Improving high speed stability
 

About an hour ago I was chasing a run in Mexico, and about 110 my car was going all over the road. It was tricky trying to keep it in one lane. And when we hit a bump my pedals vibrated(almost like abs) and felt like a loss of steering control.

Everything is stock on the car except ford 07-09 polished bullitts and 235/55/18 yokohama yk580 tires(tires were purchased a couple months ago). There was very light wind(not sure on direction).

Any ideas on what could be causing this? It's pretty sad when my friend's f150 is more stable at 120 than a pony car at 110

At 120 mine is smooth as silk, so you might want to have the wheel balance and alignment checked.

Historically, Mustangs tend to lift the rear at speed. As has been mentioned, start checking the basics and go from there. Or slow down...

I've never understood why people chase behind. it adds another risk that isnt necessary.

rridle I'll call the dealer and have an appointment set up to look at that

Hmmm never knew about the rear end lift. Think this is the only one that has acted this way, sadly

Idk why people chase around here but they do. It was 2 cts v racing though so I knew I would never catch up lol

bigger wing in back
splitter in front
check allignment, throw a touch more toe-in and decrease caster. this will cause the car to be much more stable and less twitchy. Dont get crazy with the toe, 1/8" total is all you need, maybe 1/8" on each side which would be a LOT if your car has problems tracking straight.

wing in back will help the most though. esp if you dont have a spoiler and have a flat trunk lid. dont need a stupid indy car wing, just a functional spoiler, and the factory ones usually suck ass. look at Roush or Saleen for alternatives.

Should have been easy to catch them then. V's are slow POFs.

My 2012 GT auto was very stable at high speeds in excess of 100mph bone stock. My vote is something is off with the stock suspension. I didn't need to buy an aftermarket wing or splitter to be stable.

-Alex

Have you checked the speed ratings on the tires you have? Doing 100+ MPH on 235 tires in a car weighing 3700# is bound to be sketchy.

Were you one of the douches chasing when we all rolled out? A bunch of slow ass Stang's got in the way. I didn't get to race a auto vette because 3 Stang's were taking up all 3 lanes and he couldn't get up to the race.

V speed rating, so 149. I'm wondering if it has to do with sidewall height. Cause both sets of my 245/45/19 never did this

Zeek I'm not in dfw

Ok good lol Just happened on the same night and we had 2 Vs out running with us.

Probably a combo of the small tire width and sidewall

My old car did 202mph and was stable with Steeda Proactions, BMR Springs, Forgestars with 275/295 PS2s. Even felt stable with Nitto DRs at 180s.

This was on the Autobahn...Smooth roads unlike here

202 radar confirmed?

It's not the tire size, 235/55/18 is a factory GT tire size, and when I had my 2011 GT, I ran the factory Pirelli A/S 235/55/18's up to 150mph many many times.

If you're going to be driving at those speeds at the drop of a hat (unplanned in other words) than you should be checking your tire pressures regularly.

Since the tires are new, I have to ask, how many miles are on them now? I've always noticed brand new tires feel squirmy at higher speeds until the rubber release agent wears off completely.

Also, the tires you bought are an all-season high-mileage rubber compound according to the Yokohama website, meaning they're not very sticky, so regardless of the speed rating, I would be cautious with that specific Yoko tire model period.

With the ABS feeling you encountered, it could have been just that if the Dynamic Stability Control was kicking in trying to save your butt.

Yeah...

Improving high speed stability
 

Holy shit.

How long did it take to get up to that speed? You had to of been in od right?

It wasnt that long tons of room on the autobahn, i dont know the exact though.

I shifted into 6th alot with 3.73s and boost

The problem is that a base GT suspension is just fucking straight up garbage. WAY too tall, WAY too soft, and WAY too un-dampened, with tires that are WAY too narrow for a 3600lb 400hp car.

A friend and I took a road trip in a 2012 GT auto from Hertz. It had 14k on the clock. At anything over 115 it was a complete disaster. Any cross wind at all would have had us flying off the road. We finally agreed to limit ourselves to 105 even though it had plenty of power for 140+. It was just too hairy at high speed.

