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-   -   I Need Help With Mvp Motor/battery (https://www.rctech.net/forum/electric-road/6210-i-need-help-mvp-motor-battery.html)

PRoYokOmoWaCuR 07-02-2002 10:45 PM

I Need Help With Mvp Motor/battery
 
:eek: :spidey: Ok i need help! i charge two full 3000 battery! then i played with it on the socalrc track! it only lasted for 5 minutes! when i checked the MVP, it was really hot! and smelled like it was burning! I don't think it's the battery because i used my friends battery and it happened again! The clerk at socalrc said that it could be my gearing! that it's too big! but i'm using a 100 tooth spur gear!(64 pitch) and 38 teeth pinion gear! could it be that the spur gear is too small and that the motor works too hard? should i go for a bigger pinion GEAR! please, i need help! by the way my car is geared correctly! the overall ratio is 5.92 which is pretty close to 6. my car is a pro 3!

Joe 07-02-2002 11:04 PM

Your problem is probably your gearing, I use 6.5-6.25 gear ratio for stock.

ZER01 07-02-2002 11:24 PM

Your problem is most likely that you have the mesh to "tight" between your pinion and spur so check that first. If that's okay try a differant motor, perferably a newer motor. Yokomo based stock motors are gonna run hot. Your gearing seems a tad bit too tall for a Yok based stock motor(MVP). When you got the motor outta the car make sure the drivetrain is as free as possible meaning nothing is binding up the belts and all the cvd's spin freely. I've seen an MVP melt through a Team Losi molded graphite chassis because the person had his motor shift on him in a race and it was because the mesh was too tight from the shifting of the motor.

ijnek 07-02-2002 11:37 PM

should b ur gearing...
change 2 a larger pinion,...
then set ur mesh correctly...between the teeths of ur spur and pinion gear,slip a thin piece of paper between them and then tighten the mesh...after u have screwed ur motor up,turn the spur and out the paper comes.tat way,u will have a better mesh between ur spur n pinion gear...

ZER01 07-03-2002 12:12 AM

Quote:

Originally posted by ijnek
should b ur gearing...
change 2 a larger pinion,...

Larger pinion? I always thought Yok based stock motors like to be geared a little smaller than EPIC based stock motors. In my XXXS on a large, large track I'll go as high as 5.80 for an overall gear ratio for my EPIC based stock motors.

shrekair 07-03-2002 12:48 AM

how long (ft.) is socal?

ijnek 07-03-2002 12:53 AM

Quote:

Originally posted by ijnek
should b ur gearing...
change 2 a larger pinion,...

SORRY!!!
made a mistake...
i was thinking u need a bigger gear ratio,so u need 2 change to a smaller pinion.

veri sorrie!!! :(

proudwinner:
thanx for pointing out my mistake...guess i should sleep earlier n get the rest tat i need...

imataquito 07-03-2002 12:54 AM

might be ur esc man just check other motors and see if it keeps hapening .......

and yes also try to check ur ...motor comm... try gettin a recom and some good branded brushes

sosidge 07-03-2002 05:33 AM

The MVP's are known to run hot.

Big Jim came up with the way to make the motor run cooler and better, using cut down brushes.

Basically, you should shave a little material off the top and bottom of the brush face, making it narrower.

There is a link to pics of this somewhere, but I forget what it is, try doing a search for "Big Jim MVP" and that should help.

RC Nitro 07-03-2002 06:58 AM

From "Big Jim's Motor Book" Brushes to .140" take the same of both sides. MVP do run hot and need to be geared lower than epic. A new racer tried to gear his like the GM3's we run...... comm was red and purple :eek: Newbie that did not know. If you do not want to narrow the brushes, then he advises to use 767 on positive, 766 negitive with the stock grey springs. Big Jim hangs out on hobby talk forum, general discussion, ask big jim about motors. Here the latest page.Big Jim Forum

fatdoggy 07-03-2002 11:34 AM

Quote:

Originally posted by ijnek
slip a thin piece of paper between them and then tighten the mesh...after u have screwed ur motor up,turn the spur and out the paper comes.tat way,u will have a better mesh between ur spur n pinion gear...
Nope paper won't work with 64 pitch, use something like cling wrap.

BigDogRacing 07-03-2002 06:04 PM

5.90 is WAY too high for an MVP- whether it's a Big Jim motor or not. Start with around 7.40 and then go up one tooth at a time. The motor shouldn't be over 210degrees F right after the run. You will most likely notice the car is much faster because it was so overgeared.

Alvin 07-03-2002 06:50 PM

PRoYokOmoWaCuR: The MVP runs very hot, imho however, your gearing IMHO is a bit extreme. I had to gear mine like a 14 double at my hometrack in order for it not to "burn up" ;-) Final drive I run over here is 7.4:1 to 7.2:1. Somehow this motor oddly runs better with a low gear ratio. Can be as fast as my Stock 23T :sweat:

For brushes I had to narrow mine - improves comm/brush wear significantly. Motor runs cooler, longer. Haven't run my mvp too often - the arm stacking type makes it quite annoying to true:flaming:

BigDogRacing 07-03-2002 08:07 PM

Quote:

Originally posted by Alvin
Somehow this motor oddly runs better with a low gear ratio.

The reason is that the torque curve is higher in the RPM range than all other stock motors except the GM3. If you look at a dyno sheet from a good MVP, you'll see what I mean.

I think people confuse the RPM's at a given voltage with the "sweet spot" of the torque curve relative to the RPMs. Yes, most motors that produce the highest torque higher in the RPM range will produce more RPMs at a given voltage, but that isn't always the case.

Think of it like this: a 400 cubic inch big block Chevrolet will typically make it's torque peak in the 6000-7000 RPM range in race form. (this is just for comparison). While a stroked 400ci small block will make it's power in the 7500-8500 range in race form. Both are 400ci motors, but the characteristics of the individual motors require totally different gearing.

I know that comparing internal combustion engines to electric motors isn't a very good example, but for gearing comparisons it may be easier to understand for some people...

PRoYokOmoWaCuR 07-04-2002 01:08 AM

thank you but i'm not sure about what you guys just said. my friend which is a professional racer says that you should gear your cars right! he said for stock motors, the overall ratio should be close to six but not over it! and for modified motors it should be close to 7 and not over it! and the real problem here is that i don't know why the batteries last only for 5 min! i thought that 3000 batteries with the stock motor should last about 15-20 mintures! is it because the motor is working too hard and that it's using up all the energy in the battery? please reply!


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