My Monster'ed Hyper 7

[sleebus.jones]

Finally finished the battery tray so now it's actually road-worthy. Made a run with the eagletree too, the 6S1P pack works pretty nice. It's geared 13/46, so it's running about 35 mph or so. Blistering acceleration, from a dead stop I can make 5 - 6 houses down the street in about 4 seconds.

[bl-is-future]

Looks good! Nifty design on that tray. Is it very heavy though? (the tray)

are those a123? or some other liion? thats a huge voltage drop at the begining of the run. Im sure if you ran a 6s2p that would help alot? what kinda run time did you get? and motor?

[sleebus.jones]

Originally Posted by bl-is-future

Looks good! Nifty design on that tray. Is it very heavy though? (the tray)

Not really. It's pretty thin stainless, so it's not that heavy. I meant to throw it on my postage scale, but forgot. Aluminum really wasn't an option because to get enough strength, it would have been too thick to fit in that area.

Originally Posted by dubkatz

are those a123? or some other liion? thats a huge voltage drop at the begining of the run. Im sure if you ran a 6s2p that would help alot? what kinda run time did you get? and motor?

Yes, those are A123's. The voltage drop isn't that surprising when you suck 100A out of a cell that's rated for 70A. The time scale is in seconds, so it recovers in under half a second. Actually the drop is from the front wheels coming off of the ground, the second spike is when they hit. The pack is a nominal 19.8v pack, so yeah the voltage drop is around 3v, but as fast as it is, I'm not too worried. I was running road rage tires on concrete, and just burying the throttle for the launch, so what you're seeing is a worst-case scenario. Something like crimefighters (or panthers) on a dirt track will spike less.

Yes, A 6S2P would help a lot with voltage drop, but I really don't want to pay the weight penalty. I also seem to have one cell that's a bit wonky, so that may be contributing to the drop a bit. It's pulling in closer with every cycle, but I think I may have to end up replacing it. It peaks way faster than the other cells, so something may be goofed up with it.

I've got no information on runtime, because with the testing/etc I've yet to really get out and run it. I'm pretty sure I'm in the 15 minute range. The motor in it is a 10XL, it barely gets warm. I've temped it at around 115 degrees.

I've got an embarrassingly bad video of it here:

http://www.youtube.com/watch?v=PZzHn7Pb1-M

Originally Posted by sleebus.jones

Not really. It's pretty thin stainless, so it's not that heavy. I meant to throw it on my postage scale, but forgot. Aluminum really wasn't an option because to get enough strength, it would have been too thick to fit in that area.



Yes, those are A123's. The voltage drop isn't that surprising when you suck 100A out of a cell that's rated for 70A. The time scale is in seconds, so it recovers in under half a second. Actually the drop is from the front wheels coming off of the ground, the second spike is when they hit. The pack is a nominal 19.8v pack, so yeah the voltage drop is around 3v, but as fast as it is, I'm not too worried. I was running road rage tires on concrete, and just burying the throttle for the launch, so what you're seeing is a worst-case scenario. Something like crimefighters (or panthers) on a dirt track will spike less.

Yes, A 6S2P would help a lot with voltage drop, but I really don't want to pay the weight penalty. I also seem to have one cell that's a bit wonky, so that may be contributing to the drop a bit. It's pulling in closer with every cycle, but I think I may have to end up replacing it. It peaks way faster than the other cells, so something may be goofed up with it.

I've got no information on runtime, because with the testing/etc I've yet to really get out and run it. I'm pretty sure I'm in the 15 minute range. The motor in it is a 10XL, it barely gets warm. I've temped it at around 115 degrees.

I've got an embarrassingly bad video of it here:

http://www.youtube.com/watch?v=PZzHn7Pb1-M

I have def seen worse video's
thats good runtime. im sure the low gearing, low kv motor, and hv all plays a big roll in that. Thats def. a nice setup esp. for racing. lightweight, short gearing. im sure youl realy suprise a few nitros guys

[sleebus.jones]

Heheh, I had a camera strapped to my head. Boy, did I get some looks on the street. It's a tony hawk helmetcam, but still looks pretty odd.

