Reedy MVP...kaboom!!

[B3 Bomb]

I just got my new MVP and it was very fast. After I ran it I realized that you could probabally cooked eggs on the motor. I let it cool down and ran it again halfway through the run a huge poof a blue smoke came out of the rear of my car. I pulled it off let it cool down and after taking it apart I found that the epoxie used to hold the magnets in place melted letting the magnets close in on the armature. It also caught the ID tag on the armature on fire and the comm is now red instead of copper. I was running a B3 with a 81:24 spur pinion gearing? Did I get a bad motor? Or is this a problem with the MVP?
http://www.rc10.com/shusting/CatalogHub/reedy/mvpmotor.jpg

[Grizzbob]

Actually, it seems to be a matter of first production run bugs. MVP's do NOT run nearly as cool as advertised, but they are fast & don't seem too affected by it unless it's just WAY too hot. I haven't heard of too many incedents, but I did see one MVP throw a winding, & heard of others burning theirs up(but it could easily be from overgearing, these thngs seem even more sensitive to gearing than the Rage). I think this is just something we'll have to put up with until they get all the bugs worked out(incedently, the Trinity Green Machine 3's seemed to have about the same problems early on, but they appear to be fine now)..... http://www.rccaraction.com/ubb/smile.gif

[Railman]

You were definately overgeared. A reasonable range of ratios for a B3 offroad bugy to run reasonably cool go's something like this:
Rage 18->19 tooth = 10.56 ->11.22 rollout
Paradox 20->21 tooth = 9.00->9.50 rollout
P2K 21->22 tooth = 8.75->9.00 rollout

Your ratio was 24 x 81 = 8.13 rollout!

The MPV uses the same armature as the Rage, however it has much stronger magnets. What people have been doing to them is either to drop the gearing down to the paradox range, (or lower),or modify the brush size to reduce the timing and charging of the armature poles.
Modified brush versions are supposed to run a lot cooler & have more torque. Anyway you look at it you were at lrast 2 teeth, & maybe as much as 5 teeth over on the pinion.
I rarely run a motor that I can't hold my finger on after a heat. It sounds like this info is too late to help you now but maybe it will help in the future.

[digex]

Railman, I was going to say something very similair to that, except for the whole mathematical thing you did http://www.rccaraction.com/ubb/smile.gif 18 or 19 teeth will chill that motor out nicely, or whats left of it...

[Isky]

ihate it when people don't pay attention to what they are supposed to use in a certain car...(B3 Bomb). Did you even check what gearing you were supposed to use? http://www.rccaraction.com/ubb/mad.gif pay attention man...you should use an 18-19 tooth pinion, and until then dont run your car. My friend tried his MVP in my T3 with a 19/87 ratio and this motor couldn't be held in your hand::hinthint::. Now if this happened with a 19/87 gear ratio, imagine what happens with yours...dont run the motor till you replace the brushes and armature.
-Isky

[This message has been edited by Isky (edited 04-09-2001).]

[Isky]

I had one of my Orion Chrome RSdyno'ds catch on fire with a 21/87 gear ratio even though the motor was supposed to handle it...
-Isky

[Grizzbob]

Well, they do have more torque, but not quite as much as a P2K. The P2Ks I've dynoed have max torque numbers at about 170-179Nmm, & the MVPs I've tested have maxed at about 165-169Nmm. However, the MVP's still have more of the top end of the Rage, while it's hard to get a P2K to run at high revs. The key I believe is how much torque they have at high rpm, & in that regard, the MVP definitely DOES have an advantage over all other stocks I've tested so far. It seems to be even harder to gear right than the Rage was, but once you get it right, that little motor can really fly..... http://www.rccaraction.com/ubb/smile.gif

[doublet]

Well then whats a good xxx gearing for this motor? with an 82t spur is 20 correct? or is that not enough?

[doublet]

actually I use an 82t equivalent spur, or 96t BK pitch one along with a 20 equivalent pinion, a 24t BK pitch one

[Railman]

Sounds like they run the same as the old Rage. I thought they were suppose to have a lot more torque than the Rage, due to the improved magnets & can. Just thinking out loud.

[ImprezaWRC]

Speaking of the MVP, what would I gear a rally car? I have an RS4 Rally, and I'd appreciate any help on knowing how to gear the thing, since the gearing is just as sensitive as the GM3, and i blew that hunk of junk up.

