Half Shaft angles??
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Instructor
Joined: Apr 2009
Posts: 143
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From: Tx
Half Shaft angles??
So like I have stated before this is my first C3 1972 vert. So I am rebuilding the front and rear suspension. The front is a Van Steel coilover setup and the rear is there composite spring with Bilsteen shocks. I am putting 18s on the car and notice that the rear is super high so I order longer bolts but to get the car where it does not look like a four wheel drive it looks as if half shafts are pointed up which I know is not good! I am running a 285 35 18 on the rear but going to a 40 on the aspect ratio still would not help enough. I have seen a lot of C3 run 18s with that tire combo and the ride height looks great. So all of those cars have a terrible angle on there half shafts?? What am I missing? Thought about going to a 275 45 18 but not really wanting to buy new tires. Thanks for any help.
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From: New Or-leens Loo-z-anna
If the rear shocks bottom out....will the top of the tires hit against the top of the fender well?
What is the angle of the half-shafts now.....5 degrees/10 degrees/20 degrees/more??????
What is the angle of the half-shafts now.....5 degrees/10 degrees/20 degrees/more??????
Pro
Joined: Aug 2000
Posts: 503
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From: Jacksonville FL
Half Shaft Angles
The rule of thumb around the racing community was to have them be level as possible at static ride height.
That was with 15" wheels but much taller aspect ratio tires of the time.
Some cars would have the diff crossmember relocated in the frame or the diff mounting point recessed into the crossmember.
The point is that U joints like to run just about level. High angles cause them to move alot which creates heat.
Locke
North Florida Corvette Assn.
That was with 15" wheels but much taller aspect ratio tires of the time.
Some cars would have the diff crossmember relocated in the frame or the diff mounting point recessed into the crossmember.
The point is that U joints like to run just about level. High angles cause them to move alot which creates heat.
Locke
North Florida Corvette Assn.
Racer
Joined: May 2011
Posts: 484
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From: Newcastle NSW
The rule of thumb around the racing community was to have them be level as possible at static ride height.
That was with 15" wheels but much taller aspect ratio tires of the time.
Some cars would have the diff crossmember relocated in the frame or the diff mounting point recessed into the crossmember.
The point is that U joints like to run just about level. High angles cause them to move alot which creates heat.
Locke
North Florida Corvette Assn.
That was with 15" wheels but much taller aspect ratio tires of the time.
Some cars would have the diff crossmember relocated in the frame or the diff mounting point recessed into the crossmember.
The point is that U joints like to run just about level. High angles cause them to move alot which creates heat.
Locke
North Florida Corvette Assn.
Not level at static ride height, but rather around 0.5" higher at the inner (diff. side) than the outer (trailing arm) side. This difference is to ensure that the suspension runs in the most favorable region of the toe steer curve (that is, goes into toe in under bump). When the half shafts are higher at the trailing arm side than the differential side, the suspension goes into toe out under bump - not great!
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From: New Or-leens Loo-z-anna
When you say the half-shafts are angled up.......
do you mean that the end bolted to the differential is higher?
OR......
do you mean that the end that is bolted to the wheel/trailing arm is higher?
Racer
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From: Kirkland WA
Le Mans Master
Joined: Apr 2007
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From: Graceland in a Not Correctly Restored Stingray
No, not good at all. And, not only is adverse toe-steer inherent to the C2/C3 IRS as already mentioned, but the extent to which it occurs increases progressively the further from level the half-shafts travel as a function of the trigonometry in play. This happens in both bump and droop, but is far more important when the rear is more highly loaded in bump. I'd strive to get those inner u-joints ~1/2" above the outers, raising the diff in the chassis if a lower CG is that important to your purposes. While you're at it, I'd suggest checking your front "Z" heights to see if that might also be below the point of diminishing returns up front as well.
TSW
TSW
Burning Brakes
Joined: Feb 1999
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From: Woodinville WA
Do you have new body mounts that make your car sit a bit higher?
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From: New Or-leens Loo-z-anna
26.5 is a decent heigth. My car with a steel leaf spring was at 29.75" when I bought it....I lowered it to 28.0"....with a full tank and driver it lowers to 27".
Being a rookie, I do not know how a monoleaf affects the body heigth.
Being a rookie, I do not know how a monoleaf affects the body heigth.
Le Mans Master
Joined: Apr 2008
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From: Powassan ON
