Headlights still popping up

[GoFast85]

The lights would pop up at 160 kph so I installed the front grills a few weeks ago. Now they pop up at 190 kph. I see that the PACE car in 1984 averaged 163 mph and I assume that the headlights were not up. Any ideas on how to keep them from jumping up? Now, no smart alec remarks from the peanut gallery.

[fiero308]

the Pace Car avg'd 163 MILES per hour?!?!?!  Wow.  That is a 4 cyl, isn't it?
I assume you have checked out Pennocks diligently.....?  Pretty good resource as you are well aware; just kinda slow right now (summer doldrums).   And obviously (judging by the speeds you mention) you have booked lots of time at a track somewhere, right Brian?

 

[GoFast85]

Reading the "Fiero Focus May/June issue by The Northern Illinois Fiero Enthusiasts magazine states that Rick Mears did 163.612 mph and won his second Indy 500. Yep a 2.5 little Iron Duke.
Would like to get info on the car to see if it was changed radically from stock airodynamics wings/lowered etc.

[Gizmo]

Other than putting more tension on the springs and cutting more speed holes....I seem to remember this working for those that have tried it.  Should be able to whip that up in about 5 minutes, check it out.

http://www.westcoastfiero.com/ultimate_upgrades/ultimate_upgrades.html

[GoFast85]

Yep that was on the forum. The cable will hold the covers down, but would like to keep the front of the car down as well. The popup is an excellent early warning system if I could get it to be delayed for a few mph longer.

[aaron88]

Here’s the kink in your plan.  The faster the car is going the more force there will be on the cover coming up.  If you already lost one you are likely to do worse damage at higher speeds.  First you want to stop your light from coming up, then fix the other problem.

If you want an early warning sign you could attach that mechanism so that it was a little loose.  That way your headlight would only pop half an inch or so, but not enough to get serious wind force on it.  That way you have your warning sign and you can keep your covers if they pop at 160 mph.

Aaron

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[fiero308]

I wonder if "early warning sign" is an appropriate name anymore.... it might be more aptly called a "too late" warning sign...... at 190 kph......!!!?? (Interestingly, that works out to about 189 FEET per second...)  Good brake test speed...

 And possibly aerodynamics plays more of a part than you (we) realize at that speed. 
You are possibly at a speed there that you would break them off even if they did open 'under control'....... so to speak.  I doubt you would be doing that speed at nite or in poor visibility conditions, but still,.... you may consider a 'headlite door lock' to make SURE they won't open at that speed.  A solenoid actuated latch that you could interlock to your headlite circuit thru a relay..... or a separate switch... etc.
Just a thought.

[2ML67]

Oh no here comes the peanut gallery saying smarten the f#$k up before you kill some one. I too like speed but there is a place and a time for it. Its one thing to test the limits of your car but another do do it all the time. You know like in traffic on roads used by others. I tested my car on a barely used road in the middle of the night. See I feel I have the right to risk my own neck, not others. Dan   

[2ML67]

If I remember correctly didn't the true Indy pace car Fiero's have the 2.5l SD engine which was very different from the stock 2.5l. Also need to remember the car was new not 20 years old and how many times the lights have come up and down since then weakening the springs. Dan

[GoFast85]

I guess that what I am getting at, is that I could pin the covers down (say at the track just before the speed trials). My real concern is that if there is enough force to lift the light covers at a speed of 100 mph and the car areodynamically, is capable of a sustained average speed of 163 mph WHAT IS KEEPING THE FRONT END DOWN at 160?. 

[fiero308]

wear big heavy shoes.  It's gotta help.......

You are right to be concerned, Brian.  Just for fun I looked into a couple of items that might be of interest.

maybe the car was lowered?  and a front air dam? Brake ducts? The rear raised a bit in relation to the front?  (poor man's ground effects)  Both reduce the amount of air that gets under the car.  Also is there any reason to think it was NOT specially prepped?  ie do you know for a fact that it was box stock?  They may have done things "out of sight" to help 'channel' air flows and to release air from underneath. 

However, having said that, I recall a bit about the Ford GT40 having similar probs at  similar speeds (I would guess); they made some changes to front hood scoops and venting and almost lost the cars due to increased instability caused by airflows at that speed.  And, just for interest, a fully loaded Boeing 747-300 (at something over 750,000 lbs )will lift off at about 180 kph.  Air pressure pushes it up off the ground at that speed.  So if you are thinking of driving at 190 kph (are you?) think about the ...excitement.... if you get even a BIT too much air under your 2900 lb car......
so it is a real concern, yup.

[GoFast85]

Lowering of the car would help no doubt, but the air is still being channelled through the rad and pushing up on front hood and in effect lifting the car.  Interesting analogy of the 737, though. Ever hold a piece of plywood flat in a 15 mph wind then turn it sideways. The cutting effect of the wind to a flat surface. The take-off lift that you speak of is called "ground effect" (and yeah, I really do have a pilots licience.)   Had my bike up to 134 mph (230+kph) but did not have to worry about air under the machine.  I heard of a fellow that was clocked in a fiero at 144 mph in Utah (before the speed limits) and the helicopter stopped him and just checked to make sure that he had Z rated tires.

[2ML67]

I am so happy to hear that these speeds are being achieved solely on the track and not on the streets, after all you know how much people are against street racing and speeding these days, wouldn't want to give Fiero's a bad name now. The track Indy is very rare with the SD engine and remember it had the Aero nose which other 84's did not have so it would be safe to assume that a lot of non stock changes were made to achieve those speeds.
I know from my experience on 70's Trans Ams there is quite a bit that can be done to help with aerodynamics of a car, just a matter of how much you want to spend and how stock you wish to keep the appearance of the car. For instance that ugly black wing that was on my Fiero was fully functional and adjustable which when set up to create lift on the rear it can be used to help keep front down. Using laws of physics if the rear where the weight is is trying to lift it will force the front end down. Only draw back is that if certain speeds are obtained it can turn on you and lift the entire car. Dan