Why do this happen, Is it the engine braking the wheels or what?

Engine tourque changes when accelerating , sudden weight shift changes a bit more deflection in those rubber AArm mounts, a gust of WIND! all this and much much more conspire to try and make you a smudge mark on a guardrail somewhere.
Not to mention the dreaded "bump stear" even thow you didnt hit a bump the weight xfer will make it feel like you did.

When I am running a off ramp hard and suddenly lift the throttle, the car looses a lot of the understeer that I get when I am in the throttle. You can actually point the car differently by getting on or off the gas in a hard turn.

Does this describe what you are asking?

------------------
Bob
2 - 87 GT's
85 SE 4 cyl

The dreaded "drop-throttle oversteer" in Fieros, Toyota MR2's, and Bertone X1/9 (nee Fiat X1/9) was described in detail in "Road and Track" for August 1985. See if your local library has a back issue.

Stated briefly, and quoting, "... the drop-throttle maneuver simultaneously and quickly increases slip angles of the rear tires while diminishing those up front."

That means if you're cornering hard and all of a sudden let off the gas (drop the throttle), the back end will become the front (oversteer) and lead you into the beyond.

Fiero throttle steer differently than Camaros with lotsa balls. In a Camaro, a heavy foot will give you oversteer, while in a Fiero, a heavy foot will give you understeer, but not to the same degree that a Camaro will give you oversteer. If you get into oversteer in a Camaro, you can straighten the car out by lifting off the gas. If you get into a power-understeer in a Fiero, lifting off the gas transfers weight from the rear wheels to the front wheels, increasing their grip. The consequence of this is that the front end tucks in and the car goes into an oversteer attitude. Once the car gets going, the give in the soft cradle and suspension bushings lets the back end come around further than it should and possibly spin the car.
Early 911's do the same thing, from what I hear.

but for the PITA it sounds like it can actually provide for some awesome driving. There's one ramp I take to get on the interstate every day, it's on a steep down hill, but the ramp is inclined, and the initial turn is extremely steep, but slightly banked, anyways, I can come into the corner at arround 35-40, ride the breaks hard so the front wheel are locked onto the corner, that takes my speed down to 30 but then 1/2 way threw that corner, I jam the gas and the rear end will catch and I'll be well over the speed limit by the time I hit I-95. Most people take that corner arround 15-20, my friend with a hoped up mustang almost wrecked it going shy of 30.

Just takes some practice to get used too.

slammed fiero can give some insite in this, Porsche 911's are wicked at this. let off the gas fast in a corner, and your backwards before you can blink your eyes. Its controlable if you know how and when its going to react. I almost always slow before a curve or during the very first point or apex, then accelerate out of the turn, using throttle to control the car thru the turn. If you do it right, youll need very little if any steering wheel imput to negotiate the curve.

[This message has been edited by rogergarrison (edited 05-02-2001).]

get the Grand Prix Legends sim by papyrus-sierra free down loads of demo game on the net do a search 100's of sites for gpl out there.[HotGrid's Ultimate GPL Linkspage]
this the most real driver sim ever and is not a game it is free drivers school for mid-eng cars and the snap on lifting the throttle
is in the model cars many real moves.
ALL FIERO DRIVERS SHOULD GET THIS SIM.

question wonder and stay wierd ray

A well set up fiero will not exhibit this trait. The fiero's rear suspension is soft ,that in combination with a mid mounted motor that is a tad bit on the heavy side creates quite a bit of enertia (sp?)upon "trailing throttle oversteer conditions" The secret to getting a Fiero suspension to work on a budget is to stiffen up the rear end. My car does not move an inch when a person who is 200lbs puts there full body weight on the rear of the car. Trailing throttle oversteer is a scary thing , and even the best of drivers can be bitten fairly easy. Burning out an offramp at the limits of the tires , then lifting off to regain the proper apex will surely end in disaster. I have run a few 911's , older Pre c2 cars exhibit the same traits to a lesser degree (like comparing a scalple and an axe) the later C2 911's have a much slower transition from under to oversteer in stock form. Most manufacturers set up cars so that they have a certian degree of understeer in them, this keeps joe blow with more money than brains out of trouble. It's hard to drive a Fiero with the Torque , wide rear tires combined with all your weight being over the drive wheels make the car stick very well on the rear , thus resulting in understeer worse than a snow plow. But for the most part it keeps people out of trouble. My car is currently set up so it is nearly neutral. I can dial out the understeer completley but at high speeds I would rather have understeer to a minimal degree than neck snapping oversteer. I'm still new to racing (started in cars at 16 , now 23) So I know my limits. Another problem is a short wheel base. Get a front engined car with a longer wheel base (ie Corvette) and you can drive it all day long with the rear wheels. The fiero , porsche and most mid/ rear engine cars require quite a bit of skill to drive fast. There is not enough torque to get the driver out of trouble. Loose your line in a c4-c5 corvette , just plant your foot and steer with the rear. It's not the fastest way around a track/ autocross course , but there's nothing worse than getting off line in an autocross due to understeer , getting set up again for the next gate and get back on the throttle. Espically in a Fiero that seems to need better gear spacing for it's 2.8ltr V6. Thus a skillful driver is required.

