So I never see any one talking about 3.90's. Is there something wrong with them or no one ever has any problems with them?

 

I'm kind up in the air between 3.90's 4.10's, and 4.30's for the 9" I'm gonna build over the winter.

 

They are fairly new for the 7.6, so there arent many out there. I think from a 3.73 it isnt a big enough difference, but if you have 3.42 it would be a nice choice for people who dont want 4.10.

 

I liked my 3.90's but when I blew it up I went with 4.10's i think the 4.10's are the best choice for a 6-speed. If I had an Auto I would go with 3.90's again over 3.73, people speak of less gas milage with those, but if you really care about gas milage I say go buy a hybread you yuppy...

 

A lot of people talk about specific ratios. 4.10s for M6s, 3.73s for A4s etc...You really need to look at your car individually. Look at your dyno, your gears in your tranny, tire size, trap speeds etc...You want to idealy be in the Peak power band going through the traps. A tire change will change that as well as a gear. Weather you run N/A or nitrous will change this too. Too much gear and you are too low in power range, too little and you will be looking for another gear. If you run N/A sometime and spray sometimes you need a middle gear with two sets of tires. Like 4.10s with 26s NA and 28s on the jug. This assuming you have a drag car. You may be better off with 3.42s in an AX car.

 

I don't know of anyone who offers them for a 10 bolt, if so please pm or link it up.

3:90s seem perfect for me and all mixed driving I do.

 

Motive makes 3.90's for the 7.6. Contact a sponsor that carries Motive Gear and they can get them.

 

The reason why I asked is because I ordered 3.90 for my TA. Will post up when I get them installed... on back order right now.

 

I've got 3.90 in my old school. I had 4.10's, there is very little difference between the two. I noticed maybe 5mph difference in highway speeds. ( th400).

 

Everyone just goes right to the 4.10's for m6's cause the 3.9's just arent worth it, you might as well just go 4.10's. Goin to 3.9s are like going to a small camshaft that you just replace with something bigger later. But i guess youve already ordered so it doesnt really matter. with 4.10s and +1 tires i only do like 1600rpms on the highway, its great. It really makes the 6th gear useable

 

Awesome thanks man


Why?
I mean I did the math out and how my car sounds on the highway will be pretty loud with 4:10s and just right with 3:90s, I know its only a few RPM but thats how it is I could get around it with +1 tires but that is alot more money then fact I could get what I want with 3:90s

I understand its a hair longer but seems like a good medien for 3:73s and 4:10s.

I really doubt i'll be doing more then daily with this car ever, or going with a big rowdey cam.

Is there really a good reason for me to step up to 4:10s other then asuming i'd want more?

Heck I am willing to give up a few tenths for lower rpms, I'd LOVE to stick 3:55s out back just a tad shorter but a nice hair

 

They arent worth it if you have a 3.73 already, but if you have a 3.42 or taller than it could be just the right gear.

 

I'll probably do 3.90's when I have the money. I would like to hear more about 3.90's vs 4.10's from people who have had both (performance, milage, driveability, strength, ect.)

Kevin

 

I run 3.90's (Motive) in my 10bolt M6 since adding N20 to the equation.........great gear for my cam only N20 setup. The 3.90's remind me of my 4.10's I ran a few years back... not much difference.

I ran 4.10's (Strange) in my 10bolt M6........ ok gear for cam only setup.... but highly recommend the gears below!!

I ran 4.30's (US Gear) in my 10bolt M6.........great gear for cam only setup. These 4.30's were like a night and day difference over my 4.10's!!

All of the above gears have been run on Nitto DR's 275/40 17"s

 

I've had 3.90's for about a year now, Scott@Driveline built my 9" with the 3.90's and i love it. i had 3.73's in my 10 bolt and decided to up it a bit with the 9"...plus i didn't want 4.10 as my car will soon be turbo and i don't want that big of a gear

 

red fury hit the nail finally. For lots of people like, who run nitrous and a cam, 4.10s will leave me shifting to 5th in the quarter. 3.73s would even be better then 4.10s but 3.90s put my motor right in the sweet spot.

What gears you go with all depends on your motor and at what rpms your making power at and what trap speed your running in the 1/4. Theres a lot to it when its a modded car.

 

F'it. Grow a sack and run 4.56s! I do, but on a 28" tire. I am actually thinking of coming down to a 4.10 again with 26" tires. Not sure. Winter project. The gear wines pretty loud so I have to take it apart anyhow to inspect it.

 

I run a 3.90 gear in a Ford 9" in my A4 car. It is the perfect gear for my setup. With the 3.90 gear the engine is turning 2400 rpm at 70 mph on the highway.