40mphallday

iTrader: (3)

Hi there,
My buddy has some weird behavior going on with his Associated B6.2 that I wanted to get some opinions on. His 2wd buggy on grey carpet has been behaving weird. Every corner he goes into the car wants to rotate fully around. Like once the car starts to turn the back end seems to give out and the back end flips all the way around typically over-rotating the turn.
I figured it was diffing out so I went through the rear diff for him and replaced with typical 7k oil (gear diff). This didn't stop the issue however.
What else can I look into to try and fix this? Could it be related to shock oil? The cars ride height is also quite low (13-14 mm) but that's pretty standard for indoor carpet. I think the next thing I'm going to try is to rebuild the shocks and fill/bleed with manual weight oil.
Thanks in advance for the help/advice!

sosidge

If a car is behaving really strangely I always start with a full rebuild, paying extra attention to parts that may be binding or damaged. And rebuild to kit settings. Spinning on corner entry is probably more than can be fixed with a single setup change.

BigBuckORamma

Like sosidge said, rebuild is best. Check everything to make sure nothing that sees friction is worn out, no bearings are gritty, nothing is cracked or broken, no screws or studs have come loose.

Something has clearly fundamentally changed mechanically with the car. So everything should be thoroughly inspected, and checked. And while you're at it, make sure the set up is dialed as well.

EricW

iTrader: (1)

Reduce the rear droop.

Cain

iTrader: (294)

This may be a given but worth asking, are the tires the same / same condition as what you are using without the issues?

40mphallday

iTrader: (3)

Hey great question, yeah I was able to replicate the issue with brand new tires of the same tread (fuzz-bites all around). It has been an issue that just arose from using the car over a long period of time it seems. I know a rebuild will help and likely fix but would prefer to just figure out what the likely issue may be so I could just address that first. Thanks for all the suggestions

jauntyfedora

iTrader: (9)

Do you notice it happening more in one direction than another? that would give you a place to start

Unknown Driver

In addition to the rebuild I'd consider returning to the box stock setup (or a known good setup from a local or something). A lot of people tune themselves out over time.

RazorRC

iTrader: (5)

Most likely something in the suspension is binding/broken IMO. Pull the shocks and disconnect the steering draglink, and make sure everything moves up/down, left/right freely, can flop on their own. Bearings too, unhook one ballstud on the camber links and see if each wheel spins freely on its own.

Suzukee

iTrader: (7)

Without seeing the car in person, the best advice here on-line has to be that; a tear down followed by a full rebuild.
Alternative could be, approach some knowledgeable regulars or experienced driver at the track, let them see and drive the car a couple laps.
If they too can't find the problem, then do the rebuild?

Or, if figuring out issues is what you prefer (I do too, so I understand), perhaps revert setups to kit setting, ONE change at a time?
Beside all that, consider a check on electronics and radio too, maybe.

RogerM

I have had this issue previously with my wet astroturf car going from being really easy to drive to being essentially random and untrustable. Turned out, during a full strip down, that there was a tweak in the chassis nose section that couldn't be identified until the chassis was completely stripped of the car. Whilst on the car it looked fine against a straight edge and lots of different methods of measurement.
New chassis fitted and the car is awesome again.

Lonestar

iTrader: (14)

modern cars behave properly when built properly as per stock setup sheet - they're already 95% there... a B6.2 is a modern car

As said above, full teardown, inspection for mechanical/electronic integrity, replacement of the shot parts, and rebuild is the solution here. This means the painful parts like diff, shocks, etc...

let us know what your friend found out

AussieB64D

ugh had the issue on dirt. was a number of things in the end. Poor diff setup, not dialed in caster, camber & toe properly and also had a issue with dog bones popping out on one side probably due to setup. Oh and changed tires as well to ones guys recommended for my track.

No probs now unless driver error hehe.

billdelong

iTrader: (33)

I stopped running 2WD because the tires would wear out too fast, something like 1-2 race days and on the second race day the rear end would tend to wash out just as described in the OP.

Assuming a fresh set of tires doesn't fix the issue and it's truly a setup issue where the guy is running an identical setup as a local fast guy then I would follow the chart from Hudy for prioritizing his changes:

The chart is geared for on-road cars but it covers 90% of the tuning options to get your issue resolved




***SIDE NOTE***
When I raced 4WD on turf, I would always start with about 75% steering speed with a fresh set of tires which was my base setup and after every run I would increase the steering speed between 1-2% to account for tire wear. Once the steering speed reached 100% then I saw my lap times taper off and it was time to run a fresh set of tires.

gotheframe

What is your rear pill setup?