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Old 03-11-2001, 03:05 PM   #1
jmeiers
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Cool Stock Motored N/A Cobra rips off 12.26 @ 114 before rear goes KABOOM!!!

Went to Cecil County Dragway yesterday and only got 3 runs in. It was great weather and the track was hooking, keep reading about how well it hooked.

First pass of day, I missed 3rd gear and a serious bog on launch. Launched at 6100 rpms, way too low!!!

12.90 @ 111.20 MPH, 1.72 60ft.

Hotlapped the car right back into the burnout box for very next pass, no cooldown. I knew I launched to low before, so I raised rpms up. Launched at 7000 rpms this time. Slight bog on launch and hit every gear pretty good, except 2nd gear grinded alittle. No powershifting!!! Results:

1/8 mile - 7.83 @ 90.08 MPH
1/4 mile - 12.26 @ 114.02 MPH, 1.64 60ft.

Not bad for still having front swaybar and the car is slammed with FMS "C" springs, and the motor is internally stock from TB to Oilpan.

Well, after bringing car back to pits and jumping up and down about my TRAP speed, I decided to go balls to the wall on the next pass. I knew with the trap speed, I had enough to get the 11.99 pass. I planned on powershifting this run. I let car cool off for about an hour. Then got the slicks good and hot. Raised launch rpms to 7500 rpms. Dumped the clutch and it hooked harder than a MOFO!!! Wheels came up and then KABOOM!!! Something in the rear gave way and started crunching badly if I engaged the rearend in anyway.

After being towed back to the pits, I started searching around for anything. There was no fluid leaking anywhere. There is now a stress crack in my T/A Cover. I think I destroyed the pinion gear and it took the ring gear with it.

I am sorta excited and somewhat pissed. It cost me $250 to have the car towed back to my house in Northern VA. I only put 10 passes on this rearend setup!!! It is the FRPP 31spline Trac-loc, Moser 31spline Axles, FRPP 4.56 gears, T/A Cover, and every bearing replaced. I spent the rest of my money on this and now I can't drive the car. I am literally broke!!! I might have to tap my 401k to repair this sum*****. It gets me thinking, "IS THIS WORTH IT???"

I am going to try and have the car ready for SSOTN Nats, Smackdown, and the Modular Shootout. If I can get it all together by then, the new rear-end will consist of a C-locker, 4.88's, and 28x10.5 ET Drags.

Later, Jason

------------------
N/A 1997 Cobra

1/8 mile - 7.83 @ 90.08 MPH
1/4 mile - 12.26 @ 114.02 MPH
1.64 60 ft.
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Old 03-11-2001, 05:46 PM   #2
exgmguy
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First off, your car sounds bad as hell. That is some nutty power for a stock motored Cobra.
Do you think something was not set up right in your rear end, and that is why it broke? A 31 spline traction lock, and axles, etc... should keep you safe into the 10's. I guess you'll find out when you tear it apart!

I know what you mean about the money thing. I often find myself spending my last dime on my car.

------------------
1988 Mustang GT

12.0 @ 121 on radials
S-trim Vortech sitting in a box!
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Old 03-11-2001, 09:23 PM   #3
EZRIDN
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Excellent runs.....too bad about the rear end though...

What did u mean by saying "is this worth it."

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'86 GT.
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Old 03-11-2001, 09:36 PM   #4
97snakedriver
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Man. Let me know what happened. 114 is good for 12s... Although he was probably too drunk to remember I bet fourcam a buck that you would beat him to the 11s in a stock long block Cobra.
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Old 03-11-2001, 10:44 PM   #5
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Ouch...that's gonna leave a mark.

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67'fastback- Edelbrock carb, intake, cam, valve springs. Road lifters, Comp Cam rocker arms, windage tray, cerama coated headers, dual flows with H-pipe, modded c-4, tci stall converter, perma cool electric fan, aluminum water pump, griffen aluminum radiator, accel 8.8 cable, wide cap distriburator, magnetic pick up, manley valves, v-matic hurst shifter, edelbrock performer nitrous, carter electric fuel pump, ignitor coil, solid motor mounts, magna racing suspension, poly urathane bushings, und
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Old 03-11-2001, 11:06 PM   #6
jmeiers
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Cool

Yeah, that is why I chose that rear setup, it should have lasted me well into the 10's and I didn't plan on ever getting that far trying to get Stock Motor record. Anyway, I think you may be right about something not being setup correctly. I had developed some kind of noise last week, but I let it slide and now this happens. Oh well, at least it happened at a Test-n-Tune and not any money race.

What I meant about "IS IT WORTH IT" was just that. Is it worth it to keep spending money on this? Or spending money on trying to prevent what just happened? I had over 150 passes on my stock rear without any breakage. This is the first time my car broke and it was with a built-rear, go figure.

