O Stangnet elders fleet and strong and wise, appear before my seeking eyes

[jerry S]

If I put an AOD in my car and add a lightweight alum driveshaft and lightened 4:11s, would this remove enough rotating mass such that my parasitic drivetrain loss from the AOD would be about the same as a C4 with a stock driveshaft and stock gears? I estimate that I would be reducing the rotating mass by 10 lbs.

I have concluded that my C6 is a power hog and is the source of most of my angst (car related and otherwise). I am not getting enough power to the rear wheels. I looked into a TKO and a T5Z but my finished project price would be well over $5000 once I figure in shipping, duty, install costs, etc. A built C4 is the best way to go but I really would like an OD. However, the AOD eats as much power as the C6 (figure 25% compared to the C4's 20%) so that puts me back to square one, albeit with an OD. Would reducing the drivetrain weight with the lightweight shaft and gears by 10 lbs allow me to reduce the parasitic loss by 5%?

 

[dodgestang]

Doubtful. It will help though.

I run an AOD, Aluminum shaft, and anyold 4.11 rear gears.

You can 'disguise' it a little and put 2.85, 1.71, 1, .68 gearing into the AOD....if your motor has a wide power band like mine this will really be a kick then cause you will get up into super fast

 

[10secgoal]

I would say buy the AOD if you want OD. Not if you want to gain HP. Might be dissapointed. Then it comes down to converter efficiency after that. Not to mention the AOF is based on the c-6 design.

 

[Edbert]

No, I don't think there's any way possible for a large 4-speed auto and a 9-inch rear to be as efficient as a small 3-speed auto and an 8-inch rear.

Of course there's no way the 3-speed will allow you to cruise at 75MPH and run 3.89/4.11 gears or that the 8-inch will allow you to launch hard with 400 foot pounds of torque more than a few times.

EVERYTHING you do to a car is a compromise of one benefit for another. Just decide which things you are willing to sacrifice in order to get what you want.

 

[jerry S]

No, I don't think there's any way possible for a large 4-speed auto and a 9-inch rear to be as efficient as a small 3-speed auto and an 8-inch rear.

Of course there's no way the 3-speed will allow you to cruise at 75MPH and run 3.89/4.11 gears or that the 8-inch will allow you to launch hard with 400 foot pounds of torque more than a few times.

EVERYTHING you do to a car is a compromise of one benefit for another. Just decide which things you are willing to sacrifice in order to get what you want.

I can run 4:11s with the AOD and not with the C4. All other things being equal, would the mechanical advantage of the 4:11s in an AOD get me down down a straight line faster than a C4 with 3.25s?

 

[bnickel]

I would say buy the AOD if you want OD. Not if you want to gain HP. Might be dissapointed. Then it comes down to converter efficiency after that. Not to mention the AOF is based on the c-6 design.

actually the aod is based on the FMX architecture not the c-6.

 

[1320stang]

Jerry, you have mail.

 

[dodgestang]

I can run 4:11s with the AOD and not with the C4. All other things being equal, would the mechanical advantage of the 4:11s in an AOD get me down down a straight line faster than a C4 with 3.25s?

What is the redline on your motor?
What size tire are you running?
What is the power band of your motor?

With 4.11 and a 25.5 or so sized tire you will cross the line just shy of 7000 (i think I crossed at 6800)...remember you don't use the OD gear when racing. So if your motor's power dies at 6000 or your valves float at 5500...you aren't going to gain anything in the 1/4 except faster 60 foots. Now of your only 1/8 racing there would be a benefit...

 

[jerry S]

What is the redline on your motor?

I stop building power at 5800 rpm

What size tire are you running?

235/50/16 in the rear and 225/50/16 up front. The rears should be a 25.25 inch tire.

What is the power band of your motor?

the last dyno suggests between 3500-5800

With 4.11 and a 25.5 or so sized tire you will cross the line just shy of 7000 (i think I crossed at 6800)...remember you don't use the OD gear when racing. So if your motor's power dies at 6000 or your valves float at 5500...you aren't going to gain anything in the 1/4 except faster 60 foots. Now of your only 1/8 racing there would be a benefit...

So there would be no point in 4:11s then, correct?

 

[dodgestang]

c4 with 3.25 = 3.25 Final Drive ratio
AOD with 4.11 = 2.87 Final Drive ratio (using .7 OD)
AOD with 3.25 = 2.275 Final Drive Ratio

Fun with math.....

At 5800 RPM with 4.11 you might get over 100MPH the theorical value is 102...but you will be out of gas and peaked long before crossing the line...and this value doesn't take into account converter slip, drag, etc so your car's top speed will be lower. A friend's 302 in his 66 has a 4.11 in the back with a four speed toploader....can't get the car to go faster than 89-90 MPH with his upper 5800 ish redline. We run a 3.25 in the coupe with a 4 speed toploader and a 289....the 4.11 give it some kick right out of the hole..but the car with 3.25 is alot faster all around and gets much better gas mileage without an OD.

