first let me say street racing is bad................
ok so i was crusing down the ... oh i mean race track lol at 80mph when a turbo vw jetta rolled up to me and wanted to play,
well i thought i might just see what this things got so next thing i know im crusing at 120 and he hits top speed and im still at 4 grand.
so i give it a little more gas well as i was going around a slow turn i felt a sqishynes in the handling like driving on a ballon is this my tires or the the bump stear on my 86??
my best guess is its the tyres i dont think there rated at that speed i took the car to 5000rpm in 5th dont know how fast that is?
needles to say the jetta never had a chance

[This message has been edited by 3.6lvvt6spdgt (edited 01-20-2008).]

You didn't have a chance either and are lucky to have survived. Think about it.

------------------
1987 Pontiac Fiero GT
418ci 'Mini-Rat' motor
dual stage nitrous injected
built 5-speed getrag

[This message has been edited by RichLo (edited 01-20-2008).]

a balloon basically fills up under the front end, due to air trapped in the radiator area.

Mine does that some at high speeds as well. I'm going to get lower front springs. I have heard that will take care of a lot of it.
Oh...and you must have good perf. tires and they must be the same brand front and back.

[This message has been edited by Highjumper (edited 01-20-2008).]

Hood vent.

I second RideZiLightning's idea.
If your car doesn't have a hood vent the air pressure builds up under the front end. I've read that you can develope 100lbs of lift on the front end due to the aerodynamics. This might be the cause of your problem.

P.S.
Please be careful, @ 120 mph you are traveling @ 176 feet per second. Things happen pretty fast at that speed. You could hurt yourself, (or worse, someone else.)

Bob

------------------
"Its nice to be important.
Its more important to be nice."

My front end lifted badly at the end of a 11.75 second quarter mile run.

------------------
..from beautiful Caledonia, WI
88 GT 5-speed soon to be an LS1
87 GT 5 speed V8 SBC TPI--SOLD--
08 Solstice GXP 5 speed
04 Caddy STS
00 Pontiac GTP with GTX package
96 Suburban
92 Dodge Shadow 28K miles

quote Originally posted by 3.6lvvt6spdgt: first let me say street racing is bad................

If it is bad why did you take a 22 year old car with probably some 22 year old worn out suspension parts past 120??

Ahh, to be young and invincible again.

quote Originally posted by 3.6lvvt6spdgt: first let me say street racing is bad................ ok so i was crusing down the ... oh i mean race track lol at 80mph when a turbo vw jetta rolled up to me and wanted to play, well i thought i might just see what this things got so next thing i know im crusing at 120 and he hits top speed and im still at 4 grand. so i give it a little more gas well as i was going around a slow turn i felt a sqishynes in the handling like driving on a ballon is this my tires or the the bump stear on my 86?? my best guess is its the tyres i dont think there rated at that speed i took the car to 5000rpm in 5th dont know how fast that is? needles to say the jetta never had a chance

venting the hood elimantes the problem

agreed vent the hood will also solve your headlight problem. If this is not enuf drop the front slightly and leave the back the same i wouldnt recommend more than an inch.

quote Originally posted by 3.6lvvt6spdgt: first let me say street racing is bad................ ok so i was crusing down the ... oh i mean race track lol at 80mph when a turbo vw jetta rolled up to me and wanted to play, well i thought i might just see what this things got so next thing i know im crusing at 120 and he hits top speed and im still at 4 grand. so i give it a little more gas well as i was going around a slow turn i felt a sqishynes in the handling like driving on a ballon is this my tires or the the bump stear on my 86?? my best guess is its the tyres i dont think there rated at that speed i took the car to 5000rpm in 5th dont know how fast that is? needles to say the jetta never had a chance

Not sure exactly what's happening in your specific instance, but there are a few things you can do. What wheel combination do you have? If you go with the factory wheel difference (I think it was 195/60/15 in the front and 215/60/15 in the rear) it will put your Fiero at a slightly more rackish angle. At speeds in excess of 100+ miles an hour, your Fiero (when set up like this) SHOULD actually compress the suspension more. If everything is good, your Fiero should feel more confident and true. If you have aftermarket wheels and have low profile tires, you can still achieve this desired effect by going with larger wheels at the rear. Or, you can have custom springs to achieve this as well. I'm a stock nut, so I don't like it when the Fiero doesn't look stock, but you can still achieve this angle while having the car look totally "normal".

