I was wondering if it's possible to install different ratio gears in the 700-R4 than the stock ones. Specifically, a new 3rd gear ratio, something closer in ratio to 2nd, to curb the falloff from 2-3.

If you can't do it with a stock unit, does anyone make aftermarket 700s that can be ordered with different ratios?

I'm not knowledgeable in the least about building transmissions, so I apologize if this is a very ignorant question.

 

You're stuck with stock ratios.

 

I heard a rumor that a different set of planetaries will be released sometime in 05. I have heard nothing since. Hopefully the rumor comes true in 06.

 

Not an ignorant question. The aftermarket does not really consider the 700 as a race trans. Therefore they are slow to develop and release hardcore parts. Only in recent years have people considered it possible to put semi serious power to them. I have always liked the 700 for a street strip car. I have also been very sucessful with it. Brutalforms car is a good example of their ability to run hard and live. With stock programming, his 436 made 600 ft lbs at the flywheel. He puts the power to the ground with et streets and his 60' time is great. After he tunes the car , and sorts out the bugs, I expect he will make close to, or slightly more than 650 ftlbs.
As soon as these rumored gearsets come out, I will buy a set or 2 regardless of cost. I want to use them for r&d purposes.

 

I've just always thought that the biggest disadvantage of the L98/700-R4 combo is the 2-3 shift. If you could get a gear bigger than a 1:1 that would keep the motor more around it's peak power it would help a LOT, especially with bolt-on L98s (headers, intake porting, AFPR, etc.). I'm thinking about buying an IROC with the said bolt-ons and 3.73s, and I'm thinking the biggest problem is having to shift to 3rd by the end of the 1/4, and so a close-ratio 3rd would be very beneficial. It already turns high 13s with the 3.73s, and with a closer 3rd gear, it seems like I could shave a few tenths or more off.

Is there any particular reason that the gears from any other 4 speed transmission wouldn't swap in? If so, is there another tranny that will bolt up to a SBC (auto 4+ or manual) that could be geared close-ratio like that? T-56 perhaps?

 

High gear is always1:1. Even the aftermaket stuff(as far as I know) for other transmissions retain high gear as 1:1. They usually change 1st and 2nd gear.

 

There's nothing wrong with the 2-3 shift. As mentioned above, 3rd gear is always 1:1. It's the 1-2 shift that needs to be improved. The gear spacing between first and second is too far apart. If you want a transmission with close ratio gears and an OD, pick up a 200-4R.

Powerglide transmissions have an aftermarket gear ratio option. Factory first gear is 1.76 or the weaker 1.82. There's an aftermarket 1.80 ratio with straight cut gears for $1400. That's just for the gear set, not the tranny.

 

yep, the 1-2 shift is what sucks.

with 3.27 gears out back, i go to about 30mph then shift second and ride that to 60mph and then ride third gear all the way to 100mph in the 1/4mile. i think first gear needs to come down abit to a 2.6x ratio and with a 1.9x ratio for second then into the 1:1 third gear.

 

isnt first gear like a 3.xx? why would you want to go numerically lower for first? i like the power i get in first, but then it just falls out in 2nd

 

basically if you go changing the ratios your going to have to lose out somewhere it seems. We need an extra gear and different ratios then we'd be set!

I've always wondered about this myself actually good question.

 

The idea of the 3.06 first gear in the 700R4 is to provide a good street tranny. The factory puts non performance gears in the diff. 3.27 roughly being one of the best but lets say your car has 2.73 gears. These will suck at accelleration but provide very good mileage on the highway especially with the OD. To compensate for the poor accelleration, they use a 3.06 first gear to help get the car off the line quicker.

3.06 with 3.27 gives 10:1 ratio to the tires
2.52 (TH350) with 3.73 gears only gives 9.34
2.52 with 4.10 gears gives 10.33

The 700R4 with poor gears can still get off the line about as fast as a TH350 with 4.10 gears however the 700R4 combination will have much better highway manners.

Now take the 700R4 and put 4.10 gears in the car and the ratio jumps to 12.55 which could easily smoke the tires.

As a comparrison, my car has a 1.76 first gear and 4.56 gears in the diff which gives a starting line ratio of 8.0. It's not driven on the street but I shift into second (high gear) around the 1/8 mile mark and cross the finish line at around 130 mph but by then I'm out of gears and rpm to go higher.