Later, Jason

------------------
N/A 1997 Cobra

1/8 mile - 7.83 @ 90.08 MPH
1/4 mile - 12.26 @ 114.02 MPH
1.64 60 ft.
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Old 03-12-2001, 12:59 AM   #7
Skyman
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jason- you go through the traps in 5th gear? What kind of rpms do you turn? 4.88's is a lot of gear. You sitll have stock tranny? Damn your car is fast 114mph!! Good luck w/ fixing the rear end. And yes its all worth it. Parts are always gonna break and your gonna have bad luck. Don't let it get you down!

Sky

------------------
-1989 Saleen Mustang #406-TFS Heads, E-303 Cam, Edelbrock Intake, and more. Added Eibach drag launch springs and 70/30's w/ 50/50's.
0-110MPH In car view (963k)
All Throttle through 3 gears! (497k)
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Old 03-12-2001, 01:28 AM   #8
jmeiers
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Cool

Quote:
Originally posted by Skyman:
jason- you go through the traps in 5th gear? What kind of rpms do you turn? 4.88's is a lot of gear. You sitll have stock tranny? Damn your car is fast 114mph!! Good luck w/ fixing the rear end. And yes its all worth it. Parts are always gonna break and your gonna have bad luck. Don't let it get you down!

Sky

Remember, this is a DOHC, it loves and needs high rpms!!! I cross the traps in 4th gear at around 6700 rpms. The stock rev-limiter is 7000 rpms. My rev-limiter was bumped to 7600 rpms via my dynotuned Autologic chip.

My HP peak is at 6300 rpms. By knowing my HP peak, you can see why Cobras have to run steep gears. With my old 4.30's, I would cross in 4th gear at 6100 rpms, below my HP peak. As a general rule with all cars, you want to cross the traps a couple hundred rpms above your HP peak. As you can see, 4.56 gears and 26" tires are the perfect combination for a stock DOHC, but most people are intimidated by the number and don't utilize what they already have. The biggest mistake I usually see is, people going with 4.10's or less in a stock-motored Cobra. Crossing the traps in 4th gear at 5800 rpms with 4.10's, is not utilizing all the DOHC has to offer.

With 4.88's and 26" tires, I will cross the traps in 4th gear at 7100 rpms. But, that is why I am going with 28" tires, it will bring the ratio back down to having 4.56/26" ratio, but will hook like a MOFO with the extra 2 inches of tire diameter.

Get what I am going for???

Later, Jason

BTW, when I get the new HCI intake that is being released on Mar. 15th, I will be running 5.13's minumum, maybe more, STAY TUNED!!!

------------------
N/A 1997 Cobra

1/8 mile - 7.83 @ 90.08 MPH
1/4 mile - 12.26 @ 114.02 MPH
1.64 60 ft.

[This message has been edited by jmeiers (edited 03-12-2001).]
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Old 03-12-2001, 05:20 AM   #9
Skyman
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Cool. I got it.. I'm still so impressed with how the car performs. I probably need more gear in my car I'm betting.

So whast that new intake? Can you still complete in stock motor class with that? And how much do you expect that to raise your powerband that you need 5.13's?

Also is this car your daily driver? Hows it rev on the freeway?

3rd, I can't believe you can launch that high and say that it bogs. I can't launch my car over 5500 or it spins the slicks a good 20 feet.

Skyler

------------------
-1989 Saleen Mustang #406-TFS Heads, E-303 Cam, Edelbrock Intake, and more. Added Eibach drag launch springs and 70/30's w/ 50/50's.
0-110MPH In car view (963k)
All Throttle through 3 gears! (497k)
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Old 03-12-2001, 06:20 AM   #10
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Skyman,

1) Have you had your car on a dyno? If not, you really should. I had an Autologic tune at LaRocca's Performance. Jimmy LaRocca is a Pro5.0/Renegade racer and an awesome tuner. Anyway, even on my stock-motor, we picked up 9rwhp and 15rwtq at peak, and 15-20 rwtq thru-out the mid-range. Since you got heads, cam, intake, it would benefit you more than me. Plus, it is an awesome tool to choose gearing and shift points.

2) The new intake is made by HCI, Hamilton-Clarke Industries. I was planning on placing my order for it next week, but now I have to fix the rear first. It looks like the stock intake but is a couple inches taller, I believe. It gets rid of the IMRC controllers and bolts directly to the head. It is also ready to accept the FRPP Oval Throttle Body. Preliminary dyno tests on bone-stock 96-98 Cobras have shown that HP peak is around 7,000 rpms. Torque drops off some, but HP picks up dramatically up top. Because of the torque loss and the new HP peak, I am gonna need the gear to get up to 7,000 rpms and above quickly. It should be worth 30-40 rwhp on my Cobra. The intake is the real bottleneck on the DOHC. The stock heads flow really well and nobody makes any cams yet, so all I got is this intake.

I don't run in any particular stock class, there is just a huge competition going on to see who can get into the 11's with a truly stock-motored Cobra. Although, there are a couple people jumping off the bandwagon and going with ported stock intakes with shortened runners. I will be running in the 4valve N/A class at the Modular Shootout. This class allows engine mods like porting, cam regrinds, intakes, etc, so the HCI intake will serve me well there.

