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#1
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Driveshaft Size and Clearance
About finishing the build on a 1967 GTO. Drag race only. Measured for a driveshaft with weight in car and car at ride height. 59.25" This is with stock location solid motor mounts, TH350 trans, 12 bolt rear w/4:56 gears. I expect the motor to cross at 6400-6500 RPM.
Strange would not make a driveshaft that long with that RPM range. Precision Shaft Tech. will sell me a 4" aluminum for about the same price as the strange 3.5" chromoly. Since the rear is up in the car and I had to shim the trans up for pinion and driveshaft angles I am out of clearance. Do I really need the 4" shaft? Stock driveshaft is already about hitting front driveshaft loop. No way I can get a 4" to fit without really cutting up the floor which I don't want to do. Any recommendations? |
#2
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You should be fine with a 3.5" chromoly shaft.
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Dave Polichena |
#3
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Strange wouldn't sell it due to the critical mass and the RPM. They said with that length it was only good for about 5000 RPM which I did not fully understand because we have always used a stock shaft at 6,000 for 30 years. But I don't want to spend 600$ on a driveshaft that comes apart after a few passes due to it not being to spec.
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#4
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What engine are you going to run 4.56s with?Tom
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#5
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Some good info here about selecting driveshaft materials, if you haven't read it before:
https://www.dragzine.com/tech-storie...for-your-ride/ |
The Following User Says Thank You to Sirrotica For This Useful Post: | ||
#6
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455 ci 3450lb car with me in it. |
#7
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Have you thought about using a Carbon Fiber shaft?
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66 GTO Nostalgia Super Stock/Street Legal Car 421 CID, stock block, Wenzler Intake, 2- Carter 750 AFB's, 3.90 Gears, Full Factory Interior, Full Exhaust, Stock Suspension 3750LBS 9.77@136.99 Multiple NSCA/NMCA World Champion 66 GTO 389 3x2, 4 speed, 4.33 gear, Montero Red 33K original Miles 67 GTO 2dr Post, 428, Tri Power, 3.55 Gears 80 Trans Am Black SE Y84 W72 WS6 |
#8
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Wasn't planning to have to shell out 1000$ on a driveshaft for a mid 10 second car. If its an absolute must I can. I would probably spend some time and do floor work and get the 4" aluminum to work before spending 400$ more. What RPMs and driveshafts are other A body guys using? Was using a stock 3" shaft at 6000 for years that never came apart. Just time to upgrade.
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#9
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I went the CF route for safety and damage control
Seen too many steel shafts break and tear everything up. I shift at 7200-7400 and cross the stripe about 6900. I ran a chrome moly 3.5" for about 10 years with solid U Joints that I would replace every 3 years.
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66 GTO Nostalgia Super Stock/Street Legal Car 421 CID, stock block, Wenzler Intake, 2- Carter 750 AFB's, 3.90 Gears, Full Factory Interior, Full Exhaust, Stock Suspension 3750LBS 9.77@136.99 Multiple NSCA/NMCA World Champion 66 GTO 389 3x2, 4 speed, 4.33 gear, Montero Red 33K original Miles 67 GTO 2dr Post, 428, Tri Power, 3.55 Gears 80 Trans Am Black SE Y84 W72 WS6 |
#10
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Mike , what was the length on your gto driveshaft? I'm going CF for safety also , I broke a steel one probably 20 years ago and it was bad .
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505 CID, 3560 lbs,Tiger heads, NA. 8.99@149.8 mph, 1.29 60', stock suspension |
#11
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Quote:
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#12
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Thinking about a CF shaft myself. I have seen cars about half destroyed. Breaking a steel one, it would sure put a problem in whatever race program you have going on. Might end it.
Finding floor pans for some of our old cars might be tough. Then you have all the labor. |
#13
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Mike, I am not sure of the length off the top of my head. I used PST (Precision Shaft Technologies). Made a huge difference in the car on the top end. I had 2 Chrome Moly shafts from 2 different makers, they both had a slight vibration about 130-135mph. After the CF it was super smooth. I drive it on the street as well with no issues. I can get a measurement over the weekend. All suspension is stock location with a TH400 trans and 12 Bolt so length was stock but will measure.
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66 GTO Nostalgia Super Stock/Street Legal Car 421 CID, stock block, Wenzler Intake, 2- Carter 750 AFB's, 3.90 Gears, Full Factory Interior, Full Exhaust, Stock Suspension 3750LBS 9.77@136.99 Multiple NSCA/NMCA World Champion 66 GTO 389 3x2, 4 speed, 4.33 gear, Montero Red 33K original Miles 67 GTO 2dr Post, 428, Tri Power, 3.55 Gears 80 Trans Am Black SE Y84 W72 WS6 |
#14
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Quote:
$1K is a very minor amount when you look at what is already invested. At minimum it beats your floor pans up and you're lucky. Usually it's the floor pans, exhaust system and transmission case that gets destroyed. I bought 2 and keep one in the trailer for a spare.
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66 GTO Nostalgia Super Stock/Street Legal Car 421 CID, stock block, Wenzler Intake, 2- Carter 750 AFB's, 3.90 Gears, Full Factory Interior, Full Exhaust, Stock Suspension 3750LBS 9.77@136.99 Multiple NSCA/NMCA World Champion 66 GTO 389 3x2, 4 speed, 4.33 gear, Montero Red 33K original Miles 67 GTO 2dr Post, 428, Tri Power, 3.55 Gears 80 Trans Am Black SE Y84 W72 WS6 |
#15
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Quote:
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505 CID, 3560 lbs,Tiger heads, NA. 8.99@149.8 mph, 1.29 60', stock suspension |
#16
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I've run 4" driveshafts in two of my 67's. Crowded but did have a little room to spare. Both had 12 bolt rears and 400 transmissions.
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Mick Batson 1967 original owner Tyro Blue/black top 4-speed HO GTO with all the original parts stored safely away -- 1965 2+2 survivor AC auto -- 1965 Catalina Safari Wagon. |
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