Stronger half shafts?
Thread Starter
Instructor
Joined: Nov 2008
Posts: 245
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From: Long Island, New York
Stronger half shafts?
finally made the decision to swap out the 350/270HP with a 383/440HP crate motor with 465 ft lbs of torque. I'm replacing the drive shaft U-joints with the heavy duty one's in the ZIP catalog. Should I do the same for the half's?
I keep hearing that I will probably bust the half shaft U's or twist them. I don't think this should be that big an issue with this motor, it's not only a small block, right?
I saw a picture on another thread about MT Drag tires of some halves that look like twisted wet noodles. I'm not putting MT drags, maybe just Nitto 555's 10 inch wide. Should I be concerned? Are there stronger half's or U's that I should swap out? I really don't want to bust one out on the road.
Thanks.
Bob
I keep hearing that I will probably bust the half shaft U's or twist them. I don't think this should be that big an issue with this motor, it's not only a small block, right?
I saw a picture on another thread about MT Drag tires of some halves that look like twisted wet noodles. I'm not putting MT drags, maybe just Nitto 555's 10 inch wide. Should I be concerned? Are there stronger half's or U's that I should swap out? I really don't want to bust one out on the road.
Thanks.
Bob
Pro
Joined: Jul 2004
Posts: 713
Likes: 61
From: Waterford CT
For some reason as the HP went down, chevy beefed up the half shafts. I think it was in '76 that they went to a larger dia shaft and u-joint. Pull out any of the major catalogs and look them up and you will see the shift to larger shafts at some point in the late 70's. Use those and you should be all set.
Pro
Joined: Dec 2008
Posts: 531
Likes: 0
From: Frisco TX
finally made the decision to swap out the 350/270HP with a 383/440HP crate motor with 465 ft lbs of torque. I'm replacing the drive shaft U-joints with the heavy duty one's in the ZIP catalog. Should I do the same for the half's?
I keep hearing that I will probably bust the half shaft U's or twist them. I don't think this should be that big an issue with this motor, it's not only a small block, right?
I saw a picture on another thread about MT Drag tires of some halves that look like twisted wet noodles. I'm not putting MT drags, maybe just Nitto 555's 10 inch wide. Should I be concerned? Are there stronger half's or U's that I should swap out? I really don't want to bust one out on the road.
Thanks.
Bob
I keep hearing that I will probably bust the half shaft U's or twist them. I don't think this should be that big an issue with this motor, it's not only a small block, right?
I saw a picture on another thread about MT Drag tires of some halves that look like twisted wet noodles. I'm not putting MT drags, maybe just Nitto 555's 10 inch wide. Should I be concerned? Are there stronger half's or U's that I should swap out? I really don't want to bust one out on the road.
Thanks.
Bob
If you are not running slicks and hooking up well enough to loft the front wheels i think you are fine running stock drivetrain components. At 450hp with street rubber the rear end should unload before destroying the drivetrain.
Its the high rpm launches and the abrupt loads they place upon the drivetrain that kills the components.
I am using solid joints, standard U straps, and french locks on the shafts for my 400/400 sb build '69 model - should be fine for a street driven car.
Thanks, Ed
Former Vendor
Joined: Aug 2006
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From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
The 1965-1979 rear suspension is one of the better suspension set ups you will find for standard or high performance output. IMHO, the darn thing is pretty much indestructible.
In the early 80’s we would go to the Corvette Homecoming in Bowling Green to set up at the swap meet. Every year they would have the King of the Blue Grass drags for the Corvettes and one item we would always take a boat load of as the Spicer U-joints. We sold the hell out of them from the people racing.
IMHO and from personal experience! I’ve broke one spindle, and probably a few dozen U-joints. The spindle was broken on a car twenty years ago too!
Two years ago we built a 383 for a 65 conv that did win the King of the Hill, (new name for it I guess) with Air Flow Research Heads (no juice)., a ton of mods, and ran a 11.61 1/4 with no suspension damage (and with slicks).
Your weak point on this suspension is the U-joint, and then I would have to say the spindle, but the half shafts will take just about anything you can give them. I think you will be just fine with the shafts.
Willcox
In the early 80’s we would go to the Corvette Homecoming in Bowling Green to set up at the swap meet. Every year they would have the King of the Blue Grass drags for the Corvettes and one item we would always take a boat load of as the Spicer U-joints. We sold the hell out of them from the people racing.
IMHO and from personal experience! I’ve broke one spindle, and probably a few dozen U-joints. The spindle was broken on a car twenty years ago too!
Two years ago we built a 383 for a 65 conv that did win the King of the Hill, (new name for it I guess) with Air Flow Research Heads (no juice)., a ton of mods, and ran a 11.61 1/4 with no suspension damage (and with slicks).