 

[Edbert]

If 1/4 mile times are you main purpose with the car then use the C4. They can be built for BIG horsepower, they are small, lightweight, and efficient. Many a fox owner has put them into their cars.

For street driving though an OD gear is really nice. Like I said, you just have to decide what and where to compromise.

 

[68keyblr]

Why not have the best of both?

Does anyone know much about the Gear Vendors overdrive bolt on unit? It replaces the tailshaft on a C4 and turns your 3 speed into a 6 speed, with 2 reverse speeds.

http://www.gearvendors.com/f2wdt.html

Not sure about how much parasatic loss you'd experience though. Might be worth checking out...

 

[68keyblr]

Updated URL

This URL goes directly to the C4 product

http://www.gearvendors.com/f2wd3s.html

 

[jerry S]

Does anyone know much about the Gear Vendors overdrive bolt on unit? It replaces the tailshaft on a C4 and turns your 3 speed into a 6 speed, with 2 reverse speeds.

http://www.gearvendors.com/f2wdt.html

Not sure about how much parasatic loss you'd experience though. Might be worth checking out...

At the end of the day, that GV plus a new C4 would cost me more than a new TKO and would still be eating more power.

Here is what I have decided to do. I sat down and pulled out a spreadshet I had not updated in a while and did some cipherin' and some figgerin' to see just how much money I have dumped into this car since I got it. I was pretty stunned at how much I have spent. My original plans for this car were to spend a total of $30,000 for everything (purchase price, engine rebuild, new suspension, interior, instrumentation, paint, etc). Well, I am well over that and still have to repaint and get new instrumentation. I had not been paying much attention and when I finally saw the current figure, It was a pretty shocking reality check. I am done whining. Rather, I will enjoy my car for what it is and that's that.

I am going to put the tranny on hold at least until we get back to America. Getting stuff here is expensive to the point of being cost prohibitive and getting it installed is usually over the top. So I am going to cool my jets, repaint, and enjoy the car for the next few years until I get back home. I will deal with the tranny later.

I would like to say thanks to everyone who has offered their advice and knowledge to me so far. You guys are great.

 

[Edbert]

I have a friend in London who mentioned to me just yesterday that a new gaming PC from Alienware casts about twice what one here costs. Same parts same company. Gotta love the socialist paradise of the EU!

Enough politics, sorry 'bout that.

I added up the costs on my project last summer. Including the car itself I was right under $25K, which is what I paid for my 2005-GT. Since the old one aint running yet I cannot say it, but next summer (when it is), the old one will be worth more than the new one. I'd expect your ability to get the $30K out of your car is much better than getting the $30K out of another car you had purchased off the lot at the same time. I'm not suggesting these cars be looked at as investments though, just giving some justification to spending the money is all...LOL.

Regarding the GV-OD unit...I looked hard at those and chose an AOD. The GV unit adds a lot of weight and parasitic drag. Not necessarily bad for getting a 6-speed. But the issue for me was that 2 of the 3 added gears are pretty useless since the first one is in between 1st and 2nd, and the 2nd added gear is between 2nd and 3rd. So what you end up with is an EXTREMELY close ratio 6 speed with a small OD gear. Might be useful for towing or in a car with a very narrow powerband. Neither of those two apply to my car.

 

[rbohm]

if it was my car, i would run the AOD with 3.73 or 3.89 gears, with the stock AOD gearing, or 3.50 gears with the wide ratio gearing in the trans. either way 3.89's are about as low as i would go with your combination. you want to be hitting about 6000-6200 rpm when you hit the lights.

one more thing, contact lentech and have them send you one of their modified valve bodies for the AOD. they change the shift pattern from 1-3-OD to 1-2-3/OD and you can also get an OD lockout as well.

 

[jerry S]

if it was my car, i would run the AOD with 3.73 or 3.89 gears, with the stock AOD gearing, or 3.50 gears with the wide ratio gearing in the trans. either way 3.89's are about as low as i would go with your combination. you want to be hitting about 6000-6200 rpm when you hit the lights.

one more thing, contact lentech and have them send you one of their modified valve bodies for the AOD. they change the shift pattern from 1-3-OD to 1-2-3/OD and you can also get an OD lockout as well.

I priced it and the final cost is still over $5000 to buy, ship it, pay duty and VAT on it, and have it installed. And that estimate is conservative. I have decided to wait until my wife and I go back to the US and then install a TKO. The thing with the AOD is I never can get a straight answer as to whether it will fit my 351W with long tubes or not.

 

[dodgestang]

Well...the AOD fits my Cleveland with long tubes