Intro: I've had two mustangs (2000 sixxer) and my current 2002 GT. Never can i recall why the GT started becoming so unbearable in the rain. In order to create the problem, I'll just be driving along the interstate crusing around 70 during a heavy rain storm. I understand this is probably not the best judegement on my part, but there's no way a GT is normal acting like this. I'll also always as a precaution leave traction control on, in heavy rain conditions. Otherwise it's off. The problem only shows itself in rain.

The car: 2002 Mustang GT with 18x9, 18x10 saleens, 4:10 gears, Delta Force Tuner, JLT CAI, Toxico HP shocks & struts, and H&R Sport Springs (Only mods I can think of that might correlate with my undrivability); Otherwise it's stock as far as I know.

The Problem: It just comes out of nowhere. It seems to show itself in a weird relationship to my gas throttle. Expecially over speeds of 70. The sensation scares the living **** out of me, and is a renewed "bone chill" everytime it happens It's defenitely coming from the rear of the car. It feels as though my rear end has slided back and then suddenly popped back into place. You could say it's an aggresive shutter from the rear. Definitely feels like some "hop", but I can't picture a SRA giving me this much trouble. I even thought it could be quad shocks. It's doing it at the least every 15 seconds... making my rain driving experience terrible.

Conclusion: I have no idea what's going on and i'd like to get some good background knowledge before I take it into the stealership. Searched for a good while and the only thing i could come to this is "Wheel Hop". Guys you've pulled through for me in the past, I hope you can now I.D. this one.

Best,

-kdaddy

p.s. got rear ended by a "Mitsusquishy Galant" going about 35 earlier yesterday. From a direct observation, it only appears to have knocked out the exhaust pipe and my rear bumper is slightly damaged. His car... whoa totaled. Both air bags depolyed, wind shield cracked, front end destroyed. These Mustangs are tanks...

 

How wide are your tires and have you tried it with trac loc disengaged?

My only guess at this point would be hydroplaning and what you are experiencing is the tires coming back into contact with the pavement...

 

got better tires!

 

You know this could be a good lead lol. They are 295/35/18 Toyo Proxes T1R. They are pretty much brand new. If that's not it, I suspected maybe bad control arm bushings as well? Like stated before this only happens in heavy rain conditions. I'll try driving without traction control and see it it helps. My 2000 mustang didn't come with traction control so maybe I'm just driving it to hard in the rain.. Thanks for the input guys much appreciated!!

 

+1, it's hydroplaning.

I had 275/40-17 Falken RT615s on the back and couldn't go much over 60 in heavy rain...

 

that would be my guess as well.
If you have a laptop and a USB camera (very cheap these days), mount the camera under the car at dif. points that you want to watch. I've used this trick many times to help diag. problems without being able to see real life. Although with rain and wet and all, this might be a little harder to do.
Just another thought in trouble-shooting the issue and many others.
Examples; I've watched my drive shaft to Dif. pinion turning during burn-out and launches, and watched my engine running under the hood. I couple that up with Ease Diag soft/hardware. Makes things a bit easier to trouble-shoot.
All I need now is a tuner.

 

Well, I have Nitto drag radials on my car with 550rwhp... 315/35/17's

You know what I do when it rains? Use common sense. You're driving a rear wheel drive car with plenty of low end tourque and relatively light for a power/weight ratio... you also have a suspension setup that helps put more of that tq on the ground and it has changed your stock suspension geometry... not that this is what you want to hear, but try using your head and not driving 70mph in these conditions....

all it takes is a slight corner and a build up of water to spin a car like ours when speeding... not quite the same thing, but I've blown a tire at 45mph... and I've blown a tire at 80mph... and trying to recover/manage cars at higher speeds in otherwise identical conditions is a totally different monster... now we all speed, but I can say once weather conditions get crappy, that I cant feel sorry for anyone not taking precautions to drive safer that end up wrecking...


traction control is kinda an initial 'idiot light' to slow down for the conditions, but i actually find I drive better with TC turned off...

like I said, I manage a high horsepower car with nitto drag radials in the rain just fine... just use your head and get off the gas...

 

and on a side note, i'm sorry to hear about your accident...

about 5 years ago, I had ANOTHER 2003 GT... I was stopped at a red light, slammed from behind, and pushed into oncoming traffic... I got hit at 35mph in the passenger door, spun around and hit a telephone pole... airbags out, car totalled... walked away with a sore neck and banged up elbow... these cars ARE f%&$in tanks...

out of 4 cars involved in the accident, I was the only one who didnt have to go to the hospital...

 

I agree completely with GT03 TJS about how we all speed but we need to use common sense in bad weather. But at the same time, I can drive 65-70 in heavy rain with my 265 front and 285 rear Sumitomo HTR-Z II's with no problem feeling loose or that I am even on the verge of hydroplaning.

 

Why are you doing 70 in heavy rain in the first place? You common sense, drive for the road conditions.

(And as posted, your wide wheels are leading to the hydroplaning.)