1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

FB aerodynamics at high speed

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Old 09-02-03, 10:15 PM
  #26  
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I've seen 130 before my airdam and 120ish after... I'd have to say that the after felt much much smoother.
Old 09-03-03, 08:37 AM
  #27  
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As for the Boneville record setter:
I know it's modified with smaller wheels etc, but the point is: it is a bone stock body. That "spoiler" in front doesn't look much different then the one's all stock SA's have overhere?
Most of the guys who describe unstable cars at high speeds agree on having a "not so good steering", can you blame the shape for that???
If you really have a modded FB (if it's stock and you experience high speed troubles your car is crap) that gets unstable above certain speeds (higher then maximum speeds for a stock one) an airdam, and maybe a well choosen rear wing might help.
More wings/airdams/spoilers should lower your top speed (as Pratch also says) if it doesn't, your wing isn't doing it's job... Probable the airdam can get some of the play in the steering wheel (and resulting "lightness") hidden, by putting some more force on the front wheels. But a good steering system probable could have done the same.
As for those who have a problem with the rear of the car: I never experienced that. Not with the stock 1984 (12A, no GSL-SE's in Belgium), and not with the modified 1982 Mariah (mods as described below). Maybe this really was a suspension problem, or a bad design/positioned rear wing?
I know of a guy who has a TII 250hp engine and gearbox in his (German) FB. The car has an entire FC front end welded in (so with steering and suspension) but remained FB bodied (a lot of work). He obviously drives that car "slightly" faster then most FB's, yet has a stock body, no wings!
Old 09-03-03, 10:11 AM
  #28  
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rotary emotions any way you can get pics of this car?the only rear end problems I had with my car was after the body kit and rear tail the springs then became to soft and the downforce caused a little tire rub on the fenders. I still haven't changed the springs but tires are now 245/50 15 and do not have the same proximity to the rear fenders. with the body kit the car was stuck to the road no front end lift. only problem at speed before or after body kit was the weak steering. that is soon to be fixed though. after the new paint.
Old 09-03-03, 01:50 PM
  #29  
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if you mean the TII FB, yep there are a few.
unfortunatly the builders site (pics of the construction work) is no longer available.
Some good pics are here: http://www.rx-7club.ch/pages/galerie_RX7_SA_1.htm
It's the yellow car (the red one is mine), as you can see it has slightly wider track.
http://www.rx-7club.ch/pages/galerie_members_13.htm
Again, that yellow car, now a bit newer pics, and also an engine bay shot.
Old 09-03-03, 01:57 PM
  #30  
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I have gone about 120ish in my 85 bone stock body. Only different thing to aerodynamics was teh 16 inch wheels. I can tell you this, the thing felt like we were going 60 it was so smooth. I haven't gone above that so i can't say whether it would feel that way at higher speeds, but i do know that at 120 the car feels smooth and great.

Zachstylez
Old 09-03-03, 02:36 PM
  #31  
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that yellow rx7, what kind of fender flares does he have? they're very subtle but PERFECT!
Old 09-04-03, 07:59 AM
  #32  
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The car hasn't got fender flares as such, but flared fenders instead. Before you say I'm crazy , this is what I mean: the whole car is a custom creation, and the fenders are modified stock. They are the normal fenders, bend, twisted, welded etc, to look like this. So you cannot buy these flares.
The car has been a project to show how far one can go in modifiying the FB. It also has FC brakes all-round, and five-lug wheels. It's almost an FC with a FB body...
For those who looked carefully: yep, strut towers are FC... So is subframe, etc.
Old 09-04-03, 10:22 AM
  #33  
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I had my old SE to an indicated 125-ish once... my problem wasn't with the front... the rear of the car is what got light... I think the '84-'85 cars didn't experience the front end packing up with air as badly because of the brake vents cut in the lower corners of the front spoiler... And acutally, yes.. you can attribute poor steering at higher speeds to the cars design.. in stock form, it's similar to an airplane wing in design and WILL unload the front suspension some...

--Danny
Old 09-04-03, 10:46 AM
  #34  
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Of course that's true, but I doubt the effect of that in real life. I believe the stock FB will never experience that problem.
Imagine you drive a brand new FB, and drive maximum speed. Well, I believe in that condition, the "airplane wing" effect will be minimal. And how often do you drive at those speeds??? Personally, I rather regulary drive 100mph and over, since I go to Germany rather often, and there are no speed limits there. But most of us won't drive their cars often at speeds around 120-130mph, will they?
I think an airdam (and only a good design) will become a good idea only for seriously modified cars, capable of speeds exceeding stock top speed with many mph, and also driven that hard often.
As long as you stay under that 110mph, you'll never get into trouble. Unless your car isn't setup properly, of course, but that's another discussion.
Old 09-04-03, 01:11 PM
  #35  
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I got clocked at 151 in a 65.


http://www.centralillinoisimports.org/images/chef
Old 09-04-03, 08:19 PM
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Speeds over 100 on the track used to feel a little funny in my FB... Then I got a Mazda Motorsports front airdam for it. MUCH BETTER... front end feels firmly glued down..

