The stang II

Yea so i have an auto '78 stang with the stock gears and no posi : ( .... Well I went wot in drive 1 at about 15 mph and even though I went to 50 mph in a heart beat, it felt realllly slugish. An 03 cobra was infront of me and pulled about 5 cars on me.

My question to you is what gears would you put in a 8 inch rear end? And what kind of posi or limited slip would you put in for cheap that will work?

It's that time where I need to go faster.

USMCrebel

well just b/c the cobra put that only means he's faster, and odds are he was even trying with an auto 302 only putting down like 200 hp, so dont feel bad he's only got like 200hp on you.

TexasAxMan

I think the concensus is 3.55:1 on gears, trac-loc for the diff.

jspagna1

Agreed. You will be very happy with the 3:55's. If you HAVE to do a lot highway driving then go with 3:25's.

67mustang302

Yeah, 3.25's or 3.40(prolly what I'll go with) if you do more highway driving. and yeah, 03/04 Cobras have quite a bit of power bone stock. You'd have to have a pretty healthy 302 to keep up with a Cobra, and most of them are no longer stock

The stang II

My car ran a 8.8 in the 1/8th with everything in my sig with a clogged fuel filter. stock tires you know the works. So it's not the slowest. It's actually quite a bit healthier than most think. I run better times than new edges with exhaust and intake. Run about even with a stock sn197.

But I was thinking 3.55's too but didn't know. But that trak loc is good?

Hawkins 812

If you look at it like an order of frys, a 3:55 would be medium. LOL if that makes any sense.

[sm=icon_rofl.gif]

TexasAxMan

Didn't to me .........

69FECoupe

Before you choose a new gear you need to know what you have now. I bought a new 74 Mustang II 2.8 V6/automatic and it came with an 8" with 3.89 gears standard as did my best friends 74 Mustang II 2.3 4spd. And that was with no OD and little bitty C70-13 tires.Anyhow, you really need to know where you are starting.

THUMPIN455

So you are running about where a stock LS1 runs in the 8th.(a couple LS1s have gone 11s full weight, with stock internal engines, only bolt ons, and 2.73 gears with an automatic trans) Thats pretty good if its a relatively stock 302 with bolt ons. 03/04 Cobras run a couple tenths quicker sometimes, but the way they are setup its more of a top end or from a roll type car. To get quicker from a stop, like a drag race, you do different things than you do for from a roll. deeper gears, like 3.55 will hurt you after the first 60 feet, comapred to a 3.00 or even a 2.70. Once its rolling the deeper gear is at a disadvantage.

Ok I know it doesnt sound right to small block guys. What you need to do to keep up with the Cobra (that has a blower) is make more power. Throw a Tim Allen at it and grunt some more. Swapping to a deeper gear has less impact as you increase the power. Where you are now you might gain .2 or maybe .4 in the 1/4 by swapping a stiffer gear in, but at the same time, depending on your tires and useable RPM range, you could slow down MPH wise in the 1/4. The shorter track of an 1/8 doesnt show this as much as a 1/4 does. When you go up in torque and HP the engine can push a taller gear easier, that results in higher mph, more time in each gear, and a quicker car. An extreeme example of that is a Top Fuel dragster. They are limited to no lower than a 3.20 gear, in other words they can go to a 3.50 or 4.11 but not a 3.00.

A bit of math shows with a 3.20 gear and assuming the tires grow from 32" tall to around 40" tall on the big end, they need 8000 rpm to reach 334 mph. Conversely if you have a 4.11 gear in it you will need 11,000 rpm to reach 320 mph.

From the personal experience department, I hav a friend who has a Maverick with a healthy 302. He runs a 4.88 gear in it with 26" slicks. I had 4.10 gears and 29" slicks. He ran 12.8s @100 I ran 12.0s@110 in brackets. He would be two cars ahead of me until the 1/8th mile, then he would stop accellerating and I would pass him right about half track. if he had dropped the ratio down he could have gotten the car to ET much quicker, but he liked the 1.4 60 fts, even if he ran out of RPM and slowed down at half track. Sure the Maverick was brutal off the line, but it was a full second slower when mine wasnt detuned to avoid the roll bar rule at 11.99.

My engine made all its power under 5500 rpm, his was a high rpm engine, so I would run out of RPM about 1000ft on the track, but still turn 110 mph. I was also in a car that was 1000lbs heavier than his, and making vastly more torque.

Swapping gears will make it feel faster, actually more violent, but it wont go much faster with just a gear swap. You can gain more by making more power and keeping the gears you have, especially in when going from a roll.