BillyDaKid

My V6 5speed has a 3:31to1 rear axle ratio. In heavy Houston stop and go traffic, I need to accelerate in second gear frequently from very low speed. My mechanic friend says I need to go 3:55 to 1 or 3:73 to 1, to get more power in second gear. Is 3:55 enough? Is 3:73 too much?
Also how do I find what size Ring & Pinion to order?
Thanks,
BillyDaKid

BillyDaKid

My guess is it's a 7.5". that seems to be the norm for the V6. I'd like some feed back from any of you that have changed to the 3:55 or the 3:73. I expect MPG to suck, But everything is a trade-off. Please let me know about RPM's. I don't want to always be over revving the motor.
Thanks,
BillyDaKid

akdoggie

I don't know if you ever got your answer, but I'll throw in my two cents.

I have a 07 V6 Mustang with the 3:31's on a 7.5 axle assembly. I changed out my 3:31's without limited slip for a unit out of a 04 Ford Ranger with 3:73 and locking carrier. The Ranger had only 17k on it, so the gears and carrier were like new. The set up was simple and the pattern ran in the exact pattern as in the Ranger. The difference was staggering. It was like I got another 40 hp to the wheels. The take off set you back like a V8 off the line. My rpms were about 2000 at 70 before, now they are about 2400 at 70. My fuel mileage was about 2 mph less per gallon on the highway, and about 1-2 better in the city. The car seems to act better taking off in city traffic with the 3:73's over the 3:31's.

I ran this set up about 7800 miles, before I came across a 2011 8.8 with 3:73's for $400. That I couldn't pass up. I sold my take out right afterward to another Mustang owner and he loves the difference in his manual v6.

I hope this helps you out with your decision.

timberwolffxdl

what was required to swap in the ranger rear rear? Same question for the 2011 rear

akdoggie

The Ranger is just the guts from inside the axle assembly. You have to set it up into the V6 Mustang rear housing to make it work. And that only comes from the light duty Ranger's. They usually came with 7.5 rear ends, where the V6's usually have the 8.8 rear ends.

As for the 2011, it was plug and play. Nothing was different. I reused my Bullitt springs on the 2011 set up and had no problems at all. The 2011 came with a set of the FR500 lower control arms (silver painted from Ford) so i left those on the housing when I installed the assembly. I had FR500 LCA's already so I gave them to the guy who bought my old rear axle assy. The 2011 comes with the Cobra flange already, so you don't have any items to have to switch. The brakes bolt right on, as well as the shocks. It took me, on the ground, less than 3 hours to make the swap. I could of done it faster, but I took the 2011 swaybar and repainted it before reinstalling it. Oh yes, the 2011 has a heavier sway bar than the 05-09 Gt's does, so it is lots heavier than the original Pony V6 swaybar.

Anyways, the 2011 is a direct fit, where the Ranger is take apart and reinstall (set up also so you don't get clunk or excessive backlash or whine. Hope that helps you out with my set up.

BillyDaKid

Thanks for your reply. I began to think no one had done this. I have found several Ranger rears with 3:73 gears. They want to know what size brakes 9" or 10". since I'm only going to use the carrier and the ring and pinion, are brakes a factor? Also salvage yards list the 7.5 in a v6 and 4cyl.
Thanks again BDK

akdoggie

Sorry. I haven't been on to answer. As far as a Ranger, either the 4 (2.5L) or V6 (3.0L) can have the 7.5 ring gear set up. Mine was a 3.0 V6 model. Most with the 7.5 are really 4 cyls. Any with 4.0 engines or the newer model Rangers, with V6's went to the 8.8 rear axle. As far as brake size, the 10 inch are usually on the 8.8 and the 9's on the 7.5. If you have a problem with finding a good set of 373's and a LS carrier, PM me and I have one setup I would work with you on. Good luck with your project. I know I love the difference with the 373's over the 331's.

07 Boss

If you are accurate in the kind of driving you do you will probably see an increase in fuel mileage. Not sure how you would over rev the motor. The motor doesn't go any faster than it did before. You have a rev limiter from the factory, you can't over rev it.

As far as RPMs at any given speed, just add 12.6% and that should tell you what your motor will be spinning.