MantisWorx

iTrader: (28)

So a softer clutch will not help?
Softer rear springs will not help ?
Hudy guide quote:
Softer springs give more chassis roll and more traction.

Standing up the rear shocks wont work ?

According to the Hudy guide standing up the rear shocks
inside on the arm "less side bite, more exit traction"
outside on tower "Squares up better on exit"

2 stage pistons do not increase grip all the way around?
Works on real cars!!

These are the things i did to Tonys car to help and it worked very well, dropped his laptimes about a half a second and made it much more driveable. True i do not personally own a Cobra but spend plenty of time tuning on them!
To each his own , I was just trying to help

Phil Trotta

iTrader: (4)

I think it was the opening comment of its the tendency of the car
This car is definately dialed and has a big suspension tuning wIndow

Speyederjedi

iTrader: (1)

Hmmmm? He edited/deleted his post. But you are correct Jack Hammer, I think is was the opening remark. My Cobra GT has never had a "tendency" to swap ends. It was pretty stable on the track right off the build settings and does have a large tuning window.

@ Bourbon, if it's doing it in both directions then it's not likely to be oil from the exhaust causing the problem. I know it sounds simple but stranger things have happened, check the front drive shaft grub screw to make sure it hasn't backed out. I've seen that happen and then your car becomes rear wheel drive and can swap ends very easily. Other than that, if you're going off the build instructions, I'm not sure why the car might be swapping ends???

burgboyz

iTrader: (70)

OldBourbon...All very good info that has been shared with you here! But, What ever you end up doing, Try just one major change at a time after you check that you do not have a mechanical issue.

With your limited test/tune window before your next outing, I would change the camber settings, droop, and ride height FIRST and run 10 or so test laps. That should be enough to heat up tires and give truer results than just a lap or two.
Then tires.
Then wheel base and experiment with rear toe.
Shock positions.

If these changes do not show any results, start to dig deeper like shock packages, clutch shoes/springs, diff oil, hinge pins, gearing, etc, etc, etc..

Any .28 has a lot more grunt than most .21's. Radio settings and driver tendencies play a huge role in fine tuning for the fastest lap times but the ideas that have been shared on this thread all have merit. Download a couple of different setups for GT's and compare those details to yours. Not all will work perfect for you, but you will notice many similarities in the main settings. Hth.

wingracer

iTrader: (24)

I am not familiar with this particular car but I see two BIG problems with the set-up you posted.

1. You say you are running 0 rear toe. Despite what you may think, ALL onroad cars run at least a bit of rear toe except pan cars. Even real F1 uses a touch. Put a couple degrees of rear toe in it and I bet your problem vanishes.

2. You say you set front ride height with the droop screws. Usually this means you have NO down travel in the front suspension and this is wrong. You set ride height with the front springs. I do not know the right droop setting for that car but whatever it is, the car should not be on the stops at rest (sitting on the ground). You should be able to lift the front of the car at least 1mm before the arms hit the stops and lift the tires. Hopefully Paolo or someone can fill you in on the right setting and measuring technique for this car.

Make those changes and I absolutely PROMISE you the car will drive tremendously better and run MUCH faster lap times.

Also, you say you are running 5-10 degrees of camber. If that is true, that sounds like WAY too much but again, I don't know the car so maybe Paolo can clarify what it should be.

MantisWorx

iTrader: (28)

That wasnt really what i meant, sorry if it came across that way. My explanation was more along the lines of the fact that GT cars (all of them) do not have a center dif therefore have a tendency to "ass out" on exit because there is no center dif. Coming from off road and relating to off road terms the higher the center dif fluid the looser the car becomes especially on exit. Once again I apologize as it was not my intention which is why i deleted the original post.

DOMIT

iTrader: (1)

One more thing nobody has touched on... but give this some thought as well:

A softer rear swaybar (or even simply move the connectors out as far to the ends as you can.) If you want to go extreme you could even remove the rear bar, but you are going to see more body roll and the car will likely push like a dump truck if you do that.

I'm an offroad guy, just poking my nose in because the GT stuff looks interesting... and traction is traction. That change makes a difference on both offroad and real (1:1 scale) cars.

And I agree that you need some rear toe. It helps keep the car planted.

If I understand correctly, you are running ZERO droop? Maybe add just a bit to the rear.

One more thing: We don't even run 5 degrees of camber on offroad, except if it is a REALLY blown-out track and we want to remove some side bite to prevent catching a lip and traction rolling.

OldBourbon

Can't thank you guys enough for taking the time to help me out.

Taking advice above I've started with standing the shocks up and swapping tires to rule them out. Also moved to 3 degrees - camber.

I'm building a check list off of the advice and will make 1 - 2 changes each outing and report back. Unfortunately we don't have real races here so there's no rush. Tuning is more of a hobby than a necessity to be competitive.

