MT-82 to 6R80

[Trav4011]

Damn man, you're having a very hard time understanding what you read. My point was a 6sp trans can pull great 60fts AND get great gas mileage because it has more gears allowing for the rear end to be a lot lower that it could be with a 4sp. Having those extra gears also helps with acceleration at high speeds because of what you stated, but didn't give enough credence to. I put 4.10s in my 05 and it did help acceleration from a stand still, but it fell on its face when trying to floor it at highway speeds. I liked being able to mash the gas at 70mph and hit a 80-85mph in no time, that was lost when I took my 3.31s out for the 4.10s.

I build cars for a living, and have done so for 15 years.. I don't have a hard time understanding anything that makes sense. What's you're saying doesn't make any sense. The slight advantage that the 6spd has is nill, and you can properly gear the same exact car with a 4spd to do the same exact thing, and get the same fuel economy. I know so, because I've done it enough times, both ways. I'm not guessing, or bench racing. I speak from 15 years of experience in this business.

Is a 6spd superior? Yes.. Is it THAT big of a deal? No.. It's certainly not worth the extra cost, or the hit that you would take to trade in the manual and get a new 6spd auto. You could swap in a stock 4R70W with a good converter, and full auto controller for around 2 grand. It would run great times, and get good gas mileage as well.

 

[Bmr4life]

I build cars for a living, and have done so for 15 years.. I don't have a hard time understanding anything that makes sense. What's you're saying doesn't make any sense. The slight advantage that the 6spd has is nill, and you can properly gear the same exact car with a 4spd to do the same exact thing, and get the same fuel economy. I know so, because I've done it enough times, both ways. I'm not guessing, or bench racing. I speak from 15 years of experience in this business.

Is a 6spd superior? Yes.. Is it THAT big of a deal? No.. It's certainly not worth the extra cost, or the hit that you would take to trade in the manual and get a new 6spd auto. You could swap in a stock 4R70W with a good converter, and full auto controller for around 2 grand. It would run great times, and get good gas mileage as well.

Bullshit a 4sp trans can't be in the powerband as much as a 6sp while still the producing the same 60ft (with equal TCs) and getting the same overall mpg . You just lost the tiny bit of internet cred you had.

 

[94tbird]

Bullshit a 4sp trans can be in the powerband as much as a 6sp while still the producing the same 60ft (with equal TCs) and getting the same overall mpg . You just lost the tiny bit of internet cred you had.

hes right in this case and your wrong.

 

[BAKnBLK2010]

Bullshit a 4sp trans can be in the powerband as much as a 6sp while still the producing the same 60ft (with equal TCs) and getting the same overall mpg . You just lost the tiny bit of internet cred you had.

Now I'm confused. Isn't this what Travis was just basicly saying? Man you are all over the place with your screwed up logic. Just a couple of post ago you were saying something totally different.

 

[Bmr4life]

Now I'm confused. Isn't this what Travis was just basicly saying? Man you are all over the place with your screwed up logic. Just a couple of post ago you were saying something totally different.

Thanks, you posting that made me realize my typo. I replaced can with can't.

 

[Trav4011]

Bullshit a 4sp trans can't be in the powerband as much as a 6sp while still the producing the same 60ft (with equal TCs) and getting the same overall mpg . You just lost the tiny bit of internet cred you had.

lol.. Ok.. I don't need credit from some random person on a car forum.

Tell me something? You claim that a 3 or 4spd can't hang with a close ratio 6spd, because it keeps the engine in it's powerband better, and allows you to cut a better 60ft? That's your exact statement. Then, how come you don't see 6spd autos in the quickest/fastest drag cars out there? I could sit here and explain to you why you're incorrect in you thinking, but you would just argue with me anyway.

Also, you claim that a 4R70W can't get the same highway mileage as the new 6spd auto. The overdrive ratio in each transmission is roughly the same. So, why wouldn't you get the same mileage? Guys with 6spd autos are running the same rear end gear as what we used to run in the 4R70 powered Mustangs. The mileage is within 1-2mpg of what the '11 GT gets, mod for mod. Again, your logic is off.

Travis

 

[Trav4011]

You say that a 4R70/75 can't hang? Here you go..

http://www.youtube.com/user/BADASS03SVT#p/u/34/eeC7wpRfKpU

Full weight 03 Cobra, bone stock long block, with nothing more than a ported Eaton, long tubes/exhaust, intake, and a 4R70W. It cuts high 1.4x - low 1.5x 60ft times, runs mid 10's at 480whp (no nitrous), and high 9's with a 100 shot. The car (at the time) was 100% streetable.

 

[Bmr4life]

Read every one of my posts. I said earlier the 4sp was more of a RACER MOD. I've even called out the Powerglide trans for those serious about drag racing.


You're missing my points yet again, but at least you admited the 6sp will get better mpgs.

My point is the OP is not a drag racer and that going from a 6sp to a 4sp is a racer mod. Not one a daily driver would do to their car. It will affect mpgs in a negative way so why would you chose to install it over the 6sp auto which is a gem? Seriously, answer this. I won't argue that its stronger (already agreed less gears means more strength). The original guy that did the swap did it for drag racing (trans brake, stronger, etc). Racing is not the reason the OP wants to do it.

Now about my 60ft times remark. You're obvious are stuck on thinking I was saying its a better drag racing trans, which is NOT my point. My point is since it has more gears, it can afford to have some high low end gears while still getting high mpgs on the road making it a great on road trans. Understand that now? I think you do since you admitted it gets better mpgs.

Lastly, drag cars don't need a lot of gears, they have enough power to get down the track and usually run a high rear end gear. Since on road mpg is not a concern of theirs, they don't need the extra gears. My "in the powerband" remark was referring to daily driven cars, non super modded cars. Those modded cars have a far wider and higher powerband so they don't need as many gears compared to a fairly stock vehicle.

Now focus and remember. The OP is not a racer.

 

[KJGT]

Myself I would just trade the car in for an auto, no matter what you do its the easiest thing to do. But if you insist on doing the swap I would do the 6R80 if its going to primarily be a street driven car.

No ones seems to be discussing the most important part of getting great ETs with an automatic, the torque converter. A converter is the equalizer on a dragstrip and is just as, if not more, important than the number of gears. But with a higher stall to drop less between shifts you trade efficiency. The 6R80 has some nice 1-2-3 gear spacing so its not as torque converter dependent as a two or three speed auto with a small CID engine.

Personally I'd take the lower 1st gear in the 6R80 over a 4 speed for a daily driver, it lets you run a mild rear end ratio which keeps driveshaft speed down at all mph and still get an excellent final drive ratio in 1st. A 4 speed auto will get you that, but you will have to run more rear gear with a lower numerical first gear, and that is going to translate into higher RPM on the highway.

Downside is 6 speeds are more complicated, 6R80 looks to be pretty expensive to fix parts-wise, no trans brake and no decent manual shifts. Plus a very limited torque converter selection right now. Even though the 6R80 seems to be a strong trans it WILL wear out just like any other auto and drag racing is hard on transmissions.

Ford isnt stupid, they just dont throw darts at a board to figure gear ratios. Yes gas mileage is part of the equation, but with better fuel mileage comes better overall driveline efficiency. I think they did pretty well with the auto ratios on these, and ETs from stock cars tell you right away they did well.

 

[Trav4011]

I give up.. lol..