Now the problem with the 700R4 is that it's just designed for street use. Under moderate accelleration, the low first gear gets the car moving quicker with poor gears in the diff and the OD brings the engine rpm down even lower when on the highway. Under hard accelleration, the 1-2 gear spread is too far apart. When the tranny shifts into second, the engine rpms drop down a lot farther than a close ratio tranny. This means the engine speed has dropped down below it's powerband and performance suffers as it has to build back up to where it makes it's best power.

 

Hmm....hadn't even thought of the 200-4r.

From what I've just researched, it's not that bad to put one in, just need a driveshaft and $100 for a Spohn crossmember.

With 3.73s, the 700s ratio to the tires in first gear is 11.5 - 1
With the same gears and a 200-4r, the ratio is still a decent 10.2 - 1, and has a closer 2nd


I'm now very interested in this swap. I think with this swap and a few other things, a bolt-on L98 with good tuning can go a lot faster than people think.

How about the T-56 or maybe T-10 manuals? Multiple gear ratios, or not? I would assume, as from what I've read there are different ratios in f-body T-56s than in Corvette T-56s. And according to this site the 1993 f-body T-56 has closer ratios than the later ones, but is weaker. If one can swap these into a 94-on T-56, that would work. And one last question...Can a T-56 be built to take some serious torque?

 

yeah with that 3.06 first gear, unless your power band is up over 5500rpms with 3.27-3.42ish gears, first gear doesnt last long at all. 30mph or so with a TPI car with 5000rpm shift point or a bit less.

with abit higher gear in first like a 2.7x or so, first gear becomes more useful and closer to second gear.


even with my car, i have hit 1.88-1.89 60 foots on street tires and trap 100mph, yet i cant get below 13.9. i believe alot of that is gearing from the 1-2 shift and that rpm drop. i know alot of other cars that trap near 97-100mph and they run quicker 1/8 mile and 1/4 times yet with slower 60 foot times. th350 gearing and manuals help that out and they run more optimal ET's for the traps

 

Is it physically possible to put a first gear from a 200-4R or TH-350 into a 700? That would pretty much be ideal.

 

Nope, this you cannot do.

 

Call Chris Kokkonis at www.ckperformance.com or E-mail him
at trannyman0101@aol.com. I believe he offers a 2.66:1 ratio
for a 700-r4, but you may have to buy a transmission with them
installed.

 

Nice, it's about time someone finally did it. I bet I wouldn't like the price though.

 

With the right torque converter, the 3.06 to 1.63 gear ratio is brought to about nothing. If this were not true, then the Powerglide (it's 1st to 2nd gear ratio's are about the same as the 700R4/4L60E) should be "looked down upon". The 700R4/4L60E 1st to 2nd gear shift is almost indentical in rpm drop, to the PG, the big difference is that the 700R4/4L60E 1st to 2nd gear shift occurs at less wind & rolling resistance, than the PG, therefore it is not a major concern. But this is with the right "torque converter".

 

So you're saying with a higher stall the shift isn't so bad, right? Or are you referring more to one with a higher torque multiplier effect (i.e. a better sprag and stator)? If my terminology doesn't make sense, blame the TCI webpage on torque converters .

If you're talking about a stall, how high of a stall are we talking about? 2500?

Not trying to be smart (because I'm not on this topic), just trying to learn.

I'm emailing the guy who might have the 2.66 ratio first gear to see if that's true and how much.

 

well the torque converter helps only when the rpm fall from 1-2 is lower than the stall right?

on TPI cars and cars with lower rpm powerband, like from 0-5500rpms, 3000 stall is perfect for them, but that aint quite high enough to bring up the 1-2 shift.

 

Yeah, that's what I was thinkin, but wasn't sure.

I mean, with reference to the powerglides and that idea, you'd have to stall it to the moon (like Powerglide drivers usually do). I'm thinkin more along the lines of somethin streetable.

 

so can a good torque converter help the 700-r4 1st to 2nd shift or is it only for acceleration when already moving?

 

I got an email back from Mr. Kokkonis. They DO make 700s with a 2.66 gear, but they only sell the whole trans. I'm going to call him to see how much they go for. I'm very curious to see if it's cheaper than just picking up a built 200-R4.

 

What's the name of this company with teh 2.66 first gear?

 

CK Performance

www.ckperformance.com

They don't have anything about the tranny on the website, but the guy said they have them, and to call him to discuss it.

 

He told me that he had them also... I have been so busy with other cars that I havent got back to him yet.. I want 1 for my next trans explosion