The 911 acts much like a Fiero , Go into a corner too hot you can turn and lift , again not the fastest way , but develop your driving skill and it can be an asset when you get into trouble on the track or autocross. It's like pulling the Ebrake. It can also be very scary. Some people attempt to dial out the understeer with larger rear tires , this works to a certian degree. I learned the hard way the a Fiero does not work well with equal size tires all around. Too much weight in the rear. I run 255/40/17's in the rear and 225/45's up front , it makes it easy to slide the car without fear of any adverse conditions, as well it makes transitions from understeer to oversteer almost non existant (neutral).

I can remember an event last summer where I had no access to a set of tires to "Burn off" , So I ran a 225/50/15 on the front , and a 215/60/15 on the rear. It caused the exact opposite problem to what a fiero normally displays. The car oversteered with minimal throttle input and was scary.

After about 10 laps @ speeds up to 110mph I shut it down , there is no fun in driving hard with white nuckles in an unpredicatable car. About a month later I got the aforementioned 17's. At the first autocross event My dad turned Fastest time of the day , In a Fiero. I have those results up on the fridge. Personally I have a bit of an advantage since I have had lots of seat time in a C2 911 and a Corvair. But still , perfect practice makes perfect. I had a One lap of america winner (Marc Guimont winner 2 years ago in SUV class) drive my car at the last autocross of the seaon. He loved the car , and drove it 1.5 sec faster than I did , beating the MR2's at the event..he hated the brakes.

Just goes to show a Fiero can be made into a really well handling car , not just the oppinion of a Fiero-phile. Many times I have come out saturday morning to find Both the 911 and vette sitting in the garage, and the fiero gone. According to my dad it's just more fun to drive.

I invite anyone who wants to to join the Fiero racing list. It's a good group of people , lots of engineers , rally Fiero's autocrossers , ect. It takes a lot of the Guess work out of making a Fiero handle , which seems to be a mystery due to the lack of Fiero's in Motorsports. I wish at Fiero shows they would hold autocrosses, they do at Corvair conventions , Ever seen a Greenbrier Corvair Van on three wheels?

this also helps to get it out of your system , I'm 23 and won't lie when I say I street race on occasion , but this gets all that teenage / midlife angst out in a legal way. Plus it's very addictive.

Jonathan McCreery
86 GT

[This message has been edited by Slammed Fiero (edited 05-02-2001).]

Thanks Slammed, for some excellent info.

Wade

quote Originally posted by Slammed Fiero: A well set up fiero will not exhibit this trait. The fiero's rear suspension is soft ,that in combination with a mid mounted motor that is a tad bit on the heavy side creates quite a bit of enertia (sp?)upon "trailing throttle oversteer conditions" The secret to getting a Fiero suspension to work on a budget is to stiffen up the rear end. My car does not move an inch when a person who is 200lbs puts there full body weight on the rear of the car.

Slammed
Damn! 200lbs! you must feel sand grains as you run them over!

In your opinion how would you rate a Fiero as far as setup ability?
From the eye of someone who know very little about car setup it would seem the the Fiero has quite alot of adjustments that can be made unlike most other cars.
Again I'm not much of a race driver either but the Fiero has a feel unlike anything I've ever driven and I like it! I do things in my 88 that I would never concider in anything else america has built or even my 84 for that matter (she gets quite edgey in those tight corners) the 88 can handle much more than my old 79 camaro with a poly rancho stiffend this and fatter that suspension under it (still sloppy compaired to even my 84 Fiero)

I found this link for those who are interested has ALOT of handling info
http://fiero2m4.homestead.com/Handling.html

Fiero racing list? where is this?? I gotta know!

[This message has been edited by 84Bill (edited 05-02-2001).]

I've never experienced "trailing throttle oversteer conditions" in a Fiero. Many years ago I used to be into 280z's and experienced it once very violently at 110 on a San Diego freeway interchange ramp. But I also had bad tires and there was a pavement transition. It sounds like slammed Fiero knows what he's talking about, but I have never experienced my Fieros wanting to swap ends and I have pushed them. I have experienced understeer, especially at slow speeds, with bad tires, or poor pavement (traction) conditions. That's one axiom that stock car drivers have told me is to put your foot in it when the ass end starts to come around, but with the Fiero it has never shown me that inclination.

