Alexp08

so the other day i was driving on the highway at bout 75 and it just felt like i was gonna lose the back end at any second. is this a lack of downforce issuse due to no spoiler or should i look into anyother suspension issue?

LifeAfterRx8

iTrader: (17)

Was it raining?

pdashfield

stock tyres are no good at high speed in the Rain,they are hydroplanning

Alexp08

nope, no rain. and i have snow tires on..it wasnt snowing either. it was dry

PeteInLongBeach

???
I have the OEM Dunlops on my '09, not known for being the best tire, and even in the recent heavy rains at 75-80 mph I have not noticed any hydroplaning, which was surprising...

I think the OP might have an alignment or other suspension issue. The cars drive fine without a spoiler.

EricMeyer

Assuming you haven't done so already I would look underneath your car from the bottom of the motor to the rear of the car. Doubtful but oil/trans/diff fluid (or anyone driving in front of you leaking something) gives feedback like what you offer to the drive wheels.

Tiler02

I do not have a rear spoiler or anything else on my car. I can not tell any difference in the handling at 30 or a 100.

Bigbacon

iTrader: (4)

does this happen while driving straight or on corners only?

alnielsen

iTrader: (4)

Check your rear camber/tow settings. If the alignment is off, you won't have the full footprint of the tire on the ground for traction.

bsteimel

iTrader: (5)

Are these snow tires brand new? What kind of tires are they?

Some serious snow tires are a little "floaty" at high speeds. I find they react different at speeds of 80+,especially when they were brand new. I know my snow tires are only rated for 110+ not like z rated tires.

Mine are michelin ice x2

Another thing to note is that stock spoilers do almost 0 on our cars because of the flex in the trunk. Your not going to see any difference at those speeds.

lateralus

iTrader: (1)

Highway speed definitely isn't enough for the spoiler to make that much of a difference. If all 8s without spoilers lost the rear wheels at highway speeds, I'm pretty sure Mazda would put spoilers on all of them haha.

Is your TCS/DSC light flashing at all when you feel like you are about to lose the rear?

Alexp08

No oil leaking, the tires are blizzacks, n my tcs is not flashing, n i was going straight while doing hard acceleration getting on to the interstate.

AngelKiha31

Could potentially be a road issue. What kind of road surface? What was the temp, and was there any residual snow or water on the onramp or road before onramp?

lateralus

iTrader: (1)

What is making you feel like you are about to lose the back end? Are the back wheels actually starting to slip a little?

Any time that I have done something to cause mine to start slipping, the car corrects it almost immediately and flashes the light. I would be just as curious about why your TCS/DSC light isn't flashing as I would be about what is causing the rear to start slipping in the first place.

Alexp08

it was alittle wet and the temp was about 20 degrees.

it didnt actually lose any traction it just seemed like if i turned the wheel at all it was just going to lose control.
i mean ive drove rear wheel drive before and went well over 75mph so i dont no if its just mean or what.

hotdoghogie

Its all in your head lol... no really sounds like a toe-in issue. Get it aligned recently?

twistedwankel

iTrader: (6)

Blizzack's (most ice tires) are designed to be on all four wheels on shitty rims!! Also consider a sand bag in the trunk and a full tank of gas for hills.

Max 99mph at low outdoor temps (never summer). They are deep treads with special soft bubbled compound and M+S compound underneath for the last 1/2 of tread like a normal tire. They squirm like hell under power. All snow tires are more to help you stop on ICE than accelerate.

You are over powering your skinny weak tires. You can easily pass a 4x4 on the highway at speed and out stop it by a ton with all that grip. Lighten up.

lateralus

iTrader: (1)

I'm pretty sure they are on all four wheels... And 75mph isn't anything to excessive. I don't really think him needing to lighten up is the problem. The car should be able to handle 75 fine...

Its sorta hard to figure out what is causing the problem if you feel like you are about to lose the back end, but nothing physical is really happening to make you think so... How long have you had the car?

Alexp08

ive had the car for alittle over a month, yes i am a new rx8 owner. i dont think its anything in my head lol or atleast i hope not. that would be quite embarrassing. anyways, no i have not had it aligned since i bought it, im still in the tune-up phase, im changing oil, spark plugs, wires, coil packs, antifreeze..stuff like that, and i realize most of that prop dosnt need to be done but im **** like that i dont know who had it before me so i dont know what has been done. but today i was driving at 55mph and shook the steering back and forth bout a inch both ways, i didnt do it hard and i only did it once (left then right) and the back end swayed to the left, then right, then back to the left, and back to the right, and then straightened out. first thought was sway bar lol but i had it inspected for one and i also i just had both sway bar end links changed and everything seems to be fine with the sway bar itself. could the rear shocks be bad?? i feel that if they were and the springs are the only thing holding me up it would yeild a reaction like i just explained.

hotdoghogie

What size wheel you running? Tall sidewalls or thin sidewalls will give you this effect. Bad bushings, excessive toe in/out in the rear, excessive camber up front, low tire pressure, shotty tires. Man it could be a long list of things.

Bad struts/ springs would be on my bottom list just because those really wouldn't give you an *** loose effect. I have shot struts and spring sag and my car still feels fairly stable on the highways.

I personally think the tires are the verdict here.

Alexp08

well **** lol im running stock wheel/tire size, but for the most part i feel a alignment need to be done.

lateralus

iTrader: (1)

Yeah, since you are doing all that other stuff since you just got it and don't know what was done to it before you, you might as well go ahead and get the alignment checked out too. Definitely can't hurt and may solve your problem.

Aseras

check your tire pressure.