3) It used to be my daily driver. In December, I bought a 91 Ford Escort for $800 and it is worth every penney right now, considering car is out of commission for the moment. With the 4.56's, I can still go about 80-85 MPH and still get decent gas mileage.

4) Again, these cars are very torqueless. Even dumping it at 7000 rpms brings the rpms down to 5500 when it starts moving. So, imagine, if I dumped it at 5500 rpms, I would be F*CKED!!! A slight spin is much better than a slight bog in these cars. BOG KILLS!!!

Later, Jason

------------------
N/A 1997 Cobra

1/8 mile - 7.83 @ 90.08 MPH
1/4 mile - 12.26 @ 114.02 MPH
1.64 60 ft.
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Old 03-12-2001, 07:49 AM   #11
EZRIDN
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What rpms does it turn at 80-85?

Isn't crusing that fast w/ those gears hard on the engine?

------------------
'86 GT.
Gears & Flows
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Old 03-12-2001, 12:53 PM   #12
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Yeah Sky, Remember our pushrod motors make gobs more torque at low rpm. Just try spinning a long runner EFI 302 to 7 grand though...
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Old 03-12-2001, 02:40 PM   #13
jmeiers
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Cool

It cruise at 3000-3200 rpms on the highway. The IMRC's kick in at 3250 rpms. If I cruise over that, gas mileage will plummet.

I don't have to downshift either. 5th gear is totally usable, for passing and topend end runs on the highway, just not for 1/4 mile racing.

Later, Jason

------------------
N/A 1997 Cobra

1/8 mile - 7.83 @ 90.08 MPH
1/4 mile - 12.26 @ 114.02 MPH
1.64 60 ft.
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Old 03-12-2001, 05:45 PM   #14
Skyman
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Actually I just dynoed today. I made 293rwhp@5500rpm on the first pull, with 323rwtq@3750. All said and done it put down 332rwhp@5500rpm and 351rwtq@3750rpm. This was all on 87 octane.

What is your car weight and your dyno numbers. I hope to see 110mph at the track.

Skyler

------------------
-1989 Saleen Mustang #406-TFS Heads, E-303 Cam, Edelbrock Intake, and more. Added Eibach drag launch springs and 70/30's w/ 50/50's.
0-110MPH In car view (963k)
All Throttle through 3 gears! (497k)
<A HREF="http://members.aol.com/lskymanl/burnout.mpg" TARGET=_b
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Old 03-12-2001, 08:05 PM   #15
EZRIDN
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Way to go Skyman!!! Nice numbers...

So is your car all dailed in now? How does it feel now that it has been straightened out?

How has the suspension affected launching?

------------------
'86 GT.
Gears & Flows

[This message has been edited by EZRIDN (edited 03-12-2001).]
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Old 03-12-2001, 08:31 PM   #16
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Awesome run! Launching at 7500.......COOL!! I have 31 spline trac-loc and it has gone through a few spider gears. This was after a few yrs of use each time with repeated high rpm launches. Not nearly as high as yours though 4,000-5,400. Manual trannys and high rpm launches are hard on rears. Especially when you hook well. I wish I could have seen you run. I think its really cool when you can launch it like that. No mercy !!!!!! Awesome!
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Old 03-12-2001, 08:37 PM   #17
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Jmeiers, I hope you get your car back together soon, sorry to hear about your rear end. Sky, those are great numbers, what do you think your putting to the fly? I bet you cant wait for the 24th!

------------------
95GT B303 cam, 1.7 rockers, 65mm TB, 73mm MAF, milled heads, 355's K&N, off road pipes, pulleys, msd coil, 9mm wires, Tremec 3550, Pro5.0 shifter,10.5 Motorsport clutch, FMS aluminum driveshaft, weld in subframe connectors
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Old 03-12-2001, 11:13 PM   #18
Skyman
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Fastang- I posted all the details in blue oval lounge.. But figuring 18% drivetrain loss its 405 hp at the fly wheel and 428ft/lb of torque.

Skyler

------------------
-1989 Saleen Mustang #406- TFS Heads, E-303, edelbrock intake,70MM TB, 73mm MAF, off road H, 2 1/4" exhaust, and 4.10's.
332RWHP@5500
351RWTQ@3750
Runs on 87 Octane!
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Old 03-13-2001, 07:34 AM   #19
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wow i just learned more about the dohc cars than i ever new before. I wanna see a 5.4 dohc built up and see what it can do.
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Old 03-13-2001, 04:21 PM   #20
Skyman
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Ezrdn- It runs good, and hooks much better now. I can actually challenge someone from a stop with street tires now.

Sky

------------------
-1989 Saleen Mustang #406- TFS Heads, E-303, edelbrock intake,70MM TB, 73mm MAF, off road H, 2 1/4" exhaust, and 4.10's.
332RWHP@5500
351RWTQ@3750
Runs on 87 Octane!
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