Differentail Problems while AutoX'ing
07-27-2010, 09:33 AM
#41
Team Owner
I have shimless custom hardend yokes that had nearly "ZERO" ware just a few months ago when i changed gear ratio and a new posi unit.
My stock yokes were warn past the c-clips before my 79 Vette even reached 50,000 miles and it trashed the rear end. What I have in place now has stood up to abuse that very few Vette rear end ever see.
My stock yokes were warn past the c-clips before my 79 Vette even reached 50,000 miles and it trashed the rear end. What I have in place now has stood up to abuse that very few Vette rear end ever see.
07-29-2010, 12:16 PM
#43
Team Owner
I have the tom's $850 posi unit with mid America $299 each yokes
http://www.mamotorworks.com/corvette?frame=1.3599
http://www.mamotorworks.com/corvette?frame=1.3599
07-29-2010, 11:34 PM
#45
Burning Brakes
Differential paroblems
As in another post, ditch the rear bar. The safety stewards or tech inspectors don't try to shake the top of your wheels to check for loose components? In the future, you may want to get a shorter rear spring (overall length) to move the bolts in, away from the tires.
08-02-2010, 08:44 PM
#46
Intermediate
Thread Starter
Okay, to make a conclusion, in case others use this to help solve their problem;
To fix my problem, Im making my own 6-link setup, based on this http://www.corvettefaq.com/c3/6link/index.html
Im gonna custom design something similar and a little stronger and better looking in ProE and then send it to the machine shop. Look for pics when its done in 2 years (just kidding, probably 2 monhs)
Lowered the shims on the rear leaf spring
- Disconnected the Bar
Yokes - http://www.ecklers.com/corvette-diff...1963-1979.html
Posi unit/Diff - http://duntovmotors.com/differentials-63-79.php - Great people btw!!
Spring Bolts (for leaf spring) - http://www.ecklers.com/corvette-spri...1963-1982.html
And bought a set of Nitto NT Autox tires to avoid the big buldge
Im amazed as to how many people had heated debates over this issue in other threads...
To fix my problem, Im making my own 6-link setup, based on this http://www.corvettefaq.com/c3/6link/index.html
Im gonna custom design something similar and a little stronger and better looking in ProE and then send it to the machine shop. Look for pics when its done in 2 years (just kidding, probably 2 monhs)
Lowered the shims on the rear leaf spring
- Disconnected the Bar
Yokes - http://www.ecklers.com/corvette-diff...1963-1979.html
Posi unit/Diff - http://duntovmotors.com/differentials-63-79.php - Great people btw!!
Spring Bolts (for leaf spring) - http://www.ecklers.com/corvette-spri...1963-1982.html
And bought a set of Nitto NT Autox tires to avoid the big buldge
Im amazed as to how many people had heated debates over this issue in other threads...
08-03-2010, 08:35 AM
#49
Burning Brakes
Really cool video to see the IRS at work.
I am no AutoX guy or professional anything, but I did realize one thing when rebuilding my entire rear suspension..... Those half shafts are basically like a fulcrum to keep the rear suspension travel inline. Without that halfshaft firmly holding in place that trailing arm really gets loose, especially at the top of the tire. Until you lock down the halfshaft to the differential and trailing arm you think "god whats keeping this trailing arm from wiggling all over the place in hard turns"?
Its an amazing piece of engineering.
I am no AutoX guy or professional anything, but I did realize one thing when rebuilding my entire rear suspension..... Those half shafts are basically like a fulcrum to keep the rear suspension travel inline. Without that halfshaft firmly holding in place that trailing arm really gets loose, especially at the top of the tire. Until you lock down the halfshaft to the differential and trailing arm you think "god whats keeping this trailing arm from wiggling all over the place in hard turns"?
Its an amazing piece of engineering.
08-03-2010, 09:51 AM
#50
Team Owner
Yokes - http://www.ecklers.com/corvette-diff...1963-1979.html
Posi unit/Diff - http://duntovmotors.com/differentials-63-79.php - Great people btw!!
...
Posi unit/Diff - http://duntovmotors.com/differentials-63-79.php - Great people btw!!
...
also that rear end you getting has nothing special. You could take your rear end and beef it up for only $850 with a super posi unit that won't fail for a loooooong time
08-03-2010, 10:31 AM
#51
08-03-2010, 10:38 AM
#52
Yes, it certainly is. My hat is off to the engineering and design guys in the late 50s and early 60s that got it right first time around. The extent of how it actually functions under varying conditions is frequently misunderstood and underrated, leading to ummm 'heated' debates. I had it backwards myself until I had the geometry analyzed at work. 
