Rear Gears

[6Stang7]

traction has nothing to do with your rear end gear ratio.

OOOOOOOOO yes it does. I have MAJOR traction problems now with the 4.11's in the rear. It is so easy to roast them now that even when I do a start out in 2nd gear, I still spin them if I give a little too much gas.

 

[mustangman70]

3.00 makes a nice cruising machine, but you sacrifice 0-60 acceleration, 411 will get you off the line nicely but you'll toast your engine if you like the hyway.QUOTE]

Well no one answed me, i feel loved lol but can some one explain this to me? I want some nice gears but i also do a bit of interstate driving, (to tampa for car shows and such) and i dont want to be "toasting me motor"

 

[Route666]

If you want to go HARD at the lights, and don't care about your V8 doing 3500 rpm on the highway, get 4.11s. If you want to do a little more sedate 3000rpm at highway speed, you'll have to settle for something that's going to be slower off the line, like 3.89 or 3.70, or even 3.50, which still are pretty good for performance, just not as all out drag racey as 4.11s.

It all comes down to your opinion of what is going to wear your motor out. If you do over an hour per day of highway driving, you may feel 4.11s are wearing your engine out. You might feel however, that your engine is built to go 7000rpm all day, every day, and so 4.11s won't phase you. Personally I do think the number of times an engine has spun contributes to its wear state, but I think moreso that higher rpms under more load do more damage than lower rpms, or not much load. Also, I belive if you start an engine once, and it is never turned off for more than an hour or two, like some taxi motors are run, then wear will be GREATLY reduced, as the most wear occurs when engines are cold. What I mean by that is:

If you drive 30 min on the freeway within 5 min of starting your car every day after sitting for 7+ hours, they your engine will be wearing a lot. however,

If you do an hour of freeway driving within 5 min of starting your car every day after sitting for 7+ hours, then your engine wear will be approximately 115% of the wear of doing the above, because for the second 30 min, the engine is up to normal operating temp.

4.11s will increase the rpm of your motor at highway speed, but reduce the load on the motor. How much the load on the motor wears compared to the rpm of the motor is something that you have to decide for yourself.

 

[RajunCajun]

if your truely concerned about highway use use calculators and play with tire/wheel combos with rear gears and speed's to further determine if its really what you want.
For me with a 5spd final gear of .68 and rear gear of 4.11:1 on 245/45/17
70mph = 2558
65mph = 2375
60mph = 2192
55mph = 2010
One ive used the formula stays preety much the same

 

[12sec67]

if your truely concerned about highway use use calculators and play with tire/wheel combos with rear gears and speed's to further determine if its really what you want.
For me with a 5spd final gear of .68 and rear gear of 4.11:1 on 245/45/17
70mph = 2558
65mph = 2375
60mph = 2192
55mph = 2010
One ive used the formula stays preety much the same

tell us how high you are willing to rev your engine while just cruising down the freeway and at what speed!

 

[mustangman70]

To me, honestly, it dosent really matter what rpm i cruise aton the freeway, but it does if an hour or so evrey weekend on the interstate or highway will toast my motor. high way driving would usually only be on the weekend.

 

[12sec67]

To me, honestly, it dosent really matter what rpm i cruise aton the freeway, but it does if an hour or so evrey weekend on the interstate or highway will toast my motor. high way driving would usually only be on the weekend.

all around street gear 3.55's. if you want more seat of the pants performance go with 3.80's. the difference between these two is only about 250 rpms when doing 65-70.

 

[mustangman70]

Ok now were into to this, how do i tell what kind of rear end i have? I plan on putting a locking differential when i do the gears. Its a 70 coupe, do ihave the 8 inch rear end?

 

[RajunCajun]

the Easiest way is to write what the info on the axle tag is and decode it usely found on the carrier area held on by a bolt

 

[6Stang7]

Do as RajunCajun said and write down what your rear end tag says. Post it and I can decode it for you.

 

[ratio411]

...do I have the 8 inch rear end?

Look at the front of the pumpkin.
You will see 10 or so studs/nuts around the center section.
On an 8" rear, all are easily accessible, even with a socket.
On a 9" rear, one stud/nut on the lower side is hidden behind the pinion support. It must be removed with a wrench.
Dave

 

[65stang289]

OK do what I do dont use a speed cable at all put a big 5 inch Tach with a shift light in front of it. LOL no really my set up is like this I have not been able to tell how fast Iam going for over 7 Months. Thats why when the cops put speed traps with the radar thing out I do some passes at different speeds . I have 3.73 gears I like them at 2500 Iam doing 40mph and 55 Iam doing 3k. Now when I race I know 4500 and and up is above 70mph. 3.73 IS A GOOd all around gear you might go through more gas but so what.
This is my daily drive and when it rains it is time to play. When I did shift my auto(C6 with a shift kit now that is broke ) it would get sideways on me in the rain just taken off from a light doing 5mph burns the tires. IT is fun sliding in a with drum brakes.

 

[mustangman70]

I will get underneath it tomorrow and get the code.

 

[65racecoupe]

I should have gone to 4.11s. I have 3.89s now. My 70 MPH RPM is 2300, but I have Overdrive, ha ha ha ha. (best mod of ALL that I have done, and I have done alot)