It's an '89 Iroc 350ci with a 700R4 trans. Running on the stock suspension and 2.77:1 ratio in the 9-bolt rear. To launch, I have heard to bring the RPM's up to about 1000 and just nail it. But doing that I just spin like crazy and get wheel hop. I tried this at the track last year and was pulling 2.2? to 2.3? 60ft times on street Goodyear Eagle GSC-Z rated tires with real good tread. It has only basic bolt ons like headers and catback, ported plenum, and some ignition work, so its stock. I was running in 90 degree heat and pulled a 14.2 at 99.4MPH. I did notice that I was running out of RPM's at the end of the 1/4 and had to pull out before hitting redline on every run. That can NOT be right with 2.77 gears!!!Is it possible that I am spinning to much and losing most if not all of 1st gear? How should I launch? I was thinking bring the RPM's up to 1000 and slowly bring the gas to the floor till it gets going and then just hit it the rest of the way.... How does everyone here launch with an auto????

Thanks!!!

 

Try running a few times and you'll see a difference, everyone thinks you can just nail the gas and you'll go faster, that isn't always true, especially in your case, spinning thru first gear and having wheel hop seriously hurts your 1/4 time, you'll have to find the best way to accelerate. I would recommend getting the G-Tech, it can really help you adjust the way you accelerate.

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'86 IROC
T-TOPS, TINTED WINDOWS, BRAKE LIGHT BLACKOUTS
GM GOODWRENCH 350
EDELBROCK TES HEADERS
FLOWMASTER, NO CAT
EDELBROCK 600CFM CARB.
KN AIRFILTER
ACCEL HEI DISTRIBUTOR
160* Stat
2:73 GEARS
Rebuilt 700R4, with manual valve body
B&M Megashifter
Soon to be installed
3:73 Richmond Gears and 3" Exhaust
"There is nothing more addicting than speed"

 

What rpm are you shifting at? You may have to bring your shift points up higher.

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87 IROC-Z SuperPro ET Bracket Race Car
461 naturally aspirated Big Block

Best ET on a time slip: 11.242 altitude corrected to 10.89
Best MPH on a time slip: 121.52 altitude corrected to 125.89
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Best 60 foot: 1.546

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Member of the Calgary Drag Racing Association

87 IROC bracket car, 91 454SS daily driver, 95 Homebuilt Harley

 

When I was running at the track I just put the trans in D and let it shift by itself (I dont trust the stock shifter to shift manually with). I believe that trans was shifting at around 4800-5000RPMs... I just dont understand why I hit redline and have to let off a bit before the end of the 1/4?? I am 100% sure that the gears are 2.77 since I did the trans in D and drive at 70MPH, it read about 2800RPMs.

 

Is it only running through the first two gears or are you shifting into third? Only other thing is your trans or converter is shot and doing a hell of a lot of slipping.

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'87 Bird 350 .060 over 700R4 + Lots more

 

How does she shift? I have the 3.70 gears in my 9-bolt, and my tranny shifts like utter garbage, and the car has NOTHING once the RPMs pass like 2750.

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1980 Camaro, '88 Police 350 engine, Headers, full exhaust, completely redone, my baby!
1988 Iroc-Z L98, MSD 6a, Accel coil, K+N's, Airfoil, Coolant Bypass, Flowmaster, Gears, Late model Bose, I like the 80 better

 

That does sound like the trans isn't getting into 3rd (D)... my car used to do that with it's first trans, when the thing couldn't complete a 2-3 WOT upshift.


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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
---Think your car could be pic of the week? Visit http://www.f-body.net for details!

 

I am almost positive that it shifts into 3rd at WOT. I really can't tell if the converter is slipping or not but the shifts are firm and there is no RPM flair up between shifts.

HELP????????

 

Well, just my guess too, but i agree with a few of the above...you're still in 2nd gear..why? Well, 5000 RPms in drive would be about 115-120 MPH, with 2.77's? Just guessing, but waaaaay more speed than a few bolt ons would get a stock L98 down the 1/4.

Are you absolutely sure of the rear gear ratio? Maybe you should rase the rear, spin the pinion and count the rev's the tires make...if you have the LSD, should be just under 3 pinion turns for one tire revolution 2.77's.

 

Like I said I am 100% sure that I have 2.77 gears!!!! I have a 9-bolt and according to the RPO codes the gear ratio is 2.77:1. I have also verified it by placing the trans in D and driving at 70MPH, the tach reads 2800RPM!!!! Well are you guys saying that there is no way spinning off the line so much could cause this? Anyone wanna give me any tips? I am going to the track on Friday the 13.....AHHHHH!!!

[This message has been edited by Like a ROC 89 (edited July 10, 2001).]

 

your car is probably still in 2nd gear pay attention to the shifts so you know. when my buddy runs his car that is the same basic car it only shifts D at about 1200 feet but he has a good 700 so that may be the dif.

