Trans Dilemma: c4 w/ Gear Vendors OD or 4r70w?

[zombiekiller]

Hey Guys,
As I scramble to get my galaxie road worthy before moving again, I've developed a quandary and need some additional input.

My car currently has a built c4 in it and a custom built convertor. It is behind a forged 306. Currently, i won't have the time to get my turbo setup plumbed or my EFI in. ( wah wah...I won't have the time for alot that I wanted to get done before I put her back on the road, including swapping out the brakes).

That being said, if the car is going back on the road and I'll be driving it, The C4 with my 3.50 rear end ratio will pull RPMs on the highway that I'm not keen on. Gas mileage will also be pretty terrible and will most likely get worse once the Turbo is in. After I move, it may be a year before I have adequate work space to tackle the larger stuff that I've accumulated parts for again. I'd like to be driving the car the whole year so I can enjoy driving it if not enjoying working on it.

So my choices are:

1. Buy a gear vendors unit for the c4 to give me 6 gears, a nice overdrive and hopefully not have to modify the trans tunnel. I also get to keep my c4 that I've invested a fair amount in.

2. Go 4r70w. I'll need to get one built that will handle 650-700 hp ( which should be pretty close to where I land with turbo). I'll have 4 gears and may or may not have to modify the tunnel. I'll also need a new TC, computer, etc. I will get a lockup though.

So which might work better? Keep in mind my galaxie is long and heavy. The driveshaft length is not a concern for me. I've seen shorter on long bed pickups! I realize that if i go the GV route, I'll lose the ability to have a TC lockup and do paddle shifters. But at face value, the GV unit appears to be the easier of the two to toss in and be ready to roll.

[Steve Chryssos]

First things first: How does the C4/converter/3.50 gear feel to drive? Is it sloppy? Are shifts happening at the right time? Have you looked at the trans temps? If it's working well, and you like a multi-stage approach, go with the GV. You can always hang the GV off the 4R70W later or flip it. People are always looking for used GV bargains.

If, however, the current combination is all wrong anyway, the GV will accentuate those shortcomings in the higher gears. A well built, nicely calibrated 4R70W with lock up will make for a truly enjoyable TT cruise missile. Picture a billet lock up converter with oversized lock up clutch (a single disc in your case) and a custom TT stator. The right E-trans combination is a beautiful thing.

[zombiekiller]

First things first: How does the C4/converter/3.50 gear feel to drive? Is it sloppy? Are shifts happening at the right time? Have you looked at the trans temps? If it's working well, and you like a multi-stage approach, go with the GV. You can always hang the GV off the 4R70W later or flip it. People are always looking for used GV bargains.

If, however, the current combination is all wrong anyway, the GV will accentuate those shortcomings in the higher gears. A well built, nicely calibrated 4R70W with lock up will make for a truly enjoyable TT cruise missile. Picture a billet lock up converter with oversized lock up clutch (a single disc in your case) and a custom TT stator. The right E-trans combination is a beautiful thing.

I don't have any issues with the current set up, other than the rpms are too high at cruise and the gas mileage is single digits. The shifts are nice and crisp, trans temps are good, even with only using a framerail type cooler( its a 24" wide one that i have mounted to the bottom of the radiator support and I will also be modifying the front bumper to duct to it more directly. )

This is kind of why I'm having a dilemma. It's coming down to e-trans/paddleshift/lock-up vs C4 that i've got a fair chunk of cash sunk into/6 speeds.

[Steve Chryssos]

If it's working right, the GV option is viable. Good units bring good money on ebay, so you can either sell it down the line or hang it off the back of your 4R70W. Depending on your converter stall and rear tire diameter, you might prefer a 3.73 or 4.10 gear with the GV when in high gear.

[zombiekiller]

Well i'm due for new tires, so it ends up a decision as to running a 27.0" rear ( like now) or bumping up to a 28.5" tire ( i have the room and suspension adjustability to do so).

Pretty much I'll be at a wash cost wise going GV or 4r70w and trimmings. It sounds like the different may be how much transmission fluid that I spill on my garage floor.

[SLO_Z28]

There are advantages and disadvantages to the gear vendors unit. For performance use its great, you have every gear and then every gear split, but you don't want to compression brake for more than a few seconds. For street use it is situational, you don't want to use it on long grades either up or down, as the pump will run dry and the steels will die. The gear vendors branded unit will come with a computer that will do all the thinking for you, and wont let you fry it. You could use your paddle shifters with the GV no problem too, as its operation is completely independent of the transmission itself.