I've done some cool things with splitters and body work a la Audi and 24 hrs du mons. I'll try to post a pic or two.

spooky 1

iTrader: (1)

I've raced Paulo many times now, and I've never seen his Cobra NOT hooked up. Put on his setup and you can't go wrong.

Solara

iTrader: (17)

OldBourbon.....I totally know your frustration because my OFNA was doing EXACTLY what you did on your Cobra last year at Bryon Race (racing with Paolo)...the car is great everywhere, but when entering the straight, it will kicked out 180 for NO REASON at all...and when exiting from the straight, it will do the same....for the entire weekend, I have to EASE my throttle when entering and exiting corners and that was NO FUN whatsoever driving it...totally frustrated.

But guess what...PAOLO saw it...and he told me, check my rear diff....at that time, I have no time left to open up the whole gear box and check and I have to get up to the A main in 15 minutes so I ended up driving an hour main with horrible speed in entering and exiting corners and did horrible.

When I get home I spend some time playing with the rear wheel and diff...it is the REAR DIFF...it will BIND UP like after several rotation...it just LOCKED UP, but if I turn the diff hard, it will loosen up. Then I rotate the diff more, it will bind again.............turn out, my diff housing, after some miles, it expanded a little and the SHIMMING inside those little mushroom diff gear are no longer working...I ended up removing those shim (from using one 0.1mm shim to ZERO shim)....diff finally work WITHOUT binding. And I ran the whole weekend of Mid West Series without any problem.

See that is the case on your Cobra....your case, it COULD be too loose...my case, was too tight....also, I ended up replacing all those metal internal gear cause after an hour of grinding, all of those gear are stripped like 1/2 way....I would replace the whole internal gear with new one and re-shim the meshing.

I am very much sure it is NOT your setting....COBRA with a carpet setting will still run fine...it won't do 180 because of just a setup. When car fish tail that way, it is something binding...

Overall, the rear of your car is LOCKING UP caused by some thing...it can be your diff, your CVD pin's get loose and locked the outdrive, chassis bottomed out and life the rear tires, rear tires rubbing the body and caused the lock up..............your kicking out is caused due to the FRONT WHEEL still in rotation but the rear wheel is locked/stopped......kinda like running a one-way when you apply a full brake.

OldBourbon

Solara. Thank you! I did not think of confirming there was something wrong with the rear diff. I did shim it when building! I will rebuild the rear end. The more i think of this even though these guys have pointed out some flaws in my set-up I have set this car up very similar to my Kyosho GT and OFNA DM1. Those cars hook up and this one doesn't. You have really got me wondering if there is a mechanical problem in the rear-end. hrmmm

After racing Friday night making some of the changes here like standing up the shocks, adding droop, swapping tires I had no improvement.

Will report back after Friday night.

TerribleTy

Hmmmm.... stab it down and the rear end swings away, sounds like ride height to me. If you are transferring all that weight back to the rear of the car that fast you may be bottoming out which makes you spin instantly. Add some ride height as standing up the shocks makes your rear end softer and would only add to the problem. flip your car over and see if there is scratching that looks fresh on the rear portion of the chassis.

I do a lot of parking lot racing as well and have no problems running any of my setups on prepped or even dirty lots. Verify your drivetrain first then check your ride height. After that is sorted I can give you a few clues on setup if you would like.

MantisWorx

iTrader: (28)

Yea, I am sure HUDY has no idea what they are talking about........

FYI anti squat keeps the rear from sagging under acceleration so his chassis is not going scrape coming out of a turn. Thats what anti squat does by definition. Off power at the end of a straight maybe but not on exit.

TerribleTy

Your wisdom is always appreciated. I'm trying to look at the most basic rules of setup as you guys have already gone into other aspects. Its stated that moving the shocks around didnt help so I'm trying to go a different route. Your anti squat won't do squat if your dampening or spring is too soft or you have too much droop. A .28 in a GT is going to have loads of bottom end and stabing it down will transfer the weight very rapidly to the rear. Standing the shocks up makes the suspension softer, its basic geometry. So going softer is going to give you the same result if not worse. Parking lots are full of elevation changes rocks and often cracks which can drive these cars wild unless you compensate for them.

TerribleTy

Also what kind of feel are you going for with the car? Soft with alot of roll or stiff with little roll? I have set my Serpent up both ways for various reasons. As of late I am enjoying a very stiff setup with very little suspension travel. The Serpent is just as planted either way just comes down to your preferance.

I'd suggest looking into the XXX main TC setup book as it does a great job of teaching you the fundamentals of setup. Almost everything in setup comes down to weight transfer, once you master that concept it will all start to make a bit more sense. Best thing to do is go out for a day and just make adjusmetns one at a time. Whether its better or worse try and be able to explain why it is that way as it will increase your understanding.

Best of luck and keep pushing!!!