C3 Stock drivetrain power/torque capability
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C3 Stock drivetrain power/torque capability
I have a '69 that was originally an LT1 car. I'm in the process of installing a World Motown 427 small block with a fairly serious head & cam setup and expect to be running about 550hp/500lb-ft. I have a beefed up 700r4 tranny and converter, so they're not the issue, but the driveshaft, u-joints, third member, half shafts, etc. are all stock. The question is: what is the weakest link in the stock setup, and how much power/torque can I run before I break something? I'm hoping that as long as I avoid slicks and stick with street tires that I'll break loose before I break anything. Any ideas/comments/advice are welcome.
Drifting
Joined: Oct 2005
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From: East London/SW Essex UK
I have a '69 that was originally an LT1 car. I'm in the process of installing a World Motown 427 small block with a fairly serious head & cam setup and expect to be running about 550hp/500lb-ft. I have a beefed up 700r4 tranny and converter, so they're not the issue, but the driveshaft, u-joints, third member, half shafts, etc. are all stock. The question is: what is the weakest link in the stock setup, and how much power/torque can I run before I break something? I'm hoping that as long as I avoid slicks and stick with street tires that I'll break loose before I break anything. Any ideas/comments/advice are welcome.
one of the guys on our UK forum (CCCUK) twisted-up a drive shaft, crushing an 'A' arm when a wheel spun-up accelerating over an iron manhole cover - and gripped when back on tarmac
Race Director
Joined: Dec 1999
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From: Forked River NJ
First there was no LT1 in 69 so it can't be an LT1. That really does not matter because the LT1 drivetrain only gave you caps instead of straps for the half shafts. I am running right around 500 HP with my setup and so far I have been lucky. I do have all solid ujoints a better driveshaft and 3 inch halfshafts. I have rebuilt the diff to as HD specs as a stock rebuild can have. I would say with your setup depending on how hard you are with the loud pedal you are pushing the limits of the stock drivetrain. The auto will cushion it a little but not much. Run it and when something breaks upgrade it. 
Race Director
Joined: Apr 1999
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From: CORVETTE 77 385 C.I. TEXAS
One time Chevy engineering went racing during the racing ban & broke a half shaft- they took one off a Corvette in the parking lot to continue racing. 3" half shafts came out in 75- so stock for some of us & easy for others to get + solid u-joints.
Yes, the I.R.S. will handle 500+ HP in general w/o slicks as the tires spin. It's the shock that gets them. Will hold up better w/ autos. than manuals w/ high power & driven hard.
Yes, the I.R.S. will handle 500+ HP in general w/o slicks as the tires spin. It's the shock that gets them. Will hold up better w/ autos. than manuals w/ high power & driven hard.
Team Owner
Joined: Jan 2006
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From: Crossville TN
It all depends on how sticky your tires are. If you get it to the point that it can hop and grab, your drivetrain will be at risk. If you don't put some kind of street-slicks on it, you'll likely be OK. You may want to put some half-shaft containment straps on it just to prevent major damage if one ever gives out.
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Thanks all for the advice. Gordon, I did not know about the LT1, the previous owner must have changed the shifter panel piece. It sounds like I'll stick with street tires for the time being until a Tom's Diffs setup comes my way. The half shaft straps a re a good idea, too, I'll have to look into them.
The 427 should ship from Bill Mitchell early next week, and then it's install time. I can hardly wait to burn through the crusty old radials.
The 427 should ship from Bill Mitchell early next week, and then it's install time. I can hardly wait to burn through the crusty old radials.
