KF2 over heating

[Ross]

So last night my car was coming off after 5mins being warmer than normal. It has a new shell with no air holes in, so I put holes in the same place as the shell before had, I also tightened the slipper up a bit for the last round. I went out to qualifying and it cut out with around 25sec's to go.

I did my marshalling, went back to the car, the fan had been running on the speedo to make sure it cooled down whilst marshalling. I tried the car, the steering was fine but nothing from the motor, the motor was cool, I assumed the motor had gone, it did sound like it the way the car just stopped. So I went to have a chat with a few people and come back to the car, around 20-25 mins after it stopped and tried it again, it was fine , looks like it thermaled.

So I've never had an issue with any of my KF's over heating at the club until this.

So the difference on last night car to any other night was:

New shell, no holes, the holes were added.
Ball diff, I usually run a gear diff.
I had a new set of tyres on at the start of the evening, I put a new set of rears
on for the heat that it cut out on.
I've gone from a 40g under LiPo weight to a 50g but that's been on there for at least 4 meetings.

Not that it was a different set up but the gearing is 80/24.

Would the Ball diff make the set up generate more heat? That's the only big difference. It never used to get warm before this was fitted ?

[Treedudeben]

The 80 / 24 gives a final drive ratio of 8.61, is this in range for your motor?

[Ross]

Originally Posted by Treedudeben

The 80 / 24 gives a final drive ratio of 8.61, is this in range for your motor?

😆😆 don't know. It's a NOSRAM 7.5

[Ross]

Originally Posted by Ross

😆😆 don't know. It's a NOSRAM 7.5

This one

http://www.racing-cars.com/pp/Manufa...m/NR90664.html

[Adam F]

New to the KF2 but I'm 76/22 on a 6.5 as last week it was getting v hot with 76/23.. (Gear diff, 140g ish weight)

New shell with no holes, but seems ok now, although I've also got the motor fan on it too..

[Ross]

Originally Posted by Adam F

New to the KF2 but I'm 76/22 on a 6.5 as last week it was getting v hot with 76/23.. (Gear diff, 140g ish weight)

New shell with no holes, but seems ok now, although I've also got the motor fan on it too..

you should have tried it ages ago mate ��

I'm going to try the gear diff and backing the slipper back to what it was. I'll pop it on the scales tomorrow to see what it weights.

Cheers

[Ross]

Originally Posted by Adam F

New to the KF2 but I'm 76/22 on a 6.5 as last week it was getting v hot with 76/23.. (Gear diff, 140g ish weight)

New shell with no holes, but seems ok now, although I've also got the motor fan on it too..

Ok with 50g under LiPo weight and the original Trish bits SV2 front weight under the steering, it comes in at 1630g RTR, taking just the LiPo weight out its 1580g, the batteries, Orion 4000 , Absima 4000, core 4000 and nano tech 4200 all weight between 200 and 215, one of the Orions being 215g.

I can't get it much lighter 😳😳

[andy-aj]

Nosram/LRP motors do run hotter than most others. Have you got any boost, turbo, or timing set up on the speedo? Which speedo you got? New tyres would increase friction with the ground, which in turn would add heat. Would have thought a ball diff would create less heat.

[Ross]

Originally Posted by andy-aj

Nosram/LRP motors do run hotter than most others. Have you got any boost, turbo, or timing set up on the speedo? Which speedo you got? New tyres would increase friction with the ground, which in turn would add heat. Would have thought a ball diff would create less heat.

It's run warm/hot before but never cut out. It's a NOSRAM comet HD in standard set, ie as it comes out of the box. I've never had an issue with new tyres before . I don't normally run ball diffs, I wasn't sure if it would cause things to get hotter.

[danmurphy]

I had a similar issue a while ago with overheating at silverstone. Check your drag brake, should be low to none on a high grip surface. Try increasing torque timing (punch) and drop down one pinion. This worked for me.

[Ross]

Originally Posted by danmurphy

I had a similar issue a while ago with overheating at silverstone. Check your drag brake, should be low to none on a high grip surface. Try increasing torque timing (punch) and drop down one pinion. This worked for me.

I'm sure it's all STD but I'll check later when home. I have thought about dropping down to a 23T as well.

Cheers

[racdeaf]

Maybe if u could get chance to check if the slipper run freely without pinion to see if any binding such as screw coming unloose on the back of slipper plate next to alloy mount mount

Rob

[Ross]

Originally Posted by danmurphy

I had a similar issue a while ago with overheating at silverstone. Check your drag brake, should be low to none on a high grip surface. Try increasing torque timing (punch) and drop down one pinion. This worked for me.

It's in blinky mode looking at the blue flashing light. I think I'll drop the pinion to 23 and see how it runs.

Originally Posted by racdeaf

Maybe if u could get chance to check if the slipper run freely without pinion to see if any binding such as screw coming unloose on the back of slipper plate next to alloy mount mount

Rob

I've had the slipper apart this evening, the drive train all runs freely and all the screws seem tight enough.

I have put the gear diff back in now, put the slipper back to a little less than what it was originally (slacker) it seems ok in the lounge

I did change all the bearings a few weeks ago, I was wondering if I had done the belt up too tight, so I slackened it off a tad.

[racdeaf]

Gearing on my kf2 & my son's kf2 which is kit spur 83t with 7.5 hpi motor with 22 pinion Still as quick on straight ! Motor came off warm after 6 min run.

Nosram motor do get hot as it a powerful motor as I has few in past which I ditched them to go hpi or thunder power motor