MRS4 problem

Archon · #1 02-11-2009, 02:08 AM

Hey all, just wondering if anyone could help me out.
I have a MRS4 with a generic pan chassis set at 150mm, mamba 25 w/esc and a Jr Rx. Running a rear ball diff and stock front diff.

Here's the problem. On slow acceleration the car is ok, but if there is high acceleration the car pulls to the left. Took apart the both diff's and didn't see any binding, car rolls smooth. I'm a bit perplexed.

alfred · #2 02-12-2009, 08:29 AM

You might need to adjust your steering epa......it may seem to go straight but its not. and check for chassis tweak as well.

Archon · #3 02-12-2009, 01:16 PM

tried that, smooth flat surface at slow speed it goes straight. High acceleration it pulls one way, If I adjust steering trim to match it at high speed then it pulls the other way at slow speeds.

harnois · #4 02-12-2009, 03:04 PM

Did you see alfred's suggestion about tweak? did you check that? that could definitely cause the problem you describe. Basically what that means is, if the chassis is twisted. That is the most likely cause. It is common to have to shim the chassis in certain places to get it to sit with all 4 wheels on the same plane. The small cars with minimal suspension movement are very sensitive to this. I'll try to explain more what this means if you need.

Here's some other ideas:

hold the car in your hands, not on the ground, punch the gas, don't steer, notice any twitching or movement of the steering servo? If so there could be an electrical problem. I've seen this a lot.

a bad bearing on one side

too much weight on one side of the car

Archon · #5 02-12-2009, 08:57 PM

none that i've noticed on the chassis everything seems ok.. well I'll go and take a look at the front diff and replace the bearings see if that will help. Thanks for the advice.

alfred · #6 02-13-2009, 01:07 PM

You can save some money by cleaning the bearings first......this is what i do--use a small container with a lid and put the bearings in there and soak the bearings in motor cleaner, you can fill the container til it reaches atop of the bearings......let it soak for at least 15 minutes and shake the container, you will be surprised at all the dirt and crud that comes out of the bearings.