rear end
Race Director
Joined: May 2005
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From: Millington Illinois
St. Jude Donor '08-'09
See GTR1999 quote in post #31. It is great to have forum members that have more knowledge about Corvette differentials than Gary. To me running a differential with the yokes ground down to the point you have 1/4" of endplay in the axle is similar to continue to run an engine with a wiped cam lobe. They both still work, They both have metal debris floating around in the oil and because of this they both are damaging other components that will lead to more expense when you do rebuild it. In my opinion metal shavings and chunks of C clip are not great lubricants but what do I know. I would think it would cause excessive wear on the ring and pinion gears, bearings and races, spyder gears, carrier pin and if you run a chunk of the c clip through thru the spyders a busted posi case, or if it runs through the ring and pinion busted teeth on those but, like I said I am just an old school hotrodder and don't have my engineering degree so what would I know. You would think a member with an engineering degree would realize this and know better than to give advice to continue driving it as is. I must be way stupider than I thought or am missing something here.
Last edited by 63mako; Mar 30, 2010 at 12:14 PM.
Race Director
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From: California
Le Mans Master
Joined: Jan 2006
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From: Butler Pa
It felt like a boat because the camber was so far out from the yokes being so badly worn, not because the yokes were pulling out of the rearend.
Team Owner
Joined: Mar 2002
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So when you "fixed it" did you just put new c-clips on, or did you replace the stub axles and realign the rear? 
:
Originally Posted by bashcraft
It felt like a boat because the camber was so far out from the yokes being so badly worn, not because the yokes were pulling out of the rearend.
Race Director
Joined: May 2003
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From: California
OOOH ok, so the yoke was chewed up throwing off your camber, but the reason the rear went squirrely is because the c-clips fell off? Is that really what you're trying to say? So when you "fixed it" did you just put new c-clips on, or did you replace the stub axles and realign the rear? :
ding ding ding!
So when you "fixed it" did you just put new c-clips on, or did you replace the stub axles and realign the rear? :ding ding ding!
They WERE able to get an alignment on it with the chewed up yoke....but the wheel would not stay aligned in curves because of all the play....
so... several months later when I could afford it (15 years ago) I pulled the rear and fixed it, put it back together, no more boat....
Team Owner
Joined: Mar 2002
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Like I said, unless the wheel is off the ground or slamming into something laterally, that stub axle will remain loaded inward. Period.
Did you verify they set the camber correctly? Did you make sure your strut rods were secure?
so... several months later when I could afford it (15 years ago) I pulled the rear and fixed it, put it back together, no more boat....
Race Director
Joined: Jul 2001
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They WERE able to get an alignment on it with the chewed up yoke....but the wheel would not stay aligned in curves because of all the play....
so... several months later when I could afford it (15 years ago) I pulled the rear and fixed it, put it back together, no more boat....
so... several months later when I could afford it (15 years ago) I pulled the rear and fixed it, put it back together, no more boat....
So please explain how there's many documented examples of Corvettes running around with NO c-clips in place and they have NO camber changes?
How come a 3D analysis of the suspension geometry confirms that the yokes are always loaded inwards?
Better yet, why am I getting sucked into this futile debate again?
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Race Director
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From: California
ok.... im laughing little here.... don't want to ruffle anyones feathers...
when the vet sat, yes it was aligned properly, just as you say... agree...but when in a high g force to the right or left, the wheel would pull out as the car leaned, and thus loose its alignment, causing a boat effect...it was the same as lifting that wheel off the ground a little, just as you explain...
and the yoke and c-clip were the only things that needed to be replaced....
The yokes are loaded inwards, unless in a strong lateral force, then the opposite outer side wheel is no longer loaded downward but rather dragged outward...
when the vet sat, yes it was aligned properly, just as you say... agree...but when in a high g force to the right or left, the wheel would pull out as the car leaned, and thus loose its alignment, causing a boat effect...it was the same as lifting that wheel off the ground a little, just as you explain...
and the yoke and c-clip were the only things that needed to be replaced....
The yokes are loaded inwards, unless in a strong lateral force, then the opposite outer side wheel is no longer loaded downward but rather dragged outward...
Last edited by pauldana; Mar 30, 2010 at 02:29 PM.