A few more things to consider, what is the rating of your tires? You'll want "Z" rated tires as anything less than that are not designed to go over 80 or 90 miles an hour, and definitely not for longer periods of time like what it would take you to get to 120+ and to cruise at that speed.

You should also make sure that your entire suspension is in 100% condition, tie rods, alignment, wheel balance, everything. Otherwise your car should not be going speeds like that. Pretty much any modern car has the capacity to go to 120-140 miles an hour. Because of mechanical and safety limitations, manufacturers often govern the vehicles to 105 miles an hour, sports cars are usually given a higher govern, and speciality built cars (like the Corvette, etc) are governless (for the most part). Unfortunately, the Fiero was never designed to operate at that speed, as much as I like the car, it's not a Ferrari. So if you want to be able to achieve speeds like that with confidence, you'll want to make sure that every aspect of the suspension is properly tuned and serviced.

Here's the responsible response: I'm well aware of the endorphin and adrenaline rush you get. Especially when there's a punk in another car who, like you, think's his car is for the most part, the baddest car on the planet (even if everyone else hasn't realized it yet). I also know all too well how awesome it feels when the other guy is brutally crushed by your top speed which is a whopping 10 more miles per hour. The pain and emberassement that goes through the loser only serves to fuel your own adrenaline. However, consider the fact that at 120+ miles an hour... you make one mistake, one little mistake... and you die. That's it. Hopefully, while you're careening wildly out of control towards that tree or guard rail, you don't take out Grandma and Grandpa (who are taking their grand kids to Disney World for the first time). No one is perfect, and everyone does stupid stuff now and then... but just keep that in mind every time you see the needle go 20+ miles over the speed limit.

------------------
Todd,
2006 Pontiac Solstice
2004 Volkswagen Beetle Convertible (Wife's Car)
2002 Ford Crown Victoria LX
1987 Pontiac Fiero SE / V6 (3.2) 5-Speed
1984 Porsche 944 5-Speed
1981 Pontiac TransAm (Olds 455BB)
1973 Volkswagen Type-2 Transporter

I have reported you to the Salem Oregon Police Dept. Ed

------------------

I was going to give you an earful for driving like that on public roads....but then again, I remembered when I built my first V8 Fiero and I had it over 150mph. I also street raced on a daily basis and used to win until those rice burners learned what turbos were.
so nevermind.
Dave

fist off my car is lowered 2 inches all the way around and has new every thing frame down in the suspenchion i have a lot of money in my car and it felt like the rear was doing it more than the front, posably due to the fact that i have no rear wing.
also im not in oregon at this time or the time of this event for thoughs who would like to report this to any kind of athority,
on top of that the only person i endangered was myself, it was 3am and no one elses was on the um ... track but me and the jetta and that jetta never came close to keeping up,
so with all that said i never go for broke as soon as the car felt weierd i slowed down to a slower 120mph and the problem was gone i think it was my tires they are not rated for thoughs speeds.

also like i said before only race on a track street racing is unsafe aka dont try it!

thanks for the sugestions on how to correct the problem
here is what i need to do then
Z rated tires
hood vent
and maybe a rear wing.

[This message has been edited by 3.6lvvt6spdgt (edited 01-20-2008).]

I had a similar problem pushing 125 mph on the country roads here in Florida.
It was like I was floating sorta speak,with my 86' v-6 auto.SE
If its the hood then need to have it changed before my motor is finished.
Because I am only 37 (not young and not invinsible) but there is a C-5 around here that his daddy bought him and I so want to show him you can build not only buy performance.

quote Originally posted by 3.6lvvt6spdgt: fist off my car is lowered 2 inches all the way around and has new every thing frame down in the suspenchion i have a lot of money in my car and it felt like the rear was doing it more than the front, posably due to the fact that i have no rear wing. also im not in oregon at this time or the time of this event for thoughs who would like to report this to any kind of athority, on top of that the only person i endangered was myself, it was 3am and no one elses was on the um ... track but me and the jetta and that jetta never came close to keeping up, so with all that said i never go for broke as soon as the car felt weierd i slowed down to a slower 120mph and the problem was gone i think it was my tires they are not rated for thoughs speeds. also like i said before only race on a track street racing is unsafe aka dont try it! thanks for the sugestions on how to correct the problem here is what i need to do then Z rated tires hood vent and maybe a rear wing.

You should also consider what I said about the "attack angle" so to speak. Having the car lowered (all around) only helps your car handle better, it does absolutely nothing for top speed. However, if the front of your car is dropped 1" lower than the rear (which can be done by getting larger/taller tires in the rear), this will improve the stability of your car at top speed. The stock Fiero GT 86-88 had this type of tire configuration. It also improves handling in a slolam type course.

