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Old 10-18-2006, 02:03 PM   #1
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Default ways to battle handling issues from mamba max 7700 in xxx-t mf2?

This BL motor is heavy according to some contacts on the board. I have been discussing with some how to properly adjust the diff, however, it's been said that the added weight coupled with the extreme acceleration of this motor is contributing greatly to a severe pushing problem my truck has. I can give it full juice and with the wheels cranked fully, it'll just plow ahead. The turning radius is SUPER wide at slower speeds, etc etc. It lifts greatly under acceleration. I've moved the pack forward all the way. i have the ride height set as per the baseline in the manual, but a little lower. I know the too tight diff most likely contributed, but are some suggestions for compensating for this attitude, with solely suspension components and adjustments? stiffer spring setup in back, different weight oil, different pistons, etc?

What do you all suggest as a baseline or an assortement of parts for me to get to experiment with. I would rather not add weight to the vehicle via lead or something up front; the more i can do with suspension, the happier i'll be.

I am primarily using this on tarmac for now until i get a feel for it, then i will get started on dirt.

thanks.
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Old 10-18-2006, 02:40 PM   #2
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Don't worry about it. Do not try and tune the truck until you actually run it on a race track. Once you run it on the dirt you may find the need to change things, but with the pack all the way forward you will likely not have any problems, imo at least. Unless that Castle Creations motor is really, really, really heavy.
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Old 10-18-2006, 03:19 PM   #3
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the mamba is 198 grams. dunno what a brushed runs. maybe someone can weigh one and post it. I can wiegh one when i get back home.
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Old 10-18-2006, 03:23 PM   #4
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Assuming it's the original XXX-T and not the MF2.

Front:
35 wt. on 7's
Orange springs
Shocks 2 on tower, middle on arm
Ride height arms level
2-B link w/ two washers
.120 limiters with .9 shafts
-1/2 deg. camber, very slight toe-in

Rear:
30 wt. on 6's
Pink springs for stock, Red for Mod
Shocks 2 on tower, inside on arm
Ride height arms level (not bones)
2-A link, stock rear hubs, spaced middle
2 deg. anti-squat

- Battery 1/2 inch back


Try that. If your truck still feels way off, then there are bigger issues somewhere in the construction of your truck. This may not be 100% perfect for every track and driving style but for SURE this will get you into the ballpark.
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Old 10-18-2006, 03:34 PM   #5
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I believe his truck is an MF2. I would also look and see if you are getting the full amount of steering throw. The little pushrod that connects the servo arm to the steering bellcranks might be too short not allowing full throw. The stock 8 rib tires tend to push so I recommend going to Proline M3 Edge front tires for much better steering.
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Old 10-18-2006, 04:00 PM   #6
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Quote:
Originally Posted by sport10
I believe his truck is an MF2. I would also look and see if you are getting the full amount of steering throw. The little pushrod that connects the servo arm to the steering bellcranks might be too short not allowing full throw. The stock 8 rib tires tend to push so I recommend going to Proline M3 Edge front tires for much better steering.
is indeed an mf2, as per the title. Aaron, do many of those translate to the mf2?

i will shoot a pic tonight for your review, but yeah, i am getting incredible throw. The kit was built to exact spec.

As far as the tires, i am running Pro Line Speed Hawgs on tarmac for now while i get used to 1/10 again. i have noted your recommendation for front off road tires.
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Old 10-18-2006, 04:56 PM   #7
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Yea, the speed hawgs are not that great of a tire for the front. My MF2 has a supertight turn radius. Just hang in there when this truck is right it's handling is awesome.
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Old 10-18-2006, 06:11 PM   #8
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Bah, way to go Aaron for paying attention.

http://www.teamlosi.com/ProdInfo/Files/drake-std.pdf

That's the setup I use on the MF2.

The correct front tires for your surface will depend on the surface itself. M3 Edges may work great on certain types of dirt, but everytime I've used Edges it was to make my truck push. Check with the fast drivers at your track and ask what tires they're using front and rear.

For bashing around on the street, any tire should work at least decently. The on-power push you're talking about is probably the truck trying to wheelie; no truck will turn hard when it's moving relatively quickly in a straight line.
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Old 10-20-2006, 01:00 AM   #9
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well i weighed a 19T Checkpoint money, with a 22 pinion on it.

178 grams.

Mamba is 20 grams heavier at 198.
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Old 10-20-2006, 01:09 AM   #10
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That is only going to exaggerate the on-power steering loss you're feeling, especially on asphalt.
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Old 10-20-2006, 01:35 AM   #11
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if ur having trouble go buy some tire balancing weight/lead and put it as far fowards as u can this will counteract the heavy battery, if that is the problem.
i run tc and 20grams side to side isnt a great deal but front to back i think u would hardly notice.
just my $.02
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Old 10-20-2006, 07:00 AM   #12
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'sup,

I've got a Mamba 5700 in a "most current" Losi truck ( 'sup A-Dub ) and I can tell you that the Mamba is a heavy beast and throws the CG way backwards. As a matter of fact I would say about 1/2" or so.... actually that's with Orion 4800 LiPo's which make the issue worse than with standard packs.

First, if your running NiCads or NiMh's your battery will need to go all the way forward to compensate for the porky weight of the Mamba.

Next, it's all in the suspension and yes if your diff is cranked down you'll have even less steering. Make sure you built your truck correctly and start stiffining up the rear to get the F/R traction balance where it isn't so "glued" to the surface in the rear. Again, with my experience with these motors, it's ALL in the suspension.

I spent 4 days chasing the set-up I'm running. I would hook you up with it but unless you are running LiPo's and are REALLY good at modifying parts by hand it will not work for you.

Oh, and here's my take for everyone thinking of going brushless for off-road RACING (note: I didn't say bashing). Like I said earlier, I have a the 5700 Mamba (bitchin system by the way... I HIGHLY recommend it) in my Losi truck I'm currently geared 14/90 and the motor is happy at that. Actually just about 20 degrees warmer than I'd like to see but it's okay. That's with the timing fully RETARDED!!! So, for everyone that thinks bigger is better, the problem you will run into with motors like the Mamba 7700 or the 4.5 or 3.5 or wicked hot brushlesses like those is that you will not be able to gear them low enough to keep the temps down, hence I predict you'll see newbs start bitching because they are thermalling there "fastest" brushless motors avaiable. The biggest Losi spur is a 90. The smallest pinion I like is a 13 (smaller than that and it's tough to get the mesh set right as the minor diameter radius is so tight). Gearing a brushless equals speed and HEAT if you can't get to use full throttle on the track you are on. Most electric tracks are mid-sized at best .... see the problem.

IMO, if your RACING anything hotter than a Mamba 5700 or Novak 5.5 (unless your on a big track) will cause gearing/heat problems.

talk to ya.....
Mike
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