Fiero Racing list is at www.groups.yahoo.com

There was a (highly modified and gutted) Corvair at the autoX here sunday before last. He turned in 2nd FTD behind the SAE Formula car and in front of a Saab Soneat(sp?). Now that's a weird car.

What class would Fiero w/ Northstar be in for AutoX or road racing?

I have aluminum cradle bushings in my '87 GT and they have made the rear end much more tractable, even though my struts are worn out.

Thank you for the information Slammed, and all of you that have replied so far.

A Fiero with a northstar would not be worth the money to build as a competitive Autocross car. The N* motor weighs 464lbs , the tranny weighs 300lbs , generally a GT with a N* weighs in at about 3000-3100lbs , too heavy for E mod , which is the class it would run in at SCCA events, to be competitive it should be half the weight.

The corvair pic I posted above weighed in at 2040 at it's career lightest , I know former autocrosser george ryan had a Fiero with a manapart 238hp Quad 4 the car came in at 1900lbs. That car was "swiss Cheesed" The corvair at 2040 had fiberglass hoods , no interior , basically gutted short of the point of no return. It now takes up street duty as a weekend crusier.

most cars running in Emod (engine swap class) are Light , have small displacement high HP motors , in a small chassis. Lotus super 7 with a rotary motor weighs 1060lbs!

I'm hoping to go the N* route , should work well for lapping events (N* doesn't mind being run hard as Chris moore has shown us) and the occasional autocross. I don't think I would sink a ton of money into a Fiero hoping it came out a FTD contender in a competitive crowd, this is more for my own personal enjoyment

As for the Corvair , I know what it's like to drive a fast well handling corvair , the cars are very forgiving , Built right the motrs have a powerband like a 911 Porsche. last time I drove ours in autocross trim was about 2 years ago. The only thing that stopped me from going faster was that I couldn't steer the car fast enough , plant your foot up a autocross section of cones and the car is glued to the road , easier to control in hard situations due to the long wheelbase , harder to manuver on a tight course for the same reason.

JM

How much the TDC3.4 weigh?

I think the 3.4TDC is heavy too , it's not the block that makes them heavy , it's the valvetrain & heads. In the N*'s case it weighs around 60lbs less than a comprable SBC , but the tranny weighs probably 3 times that of a Fiero tranny
http://www.241computers.com/ford/eweight.html

here is a list of engine weights. It says the 2.8 3.1 motors weigh in at 350lbs , not sure if thats iron or aluminum head. The 3.4TDC is based on the 60 degree motor.

JM

quote Originally posted by Slammed Fiero: I think the 3.4TDC is heavy too , it's not the block that makes them heavy , it's the valvetrain & heads. In the N*'s case it weighs around 60lbs less than a comprable SBC , but the tranny weighs probably 3 times that of a Fiero tranny http://www.241computers.com/ford/eweight.html here is a list of engine weights. It says the 2.8 3.1 motors weigh in at 350lbs , not sure if thats iron or aluminum head. The 3.4TDC is based on the 60 degree motor. JM

The 350 sounds like a short block weight. Sanity check: and iron block water cooled V6 is only 50 lbs heavier than the corvair air cooled F6?
A Northstar shortblock weighs 345 lbs or so, and the 2.8 is WAY heavier than that.
Thanks for that link. They have the weight of the Triumph V8 I've been wondering about.

One thing I'm not going to do is use the Cadillac transmission with my Northstar.

It seems like racing rules are set at odds with hot rodding philosophy: the first thing a hot rodder does (bigger engine) is the last thing a racer does.

How's Team Python doing with their E-mod 4.9 car?

I wasn't sure on the weight of the N* motor. I can vouch for 2 of the weights on the list. Our flat 6 corvair motor with tripple webers weighed in at 307lbs , our all aluminum 3.5ltr olds V8 weighed in at 323lbs. Same as the Triumph/ rover / olds/buick motor.

As for using the caddy transmission , reguardless of it's weight , I don't blame you , it's a bulletproof setup.

My plan is a N* for weekends and shows , then a 4.9 in an 84 that looks stock with quiet exhaust to mess with peoples heads. I believe Team python blew the getrag in their car while some people may question the strength of the Getrag , Team python runs MONSTER slicks on the car. I have blown trannies before in the corvair for the same reason.. Big slicks= no wheel spin = tons of driveline stress. Both vairs run c4 corvette axles.

The one member of team python bought George Ryans Q4 car I have mentioned a few times on the forum

JM

According to that site, the iron duke weighs as much as the 2.8 does. Hmmmm.....

Slammedfiero: What the hell do you do for a living to afford all the cool toys?!