You've hit it on the head, it's a lightweight, spunky setup for the track or for bashing. With a 17 minute charge time for the A123's, even a 15 minute runtime is no big deal. I've run this 10XL in my emaxx and I can't believe how cool it runs in the buggy. I'm hoping to get it shot with the radar gun this Sunday, and see exactly how fast it's going. As cool as it's running now, I could gear up to the 40 mph range, but I don't have a 15T hardened pinion handy. Once the Mamba 2200Kv goes in there, the 15T will be way too big for the buggy anyway.

[xcntrk]

Looks good!

So out of curiosity what weight center diff fluid you running? It sounds like you have a nice balance of slip under full acceleration. I guess the street tires help keep the front-end from excessively unloading too though…

[sleebus.jones]

Thanks!

I'm using 10K in the center diff and it's really not enough, but I'm also basing my experience on running on concrete. When I punch it, the front tires completely unload and balloon, they get yanked off the ground about an inch or so. It pretty much ignores any steering input because the tires are just skimming the ground. I'd like to put some 20K in the center, but I haven't got any on hand to test. I do have some 30K in the mail with some other parts and pieces, so I'm going to give that a shot. If it's too much I'll pick up some 20K.

Also, if I remember correctly, I have a bad O-ring (the one around the shaft) so I think I didn't fill it all that full. Might have to get that taken care of before I fill it with the new stuff.

I think you should jump up and try 50k in the center. When I had my LSP, my front tires would balloon with 50k. Ballooning pretty much stopped when I put 100k in, but when it went past 45mph, it would start ballooniing.

[xcntrk]

10k sounds really light! Isn't the stock H7 fluid 75k? For comparison, I'm running 130k (at least if I could get my conv up and running).

[sleebus.jones]

Hmmmmm. Looks like I won't have any worries about going too far with the 30K. I thought the H7 was a 5/5/5 setup stock? Xcntrk, maybe you are thinking of 7.5k (7500wt) for the middle? I bought it used as a roller, so who knows what's really in the front/rear diffs. I'm guessing 5K. I sure need some new stiffer springs tho, either that or heavier oil in the fronts, it wants to bottom out pretty easy.

Blunten: yeah I remember your pizza cutters! Thanks for the tip on the 50K stuff. I don't think I'll get any in by the TnT, but I'll bring it out anyway for the heck of it.

I took it to work today with the road rage tires on it to show my coworkers. We've got a LONG stretch of smooth concrete with lots of grip. I'm going to go run around on the empty lot after work tomorrow. I'll see how it performs on dirt with the panther tires on it now. One thing that kinda bugs me is that I've got one of the Century Gear hardened pinions in it, and it's showing some pretty obvious signs of wear already. That's not good. Either I'm being really hard on it, or the Century pinions aren't as hard as they lead you to believe. Anyone else have similar experiences?

[lincpimp]

Originally Posted by sleebus.jones

Hmmmmm. Looks like I won't have any worries about going too far with the 30K. I thought the H7 was a 5/5/5 setup stock? Xcntrk, maybe you are thinking of 7.5k (7500wt) for the middle? I bought it used as a roller, so who knows what's really in the front/rear diffs. I'm guessing 5K. I sure need some new stiffer springs tho, either that or heavier oil in the fronts, it wants to bottom out pretty easy.

Blunten: yeah I remember your pizza cutters! Thanks for the tip on the 50K stuff. I don't think I'll get any in by the TnT, but I'll bring it out anyway for the heck of it.

I took it to work today with the road rage tires on it to show my coworkers. We've got a LONG stretch of smooth concrete with lots of grip. I'm going to go run around on the empty lot after work tomorrow. I'll see how it performs on dirt with the panther tires on it now. One thing that kinda bugs me is that I've got one of the Century Gear hardened pinions in it, and it's showing some pretty obvious signs of wear already. That's not good. Either I'm being really hard on it, or the Century pinions aren't as hard as they lead you to believe. Anyone else have similar experiences?

