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Old 04-10-2009, 08:29 AM   #1
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Unhappy MBX5R UNDERSTEER PROBLEM

Guys, do you have any tips how to eliminate, at least reduce the understeer on mbx5r? Especially on loose hardpack...my current toe setting is about 1.5-2 degree out. On tight cornering, the car seems hard to turn with power on...she just wanted to go straight...when power off then she corner...but not good for lap times...any tips for tire, diff oil, shock or toe setting perhaps?

Thanks in advance....
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Old 04-10-2009, 08:41 AM   #2
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Guys, do you have any tips how to eliminate, at least reduce the understeer on mbx5r? Especially on loose hardpack...my current toe setting is about 1.5-2 degree out. On tight cornering, the car seems hard to turn with power on...she just wanted to go straight...when power off then she corner...but not good for lap times...any tips for tire, diff oil, shock or toe setting perhaps?

Thanks in advance....
Mugen MBX5R

you will find what you are looking for in this thread.
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Old 04-10-2009, 08:44 AM   #3
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Mugen MBX5R

you will find what you are looking for in this thread.
did the search but never found this...thanks for the link
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Old 04-10-2009, 10:45 AM   #4
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It's 99 pages long...try to find posts about this matter but failed...any quick tips?
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Old 04-10-2009, 11:45 AM   #5
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Well not sure as i never had this issue with my mbx5r, although i did dremel out my front hubs a bit more to allow more turn in.

Anyway i don't usually keep power on in a corner, power in lift of then power on upon exit.
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Old 04-10-2009, 12:22 PM   #6
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Well not sure as i never had this issue with my mbx5r, although i did dremel out my front hubs a bit more to allow more turn in.

Anyway i don't usually keep power on in a corner, power in lift of then power on upon exit.
how about wide corner? to rail the wide corner fast, you got to power on I guess...on this matter I always hit the divider before exit, to smoothly complete that corner, I need to decrease the speed, while other car can rail it faster...btw what tires are you running?
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Old 04-10-2009, 02:48 PM   #7
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how about wide corner? to rail the wide corner fast, you got to power on I guess...on this matter I always hit the divider before exit, to smoothly complete that corner, I need to decrease the speed, while other car can rail it faster...btw what tires are you running?
Good point, our track has only just got banked corner and hasn't opened yet.
So cant help you

Tracks vary so tyres vary im from uk and use crime fighters, bow ties or angle spikes , losi step pins.
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Old 04-10-2009, 03:51 PM   #8
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i dont maybe its cause the car weighs as much as an M1 Abrams tank?
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Old 04-10-2009, 04:00 PM   #9
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thicker rear diff or less rear toe in, thicker center diff, or maybe tire selection.
5/7/3 with 2deg toe block and a set of cityblocks should do the trick.
too light rear shock oil or not enough anti-squat.
too much front droop.

just a few to start. i would go with front droop first, then rear toe block.
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Old 04-10-2009, 05:28 PM   #10
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5/7/2 diff works good. I trick I did to help out the steering is to elevate the tie-rods on the front knuckles. I added a 2mm spacer under the ballend on the front upright, Readjust the toe-out to -1 to -1.5. Camber should be -1.5 to -2.0 degs. You can run a -1 front lower rear block and use the lower front upper rear mount. Move the upper arms forwards with all the clips in the back and see if the steering improves. Ride height and a slightly lower front nose helps a lot too.
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Old 04-10-2009, 10:13 PM   #11
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First you need to check your tires. Then Check your tires. If you dont have the correct tire, or at least one thats close enough its not going to turn like you want it. Ask some experienced and/or faster drivers what tire and compound they like at that track, and they will probably all have the same answer or another tire with a similar design. It doesnt matter where you have the arms mounted, or what your camber, caster, toe or diff fluid is (as long as its not competely off the wall). Your car is going to suck with the wrong tire. The tires are the only thing on that car that actually transfers your inputs to the racing surface.

Next thing you need to check is your driving. Watch the fast guys at the track and I bet you they dont use very much throttle in the turns. Usually, anymore throttle than halfway and the car is just going too fast for an average joe racer to corner precisely. Take your time in the corners. Concentrate on entering the corner, you cannot exit a corner until you have succesfully entered it. The inside line is 90% of the time the fastest way around the track. There are exceptions, but usually taking the outside line around a corner just adds length to the racetrack. Use smooth throttle inputs. You want to keep wheelspin to a minimum. The tires cannot offer 100% foward traction and 100% cornering traction at the same time, there has to be a compromise. While you drive take away steering as you add throttle, and add throttle as you take away steering.

When you get the right tires and start making consistent laps, then you can start tuning your chassis to reduce your lap times. Get a blank set up sheet and photocopy the hell out of it. Write down the setup that is on the car right now, and when you make a change that helped you out get a blank sheet and fill it out with your changes. Keep the first sheet and everyone after that because you may need it again someday.

Thats all I really have for you, hope it helps
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Old 04-11-2009, 04:04 AM   #12
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Thanks guys...I probably will start from the easiest first...change the tires...I suspect my tires suck just like my driving style ....this is the first time i run a buggy from previous easier-to-drive truggy...and the weather now is sunny where the track become loose and hardpacked...have you guys tried proline revolver tires?
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Old 04-11-2009, 06:59 AM   #13
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Thanks guys...I probably will start from the easiest first...change the tires...I suspect my tires suck just like my driving style ....this is the first time i run a buggy from previous easier-to-drive truggy...and the weather now is sunny where the track become loose and hardpacked...have you guys tried proline revolver tires?
Try a set of AKA City Block in soft compound. Good all around tire that lasts.
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Old 04-11-2009, 07:21 AM   #14
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Default Steering Servo?

In addition to what everyone else was saying, which you should check as well, I was having the same issue with my Hyper. Turned out I needed a better steering servo. I went from 160 oz/in to 333 oz/in and now I have all the steering authority I could want at any speed.
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Old 04-11-2009, 07:29 AM   #15
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1) reduce front suspension droop
2) reduce rear toe angle
3) try 5000 in center diff
4) stronger steering sevo
5) try different tires
6) ease-up on throttle

Hope these help
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