Dan
Old 09-04-03, 11:16 PM
  #37  
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front end gets light above 80mph. added a pacific ground effects fiberglass airdam and it really sucked the front end down, no more wandering.

that dam broke on the u-haul trailer and a locak rotary "expert" tapped the curb with it. so now I have a urethane one, by Xenon, same as the one from Victoria British and carparts.com. did 120 in turn 8 @ willow springs raceway on memorial weekend. felt pretty damn solid then!!!!!
Old 09-05-03, 12:21 PM
  #38  
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Drivefast 7, can you please post a pic of your car with the new airdam. I looked at the one on carpart.com but it is kinda hard to see what it would look like on the car.
Old 09-05-03, 02:23 PM
  #39  
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That small lip was also on the SA's over here.

Funny, I've had my SA up to about 5800 in 5th gear (you do math) and it was rock stable.

Steering play? What's that? SA didn't have any.

I wonder how many people who say their cars wander and and nightmares at high speeds, have loose bushings, balljoints, or tie rod ends, or if their cars have been aligned every 6 to 12 months like you are supposed to do. A proper alignment, even to factory spec, can make a world of difference.

edit: Also ride height. Lowering the car does some things to the center of gravity - to - roll center relationship that are just not groovy for stability - in a nutshell, it makes the front roll stiffness softer and the rear roll stiffness stronger. This is bad, it makes the rear end less stable than the front and in extreme cases the inside rear tire picks up off the ground. Even worse, the rear stiffness changes more drastically with relatively small suspension motions the lower you go, so the "feel" of the car is constantly changing as the suspension moves. (SA was not lowered and wasn't sagged either.)


Last edited by peejay; 09-05-03 at 02:30 PM.
Old 09-06-03, 11:09 AM
  #40  
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okay, im pretty new here, but i just got an 82 gs(i think) and the speedo reads only to 85mph. is that how fast the car goes or is it capable of more than that? the car is still stock. i dont know what to do with it yet.
Old 09-06-03, 08:07 PM
  #41  
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The FB body styling seems to handel the speed great to me. Obviously, a little downpressure from an airdam of some kind will help the stability at highspeeds, as will a small fin or spoiler.

Mine's only seen 110, so I don't have as much experience as the rst of you, but I DO live in PA haha.
Old 09-07-03, 10:14 AM
  #42  
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Would power steering help

Did FB power steering option work better than the recirculating ball? If so, would it make sense to switch to the PS design?
Old 09-07-03, 04:59 PM
  #43  
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Originally posted by oni-dori
okay, im pretty new here, but i just got an 82 gs(i think) and the speedo reads only to 85mph. is that how fast the car goes or is it capable of more than that? the car is still stock. i dont know what to do with it yet.
It'll go LOTS faster than that. I have my 85 Base model with badly clogged cats up to 140km/h (about 85mph) routinely, without pushing it at all...
Old 09-07-03, 05:01 PM
  #44  
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Re: Would power steering help

Originally posted by TexasGunRunner
Did FB power steering option work better than the recirculating ball? If so, would it make sense to switch to the PS design?
The PS system is still a recirculating ball.
The only real benifit is that it's a much better turning ratio, I think about 1 whole turn of the wheel less, if I remeber correctly.
Old 09-07-03, 06:02 PM
  #45  
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My streetcar's front end did get light above 80 or so when it had just ancient stock suspension. With it redone and with the ST springs its a bit better. My IT7 car is rock stable even at 140mph, and I dont even run an airdam on it. It is lowered and has mongo stiff springs in it.
Old 09-07-03, 06:13 PM
  #46  
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3 turns lock to lock vs. 4 turns lock to lock, power vs. non.

My SA had an 85mph speedometer. It would peg before getting through 3rd gear.
Old 09-08-03, 08:19 AM
  #47  
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Hmm, My SA had the 130 mph speedo, why would they use two different speedometers or was it because of the 79 was really a 78 issue?
Old 09-08-03, 08:56 AM
  #48  
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The change came about in mid 1980. I have seen some '80s with the 130mph unit, mine had the '85.

So there are two 85mph speedos... one pukey orange (FB) and one cool legible green (SA).
Old 09-08-03, 01:21 PM
  #49  
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Originally posted by peejay
The change came about in mid 1980. I have seen some '80s with the 130mph unit, mine had the '85.

So there are two 85mph speedos... one pukey orange (FB) and one cool legible green (SA).
yea i got the pukey orange 85mph speedo...
Old 09-08-03, 02:08 PM
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so what you guys are telling me, is that my 1st gen can fly?


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