------------------
Todd,
2006 Pontiac Solstice
2004 Volkswagen Beetle Convertible (Wife's Car)
2002 Ford Crown Victoria LX
1987 Pontiac Fiero SE / V6 (3.2) 5-Speed
1984 Porsche 944 5-Speed
1981 Pontiac TransAm (Olds 455BB)
1973 Volkswagen Type-2 Transporter

Hood vents in the front will help alot with front stability as others have said.

But, you said it felt as if your rear was moving around more. Moving in what way?

The famous bump steer is really only a problem when your cornering in some way under WOT at higher speeds. At least that's when bump steer showed up in my 87 GT. All other driving was fine. So, I don't think that is a contributer in your situation as it sounds you were primarily driving in a strait line at high speed. It is possible to get some if you were on a bumpy section of road making your rear suspension move to the bump point. You can control a lot of bump with a rear bar. But to get rid of just about all of it, you need to relocate your pivot points for the toe links to line up with the control arm pivot points.

With your new suspension parts, did you replace the bushings with new OEM rubber or Polyurethane? That could make a significant difference in tightening up the suspension parts and making handeling more precise.

Did you check all your mounting bolts after replacing your new suspension parts? You might also want to check the four cradle bolts, rear end alignment for toe in/out, castor/camber to make sure your in at least factory specs.

I found that when when I pushed in and out on my rear wheels(side to side) in the 87 GT, that the toe in and out would change. I discoverd that it was the springiness in the steel mounting brackets welded on the cradle. I eliminated that by making a tubular bridge tying the two welded brackets together. No more springiness or side movement in the wheels.

Tires as some have said can also give you trouble if they are not rated for your speed and with the proper set-up.

Anyway, After all the above I was much more stable at high speeds at midnight. Ooops.

#1 hood vent - gets the nose planted
#2 poly bushing - mostly for the rear - tightens up a-arms
#3 rear sway bar - flattens the ride some, and reduces bumpsteer
#4 plain old good suspension parts: ball joints & tie rods
#5 slight drop - more in front than rear, w/stronger springs - at higher speeds, suspension springs need to be stronger, because forces are higher. and, stronger springs in the rear also cuts down on bumpsteer
#6 air damn, whaletail style rear wing. the stock "open" rear wing does little. a "closed" rear wing/spoiler helps cut down "reversion" of the air coming up the rear, and then backwards across the back deck
#7 tires that can take it. dont do this on stock 185's that are old & brittle, low on tread, off balance, etc.
#8 close windows. open windows make for air drag, and if there is a cross wind - it can be unbalanced air-drag
#9 steering rack. a sloppy bushing, bad pre-load & worn pinion gear can make for scary ride. remember these thing where made when 55 was the national speed limit. 70 mph was speeding. our gearing shows that enough - just look at your RPM on the 70 mph freeways.
#10 cradle bushings. the whole drive train, engine & rear suspension is seperated from the body of the car by 4 rubber cushions. replace with poly - or better yet - solid bushings.

Need to increase your toe-in to compensate for more drag pulling the wheels further apart at speed. Also, you need more rigid bushing up front, poly or aluminum, the rubber used by GM deflects more under load.

JazzMan

i got a lot of money if the fiero suspechion aka
aluminum cradle bushings,
new hub berrings front and rear.
sway bars front and rear,
new ball joints all the way around,
polly A arm busshings,
coilovers in the rear and 2" lower springs in the front,
and just had an alinment done, so thats not the problem.

so its not the suspenchion unless its the bump steer.
i am not running z rated tires yet still have stock rims will be upgrading the rims next and low pros might fix some of the problem along with a hood vent.

well, from the sounds of it, and going back and reading your original post - yes - you are feeling the bumpsteer.

at them speeds, and in a wide turn loading up the one side - even with the rear sway bar, that loaded up rear wheel with be moving up & down, and that means it will be doing a little steering of its own. only thing to cut down on bumpsteer is tighter rear suspension. stronger springs, stronger struts.

you should have gotten a printout with your alignment. go and dbl check the rear toe specs. many shops dont realize the rear needs toe settings.

The Rear doing that is due to how a stock fiero rear end is. It's amazing how the squishy rubber mounts amplify at speed.

Wing on the back - improves gas mileage at highway speeds and impresses undereducated ricer kids, it will do nothing else. You have a big heavy chink of iron behind you doing more than any wing could in keeping your tires on the ground.

