t - unless there is a general rule of thumb/table) ?

[mattr]

Thermal cut off on my speedo/motor is (IIRC) 95 degrees C. (Thats a speed passion ESC and Thunderpower 8.5T motor)

And brushless motors will run almost indefinitely at 80-85 degrees C.
The brushless motors we buy at work (fairly similar spec to rc car motors) quote a ~6000 hour life at 80 and ~15000 at 60 IIRC, if run at steady speeds, all the up and down and running to max speed on a RC car will knock this down a fair bit, probably less than half, but try and work out how long it'll take you to run your car for 3000 hours, even if you are bashing for 2 hours a day, 7 days a week it'll take you the best part of 9 months before performance drops off noticeably. (Especially if you are only bashing, racers might notice sooner.)

Might be worth getting an IR temp gun to check how hot it actually is. Touching a motor at well below the max continuous will give you the beginnings of a burn.

And again, why bash a B44.2? It's a race car, with race set ups, and needs race car levels of service and attention?

[Hesketh racing]

Cheers Mattr.

Purchased an I.R. gun - should stop me stressing now!

Method to the madness of bashing my B44.2:

- Why would anyone want to spend £500 + on a car and only use it for 2 hours (approx) each month? To add insult to injury, my club only meets on a Sunday, and I work every other Sunday, coupled with family ties, I can only see my car being used in anger for no more than 4-5 hours each year (If I'm lucky!).

- The car was only completed a short while ago, and I want to see what it's capable of, and how it handles.
As I understand it, after a build, things get loose and need tightening (my slipper did anyway), It also gives me a bit of background knowledge about my new car, and possible set up tweeks before taking it down to my local club.

Hope this helps to answer the madness of why I want to bash this car.

Cheers

Dan.

[gazhillAE]

Bury wednesday or sunday come and talk to me
Gaz