08-03-2010, 11:18 AM
#53
Race Director
I just started reading this. I had my small camera this past weekend and was going to mount it towards the rear suspension to see how it worked on the autoX. I did not do it though. After watching this I wish I had. Mine is a little different setup since I have a dual mount spring but it would be interesting. Next time out I will for sure check out the rear suspension at work.
09-03-2010, 05:04 AM
#54
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I also would like to set the record straight on the great snap ring debate. From the 1963 corvette SAE paper explaining the new IRS, there is a cutaway of the differential and the caption reads:
"Suspension thrust in one direction is taken by snap rings located on the splined end of the short integral yoke drive shafts. Thrust in the opposite direction is through the yoke unit to the differential pinion shaft".
Pretty clearly, the engineers were expecting thrust in both directions. And yes, they did intend the snap rings to both hold the load and act as a bearing. Incredulous as it seems, every design engineer is tempted by the forbidden fruit of the snap ring - I am one and I see it all the time. If you have a car like mine with worn side yokes and an otherwise race prepped chassis, you can certainly feel it. I have a long weekend ahead of me (sic). And I did not intend this email to "pile-on" anyone. Often times designers are worked into a spatial corner, probably with a bad initial assumption that a static analysis would indicate, too late to change the surrounding pieces, and viola, what was once an oversight is cured with a skinny groove and the magic of a snap ring, a feature by golly.
"Suspension thrust in one direction is taken by snap rings located on the splined end of the short integral yoke drive shafts. Thrust in the opposite direction is through the yoke unit to the differential pinion shaft".
Pretty clearly, the engineers were expecting thrust in both directions. And yes, they did intend the snap rings to both hold the load and act as a bearing. Incredulous as it seems, every design engineer is tempted by the forbidden fruit of the snap ring - I am one and I see it all the time. If you have a car like mine with worn side yokes and an otherwise race prepped chassis, you can certainly feel it. I have a long weekend ahead of me (sic). And I did not intend this email to "pile-on" anyone. Often times designers are worked into a spatial corner, probably with a bad initial assumption that a static analysis would indicate, too late to change the surrounding pieces, and viola, what was once an oversight is cured with a skinny groove and the magic of a snap ring, a feature by golly.
09-03-2010, 11:42 AM
#55
Race Director
I also would like to set the record straight on the great snap ring debate. From the 1963 corvette SAE paper explaining the new IRS, there is a cutaway of the differential and the caption reads:
"Suspension thrust in one direction is taken by snap rings located on the splined end of the short integral yoke drive shafts. Thrust in the opposite direction is through the yoke unit to the differential pinion shaft".
Pretty clearly, the engineers were expecting thrust in both directions. And yes, they did intend the snap rings to both hold the load and act as a bearing. Incredulous as it seems, every design engineer is tempted by the forbidden fruit of the snap ring - I am one and I see it all the time. If you have a car like mine with worn side yokes and an otherwise race prepped chassis, you can certainly feel it. I have a long weekend ahead of me (sic). And I did not intend this email to "pile-on" anyone. Often times designers are worked into a spatial corner, probably with a bad initial assumption that a static analysis would indicate, too late to change the surrounding pieces, and viola, what was once an oversight is cured with a skinny groove and the magic of a snap ring, a feature by golly.
"Suspension thrust in one direction is taken by snap rings located on the splined end of the short integral yoke drive shafts. Thrust in the opposite direction is through the yoke unit to the differential pinion shaft".
Pretty clearly, the engineers were expecting thrust in both directions. And yes, they did intend the snap rings to both hold the load and act as a bearing. Incredulous as it seems, every design engineer is tempted by the forbidden fruit of the snap ring - I am one and I see it all the time. If you have a car like mine with worn side yokes and an otherwise race prepped chassis, you can certainly feel it. I have a long weekend ahead of me (sic). And I did not intend this email to "pile-on" anyone. Often times designers are worked into a spatial corner, probably with a bad initial assumption that a static analysis would indicate, too late to change the surrounding pieces, and viola, what was once an oversight is cured with a skinny groove and the magic of a snap ring, a feature by golly.
David.... could you please send a link or scan of this paper? thx.. p:-)
09-03-2010, 11:55 AM
#56
Melting Slicks
09-03-2010, 03:43 PM
#57
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the SAE paper is at the following address:
http://www.web-cars.com/corvette/196...per.php?page=0
There are some very handy suspension diagrams in this paper.
http://www.web-cars.com/corvette/196...per.php?page=0
There are some very handy suspension diagrams in this paper.
