All right. I need help from those who have changed from the stock gearing in their s197 mustangs. 1. Which gearing did you go with? 2. Did it change your gas mialage? 3. How big of a change? and 4. How much of a difference do you feel?

All help is greatly appreciated.

Thanks

 

Went with a FRPP 4.10's. Yes it changes the mileage, I would say a 10% to 20% reduction depending on your driving habits. Yes, you notice the change in performance off the line and really does not affect top end.

A bit of advice, don't skimp on the installation. I had a lot of aggravation with the gears vibrating at high speed. I had to have them installed three times (went through 3 gear sets) by three different shops including JBA, Ken Grody Ford and finally a local driveline shop got them right. I went through an aluminum driveshaft along the way trying to get the vibration out. Got my money back from JBA and returned the Powerhouse driveshaft. Would I do it again? Absolutely!

Good Luck!

 

https://mustangforums.com/m_3043943/tm.htm

 

I'm am too trying to decide between 3.73 and 4.10s. After doing a lot of reasearch, I have decided to go with 3.73 gears.

Reasons:
1. I still do a lot of highway driving. I average anywhere from 65 to 80 MPH on my daily commute. So for this MPH range, the RPMs in 5th (manual) will be between 2000 and 2500 RPMs. Mileage should not suffer more than 1 - 2 MPG.

2. At 65 MPH and above, I will be out of the dreaded drone range for stingers (love the stingers!). Anything under 65 MPH, I can cruise in 4th to stay out of the drone.

3. 3.73s are a bit lower than the optional 3.55s, making my Mustang faster than any stock Mustang on gearing alone (not to mention the other mods).

Note: This is a daily driver. If I was going to take this car to the drag strip, I would definitely get 4.10s.

 

Also,

4. I may go FI in the future. I have heard that 4.10s are a bit low for supercharged applications.

 

I read it's rare for gears to cause a vibration, what kind of vibration did you have with the first two sets?

Maybe the first two guys installed new pinion bearings with the old races.

 

I'm running 4.10s and I do 90% hwy driving. My mileage is about 22-23 mpg. Today I filled my tank up and my est range was 373 miles to E. Thats also cause I've been pussyfooting it a lil bit lately by driving the speed limit on the hwy but I still smash it at least 3-4 time a week. My buddy is running 4.10s with his procharged GT and has no tracion issues in daily driving or even when he steps on it a bit. Twin screws S/Cs and turboed cars may have more issues. IMO at a very minimal 3.73s should have been standard for the manual cars.

As far asgear whine stick withFRPP gearsets, authentic sets not motive sets. That can only help. But you may still get whine anyway. Last week I had a trutrac installed and it cured a lot of whine I had which wasn't much. Today I installed my spydershaft and now it almost all gone. 99% quieter than it was two weeks ago.

4.10s FTW!!!