Rear Axle Gear Ratio

[Frasers73]

I'm trying to figure out what I want to run.

Please let me know why you picked the ratio you did or why you like what came with the car.

Thanks!

Jon

[nova68]

i run 3.90s in my ford 9 that i put under the car. I like running these becasue i can still drive on the street and race. I also run a th-350 my motor is pretty built too. if you just want to run street and race alittle i would go with 3.73s

[AlmostStock]

Transmission and tire diameter should be considered when choosing a rear axle gear. Larger tires will effectively raise the ratio, just like if you installed a higher (lower numerically) gear. My Nova runs the stock size tire and 3.08's, and with no OD it pulls around 2700 rpm's at 65 mph. This is just about right for me, it just depends what you want. If you run an overdrive then you can get away with a lower gear for more off the line power, while still keeping highway rpm's reasonable.

You also need to consider intended use. How much highway driving will you be doing? Taking long road trips at 65 mph and 3500 rpm's would suck for many reasons. Then again if you're just doing the cruise night thing you can go wild!

[MT-2500]

Originally Posted by Frasers73

I'm trying to figure out what I want to run.

Please let me know why you picked the ratio you did or why you like what came with the car.

Thanks!

Jon

You need to match your end to the job you are doing.
It sometimes takes the right rear end to get the job done right.


What are you trying to do with it?

Tips on getting a good answer to your questions.
People trying to answer your question do not have a crystal ball.
So give them all of the info you have like year make and model and engine and transmission.
Also service cars engine and transmission service history or any recent repairs or problems.
Also a description of your problem and what it is doing or not doing.
If you have codes give up the code no.
And remember a code does not say replace the part but only points to the problem that you have to check out.
So to better help you give up all of the info you have on it.
MT

[Frasers73]

I have a '73 4 door with a 350 V8, TH350 tranny and an unknown gear ratio at the rear. I believe stock wheels (or close to it). I'm trying to build a cruiser, probably a 50/50 split city vs. highway driving. I do go to the cottage occasionally with seadoo's in tow.

I don't plan to race this car, but I would like to embarass my brother-in-law and his over-rated '95 mustang!

Any suggestions!?

Thanks

[Mines69Olds]

When I bought my car it had 4.10 but I'm probably gonna switch it to 3.73 b/c i hate that kinda gas mileage man...

[450HP]

What are your engine plans for the car?

If a mild 350... I'd go with 3:55s... if a mild to wild 350... I'd go with 3:73s.

Much more than that, it'll turn into more of a weekend warrior.

Scott

[big dwag]

I run 4.10s in my 75 nova 355 roller motor 350 trans/ with trans brake because of the tire size. And only run it at the track maybe twice a month.

[oilcanharry]

I have 3.32s. Great street. Highway mileage is horrible. Want a 200R4. Depends on stall speed also. (bro-in-laws, kick his b@tt)