Gearing/Overheating advice CAT SX

[Rich D]

Hi fellas

Had a bit of trouble at Worksop yesterday. Towards the end of the third quali, my car seemed to lose power and then stop altogether just a few seconds later.

At the time, i looked down at my tranny and it was giving me a low voltage warning ( 8.9v ) on KO Universe.

Anyway, the motor was pretty hot to the touch too. I put the car stopping either down to the radio not sending signal or overheating - i wasnt sure which ?

By the time i got back to my pit table after marshalling i couldnt find any faults with it - and it was working fine

Before the fourth quali, i recharged the Lipo in my tranny, cut a vent hold in my shell and went down one pinion to try to eliminate overheating as a problem.

During the fourth quali, on the second to last lap the car lost power again - i perhaps had 60% available. Not wanting my run ruined altogether, i nursed the car home. Motor temp seemed too hot to touch for more than a couple of seconds again but i have no clue just how hot as i didnt get a chance to temp gun it due to marshalling.

Battery is a Trakpower 3600 30c gold type - almost unused. The last run took 1900 milliamps out of the Lipo and it balanced charged fine. I think i can eliminate this as the problem

Motor Orion Vortex 5.5
Spur 83
white Idler 33
metal layshaft gear 23
Pinion 23 ( 9.32 FDR ) then reduced to 22 ( 9.74 FDR )

I have run the setup above without problems for a few rounds of the series but im usually pottering around and not pushing due to general buggy noobness. Due to gaining confidence, i was pushing hard yesterday and i think i may of pushed the motor temp too high

If you guys who are more experienced with buggies could advise then id appreciate it.

Cheers

Rich

[bigred5765]

i would say over geared mate,and a 5,5 try a 6,5 on the same gearing or drop 2 teeth

[Smartalec]

Originally Posted by Rich D

Hi fellas

Had a bit of trouble at Worksop yesterday. Towards the end of the third quali, my car seemed to lose power and then stop altogether just a few seconds later.

At the time, i looked down at my tranny and it was giving me a low voltage warning ( 8.9v ) on KO Universe.

Anyway, the motor was pretty hot to the touch too. I put the car stopping either down to the radio not sending signal or overheating - i wasnt sure which ?

By the time i got back to my pit table after marshalling i couldnt find any faults with it - and it was working fine

Before the fourth quali, i recharged the Lipo in my tranny, cut a vent hold in my shell and went down one pinion to try to eliminate overheating as a problem.

During the fourth quali, on the second to last lap the car lost power again - i perhaps had 60% available. Not wanting my run ruined altogether, i nursed the car home. Motor temp seemed too hot to touch for more than a couple of seconds again but i have no clue just how hot as i didnt get a chance to temp gun it due to marshalling.

Battery is a Trakpower 3600 30c gold type - almost unused. The last run took 1900 milliamps out of the Lipo and it balanced charged fine. I think i can eliminate this as the problem

Motor Orion Vortex 5.5
Spur 83
white Idler 33
metal layshaft gear 23
Pinion 23 ( 9.32 FDR ) then reduced to 22 ( 9.74 FDR )

I have run the setup above without problems for a few rounds of the series but im usually pottering around and not pushing due to general buggy noobness. Due to gaining confidence, i was pushing hard yesterday and i think i may of pushed the motor temp too high

If you guys who are more experienced with buggies could advise then id appreciate it.

Cheers

Rich

What speedo are you running?

[DaSloth]

I think it really is worth investing in a temp gun as touching it really doesn't give you much of a gauge imo. I've touched motors before and thought they were way to hot, only to find they were 50-60c which is fine.

If they are 3600's it could have been dumping and hit lipo cut off maybe.

just my 2p's worth =)

[Rich D]

Originally Posted by bigred5765

i would say over geared mate,and a 5,5 try a 6,5 on the same gearing or drop 2 teeth

Thanks for the quick reply Carl - i`ll try dropping to a 21 for next round then . I dont have a 6.5 or else id change the motor. Its been good to me thus far though ! Pleased you got home OK after our car park conversation !

Originally Posted by Smartalec

What speedo are you running?

ISTC

[Rich D]

Originally Posted by DaSloth

I think it really is worth investing in a temp gun as touching it really doesn't give you much of a gauge imo. I've touched motors before and thought they were way to hot, only to find they were 50-60c which is fine.

If they are 3600's it could have been dumping and hit lipo cut off maybe.

just my 2p's worth =)

You`re right bud, i do have a temp gun but i didnt get a chance to check it. I have done the same with motor temp guesswork in TC. It will be in my pocket for the next round in case

[bigred5765]

we ran a 5.5 twice on sunday the other two runs were on a 7,5 geared one 80-27, that hit 97 deg on the motor 116 on the speedo, with the 5.5 geared on 80 -20 it was at 119 speedo 116 motor,and it di seem to go soft after 4 mins with the 5.5 in

[Rich D]

Originally Posted by bigred5765

we ran a 5.5 twice on sunday the other two runs were on a 7,5 geared one 80-27, that hit 97 deg on the motor 116 on the speedo, with the 5.5 geared on 80 -20 it was at 119 speedo 116 motor,and it di seem to go soft after 4 mins with the 5.5 in

Blimey - i thought that indoor racing would be kinder on the motor than outdoor racing

How do you keep it cool when you have the drag of long grass etc increasing motor temps ?

