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Topic: Corvette Differentials and Handling!

in Forum: C3 Driveline Components


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Corvette Differentials and Handling! (1/12)
 9/5/08 10:32am
corvette440hpLifetime Member
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Here is some useful information on the latest Posi Traction Carriers: http://www.duntovmotors.com/CorvetteDifferentialsAndHandling.ht     

corvette440hp2008-09-05 08:44:19

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corvette440hp
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Corvette Differentials and Handling! (2/12)
 9/5/08 1:04pm
aceintheholeLifetime Member
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Manteca, CA - USA

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1978,two tone,Metalic Rootbeer & gold 1975 L48 4 speed


Joined: 11/20/2005
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Thank you Larry. A little education can go a long way.

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Jimmy B.
Just can't wait to get on the road again.

 
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Corvette Differentials and Handling! (3/12)
 9/5/08 1:19pm
Adams' AppleLifetime Member
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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas


Joined: 11/8/2003
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Yeah...not too bad, but.... I have to disagree with the following statement:

"You can’t get by with anything over 200 lbs of preload on a street car with steel clutch plates because low speed maneuvering (as in a parking lot) causes the clutches to ‘clunk’ and chatter."

I've got the 400# pre-load springs in my '74, and Dwain's(longhorn294) '72....I ain't had no issues with mine at all, and I haven't heard any complaints from Dwain(yet) on his. Mine was done in '99, and I did Dwain's just a couple of years ago...

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Joel Adams
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Corvette Differentials and Handling! (4/12)
 9/5/08 3:33pm
kstyerLifetime Member
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CUYAHOGA FALLS, OH - USA

Vette(s):
1975 C3 Red, T-Tops, Black Interior. All I need is time and money! Getting there!


Joined: 12/2/2003
Posts: 6424

Joel is right on the money, but for a reason.
 
He does not overinflate the tires.  Many people put too much air in the tires thinking the car will handle better.  Not necessarly true.  Many Vettes have too much air in them.  Our C3 generally were about 26 psi.  Not too much weight for the large tires.  Going to a wider tire actually requires less pressure, but from bias to radial calls for adding 3 psi, in general applications.  Tire type also makes a difference.  I am running 29 with 255/60 tires, and like it.  But I am also watching tread wear.   When it comes out of the body shop I am going to use a pyrometer to measure tred temp.  If it's even across the tread, pressure is good.  If it is higher in the center, too much air.  Cooler in the center, too little air.   Keep in mind this is after stright line cruising.   Corners can change things, so check againg after getting sporting.  You may want to consider a blend.  I may end up dropping pressure a bit.
 
If the tires are hotter on one side than the other, the alignment is out.  Start there and re-evaluate.
 
Hard overinflated tires won't flex as much and make the posi chatter a bit more, or if they slide cause a bit of howling and leave some rubber on the ground.
 
Tire flex is not a bad thing.  THe new very small sidewall tires do handle better on the track.  But on a rough surface pavement the tires may not conform to the pavement, and that causes them to slide across the pavement instead of grabbing.   The reason it works on many cars is the fact that the suspension is also designed for that type of tire.
 
So the tires, the suspension, the surface, all make a difference on what works.  I have no problem with Joels set up at all.  It works. 
Corvette Differentials and Handling! (5/12)
 9/5/08 7:51pm
corvette440hpLifetime Member
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One thing everyone should consider is using dry nitrogen to fill their tires. The nitrogen is dry, where as the compressed air has some moisture content. As the air filled tire gets hotter, the pressure will increase. With nitrogen the pressure remains a constant stable pressure. Ken, Joel, your thoughts on nitrogen?..............

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Corvette Differentials and Handling! (6/12)
 9/5/08 8:16pm
kstyerLifetime Member
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CUYAHOGA FALLS, OH - USA

Vette(s):
1975 C3 Red, T-Tops, Black Interior. All I need is time and money! Getting there!


