BaltimoreStreetMods

Ok all you guys out there that have already converted your v6 gears to 4.10 ratio and added the posi......... I am doing it for the first time.

I am fairly mechanically educated and experienced, but have never done this particular modification.

1) can I do it myelf and

2) any additional parts I am going to need to get the job done and

3) any tricks I should use whileI have the rear end open?

I have a stock 3.73 7.5" rear end and gears with no posi, and I have a 4.10 gear set and posi coming out of a 7.5" ford rear end.

I have heard of a cross-shank modifier and special lubes to use.

slegos888

first off unless you are a mechanic and know how to properly install gears dont do it!!! even some bad shops screw them up...and second if the rear is "stock" it doesnt have 3.73's it has 3.27's

BaltimoreStreetMods

ok thanks for the info...... I will still need to know if I will need any additional parts, what diff fluid to use, and.....

Does anyone know how much this mod is going to affect my 1/4 mi time? running mid 14's now.....

cobra232

if you don't know your way around the rearend, don't touch it. it demands far more attention to tolerances than a typical engine rebuild

just pay a tranny shop the $250 to do the install, and you will need a richmond gear insatll kit from summitracing.com part#RMG-8310451

don't even bother doing the gears without the install kit. you are just asking for disaster doing the rear yourself and the rear will probably fail not because the 7.5 is weak but because the gears wern't put in right

HRnB

I'm a good weekend mechanic and I decided after a few f*ck ups that I'll leave it to the pros. Trany guys are THE BEST!!!!!! Your guaranteed a guy that knows tolerances, as cobra said. And yes, there is a break in fluid and a final fluid that must be used. Take a look at my 4:10 install here. >>> http://www.cardomain.com/memberpage/450179/5

BaltimoreStreetMods

Thanks you very much, guys, for your input. I have decided that I will be better off having someone else do it.

Those pics help alot as well....... what was your top speed after the conversion? Don't suppose ya've ran a 1/4 mi with it??

I am curious what you are running, as we have basically the same setup... although I seem to have gotten lucky and gotten one of the rare 6's that outruns all the others. (don't know if that is becausse I ended up with one of the last stangs made in 04, and they had to use a diff motor - the 3.9 windsor - most were 3.8) Everyone says that they are the same, but I found out that the 3.9 has a longer stroke.... ran like an 8cyl bone stock, aside from top speed lol.

So far: Dual exhaust, CAI, BBK MAF, UD pulleys, Plat +4 plugs, new wires, thermostat, 17x9 street rims, 15x7 front/15x10.5 rear race rims, IAT mod, 4.10 + posi this weekend.

New stroker internals coming late may, procharger in the fall, then superchips (or similar) tuner.

and of course, the suspension stuff this summer, before the charger.

HRnB

Get the chip right after your gears. The gear will through off your speedo and hit your limiters too fast everytime your tires spin and what not. Plus you'll be much happy getting your shift points up to around 7k. Our engines need to be in the high RPM's to make use of it's power band. Remember, don't treat it like a V8. When I'm racing another car on the street, I shift at between 6000-6500 and I never let it drop below 4000. If I remember right, the stock shift limiter is around 4500 or less, right?

artisan00

booze - regarding what you mention about the limiter getting annoying - is that an issue when 'daily driving' or regular highway driving?

when (if) i get gears hopefully soon, will i not like them without adjusting the shiftpoints??

trebor - im not sure where you heard the 3.9 performs like a v8, but from what i hear (there are a bunch of threads on this site about them) they are the same as the v6 plus the longer stroke, which is what brings them up to 3.9 liters. but that .1 liters is not going to make it perform like it has 2 more cylinders.

HRnB

Raising your limiters doesn't change how you drive normally, it just lets you take your engine to a higher RPM when your racing someone. When you get 4:10's you'll know what I mean. With 4:10's, when you take off from a dead stop, first gear is very short on a V6 and you hit the limiter in a split second. Second gear on a V6 is very tall, which means it has a long range so you don't want to shift from first to second in a low RPM or second gear will dog you down through the first half of the gear. You want to hit second gear in your cars power band, which is at 4500 rpm and up. The stock limiter set point is purposely set below your power band by Ford for smooth shifting and economy.

PS, I think what Trebor was saying is that he beat a V8, not that his 3.9 is anything much more then a 3.8. I beat V8's quite often. I have a 4.8 V8 in my 02 Silverado, and my V6 Stang walks away from it. Of coarse V8's will always take a V6 in top end speed unless the V6 has forced air or something. I keep telling you guys, it's all in the launch. I'll keep telling you too until it's burned into your brains. [sm=smiley36.gif]
Focus on your launch when you mod your V6's and 2.3's and keep your races short. [sm=smiley20.gif]

artisan00

ok, so if i go ahead and get my gears to have some fun in regular driving, i can hold off on a chip without much issues?