JeffC

iTrader: (5)

Just cut the top deck. The car won't drive right if the flex characteristics are off. Every 21.5 black carpet setup you'll see has it cut. It's a chunk of carbon fiber, not your hand. It's replaceable.

gimpy racer

I tried out Eric Anderson's 21.5 setup and it was only marginally better then Max's ETS setup.
I followed the setup as best as possible including slotting the front c127s. The only components unable to follow is the Rebellion chassis, Hudy Tires and the Wovlerine body. BSR bumper is installed until a new lightweight arrives. Removed Avid arm weights.
Left side motor mount weights installed, right side motor mount weights not installed. Im not running a ULGC battery and the weights added to battery side of chassis throws off the Left-Right balance.

Car is still loose off power at corner entry to mid corner, its touchy and hard to drive.

Taking some rear droop out from 5.8mm to 6.0mm seemed to help. Trying the MMXC top deck and it calmed the car down. Not sure what that means lol.

I'm not sure what else to try. Ryan Maker and Essential Touring car books say lowering the rear roll center and increasing front droop/decrease rear droop should help.
Those changes seem opposite to every well respected setup for black carpet.

Maybe when setting the front-rear weight balance I messed up and its way off 50/50. I have 4 small identical scales (not a corner weight system).
Is there a proper way to measure this? When I tried I left the damper rods connected and just added up the left and right weights for front and rear to get my distribution.

Only other thing is the body. The Wolverine seems to be the body of choice. Maybe it provides that much more rear stability with setups like Eric & Kemp's.

malkiy

iTrader: (10)

There is something wrong with your car. Binding in the hubs, diffs or dampeners? Is the chassis tweaked? There is no reason for the rear end getting loose with that heavy bumper and almost no rear droop. How big of a battery are you running? Your car is acting like it has a lot rear weight bias. What track do you race at? Is there another AMX driver than can go over your car?

Lonestar

iTrader: (14)

what he said.

there is SO much that can be off on the AMX... take the car apart fully. Check every bearing, every link, axles, UJ's, etc... the car works like a dream when everything is mechanically perfect, any of the top dawgs setups for a given condition works already at 95%. If the car drives "ill" it is a hardware issue, not a setup issue. Check for something binding, broken, bent, asymetric, too tight, too loose, etc... what you describe is not about a few 10ths of a millimeter of droop here of 50CST's there or even an agressive body, it's about something fundamentally wrong on the car.

it's a very demanding car, but one of the most rewarding when it works well (I know - it went well for the first time in ages for me last weekend, and by Golly it does go like stink!!!!)

All the best - keep us posted

glennhl

iTrader: (16)

Gimpy Racer, one of our regulars was fighting a loose car with his A800 last weekend. He found a ball cup on one of his rear toe links completely bound up. He replaced the ball cup and it fixed it. Worth looking into.

BEMO2019

iTrader: (11)

To double down on this I had a P05 get slopped out and bind the rear sway bar and rear suspension. Car was not drivable when transitioning weight to the front and rear.

WayneKerr

iTrader: (2)

What shim stack are you running under the at21 and the upper arms.

gimpy racer

Thanks to everyone swooping in to help I really appreciate it! I'll try to answer everything asked.

How big of a battery are you running?
-Muchmore 6000mah with terminals facing rear. Its 22.5mm tall and 280g. I use the stock plastic battery holder. Car is balanced left to right with this battery.

Is there another AMX driver than can go over your car?
-Sadly not anymore.

What shim stack are you running under the at21 and the upper arms?
-Currently Eric Anderson setup.
-Front has the specified 2mm under forward AT21 and 2.5mm under aft AT21. Upper link has 4.5mm shims under inner ST03, 1.75mm under outer.
-Rear has 2.5mm under all AT21. Upper links have 4.5mm under inner ST03, 1.75mm under outer

The ADC kit finally arrived so I'll strip it down and check for damage when the dampers are rebuilt. The car is fairly new and hasn't seen too many hard collisions.

CraigX

iTrader: (34)

What area do you race at? Something does sound off, with that setup and if your weight distribution is at least 50/50, you should not be having so much oversteer. Does it oversteer off power in both directions? You may need to check the tweak of the car.

thecaptain

iTrader: (177)

A silly questions, but you're measuring your camber, castor, toe, and your steering links are the same length? Your droop and ride height at the same left to right?

Have you checked your bulkeads for bends, or other parts of your car issues. Like the ball cups, arms, ballstuds etc.

WayneKerr

iTrader: (2)

When I raced 21.5 6 months ago I ran 6.2-5.8 droop front to rear respectively on CRC black and had the same problem you had.

Knocked it to 5.2 rear, went away.

Might be worth a try, because it doesn't require tearing down the whole car on a witch hunt.

malkiy

iTrader: (10)

Going to 5.2 rear droop will make his issues worse. Going from 6 to 5.2 will make his car transfer even more weight to the front entering a turn. But .... I don't think droop is his issue. 5.2 may work if he ever gets his car sorted.

nickw

iTrader: (9)

Increasing droop normally increases traction. All of my lower traction setups start with more overall droop/uptravel than my higher grip setups. I normally run a .8 to .4 difference between the front and rear measurements (tune to feel - front rear balance).

First runs on CRC black I almost always start at 5.6 front and 5.0 rear droop settings. I'll decrease them both as traction increases.

If the CRC black carpet is pretty green, dirty, or is generally lower traction... running a high droop number will make the car slide around. Increasing droop will help that.

trx-1racer

Well I've joined the club... I've picked up 2 AMX cars, 1 MMXA and 1 MMX. The MMX might eventually get an AL chassis too, but to start off in USGT, I wasn't that concerned about it. Plus it gives me versatility if I end up at an outdoor race somewhere... We run indoors, but not on carpet. The MMXA will be a 21.5 car, but I still need a few things for it.

Here's the GT, I've got a Bwoah to rattle can for it:

Red5Ltr

iTrader: (24)

The ADC caps are a game-changer, and you'll love em. Remember, oil weight should be 55wt. I build mine 8 months ago and I've checked them periodically and still butter smooth.
As far as the shims under your arms. try going 2.5mm in the front and 3.0mm in the rear. Remember, raising shims under the arms increases grip. This may help you with your rear grip issue. I would also run like 5.2-5.4mm of rear droop and 6.0mm - 6.2mm of front droop. Make sure you're cleaning your tires very well and getting the track goo off. This is KEY. If you're still loose, try lowering your upper deck shims. Remember, lowering upper shims adds grip and raising takes grip away. Opposite of what the shims under the arms do. Adding shims under the arms adds grip and removing them lessens grip. Maddening I know.
LOL!!
I mention all of this because I was fighting the same issues you are dealing with and I've found the ket was higher than 2.0 under the arms and we race on Black CRC carpet at The Gate here in Northern Ohio