Race Director
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Race Director
Joined: May 2003
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From: California
Race Director
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So, refer to all the posts where those of us have actually taken the time to do the calculations and found out that GM got it right. There's a reason why the lower shock mount is mounted at a specific distance inboard of the wheel centreline. Wasn't just random placement or just for tire clearance.
As the lateral force increases, so does the downward force on the tire as the car leans. The net effect increases the inward pressure on the yoke, not decreases.
As the lateral force increases, so does the downward force on the tire as the car leans. The net effect increases the inward pressure on the yoke, not decreases.
Race Director
Joined: May 2003
Posts: 10,956
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From: California
So, refer to all the posts where those of us have actually taken the time to do the calculations and found out that GM got it right. There's a reason why the lower shock mount is mounted at a specific distance inboard of the wheel centreline. Wasn't just random placement or just for tire clearance.
As the lateral force increases, so does the downward force on the tire as the car leans. The net effect increases the inward pressure on the yoke, not decreases.
As the lateral force increases, so does the downward force on the tire as the car leans. The net effect increases the inward pressure on the yoke, not decreases.
Race Director
Joined: May 2003
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From: California
I am going home tonight, getting under the car and taking a good look at the geometry of the whole thing...I could be wrong, but I don't think so at this time....
you state, that when the car is jacked up the wheel will pull from its axal? correct?.... so, in a lateral lean, say to the left turn, the right tire will be hard in, but the left tire will be loosing weight, thus pulling outwards... why would this not be correct?....
i am truly open to input... thx, p
on a ps... just went out back. i have a complete C4 IRS sitting on the ground... loosened a u-joint u bolt to try and simulate my idea of lean, got several students to put a simulated lateral lean on the IRS and sure enough the outer wheel pulled outward, just as i have stated....
Last edited by pauldana; Mar 30, 2010 at 04:27 PM.
Race Director
Joined: May 2005
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From: Millington Illinois
St. Jude Donor '08-'09
ok, i appreciate all the help with the rear alignment question i posted. i had the car aligned, the bushings and bearings seem ok. but, the axle shaft that goes into the rear end has some slack in it. it goes in and out 1/4 inch or so with the car jacked up. it does this when you hold the tire at 6 & 12 and push/pull on it. nothing else moves except that shaft goes in and out. this car only has 27k on it. surely the rear end wouldn't be wore out. would it?
thanks, bob
thanks, bob
Edit: Just looked up your profile. Your car is a 1978. That explains a lot. I believe the 1978, 1979 cars had defective, improperly hardened side yokes from the factory. They were very soft and wore down much quicker than the previous C3-C2 side yokes. Replace them.
Last edited by 63mako; Mar 30, 2010 at 04:35 PM.
Race Director
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on a ps... just went out back. i have a complete C4 IRS sitting on the ground... loosened a u-joint u bolt to try and simulate my idea of lean, got several students to put a simulated lateral lean on the IRS and sure enough the outer wheel pulled outward, just as i have stated....
I guess you're not a physics, engineering or geometry major are you?
Race Director
Joined: May 2003
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From: California
Of course it did, you probably could have gotten that result with a 95 year old granny. The pivot point is at the junction of the strut rod and the lower shock mount. Measure the ratio of tire wheel ABOVE the pivot point compared to below. Let's say it's 3 to 1. That's the leverage you created by pulling on the top of the tire and not pushing on the bottom.
I guess you're not a physics, engineering or geometry major are you?
I guess you're not a physics, engineering or geometry major are you?
have a General contractors license also, along with a Pilots license...
I currently teach Computer graphics at a local high school, and have been building and modifying cars since I was 14yo, started on my first CJ5.... I have also taught several years of auto shop.....So, yes i have the capability to understand:-)
I will go home tonight, jack up the rear of my C3 and take a closer look....
but, anytime you put more force on one side the other will have an equal but opposing force... 1 pulling, one pushing....
ps.... my spelling sucks though!!! p:-)
Team Owner
Joined: Mar 2002
Posts: 24,160
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on a ps... just went out back. i have a complete C4 IRS sitting on the ground... loosened a u-joint u bolt to try and simulate my idea of lean, got several students to put a simulated lateral lean on the IRS and sure enough the outer wheel pulled outward, just as i have stated....