Century pinions are not hardened. I even tried heating them up and quenching in oil and that did nothing. Now that you can get the rr gears (same as mikes) there is no point to run the century, unless you run plastic spurs. I run kyosho plastic spurs on all of my buggies and have not had any issues. They do not last as long as the steel spurs, but I hate the metal to metal noise. Plus the teeth do not really wear. It wears where the output shaft comes out of the platic spur, wish it had a metal insert.

[sleebus.jones]

Originally Posted by bdebde

A couple runs ate up a century pinion on mine. Gotta go with the ones from Mike, they really hold up well.

Well, that just kinda sucks. Looks like I'll be placing an order with Mike real soon.

Originally Posted by tc3_racer_001

are you running a metal spur? how long do the both gears last, metal on metal? id upgrade to the kyosho but if they last ages i may just not. but then again, the metal ones are noisy as!

Yes, I'm running a hardened metal spur. Metal-on-metal is supposed to last a long time, that's what a nitro buggy uses: metal clutch bell and metal spur.

Do NOT fall for the Kyosho plastic spur hype. I did, and found out that it didn't work for crap. In the H7, yes the kyosho spur will screw on, but it does NOT seal. So, if you don't mind slinging diff oil everywhere, go for it. I tried to come up with a nice neat seal solution, and what I tried did not work. I have heard of some folks having luck with using several paper gaskets, I did not try that. Also, the recess for the shaft o-ring is too shallow, and that tears up the o-ring in short order. Even if you get it all set, it doesn't spin as free (I'm assuming from the extra friction from the shaft seal) so that makes your diff oil choices kinda weird. I just didn't like it at all. Getting a hardened (or "hardened" in my case) pinion is the most trouble-free solution IMHO.

Originally Posted by bdebde

Yes, running metal spur. Been running for a couple months (couple runs a week avg.) with the same ones and they show little signs of wear. The metal gears are noisy, but my Muggy has enough power (and weight) to tear up plastic spurs in a hurry. I like the plastic ones, my buggy is nearly silent running one.

That is really good to hear. I don't find them to be too terribly noisy, but I agree the plastic spur is eerily silent. I wish I could run them also, but I too blasted teeth off of mine pretty quickly.

Originally Posted by lincpimp

Century pinions are not hardened. I even tried heating them up and quenching in oil and that did nothing. Now that you can get the rr gears (same as mikes) there is no point to run the century, unless you run plastic spurs. I run kyosho plastic spurs on all of my buggies and have not had any issues. They do not last as long as the steel spurs, but I hate the metal to metal noise. Plus the teeth do not really wear. It wears where the output shaft comes out of the platic spur, wish it had a metal insert.

Well, I gotta agree with you on the "not hardened" bit, even tho tower sez:

Originally Posted by towerhobbies.com

FEATURES: Hardened steel construction
1.0 Mod pitch

I was going to do the heat up/quench bit. Just curious, did you use new or old motor oil? Also, did you do a final quench in ice water? My main problem with plastic (if it fit) would be that I have a tendency to knock teeth off. Probably my driving (and I use that term loosely) style. Probably that hitting the ground at full throttle thing.

[xcntrk]

Originally Posted by sleebus.jones

I have heard of some folks having luck with using several paper gaskets

I would refrain from doing that. I just destroyed the internals of my center diff and it’s believed multiple (2) paper gaskets were to blame; by spacing the bevel gear too far away from the spider-gear assembly resulting on the teeth only making contact at the very end of the tooth surface. Combine that with BL torque and it only takes one tooth-jump to begin rounding the surfaces of all the gear teeth.

[bdebde]

A couple runs ate up a century pinion on mine. Gotta go with the ones from Mike, they really hold up well.