I have an '86 305 tpi, with a 2.66 rear end... thought about going to a higher rear ratio, but current performance at high speed is too sweet to mess with.

It would be cool to use a different 1st gear 700r4... granted, the 3.08 (+/-) is good, but 30% higher would be interesting...

anyone have input to this goal?

 

Raptor (or PATCO?) 's website mentions a 2.66:1 low, which got my attention. However, when I called to inquire, I was told that it is in development and likely to be several years before it MIGHT be available.
Bill

 

first off, factory 1st gear ratio is 3.06, secondly, as of now, there are no aftermarket ratios available.

 

I see what you're trying to do but I think you should focus more on the gear spread than the performance of any one single gear. The spread between 1st and 2nd gear is already too high making the engine speed drop too far for good performance. Making 1st gear higher would produce even a larger drop in engine speed during the 1-2 shift. Your car would be slower than before.

If it were me, I would use a lower 1st gear to tighten the 1-2 spread and use the rear gear ratio to keep the engine in it's prime power band during acceleration. This is usually between peak torque and peak power. But the real goal is to maximum the power development during the entire acceleration run. In the real world, this is the area under the curve if you plotted torque vs. time for your 1/4 mile run. That's how you make a car fast....

 

I grant that I stand corrected... 3.06:1 is proper...

QwkTrip: I like 2200rpm at 80mph... just stepping into the most prime part of the power curve with a tasty 2500 to go...

Shagwell... ever hear of a transmission shop making a gear or two? I haven't explored the local talent yet...

30% increase for 1st, 20% increase for second and 7.5% increase for third... keep the overdrive as is...

sounds like a reasonable request to me...

 

Do you know what's involved in making a gear? It's not the kind of thing that the "local talent" is going to be able to do, and certainly not cheaply if they could.

 

Swap out to a richmond 6speed double over. you can get a 3.27:1 first and a 0.78 fifth and 0.60 sixth. that swap will be much cheaper than trying to get some oneoff gears for a 700R4.

 

duckmanquacker... good reply.. let's see 3.06-3.27 = .21, .21/3.06 is about 7% increase in first... I'm was hoping for something closer to 4.0:1 first gear, but that is just plain heresy...

Richmond 6speed double over... I'll try hard to blow up my 700R4 in order to justify that swap!

 

poor 700 snif snif.

 

instead of spending rediculous amounts of money trying to come up with enough gearing tomake what you have go fast, why not spend a little money making some power and let it pull the gearing?

 

****....

where should i start... by explaining why the sky is blue and the water wet?

i do because i can....

and if you stop by slip f-18, bahia mar, say hello to travis magee for me...

 

1st off I am not bashing your goal, but where is it nessecary to do 80MPH or more in the US for an extended period of time? My orig setup was the LG4/700R4 and 2.73s. I did 140+ a few times for a short period easily. And yes the 305 was pretty much done as far as pulling. I have a 140 speedo stock. If I had your gears Im sure 150 or more could be realized. But doing illegal and dangerous stuff aside, there really isnt much need for you to get a (lower) 1st to get a higher rear gear. Is that your goal?

 

no offense intented... it was the most sincere sarcaism that I could muster...

a tool of the weak, they say....

no travis magee fan?... action hero, john macdonald... old school rockford files type... who, as we all should know, drove a pretty sweet gen II...

true about top speed... but, it's nice to know it's there

I'll just stick with what I have plus a shift kit

 

sounds like you want a truck, so what exactly are you towing with your trans am? :P
but yeah your working in the wrong direction if your not building a truck, heh... the 700r4 with those numerically low rear end gears gives you a ridiculous rpm drop between gears already, in stock form your already in overdrive before you even realize your rolling yet, at that point your governer would have to be hella retarded to even let you use First gear for anything past 3mph unless you were buried in it :P

 

dr1... I see that you too must be told why grass is green and the chicken was first...!!

give me that address to your trailer and I'll send you the math...

 

im sorry you and your buddies are so incredibly uninformed, feel free to take it out on me.

 

Let's keep this civil. Personal attacks are not tolerated on this forum.
This is the "you have been warned" post.

 

Does anyone agree with me that 1st gear in a 700R4 is too low (numerically too high), especially when coupled with a 3.73:1 axle ratio, and that the 2.66:1 1st gear (numerically lower, "higher" gear) would make 1st gear more useful traction wise? I would like to have it.
Bill

 

I guess it depends on the car and combo. I was able to hook it up, so for my car I would disagree. For my ride it was also too much gear, so the 3:73's came out. I would love to get my hands on a set of planetaries to drop the first gear ratio a bit. I think the market would be well served if they ever do produce them. With gas prices what they are, having a 700 built with turbo 350 style gear ratios would be a nice option for many.

 

I partially agree. It depends on the setup. Yes the gap between 1st and 2nd is not a good exchange but that deep 1st is great off the line if your traction is there. I thought maybe pulling 2nd closer and maybe, maybe dropping 1st to 3.00 isshtead of the 3.06. But then 2nd to 3rd would be different. Moving just 1st or just 2nd I wouldnt care for much. I have 3.42s in the rear BTW. If it were a 5 speed auto.....hmmm

 

what i would like to see is something like 3.00 first, 2.00 second, 1.00 third and then about a .65 OD. Now, as soon as I pick up the holy grail, I'll get to work on it.

What you have to realize, is that there is no real way to only change 1 gear ratio. There are only two planetaries in the trans, therefore each gear ratio is a multiplier of what is locked vs what is spinning. If you change first, something else will be different also, and not neccessarily in the direction you want.

As for the low(numerically higher) first gear and a low rear end ratio; First off, it will be easier to hook the tires, beacuse the lower gearing raises the wheel speed slower. Most tires aer controlled spin(especially street tires) Yes, the low gearing lets your rpm come up faster, but the wheels speed is brought up slower, thus making it easier to control the spin. - I've tried explainging this many times, but most people don't understand it until they make a fairly drastic ratio change. Secondly, yes, it will shorten your time in low gear. You will reach your max rpm quicker, therefore shift sooner. In drag racing, low gear should move the car. After the car has physically moved, you should be in second. About the only time this doesn't hold true is with a 2 speed trans. A steeper(numerically lower) low gear ratio or a steeper rear ratio will lengthen your time in each gear, as you will need to travel faster to achieve the same rpm shift point, and the steeper ratio will result in a more drastic rpm drop between gears.

 

What do ya think anout a 700R4 with a 3.42 vs with a 3.73 out back? As far as the acceleration and gear changes