im running a 3.0 right now because i had a 4.11 with a 351 c4 and it was wound out at 55 so i tossed in the 3s and am gonna order 3.55 from speedway unless someone knows someplace else with better prices

 

Yep. For a daily driver you will be winding out those gears. Need more info though , like trans ratio, etc. You will , at least need overdrive to help keep the RPM's reasonable. There are SO MANY variables for your setup that I would suggest you talk to some drive-train specialists in your area. Even some of the 'speed' shops should be of help. As for Summit, they have a huge assortment of 9" parts, you may just be shopping in wrong section.
Since you post as being a 'NOOBY' what exactly are your intentions with the car and why the motor choice. These are things you should have thought about well before you started just throwing parts at the car.

 

You'll probably hate 4.11 gears without an overdrive transmission. With your C4, the engine will be screaming at highway speeds so unless you don't want to drive faster than 50 mph, go with a higher ratio. 3.80 is probably still pushing it for a non-OD transmission. Consider this - most people swapping gears in later model Mustangs (all with overdrive transmissions) usually go for 3.55 or 3.73 gears. My '99 Cobra has 4.30 gears and a 5 speed and I turn close to 3000 rpm at 70 mph.

If you plan on swapping to an OD tranny in the near future, you could use either ratio, but the 3.80 would be a better choice. My '66 has 4.11 gears, but I also have a 6 speed transmission with a .50:1 6th gear, which means my engine will be turning at half the RPM in 6th gear that yours would with a C4 in 3rd gear (plus or minus a little due to tire size differences). If you have no plans for an OD tranny, you are best off staying in the lower half of the 3's (somewhere in the 3.25-3.50ish range). Before you decide on a ratio, use one of the RPM calculator tools you can find online - you can plug in your tire size and gear ratios and it will tell you what RPM your engine will be turning at a given speed.

Finding parts is easy. I personally like Randy's Ring & Pinion. I bought all my rear end parts from them. You can get individual parts or a whole overhaul kit. As far as your rearend, if it's got a removable center section (3rd member), it's a 8" or 9". If you can get a socket on every one of the retaining bolts, it's a 8". If a socket won't fit on one of the bottom bolts (necessitating the use of a wrench), it's a 9". Other than that, they look virtually identical to each other. If you are swapping gears, it would be a good time to add a limited slip differential if your budget allows. There are many choices out there - I am using a Yukon Dura Grip. I wouldn't even consider a junkyard for used gears - the chances of you finding anything other than the stock ratio are pretty slim.

 

I have a 68 vert C code C4 with stock rear 2.79:1. 4.11 would be nuts unless daily is a couple blocks to church! IMO 3.25:1`is good 3:50 is radical wild winding!

This not a NASCAR 9000 RPM engine!


Slim

 

Im running a fresh c4 with shift kit w/ 3.25 gears - RPMS around 3200 or so at 70 MPH... it's fun to drive but if I had it to do over again - I would have invested in an AOD w/ 3.8 LSD. Anywho, summit also has the kits you need or you can call Randy's and they can give you good advice...

 

I swapped my trans to an AOD. I just ordered 3.55 gears for it and I plan to use as a daily driver. Talk to TJ he is great to work with and very knowledgeable. Lots of people here have ordered gears from him. Ford Eight inch Rear End Mustang or Street Rod 8 " Trac Loc Posi 550HP 9 | eBay I played with an RPM calculator working out where I wanted my cruising rpm. With my AOD 3.80 gears were at about 2800 rpm and 3.55 put me close to 2300 at around 70mph. So I went that route. I'm betting 3.25 is max for that c4 for a daily driver. TJ will let you send the 3rd member back to him and change ratio for a small fee, and he wont charge you shipping when he sends it back. He's really a nice guy to work with. I will be dropping my 3rd member in this weekend, weather permitting.

 

I have had two vehicles in the past that were daily drivers and had 4.10/4.11 gears in them. The first was a truck without overdrive and first gear was "granny gear" so basically all I used was 2nd-4th. The truck never bothered me, it had long tubes on it so was not super quiet but just did not bother me and perhaps because I was simply younger at the time. The second vehicle was a Fox body Mustang with a 5-speed transmission so had overdrive and I just did not like it at all. It was not really cruising speeds that bugged me, it was the fact that a lot of intersections with normal driving I was doing one or two gearshifts, meaning I was in 2nd or 3rd gear before out of the intersection. Now I was 6-8 years older when in the Mustang so it could just been age causing me to tolerate less. On that Fox Body I swapped to a 3.31 gear and was very happy with my choice.

Gear selection, not for optimal 1/8 or 1/4 mile drag times can be a tricky slope. What one person is fine with can drive another person batty. I think though many, many, many people will say no to the idea of 4.10ish gears with a 3-speed auto in a daily driver. For my current daily driving needs it would not bother me at all since would be an automatic and not having to deal with constant manual gear changes.

