Stub axle
Thread Starter
Racer
Joined: Jan 2013
Posts: 302
Likes: 2
From: Sayville New york
Stub axle
1971 corvette sm. block; can I install big block HD. Caps on stock small block stub axle .i wil try to beef up rear end to accept new 406" 480hp sm. block with turbo 400 trans..the gears are 355 in mint condition.is there a difference between sm block and big block stub axles other then the obvious hd. Caps?
Le Mans Master
Joined: Dec 2003
Posts: 5,727
Likes: 38
From: Fremont CA
The Big Block/LT-1 side yokes off the differential have forged caps that bolt on VS a weaker "U" bolt on the low HP cars (although my numbers matching 72 L-48 roadster has HD yokes on it....assembly line mistake?)
The prices for original GM caps are quite expensive, having just gone through this journey for a fellow CF member, I would look at buying a set of new GM Restoration Parts yokes/caps from a CF vendor.
The prices for original GM caps are quite expensive, having just gone through this journey for a fellow CF member, I would look at buying a set of new GM Restoration Parts yokes/caps from a CF vendor.
Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,852
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
The HD yokes will install in the rear end without issue.
You have to replace the yokes... The holes are smaller in the standard yokes and threaded on the hd yokes.
http://willcoxcorvette.com/product_i...oducts_id=2567
You have to replace the yokes... The holes are smaller in the standard yokes and threaded on the hd yokes.
http://willcoxcorvette.com/product_i...oducts_id=2567
Last edited by Willcox Corvette; Dec 18, 2013 at 04:19 PM.
Thread Starter
Racer
Joined: Jan 2013
Posts: 302
Likes: 2
From: Sayville New york
Oh man Willcox that info hurt! I am a senior citizen that does all his own labor on my vette. I lay on my back and remove that rear,changed gears from 3.08 to 3.55 and new seals,bearings,etc. I wish I knew the weak piece in the driveline was those yoke caps now the through of pulling that rear down on a cold concrete floor-------ugh! bTW is the yoke physically larger or is it just a larger threaded hole and bold. I could enlarge the hole in place and use the grade eight bolt and nut idea.
Melting Slicks
Joined: Mar 2009
Posts: 3,126
Likes: 15
Oh man Willcox that info hurt! I am a senior citizen that does all his own labor on my vette. I lay on my back and remove that rear,changed gears from 3.08 to 3.55 and new seals,bearings,etc. I wish I knew the weak piece in the driveline was those yoke caps now the through of pulling that rear down on a cold concrete floor-------ugh! bTW is the yoke physically larger or is it just a larger threaded hole and bold. I could enlarge the hole in place and use the grade eight bolt and nut idea.
Team Owner
Joined: Sep 2002
Posts: 38,351
Likes: 2,077
From: California
There were kits out to do this!
They used to come with a drill, tap and tap handle. I also think the HD yoke units are a higher grade of steel? But someone else would have to answer that one! I am a little rusty on stock type parts. Those are all laying on the shelves replaced! Also on the caps (there are the strap style and then there are the truly heavy duty cap style ones). And even like Moroso sells aftermarket units. Also you might look into the Mark Williams Solid U-joints!
Last edited by TCracingCA; Dec 18, 2013 at 06:06 PM.
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Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,852
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
Captain bob... Run it the way it is....... You're not going to "enlarge" the hole and change it.. (unless your into complete demoralization.. You'll never enlarge the hole and tap it... The yokes are hardened, and you'll waste more time than you or I have).
Team Owner
Joined: Sep 2002
Posts: 38,351
Likes: 2,077
From: California
He's right!!!!
If you really want assurance, go to the Tom's Differential Idaho based companies website and buy axles from them like me!!!
But even the u-bolts will hold if carefully snugged equally and torqued to a respectful level of power and the halfshafts and such are in a good alignment to the axles. The caps and such are just insurance and allow you to hammer on it a bit more!
Last edited by TCracingCA; Dec 18, 2013 at 10:27 PM.
Instructor
Joined: Jul 2004
Posts: 232
Likes: 2
From: Langley B.C Canada
When I bought my 69, which is a numbers 427/435 car I learned that in its previous life before me, someone installed a replacement diff, assuming original unit was damaged or broken, at some point. The new replacement or warranty unit had small block yokes. They must of ordered the wrong one, when it was in for repair. Anyway it had the HD caps!!!! They had bolts going through both cap and yoke, and nuts on the other side, so not correct.. I found the caps on the U-joints walked around inside the yoke causing wear, and a failed U-joints on both sides. At the time I didnt know any better, so I replaced the u-joints, only to find after one summer of driving, they starrted to walk around again... Will post a pick later..
Thread Starter
Racer
Joined: Jan 2013
Posts: 302
Likes: 2
From: Sayville New york
Thank you ever so much who would ever think the small block yoke with big block caps and thru bolts and nuts would be worse then leaving the cheap small block straps ,it makes o sense at all but your the man (seeing is believing ). My 406" will make a honest 480hp I can see this as the weakest link in the chain even with auto trans.
Race Director
Joined: Jan 2000
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From: Corsicana, Tx
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I would worry about the outer stubs, u-joints and halfshafts themselves long before I'd worry about those straps.
I've seen a lot of broken stuff under Vette's over the years, but not once have I personally seen a failed strap that didn't have something else happen first.
JIM
I've seen a lot of broken stuff under Vette's over the years, but not once have I personally seen a failed strap that didn't have something else happen first.
JIM
Last edited by 427Hotrod; Jan 1, 2014 at 07:15 PM.
Race Director
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The order of issue is usually the u=joint (use solid Spicers), the outer stub axle itself where the bearings are (get good ones..not stock replacement- Tom's makes good ones), halfshafts. The 3" will be a little stronger...best is to get aftermarket made out of heavier wall tubing.Any local driveshaft shop can do it or there are several good places that pre=make them.
Traction is the problem..running street tires and spinning saves parts.
JIM
Traction is the problem..running street tires and spinning saves parts.
JIM
Thread Starter
Racer
Joined: Jan 2013
Posts: 302
Likes: 2
From: Sayville New york
The order of issue is usually the u=joint (use solid Spicers), the outer stub axle itself where the bearings are (get good ones..not stock replacement- Tom's makes good ones), halfshafts. The 3" will be a little stronger...best is to get aftermarket made out of heavier wall tubing.Any local driveshaft shop can do it or there are several good places that pre=make them.
Traction is the problem..running street tires and spinning saves parts.
JIM
Traction is the problem..running street tires and spinning saves parts.
JIM
Race Director
Joined: Jan 2000
Posts: 13,017
Likes: 2,261
From: Corsicana, Tx
2020 C2 of the Year - Modified Winner
2020 Corvette of the Year (performance mods)
C2 of Year Winner (performance mods) 2019
2017 C2 of Year Finalist
The rear under my car is a custom Dana 60 made into an IRS. It used straps to hold the u-joints. They're big 'un's...but still just straps.
JIM
JIM
Melting Slicks
Joined: Nov 2010
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From: Michigan