CR gearing ?s

MoPower05

MoPower05

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May 24, 2007
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I have 4.56s with 33" tires and this is the right gearing in FL for heavy sleds and short tracks in 3rd lo. I am trying to decide what gear in the transmission to run for a Lowery or Hagar sled on a 300' track. I guess what I need to know is what is stonger and less likely to break, 4lo OD or 1st hi(convertor locked) ? I have the motor and gear to pull either. Didnt have the speed I needed last week at TS pulling 4lo 3rd conv locked and next week end pulling in Richmond KY. I want to pull OD because it is faster (40ish) than 1st hi.

thanks
 
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Neither of those seem like good options for sleds like that or tracks other than slop. Your tracks must be real loose down in florida?

On edit now that I punch that into th gear calc it looks like 1st high would yield you 30 mph given 3500 rpm, just gotta lock that converter.
 
Gotta lock that converter very soon after leaving the line. You only got a few seconds of time to go down the track so the faster you can get the wheel speed up the farther you'll go. I always pulled in low range and left the line in 1st.. As soon as boost and rpm was up, like almost instantly, hit lockup, soon as the engine recovers hit 2nd, and the same when going to 3rd. If you're not a full wheel speed by the 50ft mark, your hurting yourself on distance. I have 3.73 gears an 33" tires...from what I could figure on gearing, you need higher ratios with an auto trans than with a manual.
 
MoPower05 said:
My main question is LO OD stronger than HI 1st?
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not sure which is the lesser of the two evils. I always wanted to try a first high run but my tranny builder very highly recommended i didnt. My truck hit od low four times going down the track lastyear and completlly toasted that clutch pack. Also the 3rd to od seemed like a big jump and the truck never liked it .
 
Lookout OD and pull on the low side, high side is hard on stuff.
 
I agree stick with 3rd low loc tc over drive off. I think you wil better luck trying to get wheel speed up before half track as most your videos.
 
I pull 3rd gear locked with 35's and 3.73's the truck wants od but I lock it out or it falls under the turbocharger
 
What about going to 35's with the 4.56's you have? Would that drop rpm enough to allow you to run 3rd lo on a 300' track without hitting the govenor
 
33" to 35" doesnt make much difference. With 4.56s vs 3.73s its almost 1/4th revolution less, a lot slower. I was thinking instead of bigger tires keep the 33s and pull another gear. I figured because of the lower gears maybe OD would have less stress.
 
O/D is a .69 ratio. Pretty steep. You better have some power to spin out of your gonna snuff it when the weight hits.
 
BigB82789 said:
O/D is a .69 ratio. Pretty steep. You better have some power to spin out of your gonna snuff it when the weight hits.
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I was thinking of trying to hit my OD lockout button at just the right time so when the weight came down I was back in 3rd.
It would be nice if I could set the valve body to down shift sooner.
Yes I expect to snuff out or break, but I was hoping to get the addional speed needed. I also have to qualify without breaking or there is no point.
 
conk said:
I pull 3rd gear locked with 35's and 3.73's the truck wants od but I lock it out or it falls under the turbocharger
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That makes your final gear ratio 10.51 and you run 35" tires. I have a 12.40 final gear with 33" tires. Can you keep your convertor locked at the big end or do you snuff?
 
I tried high once last year and couldn't get the turbo lit. gave up got pulled back and went for low and spooled tons better. also my trans guy told me the same thing high range is terrible on things and to never try it again. I also lock out od it is just too much of a gear drop to recover it usually snuffed the turbo out.
 
cumminsmannow said:
I tried high once last year and couldn't get the turbo lit. gave up got pulled back and went for low and spooled tons better. also my trans guy told me the same thing high range is terrible on things and to never try it again. I also lock out od it is just too much of a gear drop to recover it usually snuffed the turbo out.
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I agree with all but the part about high range is hard to lite the turbo. I found it much easier to lite the turbo in high range. But I too am going to stick with 3rd Lo and changing to 35" tires for a little extra speed.
 
MoPower05 said:
That makes your final gear ratio 10.51 and you run 35" tires. I have a 12.40 final gear with 33" tires. Can you keep your convertor locked at the big end or do you snuff?
Click to expand...

loose track it spins out tacky track it snuffs out with the converter locked
 
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