The 4 speed will work in all situations, and I cant help but think its cheaper than the $2500 a gear vendors would cost you? I regularly buy 4R70W's for $1400 with a 3 year 100,000 mile guarantee.

[camrat68]

Since you have a lot invested in the C4, I'd go with the GV unit. I have one behind a 502/TH400 and went from 9mpg to 13mpg.

Jim

[zombiekiller]

There are advantages and disadvantages to the gear vendors unit. For performance use its great, you have every gear and then every gear split, but you don't want to compression brake for more than a few seconds. For street use it is situational, you don't want to use it on long grades either up or down, as the pump will run dry and the steels will die. The gear vendors branded unit will come with a computer that will do all the thinking for you, and wont let you fry it. You could use your paddle shifters with the GV no problem too, as its operation is completely independent of the transmission itself.

The 4 speed will work in all situations, and I cant help but think its cheaper than the $2500 a gear vendors would cost you? I regularly buy 4R70W's for $1400 with a 3 year 100,000 mile guarantee.

I was not aware that you could use a paddle shift withe gv unit!

As far as equal cost goes, I figure 1400 for the trans that will hold up to the hp/tq goals then new mount and/or crossmember, new torque convertor, possibly new flex plate. (my c4 is an early 6 bolt model that is 11.5 in bolt pattern. ) the controller and then the paddle shifters.

Now I'm at the same or more as the gv unit, then subtracting whatever I can get for the c4. Which is probably 800-1000, depending on who is interested.

That and it's entirely possible that I'll have to modify my trans tunnel to deal with the deeper bell housing, as my motor is set back about 3 inches.

I'll probably have to modify it with gv unit too, as everything is tucked up tight and I'm not sure that the skinny part of the gv unit will clear the bracing in the floor.

[Steve Chryssos]

A trans --any trans-- that can handle an honest 600 Ft-Lbs of input torque or more will cost good money. The same can be said for torque converters. A lot of TC companies over-estimate the capability of cheap stamped converters and stock lock up clutches, then shrug when their customers drives over the fragged parts. A stock lock up clutch is about the width of your shoelace. A proper lock up clutch for this app looks more like the clutch from a 3 pedal car. And that billet front cover emulates a proper flywheel surface.
The E swap will be more expensive than adding the GV, if you do it right. The lowest common denominator, here is the Twin Turbo plan. The options are wide open for your current 306, but those two hairdryers change everything.

Better to raise that flag now, right?

[zombiekiller]

A trans --any trans-- that can handle an honest 600 Ft-Lbs of input torque or more will cost good money. The same can be said for torque converters. A lot of TC companies over-estimate the capability of cheap stamped converters and stock lock up clutches, then shrug when their customers drives over the fragged parts. A stock lock up clutch is about the width of your shoelace. A proper lock up clutch for this app looks more like the clutch from a 3 pedal car. And that billet front cover emulates a proper flywheel surface.
The E swap will be more expensive than adding the GV, if you do it right. The lowest common denominator, here is the Twin Turbo plan. The options are wide open for your current 306, but those two hairdryers change everything.

Better to raise that flag now, right?

Agreed. The Torque convertor in the car now was just a WEEEEEEEE bit more pricey than your standard $250 hughes street rod TC. I've also got about $2500 into the c4 with all of the heat treated doodads. I think for the time being I'll be opting for the Gv unit. I don't really know how much use paddle shifters would get in a car this big, but they're really fun in a few of my friend's cars! I'm probably better suited to going for paddle shift in a track rat.

Thanks for the input guys!

[SLO_Z28]

To clarify the paddle shifters will operate the car normally, then you would have a secondary switch that would operate the on/off of the GV unit. You could probably use just the paddle shifter for all 6 (3 real and 3 split) gears with something like a isis unit (or any programmable logic controller) to interpret the intended gear.

Its too bad you're in Tennessee, I would love to wire something like that up, I could have fun with it.

[Steve Chryssos]

Get the GV install done and I'll lend you a demo paddle shifter for testing. HOLD YOUR CALLS: I never led out paddle shifters. This is only because I do luvs me some fastback Galaxie time machine.

For the immediate future, built C4's are worth good money, especially if they are in a running car. Put some feelers out there. These days, you can shoot a quickie operational You Tube video and offer test rides in your ad. It really builds confidence. You might just get all of your money out of it.

[Steve Chryssos]

....Also, there's a real zombie problem here in Daytona. I might need help some day.