I need 3.73 gears...these ugly 2.77 are killing me. The things I am doing before anything else is taking care of the most performance robbing aspects of tpi..intake and gears in my case. Whats the best way to go? A new..higher bolt rear end. A used rear end out of a v6...or get the 3.73 conversion for 9 bolts around 500 bucks? What has anybody else done?

 

Gears are always good, especially if you're stuck right now with 2.XX gears!

Personally, I'd at least install the gears in the stock rearend, along with a rebuild kit. Of course if you have money to spend, I'd get a nice Mark Williams setup

 

I put Yukon 3:73's and the installation kit into my stock 9 bolt. Love them!! I would highly recommend them.

 

Personally, I think I'd go with 3.23s or 3.42s. A TPI 350 motor would run out of steam too quickly with 3.73s I would think and would have MAJOR traction issues on the street with the steep first gear ratio of an automatic.

 

My vote would be to install the gears in your nine bolt and I believe you will need a carrier also.

 

Well he also has plans for a 383 later on that could use those gears

 

Where can you get a 3 series carrier? As far as websites or local salvage yards .

 

Only if he has a free flowing intake. Doesn't make sense to me to use a higher numerical gearing on a more torque-producing motor unless you set it up to rev high. Good luck with traction on a TPI 383 motor and have fun on highway gas mileage. I'd say 3.23s or 3.42s max for a TPI 350/383 unless it is a heavily modified/aftermarket intake that lets the motor breathe a bit higher up top. If its a near-stock TPI that only breathes low, I'd say use some lower numerical gearing..just makes sense to me.

That way you have power over a broader range of MPH and you won't wind the car out by 100mph, and you aren't going to be fighting for traction as much as you would with 3.73s on a high-torque TPI 383. I know its possible to get traction, just not all that well for the street I couldn't imagine.

 

Your motor must be a dog if you think 2.77's are killing it. I need to get a posi unit for my car because I have traction problems with 2.73's (I used to run the stock 3.73 ratio, what a useless 1st gear that was with the T5 in my car, never mind the massive increase in fuel economy I got from doing the swap to the lower ratio).

If you can get traction with 3.73's, so be it... but the longer you can stay in 1st gear while being on the verge of breaking the tires loose is the fastest.

 

 

Slap a supercharger or turbo on that sucker. It WILL breathe then!

 

Do your exhaust before gears... skip righ past a 3 inch unit and go right into a 3.5 or 4 inch unit. The 3 inchers are great for V6's ( https://www.thirdgen.org/techbb2/sho...hreadid=300497 ) somethings tells me you expect more out of your car. If you don't do it before hand, be sure it's very close to the top of your list.

 

um.......4 inch exhaust?.......3 inch on a v6?.......unless im missing something, i dont think our cars are diesel, so maybe 4 inch is a little overkill. Imagine the nose dive a 2.8 will take from a 3 inch exhaust.

 

I have 3.73's on a 5 speed car . They rock period. Yes they aren;t the optimal choice for E.T's but if you are looking for a nice street car. It will not disapoint. Gas milage ? I am still in the good category. I sit at around 1750 at legal spped here ( 80 km/h) , so thats not an issue. As far as the car dieing at 100 mph ...... hahahaha that just isn't true when in 5th it really gets flying up there ( louvers got sucked off at above 245 km/h ...at the track )

So ...if you want to feal fast get them .... if you are bent on optional track times ....go with the 3.42 . I didn't notice but if you have an auto ...... DON'T get then 3.73's ....thats too much gear for the auto .......

 

Nose dive from what exactly? The lack of backpressue? Oh dear, not the lack of power stealing backpressure. The 3.4 picked up substantial torque EVERYWHERE (EVEN DOWN LOW, where "Backpressue is so vital") in the powerband, the 2.8 would just have picked up a little less power along the way. The least power picked up was about 7 ft/lbs, and the most being almost 20! That's an AVERAGE gain of 13.5ft/lbs, out of a tiny 3.4. Imagine what a L98 would gain from the same type of freely flowing exhaust in ratio to it's displacement.

...retyping the flawed logic that you have read someplace else that plagues these cars and their exhausts... ? Think freely. 305's make power from mods just as 350's do, just not as much per mod typically. If a 3 inch exhaust was enough for a 350 to flow it's best, by your "LOGIC" wouldn't a 305 suffer? Ahhh, but they don't; and if they don't - than obviously the 350 could use even a larger exhaust still, to flow it's best... right? But how large? And then who's to say that the 305 wouldn't still pick up power at the next size up? What, because some college kid, 10 years ago, misapplied fluid dynamics to exhaust flow, and it sounded technical and official, you are going to lower your own standards to just mindlessly assuming it's correct???

Fluid dynamics has no place when discussing exhaust flow, period. What is commonly accepted as truth about exhausts and your cars is wrong. It's been shown that a 3 inch exhaust gave a 3.4 JUST ENOUGH room to breath well - as evidenced by the fact that the cutout didn't provide any substantial gain.... so let's strap it on our v8 cars with 40% more displacement!

Our engines might not be diesel, but they can operate up too twice the speed of one - so in very rough estimation for example purposes only if the L98 was half the size of the diesel (which would make for a 11.4 liter diesel - not exactly Ford's PowerStroke), but operating at twice the speed, they might roughly produce the same amount of exhaust to move and channel through a pipe. But since we know that most diesel's are in the area of 6 - 8 liters, and 4 inch exhausts are perfectly fine for them, what's so wrong in assuming that it would be perfectly fine for us?

 

Because diesels have so much compression they need an exhaust like that, ever seen what a diesel head bolt looks like? There like 8 inches long, anything shorter and the pressure from the cylinders would send the heads off through the hood. Jegs makes an exhaust for diesel trucks called the "subway tunnel", its a 5" exhaust, so someone on here can tell me that they think that they can benefit from having an exhaust like that, ill stick with my 3" pipe thanks. Since that barely fits over the rear axle anyways.

 

Internal chamber compression has little to do with overall air consumption and therefore exhaust production. Why you would even compare the two tells me a lot about the person I'm speaking with.

The three primary elements that determain the amount of "Material" that an engine will have to exhaust is the displacement of the cylinder being filled, speed - or the number of times that cylinder will need to be filled, and the volumetic efficiency of that cylinder. If you refuse to accept than a 305 cubic inch engine will displace more air and fuel, at the same speed, and nearly the same VE as a 207 cubic inch engine than you are just being "Hard headed," or are unable to understand how engines work. More material = a greater need to space to move that material at the same rate of speed. For further on that see my above posts in the 305 vs 350 thread.



PS: if that 3 incher is a little too big to fit over your rear axle easily, I'd look into replacing those springs. They have to be saging pretty bad.

 

Im gonna stop this before it gets out of control, this was about gears but now its not, im just stating the fact that i believe that haveing a 4" exhaust on anything less than a 396 is serious overkill. I also re read my last post and realized how i compared the two, yeah i ****ed up on that. I am also stating facts from my experience, i put a 3" cat back on my 305 and it ran worse, bogged down in low rpms, loss of torque down low. I have since remedied this problem though. Also, with only 63k original miles i think my springs are doing fine right now.