Wheel hub Extensions on a 1980 C3

I guess I'm asking if anyone has done it before to their vettes.

Requires putting a wheel-hub spacer before bolting the rims on.

Would it weaken the cars performance in any way ? IMO it should actually add more stability , right ?

I'm not sure anyone can answer your question. Adding a hub extension changes the geometry designed into the car by cantilevering the wheel an inch beyond it's normal position, which will add stress to the wheel bearings and spindles; it will also change the rear wheel alignment a tad. For those reasons it's probably NOT "advisable"... now, whether the added stress is enough to cause serious issues/failures is not easily answered except by engineering calculations or extensive testing, neither of which has been done by Chevy. I doubt anything catastrophic will happen, other than that you may need to change the wheel bearings sooner than you normally would. I doubt any improvement in handling would be enough to notice.

Hmm...

ok.. but it does give the car a mean ass look ! I would never really push an old C3 really hard anyways.. a 30 year old car should not have to prove anything... just drive around and age gracefully (poetry in motion, so to speak)

I tried jacking it up this weekend and loosening the wheels and pulling them an inch outward and then standing back to survey. Damn it looked nice... So its settled then, in go the extenders . Another addition would be extruding the flares over the wheel wells a bit to meet the wheel extension. This may seem like a wierd thing to do, but it makes people turn around on the street. (if done properly) Believe me, I have seen a car like this in the bay area.. it looks like a killer shark !

Speaking of a Killer Shark

setting a narrow tire out wider only makes it look sad. My guess is that those that turn around might be thinking the opposite of what you think they are.

HOLY GUACAMOLE BATMAN !!! thats exactly what I had in mind. Yes i know about the wide tires bit. Mine are deep rally wheels.

Yes, you can cause problems. What are you trying for, the ricer look? Skinny tires a foot outside the car?

First, the front end is dependent on where the tires sit as to rubbing and hitting. The stock wheel is 8"x15" with 4-3/4" backspacing. With a

255/60-15 tire, the inner fender required trimming on '79 and earlier and not sure about '80 and up. The factory trimmed those optioned with the 255/60-15 in '78 and not sure if they trimmed some, all, or none in '79.

Placing that same 255/60-15 on an aluminum wheel 8"x15" with a 3-1/2 backspacing (much safer than spacers) means that it rubs when turning in the fenderwell at the back.

On the rear tires, this places the tire 1/2 to 1 inch outside the fender which gets things chipped and dirty if you are driving and not just sitting and looking.

Spacers are bad on the studs, placing much greater stress than designed. Corvette uses a 7/16 stud stock. In road racing, C3s during the '70s and '80s used longer and thicker studs to prevent loss of wheels. Typically the

5/8" x 3" Moroso studs where used. It is generally recommended in racing that NO spacers be used, however, they are not banned, but tech will usually shoot you down as unsafe for any over 1/4 inch.

Mid America Enterprises (and others I believe) used an engineered spacer/adapter to mount C4 wheels to the C2 and C3 cars. HOWEVER, these spacers where necessary to fill the extra backspacing of the C4 wheel, so the basic geometry of where the tire patch center was did not change. These were also a high-tech aluminum alloy designed for strength and used to bolt to the hub and then the wheel to the adapter, not merely a spacer.

So much for just the strength issue, now to design and safety.

Go to a BMW drivers school, one where they spend a day in class showing BMW design videos and driving techniques, not just a "show up at the track and drive".

You will find that BMW has researched the suspension geometry in much depth before many manufacturers ever discovered that life existed beyond 1/4 mile driving.

The location of the center of contact of the tire patch is very important to safety and handling. It is hard to show without drawings, but imagine a line from the upper pivot point to the lower pivot point. In the case of the

1980 Corvette, upper ball joint to the lower ball joint. Now extend that line to the ground. This point is the ideal pivot on the ground. The further outside or inside of that point a tire patch center is, the more force a tire exerts on the car to turn left or right. In normal driving, the left tire balances the pull of the right tire, however they are constantly fighting. The further the center is from the point, the more they fight. Add poor adhesion (water, oil, sand, snow, etc.) and you suddenly have a car veering off the direction you wanted, i.e., ditch, oncoming traffic, etc.

Have a flat, and you have a violent pull to one side. This is the very problem that Ford had with the flat tires on the Explorers. They were designed for a tall tire and so when it went flat suddenly (blowout), the tire "moved" the contact point further from the ideal pivot point and there was a violent pull that took the driver by surprise and, combined with the high center of gravity, flipped them.

The Corvette, being much lower, will not suffer that flip, but you could find yourself suddenly off the road or into oncoming traffic.

In summary:

1. Spacers over 1/4 inch are a very bad idea.
2. Corvette does not have excessive fender room to accommodate offset tires.
3. A wider tire and wheel combo, with proper backspacing and offset, with achieve the look you want and remain safe.
4. Wider tires and wheels will put a strain on the suspension, and the weak point is the studs. Enjoy changing the rear ones. :-)

I love that car! BUT I would change the wheels to period correct, old Vettes just don't fit with Billet Wheels. And I think he blew it putting that crankcase evacuation system on the collectors...... They don't do diddly squat below say 6000rpm.... Plus they aren't installed at an angle into the collector so I doubt they would create much vacuum at all, even over 6000rpm.

I absolutely agree, using stock wheels and tires with wheels spacers would be cheezy IMO as soon as you caught a 3/4 or rear view. But you know me, never replace stock wheels and tire without going bigger on the back, as big as you can stuff in there. But that's just the way old hot rodders from the Halcyon Days think. LOLOLOL

LOLOL Get with the times man!! 13in dia w/3 in spacers....that was in the Vanilla Ice days! Now it's 24 in diameter and 6 in wide ultra cheezy wagon wheels. hehehehehe

Actually those are oxygen sensors used for feedback to the computer.

Thanks 'Tom in Missouri'.. That was the kind of input I needed. Good thing I havent bought the spacers yet. I will stick to 1/4th as recommended. My new wheels and tires are a little wider than stock already. (atleast the new set i bought are, the car is still sitting on the original stock rallies.)

Ricers ! yuck ! wouldn't go near those flimsy little japanese pieces of sh** with a 10ft. pole. I honestly dont understand them anyways, waster of money and mostly bad styling (especially those horrific spoilers I see on WRXs and Civics...)

Huh.......... good catch. I got the zoomed pic of the engine and can barely see the fuel logs. He must have rubber hose or something over the sensor wires...... Still... maybe mount on the inside, but I guess you might have to notch the rocker area..

Dad wrote:

RE: "LOLOL Get with the times man!! 13in dia w/3 in spacers....that was in the Vanilla Ice days! Now it's 24 in diameter and 6 in wide ultra cheezy wagon wheels. hehehehehe"

HAHA.. 20 inch blades on the Impalaaa !!! (words of a Hip-Hop song i heard on the radio) insight into whats cool these days. Honda civics with 19inch rims !!! Escalades with Ox-cart like chrome wheels !!! Chevy Silverados with flames paintjob and 13inch wheels (2 inches ground clearance... WTF ???)

20 inch spinners on a Toyota Camrys.

:-) tsk tsk tsk !!! I don't know whether to laugh or cry.