 

My '67 had 4.11's (289 c4 combo) in it most of the time I drove it and I loved them. I even drove it back and forth from Houston to College Station like that. I removed the 4.11 to have some work done and put a 3.00 pumpkin in it and hated the way it drove. To each his own I guess.

 

I went with 3.70s...but I have OD too

 

4.11 are crazy for a DD with a C4. 3.25 are a better choice unless your going with a AOD. My two cents

 

Hey Sancho! Looks like we agree!


Slim

 

Ok by nooby I meant that I hadnt been doing this for as long as yall have, i do not have an aod c4 so that answers that... i understand how everything works and do most of my work myself. I want something that I can daily drive but I want to be able to get on it from a light and I want to feel it. .. the choice on the engine was a screw up situation... I rebuilt the 289 and dropped it in the car then my poor dad rounded my cam lobe torquing my rocker arms. .. long story short we knew a guy ditching his project and had an E303 and iron windsor srs Off a 351 ready for a roller setup... so we bought that for $150... so all I needed to buy was roller rockers and lifters with guides... so that is why I have a frankenstien motor that every one flames me about.... I was told that with my setup with stock gears and stock converter I wont even feel a difference between stock and now.. so that's why I wanted input on a new rearend...... all ive gathered is some people say I need 3.25 and others saying 3.80 is way to much....

 

.... all ive gathered is some people say I need 3.25 and others saying 3.80 is way to much....

Go with the 3.25 - its a nice balance using the C4.

If you go with an AOD - then a 3.8 is fine....

 

Haha my 99 cobra has 4.3s and its my daily. Someone put them in there before me and I sure ain't changing them. It's my dd and I've already drove 8k miles like this

 

Does your Cobra have the T56 ,that would basically be double overdrive gears? Big difference.
Sorry 'hunter' if you took offense, after all it was you that posted 'newbie'.
Sounds like you're sticking with the C4 and looking for minimal change, therefore I would suggest nothing larger than a 3.50:1 gear set. Which Summit carries (ring/pinion) for about $190.

 

If you want to make a big difference, use 3.50 gears. I wouldn't go with the 4.11 unless your commute is under 10 miles and you rarely go on the highway. My mother had a 66 K code with a 4.11 locker, and it was great around town, but kinda sucked on the highway from engine noise.

 

Tire size makes a difference too. I have a C4 with 3:89 gears at 65 I'm a little under 3000 RPMs

 

I have a restored kcode coupe and I took the 3.50 factory gear out and used the 3.25 ratio with 14 inch tires-this allows me all the street wailing I want, yet when driven at highway/freeway (60-70) speeds it runs 2600-2700 rpm.

 

if you have a 8in rear end speedway motors has a better selection of gears for it then anyone i can find if it's a 9 speedway summit jegs they all have what ya need

 

I'm running 3.40's and its the limit for c4. I am looking for an aod so when that time comes, in goes the 4.11's.

 

Not all 14" tires are the same height. 14" is the inside diameter. You can get tires that are 26,27, or 28" tall. There are many sizes and it all comes into play.
I've got tall 15" with 3:89 gears. I'm running 2700 2800 RPMs at 65.

 

3:25 to 3:55 with a C4. Sometimes, more is not better.

 

I'd go at least 3:55 but that's just me and that's the way I roll. If I had to commute that might change. That cam needs lower gears to get off the line. You will need to lock up the rear also.

 

I have 3.50s with 14 inch wheels. I have considered 3.80 a couple times. Still might at some point, even with a c4. That said I live in a small town with no 4 lane highway for 30 miles. I really dont have a desire to drive distance on the highway, I have a truck and car trailer for long trips. Mostly I cruise around town and to the local lake and car shows usually not more than 30 miles. I like to smoke the tires whenever. It depends what you want and expect of your car. Make it run the best, the way you want to run, it so you enjoy it to the fullest.

 

I got the t45 in my cobra.

 

My 2 pennies.
I have a '66 GT350 and I run 3.0'"s now with the 4 speed. I love it that way. Yes, it's not real fast off the line, but at my age, I don't care. I just like to run on the freeway at 65-75 with out the engine screaming. Yea, it comes with age. As a young lad, way back when, I had a HiPo fastback and I use to run 4:56's on the street as a DD. Didn't think any thing of it at the time, worked just fine.

Getting ready to install a C4 and I think I might put in 3:25's, but I will leave the 3:00's for now.

So................ As a DD, I would Use 3:25-3:50's. I assume you have an 8" under the car right now, so you should be able to find several "pumpkins" that you can swap out and try. It's not an exact science and you will have to find a ratio that YOU are comfortable with. Good luck.

Steven

 

Dude its your car and we're just trying to give you numbers for a livable daily driver. If you said it was a weekend worrier I would of said 3.80-4.11, but for all around fun drive 3.25 gives you the best of both worlds. IMO
That said, I would recommend Motive Gears and not Summits Richmond Gears. I installed a set of Richmond Gears with bad results.