I have a 96 Formula automatic and have a question about the top speed in it. I have been seeing lots of people having pretty high top speeds but mine doesn't seem to get close to what I see. As far as I know it has 2.73s but the highest top speed I've hit is 138 mph. My friend has a z28 just the same and has done 155 plus several times. Does anyone have any idea as to why I can't get over 138? When I get to that speed my car tries to shift at 5500 RPM's but has no gears left to go to. Any ideas would be appreciated.

Thanks,
Aron

 

Do you possibly need a tuneup? Also are you running in 3rd gear your on OD? When I start getting to speeds above 130 my car keeps wanting to downshift to pull harder but then wants to shift back into OD cause I'm getting close to redline. Speed limited cars have the limiter set at 110mph I think, maybe 120mph. I doubt you have that problem though. Any other things like T-tops off,windows down,etc. I know they're obvious but sometimes you don't think of that stuff.

 

I think it's in need of a tune up now, but wasn't when I was seeing how fast it would go. I was in OD with the windows up and everything. I've done it several times and each time it did the same thing. It's making me think someone might have put a set of gears in the car, but I don't know what gears. I really don't want to pull the cover off to find out but I may have to, out of curiousity. In the 1/4 I went 14.0 but my launch was awful and the car was overheating, due to the waterpump going out. My dad told me when I ran to keep it in third cause I probably would need any more than that, but it needed to shift close to the end. Don't know if that might give any clues to anyone. I haven't driven any other f-bod with the 2.73 so I don't know what the 2.73 feels like. I always assumed that's what mine had.

Thanks,
Aron

 

if your car is stock and the gears hasnt been changed, with 2.73 gears you should not have a 1st gear selection, if it starts at 2, then it would have came stock with 2.73. now with my 3.23 I top out of 3rd gear at about 120mph or so. So maybe with the 2.73 gears you're topping out of 3rd at 138 or so due to the smaller gear ratio. Is your car shifting into 4th? maybe its not and you're topping out 3rd and not shifting to 4th. could be your 3-4 clutches are toast a bit.

 

If you have 2.73s, at 80mph, you'll be doing 1,996 RPM's in overdrive. You can always jack the rear of the car up, and see how many times the driveshaft turns per each time the rear wheels turn.

 

I know it shifts into fourth. I know that it doesn't have the indicator for 1st but it will shift into first. So there is no stop on it anymore, not sure if someone slammed it back or pulled it out. I'll probably try jacking it up then and see, cause I'm curious as hell now. I had been thinking about doing gears on the car but now am curious if someone has already beat me to it.

Thanks,
Aron

 

Having first gear selection on a car that doesn't come with it is just a matter of popping off the shifter plate and snapping off the plastic tab that prevents it from going into 1st.

 

I know that's all it takes, I'm just not sure if they bothered doing more to the car when they did that. Everything is stock so far, but they could have changed it all back before they traded it in. It sure makes me curious. My dad thought it might have had a shift kit put in it but I don't know. I don't know of anyway of telling what has really been done by the previous owner.

Thanks,
Aron

 

Last time I tried my car i think the best i could get was close to 135mph. I was kinda bummed but I realize that this car just doesn't have the power to get up there. I used to have a 99 Formula M6 with a few mods and that car would bury the speedo no problem. 150 mph was like hitting 100 in this car. But I'm installing Jet-hot LTs, losing the cats, doing a tune-up, and changing all the fluids. I'm hoping that will get me to at least 150.

 

ummm LT1s can bury the speedo at 155 stock.

 

If I'm checking the gear ratio by spinning the tires while it's jacked up, how do I convert the numbers? Is it the same ratio as the gears, like 1 wheel turn equals 2.73 driveshaft rotations if it's 2.73s or is it different? I would assume it's the way I said, but I'm unsure. Would a shift kit change the top speed or no? That's what my dad thinks it is, but I don't seem to believe that would change anything but how hard it slams me into my seat.

Thanks,
Aron

 

here fiddle with this, maybe it'll help.

http://www.f-body.org/gears/


wait, nevermind, it wont

 

So how do I go about checking the gears while it's in the air. Is the driveshaft to wheel ratio the same as the gears or will it be different?

Thanks,
Aron

 

Right on.

Get it in the air in nuetral and count the turns of the driveshaft while someone watches the wheels. Unless your posi is absolutely blown it should be straightforward. If your posi was compeletly blow out it wouldn't work out so easily because the spider gears would allow the wheels to turn differently and screw everything up, but you probably don't have to worry about that especially with no load.

-brent

 

While the car is in the air, take some tape, or chalk and mark the bottom of the drive shaft and mark the bottom of one of the rear tires. Then rotate the tire one complete turn, and count how many times the driveshaft turns. if it turns 2 3/4 turns you have 2.73s, and so on....