C3 1-1/2" Engine Offset
- Thread starter toobroketoretire
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Vettehead Mikey
Well-known member
I think in another post you stated that you'll admit when you're wrong. Let's put this to the test.
The engines are offset to the right as stated, but it's got nothing to do with the steering box. When designing the independent rear suspension, GM realized by having equal length half shafts, the diff input would be offset and not centred with respect to the frame. To keep the drive line straight and minimize deflection of the u-joints, the engine and transmission were offset accordingly.
Awaiting your apology, but not holding my breath.
The engines are offset to the right as stated, but it's got nothing to do with the steering box. When designing the independent rear suspension, GM realized by having equal length half shafts, the diff input would be offset and not centred with respect to the frame. To keep the drive line straight and minimize deflection of the u-joints, the engine and transmission were offset accordingly.
Awaiting your apology, but not holding my breath.
SVO
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I like brownies with walnuts.
Other than that, I got nothing....
Other than that, I got nothing....
Peer81
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If the axles are switched what would be the outward offside of one wheel?
Greetings Peter
Greetings Peter
Vettehead Mikey
Well-known member
If you mean half shafts, the difference would be zero.
Vettehead Mikey
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dougelam
Well-known member
TrueIf that was a concern, they would have put the steering box on the right too.
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Peer81
Well-known member
Sorry, stupid me of course they are the same. On our dutch forum there is somebody with different length half shafts so i was thinking maybe he switched them. But as i had mine in my hands several times I should have known they are equal
Still thanks for the wake up 
Greetings Peter
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Toms007
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Me too and me either!- Thread starter
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toobroketoretire
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Also the left exhaust manifold of my 454" misses the rear of the left upper control arm by just 3/8". Another reason why the engines are offset 1-1/2" to the right. As the big blocks were destined to be used in the C2's and C3's from the very beginning they had to offset the engines. When looking at the drive shaft from the underside you can see it almost touches the right side of the drive shaft tunnel because of that 1-1/2" offset.
The big block exhaust manifolds actually have a dimple in them right next to the control arm to provide a bit more clearance. As my control arm bolts have been tack-welded to prevent rotation I had to remove my left side exhaust manifold when I put new bushings in so I could remove the upper left control arm.
The big block exhaust manifolds actually have a dimple in them right next to the control arm to provide a bit more clearance. As my control arm bolts have been tack-welded to prevent rotation I had to remove my left side exhaust manifold when I put new bushings in so I could remove the upper left control arm.
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Vettehead Mikey
Well-known member
Again, it's got nothing to do with engine compartment clearance. Straight from the 1963 SAE paper authored by Duntov on the new 1963 Corvette.
"To achieve a [47/53 front-rear weight] distribution in this range, the passenger compartment was placed as far back as possible and the engine centerline was offset one inch to the right, taking advantage of the fact that passenger foot room requirements are less than those of the driver. This offset also reduced the width of the driveshaft tunnel, because the crankshaft and offset rear axle pinion were now on the same [plan view] centerline."
Had GM mounted the diff dead centre in the frame, the unequal length half shafts would result in unacceptable asymmetrical suspension geometry.
As expected the OP will not admit he was wrong and instead ignore all evidence that demonstrates this. :eyerole
"To achieve a [47/53 front-rear weight] distribution in this range, the passenger compartment was placed as far back as possible and the engine centerline was offset one inch to the right, taking advantage of the fact that passenger foot room requirements are less than those of the driver. This offset also reduced the width of the driveshaft tunnel, because the crankshaft and offset rear axle pinion were now on the same [plan view] centerline."
Had GM mounted the diff dead centre in the frame, the unequal length half shafts would result in unacceptable asymmetrical suspension geometry.
As expected the OP will not admit he was wrong and instead ignore all evidence that demonstrates this. :eyerole
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Um....I'm kind of siding with Zora on this one. If they needed the engine dead center they would have put it there and designed the manifolds, steering ect. around it, not the other way around.
Tom
Tom
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toobroketoretire
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I took these pictures this morning so you can see for yourself why the C2 and C3 engines had to be offset. Picture #1 shows the tiny 3/8" clearance between the left control arm and the front of the exhaust manifold and picture #2 shows the 7/8" clearance between the steering box and exhaust manifold. Knowing the big blocks would eventually be used in the C2's and C3's the engines HAD to be offset 1-1/2".
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dougelam
Well-known member
I guess that I'm confused 
If the frame is square
The control arms are the same length
Mounted so that they mirror each other to keep the tires placed under the fenders even
The engine block is concentric to it's center
WHY would someone offset the engine just to clear control arms?
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If the frame is square
The control arms are the same length
Mounted so that they mirror each other to keep the tires placed under the fenders even
The engine block is concentric to it's center
WHY would someone offset the engine just to clear control arms?
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Hib Halverson
Technical Writer for Internet & Print Media
I tell ya, "toobroketoretire", it is exhausting:W to deal with some of the incorrect information you post.
There is only one reason the powertrain in C2/C3 was offset:
To make the dirver's footwell wider.
As the SAE Paper quoted by "Vettehead Mikey" suggests, an added benefit of that was the CL of the rear drive axle's pinion and the CL of the crankshaft being in the same vertial plane allowed the tunnel could be narrowed.
In the late-59/mid-61 period, when the chassis was being laid out, the Mark engines were still several years in the future so the need to offset for a new engine did not exist.
Further, let's imagine the offset was to accomodate the Big Blocks. Don't you think they'd have offset it enough such that they wouldn't have to have stock exhaust manifolds with dimples? I mean:eyerole–why the f*** would you spend millions to develop an offset powertriain for the Big-Block and then not offset it enough? But...I digress.
There is only one reason the powertrain in C2/C3 was offset:
To make the dirver's footwell wider.
As the SAE Paper quoted by "Vettehead Mikey" suggests, an added benefit of that was the CL of the rear drive axle's pinion and the CL of the crankshaft being in the same vertial plane allowed the tunnel could be narrowed.
In the late-59/mid-61 period, when the chassis was being laid out, the Mark engines were still several years in the future so the need to offset for a new engine did not exist.
Further, let's imagine the offset was to accomodate the Big Blocks. Don't you think they'd have offset it enough such that they wouldn't have to have stock exhaust manifolds with dimples? I mean:eyerole–why the f*** would you spend millions to develop an offset powertriain for the Big-Block and then not offset it enough? But...I digress.
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toobroketoretire
Banned
Engine Offset
As there is only 3/8" clearance to the left side upper control arm with the engine offset 1-1/2" you can certainly understand why it had to be offset. And even with the 1-1/2" offset the big blocks BARELY fit.
As there is only 3/8" clearance to the left side upper control arm with the engine offset 1-1/2" you can certainly understand why it had to be offset. And even with the 1-1/2" offset the big blocks BARELY fit.
Antz81
Well-known member
For this to make sense the front suspension would have to different on each side. Otherwise the offset would solve the problem on the left by making worse on the right.
dougelam
Well-known member
So does that mean that the right side
of a big block is missing 1-1/2" of metal?
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