Vent your hood, and stiffen up your suspension, replace the grocery getter parts with solid parts, a upgraded rear sway bar will help a bit as well.

A bit of professional advice I got from real racing guys, "If racing, you need to make sure your car is in 110% repaired anything less is simply stupid." Those words were told to me by several formula racing guys back in the 80's when I helped in the pit crews at Sebring.

Oh find a local track to race at, It's way more fun.

EDIT: duh.... I mis-read that jazzman basically said this, his post about adjusting the alignment is also very good.

[This message has been edited by timgray (edited 01-21-2008).]

quote Originally posted by 3.6lvvt6spdgt: i got a lot of money if the fiero suspechion aka aluminum cradle bushings, new hub berrings front and rear. sway bars front and rear, new ball joints all the way around, polly A arm busshings, coilovers in the rear and 2" lower springs in the front, and just had an alinment done, so thats not the problem. .

Alignment was done to factory specs, which in turn were derived from the car being driven at normal road speeds. There is play in the suspension, and always will be unless you replaced all pivot points with heim joints. Bushings deflect, period. When the car is in motion there is wheel drag due to road friction. When the wheels drag they push back against various bushings and balljoints in the suspension and tie rods. They deflect. When they deflect the wheels turn outward on each side. The faster you go the more they deflect, basic physics here. So, if it was aligned for 70 mph and you go 120, you're getting more deflection, ergo more toe-out, and that could easily cause wandering.

So, back to what I said. I bet you'll need another 32nd to 16th of toe-in to compensate.

But do what you want.

JazzMan

I like what Timgray said, just to throw that out there. I have decided to NOT speed, it ain't worth it, specially what I saw a couple days ago, this kid was driving a CRX at 115 mph, I was surprised it got that fast, it must of took him like 10 minutes to get to that point, but anyways, he hit what I call a "Mainely Bump" at 115mph and it sent him straight into the woods into a "Mainely Pine" and thats all she wrote, it killed him instantly. So I figured on top of my speeding tickets and that wreck I am not interested in going that fast on the street, if you want to race me, come to the race track and get imbarassed in front of hundreds of people, most people back down pretty quick, so far I have 4 people that want to race me this summer, at the track.

Edit: better tires will improve the stability of the car at higher speeds and increase traction. The stickier the better.

[This message has been edited by craigsfiero2007 (edited 01-21-2008).]

Coming from an ex-street racer, current hot rodder. I have to agree with everyones suggestion about a hood vent.

That is your #1 mod. Get the nose to stay on the ground at high speeds.

I am sorry I did not read this entire thread, I just kinda skimmed it.

50 series tires, or lower are a good mod. I ran 225/50/16's on my 85GT and it was great.
At the very least, poly control arms and cradle mounts.
Pick up a set of cheap poly sway bar bushings. That will also help. (its only about 20bucks and it does make a difference)

Your only real other option is not to not drive at 120+mph. But that's no fun at all. So I say, hood vent and do all the other stuff.

Fiero's can be setup to run stable at 140-150mph. There are several people on this board that have experience doing this. They may not all speak up for fear of being bashed but they are out there.

I don't know if it is still nice or not, but there use to be a great stretch of I-5 from Salem to Aurora that was mostly farmland. (except around Woodburn) that you could run nearly Wide Open late at night, Oh I miss those days. Use to run it in a 76 Merc Capri flat out back in the day.

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85GT 5spd ,93 Eldorado 4.9 Dual O2 Custom Chip, Archie Clutch. Custom Exhaust. MSD Everything 245/50/16's Not Your Average 4.9 Capt Fiero Com --- My Over View Cadero Pics Yellow 88GT 5spd Stock.

OK. Everyone agrees hood vents are good. Now....How do you do this. What is the first step. Where do you put the vents etc.
Thanks

quote Originally posted by Highjumper: OK. Everyone agrees hood vents are good. Now....How do you do this. What is the first step. Where do you put the vents etc. Thanks

many threads on this. the basic answer is, cut 3 lines into the hood, like a "U", and push down. other options is buy one, and cut a hole in the hood to fit. other option is to just plain old buy a hood already done.

First step is to go to 'search' up there on the right hand side, and click on it. Then type in 'hood vents'..select Technical Discussion & Questions in the category, and hit the button!! There is so much guidance and help within this Forum, you can find it ALL easily with this search facility!!
Good luck!!
Nick

OK....we'll do.

as Jazzman said...alignment

daveg

Do the simple math

quote 3.6lvvt6spdgt:... im crusing at 120 ... im still at 4 grand. ... i took the car to 5000rpm in 5th dont know how fast that is? ...