Your weak point on this suspension is the U-joint, and then I would have to say the spindle, but the half shafts will take just about anything you can give them. I think you will be just fine with the shafts.
Willcox
Last edited by Willcox Corvette; Feb 28, 2009 at 10:38 AM.
Le Mans Master
Joined: Apr 2007
Posts: 7,353
Likes: 72
From: Graceland in a Not Correctly Restored Stingray
Tho I've never run slicks on my NOM '78, I have broken my share of IRS bits over the years, and have thus methodically replaced/upgraded nearly everything, including HD 12-bolt IRS conversion; sole exception being the factory HD half-shafts. So, I can attest that they're indeed stout. But, having learnt the hard way that given enough power and sufficient bite something is eventually going to break, I admit to considering changing them out in preparation for the fresh 500+ HP 427 I'm in the process of building up.
FWIW, if you have a stick, do yourself a huge favor and get a ~15# flywheel. Not only will it greatly reduce the shock to your drivetrain, but it will promote easier shifting (especially down) during spirited driving. In any event, I suggest only Spicer solid U-joints behind high-perf mills, and to make sure your suspension doesn't squat excessively under acceleration so as to not bind a U.
TSW
FWIW, if you have a stick, do yourself a huge favor and get a ~15# flywheel. Not only will it greatly reduce the shock to your drivetrain, but it will promote easier shifting (especially down) during spirited driving. In any event, I suggest only Spicer solid U-joints behind high-perf mills, and to make sure your suspension doesn't squat excessively under acceleration so as to not bind a U.
TSW
Last edited by TheSkunkWorks; Feb 28, 2009 at 03:07 AM.
Pro
Joined: Dec 2008
Posts: 531
Likes: 0
From: Frisco TX
FWIW, if you have a stick, do yourself a huge favor and get a ~15# flywheel. Not only will it greatly reduce the shock to your drivetrain, but it will promote easier shifting (especially down) during spirited driving. In any event, I suggest only Spicer solid U-joints behind high-perf mills, and to make sure your suspension doesn't squat excessively under acceleration so as to not bind a U.
TSW
TSW
thats what I wanna hear, I am going with a 15lb flywheel/10.5in clutch on my '69 sb
- M-20 tranny w/ 3.70 rear also
Tech Contributor
Joined: Aug 1999
Posts: 15,175
Likes: 3,990
From: Connecticut, USA
with under 500 hp, st tires, no hard continuos launches the 3" with solid spicer are all you need.
The parts that break inside the diff are the posi cases,spiders. The 65-68 were not too strong and often are crack prone. The 69-79 are better but in stock form still weak to an extent.
Zerk joints are a waste of money and have failed in non racing use.
Rear spindle damage a lot of time is due to bad bearings locking up.
High power will break a lot of these parts so it all comes down to how much you have and how you drive.
The parts that break inside the diff are the posi cases,spiders. The 65-68 were not too strong and often are crack prone. The 69-79 are better but in stock form still weak to an extent.
Zerk joints are a waste of money and have failed in non racing use.
Rear spindle damage a lot of time is due to bad bearings locking up.
High power will break a lot of these parts so it all comes down to how much you have and how you drive.
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Le Mans Master
Joined: Apr 2007
Posts: 7,353
Likes: 72
From: Graceland in a Not Correctly Restored Stingray
Yes. I've cracked a 10-bolt case at the window and have broken spiders and pinion shafts (the shaft connecting the spiders), on one occasion spitting parts out thru the housing. After that last one, that's when I had my first 12-bolt done. BTW, Gary, I may send that one to you this summer to be rebuilt and upgraded to full HD.
Le Mans Master
Joined: Oct 2000
Posts: 8,897
Likes: 1,357
From: Santa Ana CA
I would (and did) get rid of the SB half-shaft U-bolts and upgrade to the BB end-caps in the pumpkin. I also replaced the U-joints with Zerk fittings with solid units.
This was after one of the U-joints let go and took out the rear end and did lots of other damage back there (>$3K). I had a half-shaft actually come into the car when shifting into 3rd at the 1/4 when the U-joint let go. This was right after I just had the entire rear-end replaced due to failed spider gears (from launching in the 1/4 on street tires with lots of VHT on the track surface..., also ~$3K).
This was after one of the U-joints let go and took out the rear end and did lots of other damage back there (>$3K). I had a half-shaft actually come into the car when shifting into 3rd at the 1/4 when the U-joint let go. This was right after I just had the entire rear-end replaced due to failed spider gears (from launching in the 1/4 on street tires with lots of VHT on the track surface..., also ~$3K).
Last edited by toddalin; Feb 28, 2009 at 12:38 PM.