I think the motor companies ought to release gear ratios with their motors, instead of relying on us to know what to gear. I'm new to this; how am I supposed to know? http://www.rccaraction.com/ubb/mad.gif

[Grizzbob]

The problem with them doing that is the fact that everyone runs their cars in different situations. Big tracks, little ones, fast sweepers, tight corners. There are just too many things to consider for them to come up with one ratio that'll work everywhere. I think its best they let us figure it out for ourselves, & for me, that's some of the fun..... http://www.rccaraction.com/ubb/smile.gif

[B3 Bomb]

In the B3 tuning guide the 24 degree stock gearing in 24:81. I alayways use that as a starting point. Before the motor kaboomed my car turned 30 laps everyone else had 23 or lower. Seing this I left it alone. It was doing good. After it blew up it still ran but just a little slower. And I run a 23:81 on myP2K. It is also one of the fastest motors on the track. The P2k does not get nearly as hot. And if you have seen the venting holes on the rage they are tiny!

[Nairb]

If anything, the MVP should be geared at least one tooth LOWER than the P2K, not higher. It'll run cooler when you use smaller pinions. Since you were stomping the whole field of racers, I would have DEFINITELY gone down a tooth or two to be easier on the motor.

[Railman]

NAIRB, RCCA had a chart many years ago for gearing that was about 1 1/2 to 2 points over on rollout ratio's (7.66 for buggy stock, way high!). It's a shame someone can't update their recomended ratio info to current motor tecnology, so that fewer
people trash their equipment.

The accepted rule of thumb for the Rage is to drop 2 to 3 teeth from the Midnight2/Paradox ratio. With the P2K you go up 1 or 2 teeth from the Paradox. Big spread for very different motors, & many just can't figure it out. We ran all of these motors (me & three sons) with good life & performance at these ratios. Everyone just needs to update their manuals!!

[ImprezaWRC]

Grizzbob, I understand where your coming from, and to an extent, I agree. But you must look at it from my point of view.

I'm still relativley new to the hobby, and thanks to a gear setup that came with my HPI RS4 Rally, I smoked a Trinity GM3 and two Trinty Sanyo matched 2400 packs. Worse, I start my rally season with my friends in a month, and within that time, I must replace more than $150 worth of gear.

Of course, most will say that's my own fault, but not only am I new to the hobby, but HPI gave me no ideas where to even start; except their stock gearing setup....30T pinion and 90T spur. I was WAY overgeared, but my P2K handled it. I throw my spanking new GM3 in it, and BOOM! The motor, and my packs are goners. Granted, the GM3 turns out higher rpms, but a stock single gear setup should still be able to take two different stock motors. And believe me, HPI got an earful from me too.

This is where those interested in the hobby but not IN the hobby become weary; how can anyone say that R/C is affordable? I certainly can't afford to replace all of that gear, yet R/C Car Action is all over the mag, convincing us that the money doesn't matter when all of that fun is there, or instead of mentioning expense, try to reel'em on in first. HPI or Trinity couldn't even give me a place to start.

And believe me, when experimenting costs you a lot of dough the way it did me, figuring things out for myself isn't fun anymore.

[DerekB]

ImprezaWRC,

I don't understand how We (RCCA) became responsible for you overgearing/blowing up/running underwater. I have never read anywhere that this is a cheap hobby/sport. It racing, that's expensive-speed is expensive. If you are worried about expense then don't buy racing motors. Buy a motor that is made to fool around, like a Speedgem. You'll go faster than your stock motor and you won't have to gear it to the moon. Ask somebody before you put gear on the motor if you don't know where to start.

Derek

[zenlosi]

Also, if you check the HPIracing site, they have downloadable gear charts for their cars that can help you out.