09-03-2010, 03:49 PM
#58
Race Director
the SAE paper is at the following address:
http://www.web-cars.com/corvette/196...per.php?page=0
There are some very handy suspension diagrams in this paper.
http://www.web-cars.com/corvette/196...per.php?page=0
There are some very handy suspension diagrams in this paper.
09-03-2010, 04:03 PM
#59
I also would like to set the record straight on the great snap ring debate. From the 1963 corvette SAE paper explaining the new IRS, there is a cutaway of the differential and the caption reads:
"Suspension thrust in one direction is taken by snap rings located on the splined end of the short integral yoke drive shafts. Thrust in the opposite direction is through the yoke unit to the differential pinion shaft".
Pretty clearly, the engineers were expecting thrust in both directions. And yes, they did intend the snap rings to both hold the load and act as a bearing. Incredulous as it seems, every design engineer is tempted by the forbidden fruit of the snap ring - I am one and I see it all the time. If you have a car like mine with worn side yokes and an otherwise race prepped chassis, you can certainly feel it. I have a long weekend ahead of me (sic). And I did not intend this email to "pile-on" anyone. Often times designers are worked into a spatial corner, probably with a bad initial assumption that a static analysis would indicate, too late to change the surrounding pieces, and viola, what was once an oversight is cured with a skinny groove and the magic of a snap ring, a feature by golly.
"Suspension thrust in one direction is taken by snap rings located on the splined end of the short integral yoke drive shafts. Thrust in the opposite direction is through the yoke unit to the differential pinion shaft".
Pretty clearly, the engineers were expecting thrust in both directions. And yes, they did intend the snap rings to both hold the load and act as a bearing. Incredulous as it seems, every design engineer is tempted by the forbidden fruit of the snap ring - I am one and I see it all the time. If you have a car like mine with worn side yokes and an otherwise race prepped chassis, you can certainly feel it. I have a long weekend ahead of me (sic). And I did not intend this email to "pile-on" anyone. Often times designers are worked into a spatial corner, probably with a bad initial assumption that a static analysis would indicate, too late to change the surrounding pieces, and viola, what was once an oversight is cured with a skinny groove and the magic of a snap ring, a feature by golly.
I would have made exactly the same statement as the original designer engineers if it was me writing the paper.
It DOES NOT state at what time and under what conditions the snap ring comes into play. If the SAE paper does come up with actual loads under specific conditions, lets see them.
The rest of the post from David is speculation, assumption, and maybe even a cover up conspiracy plot for good measure.
This is getting old
09-03-2010, 06:13 PM
#60
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The cross-section with the differential and the quote is on this page:
http://www.web-cars.com/corvette/196...er.php?page=10
A conspiracy assumes I actually know someone. I don't. My only motivation is trying to figure out what is happening with my car and eventually how to permanently solve it.
The loading diagram that Mike is after is on page 5 - it only shows the outboard wheel in a turn in a static condition. I think by watching the video it is pretty clear that the loading is anything but static. If you watch carefully, as soon as the tire rolls from its inside edge (where the static load analysis is applied) to a condition where the load transfers to the outer edge due to hard cornering (or when the suspension is in rebound and the tire is camber outward), this pulls the top of the tire outboard and this is when the snap rings limit the motion.
static load diagram:
http://www.web-cars.com/corvette/196...per.php?page=5
camber diagram for rear wheels, anything over 1" of rebound movement results in the rear wheels being camber out.
http://www.web-cars.com/corvette/196...er.php?page=10
http://www.web-cars.com/corvette/196...er.php?page=10
A conspiracy assumes I actually know someone. I don't. My only motivation is trying to figure out what is happening with my car and eventually how to permanently solve it.
The loading diagram that Mike is after is on page 5 - it only shows the outboard wheel in a turn in a static condition. I think by watching the video it is pretty clear that the loading is anything but static. If you watch carefully, as soon as the tire rolls from its inside edge (where the static load analysis is applied) to a condition where the load transfers to the outer edge due to hard cornering (or when the suspension is in rebound and the tire is camber outward), this pulls the top of the tire outboard and this is when the snap rings limit the motion.
static load diagram:
http://www.web-cars.com/corvette/196...per.php?page=5
camber diagram for rear wheels, anything over 1" of rebound movement results in the rear wheels being camber out.
http://www.web-cars.com/corvette/196...er.php?page=10