So really, your saying that the design of the SX doesnt lend itself to keeping it cool enough for a 5.5 at Worksop ? Its just that if i gear too much lower then my car will be up to full speed by the first third of the straight. It seemed to hit full speed by the end of the straight with a 22 pinion in. Perhaps i wasnt up to full speed with a 23 in hindsight.
It was a faster track than most of the other layouts i have had experience of.
For me personally, it suited my style and so i was able to push a lot more than i normally would.
I`ll go with what you reckon cos tbh, i have very little experience of the SX or modern indoor buggy racing in general.

Cheers

[Smartalec]

Originally Posted by Rich D

Thanks for the quick reply Carl - i`ll try dropping to a 21 for next round then . I dont have a 6.5 or else id change the motor. Its been good to me thus far though ! Pleased you got home OK after our car park conversation !




ISTC

Hmmm, sorry I haven't used one of those so I can't comment. I had a similar problem with the CAT and a Tekin RS Pro. I could run a 22 tooth pinion with a 5.5 and an LRP Sphere but when I changed to the Tekin to keep it from thermalling I had to drop to a 19, making the car too slow so I went back to the LRP and didn't have a problem.

[Rich D]

Originally Posted by Smartalec

Hmmm, sorry I haven't used one of those so I can't comment. I had a similar problem with the CAT and a Tekin RS Pro. I could run a 22 tooth pinion with a 5.5 and an LRP Sphere but when I changed to the Tekin to keep it from thermalling I had to drop to a 19, making the car too slow so I went back to the LRP and didn't have a problem.

Nosram ISTC is the same as the LRP Sphere TC Spec in a red case instead of blue

Are those gears i listed the std ones ? I counted the teeth on them but im unsure what the std ones are

[Smartalec]

Originally Posted by Rich D

Nosram ISTC is the same as the LRP Sphere TC Spec in a red case instead of blue

Are those gears i listed the std ones ? I counted the teeth on them but im unsure what the std ones are

Sorry missed the "Nosram" bit LOL ......... I had to cut loads of holes in the shell of the cat for the Tekin but it still thermalled. I run the LRP in the Durango and that's very enclosed like the cat but i've not had a problem with that. The only other thing I can think of is that something is binding up?

[mikeyscott]

Originally Posted by Smartalec

Sorry missed the "Nosram" bit LOL ......... I had to cut loads of holes in the shell of the cat for the Tekin but it still thermalled. I run the LRP in the Durango and that's very enclosed like the cat but i've not had a problem with that. The only other thing I can think of is that something is binding up?

Not what I want to hear when I'm heading to Petit with a Tekin RS Pro and maybe a 6.5 Speed Passion v3 motor.. It gets hot with a Losi 7.5!

[bigred5765]

try reversing the direction of the fan(turn it the other way up) so it blow hot air up to wards the top of the shell, make sure you have plenty of air holes in the shell, front rear and side pods,i cut out the back bit of the shell and most of the front for indoors, and have cut the side pods air vents right out, seems ok like that 110-120 motor, speedo, temp is no problems,

[mikeyscott]

I thought a 4WD car needed to be around a 10 FDR?

[bigred5765]

you need to gear it for the track and the motor your using on that track, what we try to do is get it geared so it tops out 3/4s way down the straight unless its very low grip then we over gear to take the sting out of the motor,

[Smartalec]

Originally Posted by mikeyscott

Not what I want to hear when I'm heading to Petit with a Tekin RS Pro and maybe a 6.5 Speed Passion v3 motor.. It gets hot with a Losi 7.5!

Loads of people use the Tekin without problems so I shouldn't worry too much, it's just preference. But I do know that some people ream out some holes in the case of the Tekin and aim a fan at it ............ don't know how that would hold up under a warranty claim though

[MattW]

Rich, which version of Orion motor is it?? and any ideas which rotor??

I ran an Speed Passion 5.5 on 21-83 - EVERYWHERE! Indoors, outdoors virtually regardless! This was with 12.5mm rotor, I dropped to 12mm rotor to smooth the power delivery a touch and went to 20 pinion. Smoother bottom end, more top!

23/33 is the internal ratio I always ran. I think this is Kit std, but not 100% sure, as i've never had a kit!

[Rich D]

hey Matt

Not sure on the rotor - whatever the std one is !

Its the same as below if that helps ?

Timing is set as std in the middle as pictured and has never been played with.



I have owned it from new. I`ll try the 21 pinion for sure at the next round cos if yours was fast enough then mine will be .

Ive also cut the holes in the shell as Carl suggested.

Thanks again to all for your help.

[Mossy]

Agree with Matt. Yesterday i ran a speed passion 5.5 on 22x81 on a 33 pulley and had no issues, in fact i ran around for another 3/4 mins after the A final to try some tyres and only pulled off because i wanted to go home! Indoors however i do run a cut down under tray, either with holes reamed out (looks like a cheese grater) or yesterday i cut the centre out and ran the edges. To be fair, the difference with a full undertray and the one i ran yesterday was only 10 degrees at the end of the run, I wouldnt of been close to thermalling with a normal undertray anyway.

Id be thinking speedo.

Si

[MattW]

Try 21 and potentially even a little less timing. I think those motors had small ish rotors - certainly not the big stump pullers that the very first Orion's and Speed Passions came with. Would probably have run about 24 with those!!

Last winter I was running with the early prototype shell, that had the smaller air vents!

Sure it got warm, but nothing to worry about! That was with Nosram/LRP TC speedo.