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Black 89 Iroc 5.7
355 in. SB
many other mods and more to come

 

Well I dont know if I have the "good" 700 that you are talking about bottlefed89. Considering my car only has 60k miles on it and is in excelent condition I believe the trans is still in good shape. I do believe that it did shift into 3rd but have nothing to back it up. On Friday I will check that the trans does shift. Could my tach be off by about 1500RPMs???

 

Either your gear ratio is not 2.77 or your tach is reading incorrectly. At 2800 RPM your car should be doing 78 MPH in drive not 70 MPH. I have a 1987 GTA 350 with 2.77 gears and it shifts into 3 rd gear about 200 feet before the finsh line. Are you positive you are shifting into 3 rd gear and not at the top of second gear? Your 99.2 MPH indicates to me that you are in third gear but you should be no where near the red line at this speed with 2.77 gears.

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1988 Formula 5L/5sp 3.45 gears, SLP cold air kit, MAS gutted, TPIS air foil, TPIS AFPR, MAC headers, Mac under drive pulleys, MAC cat back, Relocated MAT.
Best ET street tires 13.85
Best 60 FT street tires 1.930
Best MPH street tires 99.29

 

Well I am now 150% sure they are 2.77:1 gears! I jacked the car up and counted the turns of the driveshaft: 1 turn of the wheels gave about two and a half turns of the driveshaft. I HAVE 2.77 GEARS!!!!! Well I 'll have more info Friday night when I get back..... Anyone with any tips, I am racing a 95 5.0 auto stang with headers, no cats, h-pipe, flows, bigger MAF, underdrive pulleys, 3.73 gears, huge 315mm street tires, transgo shift kit, and of the shelf prom.

 

Listen, the more you burn your tires in 1st gear the lower the speed/rpm will be in the top end of the 1/4 mile. From everything that I have read above you are "attempting" to make a 2-3 shift?! It is not happening, that is why you are "running out of revs". You are still in 2nd gear.
27" tires, 2.77 rear end gears, 1.63 2nd gaer ratio = apx. 5,610 rpm at 100 mph (maybe 200+ rpm). What were your rpm,s at the end of the quarter?

 

You should be at about 1722rpm at 70mph with 2.77 gears and 26.5" tires. Sounds like you are in 3rd on the highway (never in 4tf/OD) , 2nd gear max at the strip, AND your converter is never "locking up" to top it all off...

 

Because, if you were at redline in drive, your speed would be much higher than 99mph, I "guesstimated" 115-120, but maybe even higher, based on your 2800 in drive at 70, would indicate that your car would be going 140 MPH at 5600RPM in Drive...as you can see, there's no way you have the HP to pull that speed in a 1/4mile, regardless is you spun in place, without moving for 10 seconds and the car shifted through 1st, then 2nd and into drive before you left the line...what would happen is you wouldn't have enough torque to maintain the RPM, and once the tires hooked up (and assuming the trans wouldn't downshift) you'd bog the motor down and not be able to pull that high of a trap speed anyway (120+).

This is why everyone saying you're either in the 2-3 shift at the end of the 1/4, or the gears are much lower (higher numerically) than you thought.

Since you've verfied the gear ratio, you MUST be into the 2-3 shift causing the problem.

 

Ok I've come to believe that I am just about to shift to 3rd at the end of the 1/4. I ave checked the code on the axle tube and it IS 2.77. Well this is telling me that I need a lot more gear!!!! What ration do you recomend: 3.45 or 3.70? Remember it is a700R4 autotrans.

 

Hmm..not right...when i had my auto with the 3.42:1, 70 mph was 2300...something isnt right!! with my t5 and 3.42:1 im pushing a little bit higher (more mods etc)

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1989 Firebird
2.8 v6, t5 swapped in

Ram Hi-po clutch, Cold Air, 1.6 rockers,Lakewood LCA's, Lakewood Lift bars, Wonder Bar, 3" y-pipe, Random Tech Cat, 3" I-pipe, Flowmasters, MSd 6a, MSD Coil, Accel 8.8 wires, Auto Meter Gauges (Water, Clock, Fuel Pressure, and 5" Sport Comp Tach)TB Bypass, 4th Gen Seats

Coming for my v6:
Panhard Bar, 4thgen front seats, Nitrous, Line Lock, Posi, Spohn Torque Arm & Subframe connnectors

"I'd rather run last in a full out race, than to NOT have run at all"
#3 Forever

 

You guys dont understand!!!! I am driving in D the 1:1 gear in the 700R4 trans, 3rd gear!!!!! NOT OVERDRIVE!!!!!!!!!!

 

OK I believe that you have 2.77's. I know that the 3rd gear clutches aren't the best. It could be that at WOT you're overpowering the trans, and it's slipping. I've seen it happen many times to 700's with some miles on them and poorly adjusted TV cables.

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'87 Bird 350 .060 over 700R4 + Lots more

 

no way are you going to over rev in third gear at 99 mph.