120/4=30 per grand

30x5=150

quote Originally posted by 30+mpg: Do the simple math 120/4=30 per grand 30x5=150

If only it was that easy.

At 5000 rpm he was probably around 127-128mph. Then again he states the front was "floating" so he also had aerodynamic drag on the body. Chances are the speedo is off as well so at 4000 rpm he was probably not really doing 120 mph.

To calculate your speed you need the RPM of the engine, The gear ratio of the gear you are in, The final drive of the transaxle and the tire size.

And at what speeds to you need to start compensating for tire slip? I'm betting at an indicated 125 the actual speed is more like 121 or 122. Only good way is either with radar (internal or external) or time traps.

JazzMan

What engine's in the car? Stock 2.hate won't turn 5K in 5th...

nice combo......planted on the road @160mph

Poly everything helps as well

quote Originally posted by Capt Fiero: Fiero's can be setup to run stable at 140-150mph. There are several people on this board that have experience doing this. They may not all speak up for fear of being bashed but they are out there.

I'm not worried about someone bashing me and I'm sure others feel the same way. It really boils down to not knowing the driver or his car, and every detail about it. so that you could make confident suggestions, or tell them they're crazy !!!

At the speed you mention in your quote, there are many risks. I've taken my car above that level, and thankfully nothing happened. But I will tell you that I don't plan to improve upon it unless I go to the Salt Flats (no other cars, critters, trees, un-even terrain, etc), and that's not likely to happen.

Do I recommend anyone pushing the top speed of their car, Nope ! It's a personal choice. You can only hope they did their homework.

I crack the 120 mph all the time. I would say about 2 or 3 times a week. Snow, ice, rain, I don't care. I am old and have been driving this way since the mid 80's

My 2 88 GT's get a bit light at high speed and I plan to install the f body door vents under the hood to vent into the wheel wells as described in a previous thread. My 85 SE 3.4 turbo is my fastest car but does not have the high speed instability. It has darrell's(now Held) slalom front suspension and an 88 rear with coil overs all around. I have the nose quite a bit lower than the rear. It has the stock notchie front and luggage rack on the rear. Front bar is 1.25" Herb Adam's with rod ends and the rear is a 1" Addco. Poly bushings or spherical bushings all around. 12" Wilwoods at each corner for brakes. Stable and fast but not a great daily driver. Tires are Goodyear Eagle F1's on all my cars. My newest 88 GT is getting an LS4, I bought stiffer shorter front springs for this one.

Hello All,

Just thought I'd chime in with an ACTUAL piece of info on front end lift in the Fiero. This piece comes from the "PONTIAC FIERO Technical Analysis" that appeared in Road & Track in 1983 (note the ALL CAPS SECOND PARAGRAPH):

"Aerodynamics may not have been a high priority consideration in the original Fiero design. With a relatively low weight and small frontal area (by American standards), good EPA mileage figures were possible without going for the ultimate in low drag coefficient. The reported Cx is 0.377, which is not bad for such a short car, but not too strong an advertising point either. The obvious problem is the notchback rear window, which is almost a necessary evil in a mid-engine car. Although it allows easy engine access
and ventilation, it really disturbs the upper air flow and increases drag while reducing potential down force from any rear spoiler.

THE FIERO'S OTHER PROBLEM IS THE NOSE-UP LEADING EDGE OF THE FRONT BUMPER. THIS DESIGN ALLOWS A GOOD OPEN ANGLE AND RADIATOR INLET, BUT IT ALSO RAMS A LOT OF AIR DOWN UNDER THE NOSE. NOT ONLY DOES THIS USUALLY INCREASE DRAG, BUT IT ALSO GENERATES A LOT OF LIFT, IN SPITE OF THE BOTTOM-BREATHER RADIATOR INLET. REPORTED FRONT LIFT FIGURES WERE ABOUT 120 LB AT 100 MPH, WHICH CAN BE SIGNIFICANT WHEN THE STATIC FRONT WEIGHT IS JUST OVER 1100 LB.

It also appears that the opened headlight buckets were not as well researched in the wind tunnel as the Corvette's, as they raise the Cx to 0.417. Be that as it may, the pop-off plastic body panel concept means that better aerodynamics can be incorporated easily in the future.

I'm posting this in a separate thread for easy searching in the future since it seems to come up a lot.

-Gary