opinions on rear gear ratios

[thexrcist68]

im ordering gears for my cougar and i wanted to get some input on what a good ratio would be. its a 8 inch with 2.79s now i wanna go at least 3.8 but was also considering the 4.11s to take advantage of the fact my engine has a lot of top end. its only driven occasionally and around town so mileage isn't an issue, but i'm worried the 4.1 might be too low
so what do yall think

 

[blown65]

If your not driving much highway stuff at all, then 4.11 would be fine, if its some mix then 3.89 is a good choice. I drive my 4.56's all over town and they dont bother me, but it never sees the freeway where I life so I could care less.

 

[SadbutTrue]

With a C4 I wouldn't want more than 3.55s. When I had my C4 I put in 3.25s. They worked okay but that was with a mostly stock engine. In an application like yours, I might have been willing to go 3.73s or 3.89s. 4.11s are a lot for a C4...

With my T5, I now kinda wish I had 3.55s or maybe 3.73s. With my heads/cam, it'd be nice for the gears to be a little more 'rev-happy'. However I'd have to get quieter mufflers if I did that, the Flows I have now already are a bit too loud on the freeway even with 3.25s.

However, my mustang has always needed to be at least a semi-DD. It sees freeway use, needs to get decent gas mileage, can't overheat and doesn't have a $1000 radiator setup, etc... so 4000 rpms at 60 mph wasn't acceptable. For your purposes, it might be.

 

[blown65]

Mine had 3.89's since High School with a C4. It worked just fine with no over heating. Its about 3000 rpm at 60mph. Was that way for about 4 yrs as my daily driver.

 

[thexrcist68]

thanks for the comments, goin with the 3.8s but just out of curiosity is there a noticeable performance difference between the 2 doesnt seem like thered be a whole lot

 

[thexrcist68]

btw blown 65, your car sounds awesome, im hoping to build an engine like that for my capri one day in the distant future

 

[jcode68]

I went from 2.79 to 3.8 with my T5 and the difference is dramatic. I think it's a great ratio for all around driving situations.
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[blown65]

ya, mine was 2.79's way back in the 8" before I blew it up. LOL Going to 3.89's is night and day difference, especially on a mild build. Not sure what your stall of your converter is, but having the gears with it is going to make it even more noticeable IMO.

 

[thexrcist68]

it stalls around 3k, and i just ordered the gears, cant wait to put em in and go for a test run, hopefully they'le help the trans run cooler too due to the tc slipping less