Now to decide. 3.80 or 4.11

I'm having a hard time deciding between 3.80 or 4.11 gears. Its a 302 with a c-4. I don't think it will get all too much time driving on the highway, just mainly cruising around. Any input would be great.

Also, so I get the correct posi, I need to get it for a 28 spline axle correct?

 

Yes you will need 28 spline unit.....

For me to suggest a gear I would like to know the following....
Tire Height give me a brand and size and I can look it up...
Also Your cam specs and engine combo in general....

 

Thank you.

I'll get all the info for you when I get home for lunch. The wheel is a 15in but I forget the tire wall size.

And I bought the cam so long ago that I don't know the specs anymore. I went for an aggressive Crane cam. And I don't remember where I put the cam card either. Sorry

Edit: Engine is a 302 from an 88 Mustang. Has rpm performer II intake, 650 holley, 1.6 roller rockers, crane cam, hooker 6901, ported stock cylinder heads

 

I'm pretty sure the height was 55 or 60

 

That number is not the height it is part of the aspect ratio or percentage...

the easiest way to think of it is like this if you have a tire that

lets say you have a 20550r15

205 is the a measurement of the width in millimeters. the 50 would be a percentage of the side wall compare to the width.

R stands for Radial and 15 is the inside diameter

So I need the whole size

 

Oh ok, my fault.

225 55 r15 from what I remember.

 

Had 4:11 in mine for years and years till I broke at the drag strip. Put 3:79 in it and I like them much more.
Dan

 

If your car is to be used on the street at all - go with the 3.80 gears.

 

I have 3.80 and can use it on the highway. But it is revving pretty good, and I wouldn't want to do any highway cruising at anything higher than where it is...3500-ish at 65.

But on the streets, under 50 mph in town, I would love to have 4.11 gears.

My tires are 255/60r15 running about 27" tall.

So I am not voting. You need to make a decision on what rpm you want to cruise at and at what speed, then decide based on that. If you don't mind doing 4000rpm at 60 on the highway for long distances, than go 4.11, but I bet you would get tired of it soon.

 

I have 4.11's in mine now with pretty tall tire, I have cruise the interstate for a minute and that was enough.

 

I'd go with 3:55s if your planing on sticking with the C4. If a overdrive is in the future, I'd go with the 3:80s.

 

I dont know all specs but i would lean toward 3.80

 

that puts you at around 25 inch tall tire....

Personally I would put 3.55 in it....

I had 3.40s with a 26 inch tall tire did great cruising and racin

 

I voted 3.80s.
The 4.11s certainly make a C4 more fun, but they make top end hellish, and your intake won't lend itself to 4.11s either. Every time I have used 4.11s, a single plane intake ran circles around even the E'brock RPM. Even the 3.80s might like a single plane better than a dual plane.

Anyway, the C4 has a high first gear, so 4.11s are nice for response, but sometimes it's just not worth it. I drove 4.11s on the highway everyday to and from work, when gas was cheap. It's fun as long as you don't have too far to go... My commute was only about 10 miles each way, and only half that on the interstate. No big deal, even on a daily basis.

I still vote 3.80s though. Even 3.40s/3.55s would be cool with a short tire and/or RPM dual plane.

 

After reading 5946's and ratio's responses having had experience driving 4.11s on the highway, I went ahead and voted for 3.80. Highway is not too bad with my 3.80s, but I tend to be the guy in the slow lane doing 60 in the 65, windows down, arm hanging out, enjoying the scenery and the sound of dual Flowmaster Super44s...Wish I had a radio, so I could complain about not being able to hear it over the car...