Joined: 12/2/2003
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Nitrogen does improve the stablization of a tire.  For racing, it is excellent.  For long term, the dry air is better than the moisture in the rim to prevent rust and or damage to the tire.  I'm talking long term here.
 
Keep in mind, the air around you is already about 78% nitrogen.  So while there is an advantage, it's not as much as some would leave you to believe.  If you have a slight leakage, and need to refill the tires on a regular basis, It's probably not worth it.   In my daily driver, it's not worth it.  For our C3s, it could be a good choice.
 
So is nitrogen a good thing?  Yes.  Is it always worth it? No.  But sometimes it is.
Corvette Differentials and Handling! (7/12)
 9/5/08 10:50pm
sundew
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Eagan, MN - USA

Vette(s):
Gone, but not forgotten: 1974 Coupe Red, matching numbers, Black Interior, L-48 w/ 4 speed; The “Admiral”, also gone and never to be forgotten. 1994 Admiral Blue LT-1 coupe, Black Interior Automatic


Joined: 6/18/2007
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Most of the guys I raced with , Ken, used dry compressed air. As you said, air is already 78% Nitrogen so it was hard to justify the added expense. Wouldn't a good moisture trap on an air compressor dry the air out adequately? That is what I use today. Of course we were just a bunch of amatuer road racers. I am sure the pro teams in NASCAR and SCCA probably use nitrogen. Since all gases obey the universal gas law, PV=nRT, how would nitrogen stabilize a tire over dry air? Since volume is constant, as temperture increases, pressure has to increase. Does it have something to do with the thermal conductivity properties of pure nitrogen vs. air?...just curious....
 
 
sundew2008-09-05 19:58:40

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Corvette Differentials and Handling! (8/12)
 9/5/08 11:02pm
Adams' AppleLifetime Member
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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas


Joined: 11/8/2003
Posts: 20126

I do remember back in the '70s, all the Funny Car/Fuelers that I hung out around were using Nitrogen in their tires. Even borrowed some one night after the races when I found my motor-sickle had a flat tar...

I don't think a regular water trap would be able to remove all of the moisture from compressed air in a compressor. Most compressors also add a bit of oil into the air, too...

And, in response to Ken's response, he is correct...I don't over-inflate the tars on my cars. My '74 runs exactly what it says on the placard...20psi. If I am road-tripping with extra weight, I'll pump it up to 26-29.

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Joel Adams
C3VR Lifetime Member #56    

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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

Corvette Differentials and Handling! (9/12)
 9/5/08 11:31pm
kstyerLifetime Member
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CUYAHOGA FALLS, OH - USA

Vette(s):
1975 C3 Red, T-Tops, Black Interior. All I need is time and money! Getting there!


Joined: 12/2/2003
Posts: 6424

The 21% oxygen and 1% mis gasses still expand more than nitrogen, so it is a bit more stable than dry air, but not a lot.   And as Joel says, dry air is hard to find.
 
And the placard is missing on my car, and memory lets me down a bit on this one.   That's another reason I am considering dropping my pressures a bit more.   But thats after the dang thing is painted and back on the road.   By the way folks, with the correct pressure, they ride better as well.
kstyer2008-09-05 20:34:46
Corvette Differentials and Handling! (10/12)
 9/6/08 8:18am
corvette440hpLifetime Member
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Helium???

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Corvette Differentials and Handling! (11/12)
 9/6/08 8:24am
corvette440hpLifetime Member
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I worked in the HVAC profession. I've heard of guys putting in R22, or other refrigerants to get to an air fill-up station. It actually was a dangerous thing to do, because the pressure increased dramatically with temperature. It's a direct relationship. 

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Corvette Differentials and Handling! (12/12)
 9/6/08 10:17pm
kstyerLifetime Member
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CUYAHOGA FALLS, OH - USA

Vette(s):
1975 C3 Red, T-Tops, Black Interior. All I need is time and money! Getting there!


Joined: 12/2/2003
Posts: 6424

And yes, nitrogen expands slightly less the the other gasses in the atmosphere.  So a bit less expansion than dry air.   Not a lot, but a bit.
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