-Zen

[B3 Bomb]

Can someone give me good gearing starting points for some stock motors. Since my starting point in my manual is outdated. I dont need to ruin anymore equipment.-thanks http://www.plauder-smilies.de/dogrun.gif

[Grizzbob]

I do understand your point of view, Imprezza, I was in the same situation when I was in college. The point I was trying to make, though, was that you should NOT count on the gearing suggestions given in most of those cars' instruction manuals, because they(the manufacturers) do most of their testing on big speed tracks, where those ratios they mention actually work, but most tracks we race on aren't nearly that large. Because of that, when you try the suggested ratio, you run a high risk of burning up motors(as you did). By far the best thing to do is ask the locals at your track what they think a good starting point is, then experiment from there. I try not to take anything for granted when gearing a motor, & as a rule of thumb, I'll try a conservative ratio first, then see how the car tops out on the straights, & if its close I'll fine tune from there. Taking time to do it is more than just thorough, it can also preserve your equipment(saving you the expense of replacing motors, batteries, so often) & give you a chance to concentrate on driving(that's where the fun comes in)..... :)

[ImprezaWRC]

DerekB,

I don't remember blaming RCCA for my motor blowing up. What I did was remember a few responses of Pete's in the letters columns, and also in his editorial suggesting to reel a potential modeler into the hobby and reserve talking prices. It's a bit ironic, that's all.

HPI and Trinity are those I hold responsible; HPI for including a pinion in their RS4 Rally kit that they claimed that could take ANY stock motor, and could also be used with and up to, a 17T mod. Since the GM3 is a stock, what happened?

I don't blame Trinity so much, but I feel that when selling motors, instead just letting people wing it, and include nothing, just give some info, even if it's as simple as letting those know that though the P2K and GM3 are somewhat similar, you should drop a couple of teeth because of the higher rpms on the GM3. That tidbit alone would help a lot, despite the fact that some people already know it, and some don't own P2K's.

As for the prices, I am well prepared to pay for quality equipment, but it had better work. It didn't.

And I never said that the hobby was cheap, either. I wouldn't say that, I just lost $150. What I am saying is that if I'm plunking hard earned money for "quality" equipment, I expect that equipment to work to my expectations. And experimenting and fooling around until I get it right isn't worth the kind of money it's costing me just to keep things running. I'm spending more time on the sidelines than I am running the car, and there's no fun there. :mad:

[rc51racerx]

well I'm practically brand new to this too. I have had a nitro rustler but that doesn't count. I'm running a TC3 and a P2K motor, and guess what!!! my old traxxas radio and ONE countem ONE pirahna 1500scx battery pack. I have prob one of the cheesiest batteries, but I opted for the good Tekin ESC and after the kit motor esc I was spent. I DID however get the pinion set from RR and have since spent ONE countem ONE evening with my car and pinions setting it up. now I am all set to go with it, everything runs cool, and I can wait till I can afford the better batts and a nicer radio. Just invest the time and it will be all good. also don't get another GM3 unless you want to fry something else. later all

-John

ps I have no clue what I'm doing but if you invest the time you will do it right... I did.

[B3 Bomb]

I hate it when people try to blame manufactures or other people for stupid things they do. I smoked the mvp, I over geared it. Although it being a reletively new motor I thought it might have been an early production problem.

[Nairb]

ImprezaWRC (BTW, I just read the review of this REAL car in Car and Driver, and it sounds great), are you sure you toasted your batteries? What makes you think you did? I would try them with a new motor before you toss 'em.

[Grizzbob]

That is a possibility, B3Bomb. I did see a buddy throw a wind in his MVP & he definitely did NOT overgear or otherwise abuse it(in fact, he asked me to help him set it up before he ever put it in his car). But the same can be said of the early GM3's, some of them did the dsame things, & I expect that the MVP's will get a little better with consequent production runs. I do still; believe, though, that not all motors are for everybody, some of them are just too difficult to dial in quickly(read: for obsessed gearheads like me, lol). By the way, Imprezza, the motor manufacturers DO give a small recommendation on gearing some of their motors, Trinity usually tells people who buy a GM3 to gear it a few teeh on the pinion lower than they would a P2K, you just have to read the instructions that came with it..... :p

[ImprezaWRC]

Evidently, mine had nothing in the instructions, and when I wrote Trinity, they did say that the instructions were re-wrote after their first few intial runs, and the info I asked for is on the new sheet--go figure.

As for blaming manufacturers B3, hate it all you want. I will continue to do so under any circumstances where use a piece of equipment as per the instructions and it still does not function properly.

Thankfully, I got my Reedy MVP in the mail today, and I'll begin to try to understand all of this. As for my batts.....well, I got my reedy MVP today....