78 nova rear gears

[lloyd tucker]

I need help folks. I'm new at dirt track racing. I race on a local 3/8 mile high banked dirt oval. I'm racing a 78 Nova, 305 2bbl 3 spd auto completely stock. We're allowed to change rear gears (no positive) but no motor modifications. They drench the track with water before this particuar race so it is the worst imaginable scenario but extremely fun.

Is there any way of telling what gears came in this type car without pulling down the rear? There is no tag on the rear. What gear should I put into this rear end & what kind of vehicle should it come from?

I've been told I should run a smaller tire on the inside of the car. The outside tire is a 205/70/14. What size tire should I put on the inside to produce the best results?

What kind of tire pressure should I run on the tires to produce the best results? It appears other drivers tires are fully inflated. (no slack)
I'd appreciate any help anyone can offer. I know there is someone out there that can help me. Thanks in advance for your help.
LLoyd

[miltystu]

Originally Posted by lloyd tucker

I need help folks. I'm new at dirt track racing. I race on a local 3/8 mile high banked dirt oval. I'm racing a 78 Nova, 305 2bbl 3 spd auto completely stock. We're allowed to change rear gears (no positive) but no motor modifications. They drench the track with water before this particuar race so it is the worst imaginable scenario but extremely fun.

Is there any way of telling what gears came in this type car without pulling down the rear? There is no tag on the rear. What gear should I put into this rear end & what kind of vehicle should it come from?

I've been told I should run a smaller tire on the inside of the car. The outside tire is a 205/70/14. What size tire should I put on the inside to produce the best results?

What kind of tire pressure should I run on the tires to produce the best results? It appears other drivers tires are fully inflated. (no slack)
I'd appreciate any help anyone can offer. I know there is someone out there that can help me. Thanks in advance for your help.
LLoyd

If I'm not mistaken the axle ratio should be on one of the axle tubes. Can you use after market ring and pinion.

[nova68]

goto www.novaresource.com

[NOVA71]

OK, you can get a fairly accurate guess on what gears are in your car if you jack up the rear and put the trans in nuetral, mark a line on the inside of one of the back tires and a line on the driveshaft. Now just rotate the back tire one full revolution and at the same time count how many revolutions the driveshaft makes. Eg. If the driveshaft makes almost 3.5 revolutions than chances are you have 3.42 gears, if it makes just a little over 3 revolutions probably 3.08 gears, etc,etc. This method has has been bang on for me every time. Or if you pull the cover off the rear end, just rotate the gears and you will see a number on the side of the ring gear that will look like say 41:11. Just divide the 41 by 11 which equals 3.73. This is your gear ratio Or say 41:12 would be 3.42 etc,etc.

A 78 Nova should have a 8.5 inch 10 bolt rear but may have the smaller 7.5 inch version. Look at the bottom of the center section and see if it has 2 squared off edges or 2 little curved points. The 8.5 inch will be squared off, the 7.5 inch has the little curved points. If you have the 7.5 inch take it out and THROW IT AWAY and find a 8.5 inch. If it has the 8.5 inch you should be able to get gears out of 70-81 camaro/firebird 84-87 buick grand national/regal 77-87 K10 K20 truck 4x4 front axles, 80-up truck/van rear axles and many other rwd chassis. I beleive thereare only 2 different carriers on that accepts 2.56 and down and on that accepts 2.73 and up but I'm not 100% sure of this.

As for the dirt track racin I can't help you with that, sorry.

[bobss396]

See if anyone has a RPM calculation chart for your track. Basically you multiply the transmission gear that you run by the rear end ratio to get your overall ratio. You select what RPM you want to run first and work it backwards. I would run the automatic in 2nd (use 1st on restarts), so you have to know that also to select the rear. Are you allowed to run a Ford 9" rear with a spool in it? Those are easier to set up than a Chevy rear and eliminates the "c" clip problem. But do get the axles redrilled for the Chevy bolt pattern.

Stagger... let me see. The higher the bank, the less stagger you need. I would start with an inch of stagger, but you might want to go as high as 3" on dirt. Make up a couple of "stagger sets" and go out early for practice. Get a thin 10 foot tape measure and measure the tires around the center of the tread to get the circumference.

I always ran the left rear down as low as 8 lbs on asphalt, but kept a tube in that one only to help the tire stay on the rim. The LF I ran around 22 lbs, RF around 28, LR around 30. This worked for asphalt, you should really ask one of the guys that runs with you what they do. It is in their best interest to have you running as best as possible so you don't take them out accidently with a poorly set up car.

Bob