32 replies to this topic

[Brinkley47]

Can you give a list of items that would cause a psfk to get hot? This is not in a car, just running on an analyzer some motors would get super hot. I will start:

1) Loose magnets
2) Loose bushing

This is no dig at the psfks. I like them. I had a few screamers this weekend I could not keep cool. Finally chanced it in a race and it was a smoke show. Just trying to learn something. Thanks.

[Zippity]

Armature not running in true "sweet spot" due to can bearing being tapped in to remove slop?

[DOCinCanton]

The brushes will do this sometimes. Pre-radius the brushes and break them in at 3.5V. Maybe for 45 minutes. If there is any arcing, stop. Investigate. Look at the wear pattern on the brushes. You might have to swap out the brushes for another pair.

[Ramcatlarry]

Maybe a solution, but may not be in our future:

 

New brush hoods that are vertical brushes with inline hardware.

 1) makes mounting in retro cars and many other chassis easier.

 2) breaks the leading and trailing corner from the brush causing the overlap.

[havlicek]

 

 

Can you give a list of items that would cause a psfk to get hot? This is not in a car, just running on an analyzer some motors would get super hot. I will start:

1) Loose magnets
2) Loose bushing

 

Well, if the magnets are loose enough to have moved forward or rearward, that "could" cause the arm to no longer be centered (*if it ever was) and that can cause excess heat.  If the bushing is loose, it could cause vibration and heat.  If you've been tapping the can bushing as Zip said, that could cause binding (heat) AND moving the arm from the field center (more heat).  It stands to reason that some (*new) motors getting hot and others not so much would point to manufacturing/assembly variances, but people screwing around with the motors to "improve" them is always a possibility.

When you have inexpensive motors that are spec'd to run relatively fast, it shouldn't be a surprise that some of them will run well and others not so much.  That so many run well and fairly consistent is a pretty great thing when you think about it.  What I'm getting at is that you have motors you're not supposed to screw around with (much), and that are cheap to boot...it's pretty much the nature of the beast.

 

-john

[willy wonka]

Well john I think Brinkley was referring to this past weekends race in Tennessee where you could in fact fiddle with your ps-fk some.. Tracy runs is own kinda rules there so that's why will is asking I'm sure.

[havlicek]

 

 

Well john I think Brinkley was referring to this past weekends race in Tennessee where you could in fact fiddle with your ps-fk some.. 

 

...which is why I said:

 

 

 

you have motors you're not supposed to screw around with (much)

 

*emphasis added

You either can or can't build the motors.  Ironically, the less expensive the motors are, the more likely it is that some of them will need "tweaking".  The motors being manufactured/assembled in large numbers for such a low price (*which includes shipping from the other side of the planet) means they are less likely to be "perfect", and more likely to need "work".  Again, that they generally work as well as they do is pretty remarkable.  Still, if you can only tweak them "a little", whether it's to simply "improve" them or to correct slopppy tolerances, you are faced with either making them worse or trying to do things you're not supposed to.  I can't speak to his exact situation (racing at Tracy's), but what I said holds true about these motors.

 

-john

[John C Martin]

The end bell bushing on a lot of these are not fully pushed into the correct position ,causing NO to very little end play == excessive heat ..

[MSwiss]

Will,
Did anyone try cutting the brushes at the race?

This past Saturday, it made a big difference on one of my hardbody racers 4002FK.

It was getting crazy hot in 10-15 laps, and I made the mistake of planting my finger on the can hard, and got a mild burn.

The bottom of the chassis was almost too hot to touch.

After the trim, I couldn't believe how much cooler it ran.

I never asked him how hot it ran during break-in.

Was there a prevalent gear ratio that was run?

Were there many blown motors?

By the lap totals, it doesn't appear there was.

[willy wonka]

Mike there wasntnto many issues with the motors.. couple but that's a given. I ran 8-28 for consi and switched to a 27 for the semi and main..I heard of a few trying or running a 9 but I didn't want to rush it..

[MSwiss]

Willy,
Why do think there were less issues then you typically see at MMW?

[Arne Saknussem]

As long as we're discussing heat...

 

My local raceway runs PS-FKs in sidewinder chassis (cars weigh in at 105 grams give or take a couple) and the most popular gear ratios are 10/28 and 9/26.  Based on what I read on Slotblog, heat seems to be no better or worse than anywhere else.  Anyone have an opinion on in-line vs. s/winder setups and difference in gear ratios?

[Eddie Fleming]

the tire size would make the gear ratios different also.

 

I think Will is talking about motors that produce abnormal heat compared to other motors under similar situations.

[havlicek]

...and while we're at it, springs can make a huge difference, as well as the particular brushes used (*and not Mike's suggestion about cutting the brushes too)

 

-john

[willy wonka]

I think there something to do with the power at mmw I'm no expert but there shouldn't be as many issues as there are at marks. It happens with either motor the ps-fk or the hawk..

[Brinkley47]

I tried cut brushes and the motor seemed to get hotter on the analyzer. I did not have a temp gun to accurately diagnose. We ran full brush in all but one motor. And that was not the fastest motor.

It seemed like a common theme this weekend was keeping it cool. And every motor I thought would burn up on the track did. You could feel the heat on the power supply in seconds. I tried alot of items to get them to cool off and I was unsuccessful. They were my two best motors as well timewise. However, they were really only good to qualify.

[MSwiss]

What were you geared?

[Brinkley47]

8.27

[MSwiss]

Not crazy gearing, but  burning up is burning up.

 

Hindsight is 20/20, but maybe you should of tried those motors with a 28 or a 29 and seen if they were still competitive.

 

In my wing days, stuff with more timing usually ran hotter on the supply, but you are talking a much milder wind and an arm that starts off with low timing.

 

Maybe take apart the blown motors and see if they had more timing.

 

Wish I could help you more but we mostly just use these motors for hardbody's.

 

I don't race all the time, and when you get a good one, it usually lasts a long time, so I don't break in a lot of them to notice if some get hot.

 

PS-anyone try the handout Retro Hawks in practice?

 

If so, how far off the pace were they?

[willy wonka]

They we're well all pace Mike.

[willy wonka]

Well off pace sorry

[MSwiss]

I think this can put to rest the theory that these 2 motors can compete against each other in a serious race.

[John C Martin]

As I've said before this last batch of RHs or the last 6-8 months they have not been up to their usual quality or speed..at least on Tracy's track.
I did blow the com off one P.S. Fri. Testing. Also blew one in consi. Costing me a move-up . Geared 8/27 .RPM cut brushes..motor not that hot ,,these things would like a wrapped com.
I know of 5 that blew in practice or race.
I've seen RHs run in the 3.6 range as were the PSs but not lately. The 3 RHs were well off the pace..

[John Streisguth]

The last batch of 5 RH motors I purchased took a LOT of time to break in. Two hours each on the monster dyno, and then probably 200-300 laps on the track in practice.  A couple of them were going good at that point, but some of them still need more time, and they actually seem to run faster as they got more heat in them (the motor I ran in F1 this past weekend was like that). Quite a bit different than past motors.  This would be a good batch for our annual enduro!