BicketyBam

I have Motive 3.90's and a Vortech Mongoose kit from MPH. A while ago someone asked me to give my impressions of the combo.

Let me begin by saying that my gears whine more than a 3 year old looking for candy. The guy who put them in (I have 2000 miles on them now) is going to try and adjust them to remove the whine, and I'm praying it gets better. He originally spent the better part of a day putting them in and when I picked the car up he told me the install was nghtmarish. When I was at MPH they said that they won't deal with Motive gears because they are a pain in the ***. He said he spent all day trying to get a set right and it was a nightmare (sounds familiar). But then again, I know there are plenty of people with Motive gears that have no issues at all. I also read that 3.90 gears are difficult to install in the Mustang, but who knows.

With that being said, I really like to 3.90/supercharge combo. 1st goes by real fast and if I just slam it into second (assuming I avoided major spin on the launch) the tires will break free, so I have to be carefull. I'm running Goodyear Gatorbacks for now, but will be switching to some sort of 315/35 drag radial very soon so I should have less wheel spin. What I really like is 3rd and 4th gear acceleration. You really feel the pull. When I am in 5th on the highway doing 65-70 and I drop it into 4th and nail it, I get put back in my seat. I don't think running out of gear at the track would be an issue either as I had the car up to almost 120 in 4th and with the rwhp I am running now that will be fine for a 1/4 run.

All in all, I think 3.90's are a great gear for a s/c car with 400 rwhp or under. With more hp, it might become a problem. I'll let you know when I build my bottom end and jack up the boost!

jdaniel

Well just a little insite... MDValdosta had 4.10's in his before the blower. Then he dropped down to 3.73's and was un satisified. He went back to 4.10's and ran his best times yet with them, which was an 11.4 and a 1.5 short time.

I would do 4.10's if you go with the centrifugal. 3.55 or 3.73's at he very most with a positive displacement blower.

JHonor

Bickety, I see you have 135k on your car. You still have the stock shortblock in it? How long has the supercharger been on? I have 82k on my car and I want to boost it, but I was curious how you do with the high miles. Thanks

mdvaldosta

folks say 3.90's are a pain because Ford doesn't make them, thats all. All gears are pretty much made of the same materials... nothing wrong with Motive. Folks recommend FRPP gears because their cut to the same tolerances as your factory gears, meaning that most likely you wont have to setup the rear end as long as you stick to Ford parts. Pretty much any numb nuts (like me) can install Ford gears with no problem, but it takes a good rear end man to put non-Ford brand gears in because they have to be shimmed properly with the right tooling. Most places just eyeball it and check the wear pattern on the ring gear, well thats fine for functionality but not for preventing noise.

BicketyBam

Shortblock is still the original [sm=signs007.gif]. I just had the blower put on by Modular Powerhouse in GA. The high miles on my car is one of the reasons I went there (that and they are the best!). With Tim at MPH, you know you are getting a good, safe tune. 95% of the miles on my car are pure highway miles, and I never beat on it....until I got the blower [sm=icon_rock.gif]. I've been hitting it hard since and nothing's broke yet. I am a realist though. I understand that at some point something will take a dump and then I will have perfect excuse to get a shortblock from MPH and jack up the boost!

BicketyBam

I called 2 Ford dealerships today to see what they would charge to change the gears - labor only. Both quoted 8 hours at a $90+ shop rate. Thanks, but no thanks, MPH charges $250.

mdvaldosta

Screw Ford, MPH is the best in the country. Good choice.

andy98gt

does MPH have a website?

mdvaldosta

modularpowerhouse.com