You guys going over 120 with any regularity in a stock suspension GT are idiots. Sorry if that's you. You may not have enough high speed driving experience to realize when you're in over your head.

To fix: replace the springs, struts, and wheels/tires with just about anything from the aftermarket.

Agreed. Well said, Danny. The thing about the 5.0 suspension is that the car is heavy and when everything is going okay, the car feels solid and smooth giving a false sense of confidence. The problem lies in when the suspension comes unsettled and it quickly becomes a nightmare.

I think I had my car over 100 once before I dropped it. My F-150 felt more stable at 100 MPH than the car did.

With the suspension setup now, it feel much more planted and stable, but still sketchy as hell when you hit a small divet in the road....thanks SRA!

FWIW, the Brembo GT and Boss 302 suspension is much better than the basic GT suspension I was talking about above.

Details on "old car" and said event. A legal and legit 2 bills is way cool.

Who said anything about doing it 'with any regularity'? And I hardly consider myself an idiot nor do I believe anybody else does who knows me. I have hit 120 twice in the 'Stang and even though it was smooth (as I said in my post), I immediately backed off because I was aware of the dangers of the moment. And I just might have enough high speed driving experience to know when I'm over my head.

Don't take it personally, Danny really didn't mean anything directly at you. He's just a point black type of guy and not one to spare anyone's feelings. Partly because he's an asshole, the other part cuz he's lazy and it just takes too much effort to be polite. I can kind of relate to that. lol

No event I was stationed in Germany from 2007-2012. Driving over there is like driving on racetrack 24/7. Cops dont really patrol the street like here. Sold the car when I left and the motor didnt make it much longer with the new owner. He used if for ring and autobahn abuse. With the suspension I mentioned above and the PS2s it was an awesome combo. I think it would have lasted but for some reason he put the stock plugs in it and played with the timing with the handheld.

When I had it
http://i32.photobucket.com/albums/d2...T/DSC_0524.jpg

New Owner
http://i32.photobucket.com/albums/d2...psca31a6d7.jpg

Don't be too sensitive. The car, as Ford built it, is squirrelly as fuck at high speed. But that's easy to overcome with a few aftermarket parts.

Well alignment scheduled for Wednesday plus them checking out why my gauge cluster goes dead while driving. Service advisor didn't know if I need a 2 or 4 wheel alignment so she wrote down 4

I could be wrong, but is it even possible to 4-wheel align a Solid Rear Axle anything?

You are correct.
Maybe they mean't they will check the panhard bar alignment. Although i doubt this is the issue.

Having a panhard bar could be part of the problem. If you are attempting high speed runs on an uneven/rough surface (anything but prestine tarmac), you are going to feel squirly in the backend under acceleration. The panhard bar does it best to keep the rear axle planted, but when you go over any type of bump, the travel of the axle is not straight up and down as one unit, it moves in a parabola or an arc. Meaning, both rear wheels do no touch the ground at the same time. IRS cars really don't have this issue and the best thing you can do with the rear is a Watts Link. I have one and it has helped tremoundously with keeping the rear planted, but an IRS will inspire more confidence than the stick axle we have.

Very cool. So track events over there don't required a helmet? They must not have as many lawyers as we do. LOL

Shit, mine feels like crap at 80 with 3.73's. Maybe its the Nitto 305 DR. Who knows.

Yeah I have no clue how they're gonna do the alignment. Ford dealer service hasn't impressed me these past couple days with their lack of knowledge

Well finally got the repair order back after waiting for 7 hours.
http://i1024.photobucket.com/albums/...pses8hvbit.jpg
Add to that a $100 diagnostic fee and tax. Almost $1,000!

I told them no thanks, I'll talk to geico and the body shop since the dealer thinks that the wheel bearing issue stemmed from a wreck, and discount tire should warrant their tpms sensor work

If the car was in a wreck, and you still have systemic issues relating to that accident, the Insurance company should definitely be involved.

I had a similar situation about 6-years ago. The dealership just called the insurance company back a month after all was supposedly fixed, and amended the repair. Got wheel bearings replaced, along with 2-new wheels, and 4-new tires from incorrectly performed alignment during the first repair.

Its the soft sidewall of the DR's.

What does chasing a run mean?