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Crawl ratio question

Magikal

Magikal

1/2 ton status
Joined
Nov 25, 2007
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Location
North Idaho
Recently installed a 203/205 doubler in my k5. Im a little disappointed, the crawl doesn't seem as low as i was expecting. Granted, i never did the math, i just assumed it would be super slow. Im running a stock 4l80e, 203/205 (also stock gears) with 4.56 axles on 40's. Any of you gurus know what my final ratio should be in 1st gear, low/ low? Honestly, my 99 superduty stock crawls slower in 1st gear 4 low then my k5 does with the doubler.

Almost seems like something's not right yet everything works and it moves and goes...

Im just looking for some experienced insight.....
 
I don’t know the trans ratio but it’s like this -

2.48 x 2.0 x 1.96 x 4.56 = 44.33 crawl ratio

I believe automatic trans folks double their final number because of the torque converter, so 88-ish.
 
1st 2.48:1, Doubler 4:1, axle 4.56:1. Multiply it all together and you get 45.2:1.
 
Magikal said:
Recently installed a 203/205 doubler in my k5. Im a little disappointed, the crawl doesn't seem as low as i was expecting. Granted, i never did the math, i just assumed it would be super slow. Im running a stock 4l80e, 203/205 (also stock gears) with 4.56 axles on 40's. Any of you gurus know what my final ratio should be in 1st gear, low/ low? Honestly, my 99 superduty stock crawls slower in 1st gear 4 low then my k5 does with the doubler.

Almost seems like something's not right yet everything works and it moves and goes...

Im just looking for some experienced insight.....
Click to expand...

Yeah your crawl ratio is only 44.33 to 1
First gear in your trans is only 2.48
 
Magikal said:
I hate that tranny. My k5 is off road only. I suppose built right it would be good. Time to swap in that ole sm465 i have laying around....

Thanx guys!
Click to expand...
Yeah, I didn't do math on yours. My 465/203/205/4.10s puts me almost 105:1
 
It's good in that heavy rock section. Otherwise I direct the 203 and run 52.5:1 which is still lower that what you are doing now locked all the way down

Clutch pedal. It's a thing...
 
These are my options, and the 159 is pretty rediculous.
Crawl ratio Both low 159-1

Or Magum low 81-1

Or 205 low 58-1
 
skunked said:
I’ll run that 4L80E all day but with better gearing behind it.
Click to expand...
5.13 gears only kicks the low/low crawl ratio up to 49:1. Does anybody sell different gearsets for the 4L80e? Or at least a deeper 1st gear?
 
ZooMad75 said:
Does anybody sell different gearsets for the 4L80e? Or at least a deeper 1st gear?
Click to expand...
TCI used to make a 2.97:1 planetary set for them, but it's discontinued. I think you can still get the 2.75 https://www.speedwaymotors.com/TCI-277500-Planetary-91-96-4L80E-w-2-75-1-1-57-2,333760.html

The irony is that towing and racing guys complain that the 1st to 2nd gear drop is too big on the 4L60E. All reasons why we are now seeing 6+ speed transmissions.

And yes, unless you have a weird torque converter you apply a 2x value for automatics. So make sure you're comparing a manual swap fairly.
 
skunked said:
you forgot to include the planetary box.
Click to expand...
2.48 x 2.0 x 1.96 x 5.13 = 49.87 by my calculator.

Blue85 said:
TCI used to make a 2.97:1 planetary set for them, but it's discontinued. I think you can still get the 2.75 https://www.speedwaymotors.com/TCI-277500-Planetary-91-96-4L80E-w-2-75-1-1-57-2,333760.html

The irony is that towing and racing guys complain that the 1st to 2nd gear drop is too big on the 4L60E. All reasons why we are now seeing 6+ speed transmissions.

And yes, unless you have a weird torque converter you apply a 2x value for automatics. So make sure you're comparing a manual swap fairly.
Click to expand...

I have a 700 so I know the crappy gear split from first to second all too well.

Also isn't the most torque multiplication happening in the torque converter when are at or near stall speed? So if you aren't near stall on the converter you aren't getting the 2x value on torque. Or at least that's what I'm remembering on torque converters.
 
ZooMad75 said:
2.48 x 2.0 x 1.96 x 5.13 = 49.87 by my calculator.



I have a 700 so I know the crappy gear split from first to second all too well.

Also isn't the most torque multiplication happening in the torque converter when are at or near stall speed? So if you aren't near stall on the converter you aren't getting the 2x value on torque. Or at least that's what I'm remembering on torque converters.
Click to expand...
Yes it’s variable, depending on several factors in the converter.
Fair to say it will multiply up to 2x at peak
 
I have one buggy at 6.55(sm465)x4(Dana 300 with LoMax 4)x5.13=134.06
one is at 2.52(Turbo 350)x2.28(stock Toyota)x4.7(lower Toyota)x4.1=110.71
on at 3.92(W56)x2.28(Toyota)x2.28(Toyota)x4.7(Toyota)x6.17= 590.93
 
ZooMad75 said:
2.48 x 2.0 x 1.96 x 5.13 = 49.87 by my calculator.
Click to expand...

the 241 planetary is 2.72 and I’ve never felt the need to have anything geared lower than my current configuration. But I also have BBC torque feeding the drivetrain, not a 4 banger bouncing off the rev limiter.
 
skunked said:
the 241 planetary is 2.72 and I’ve never felt the need to have anything geared lower than my current configuration. But I also have BBC torque feeding the drivetrain, not a 4 banger bouncing off the rev limiter.
Click to expand...

I have always believed in gearing instead of power. I have had several Toyota buggies I have wheeled in the past. although I have sold or traded all those off and right now every buggy is running a V6. I have never had a V8 buggy but have wanted one. I bet the BBC is a good crawler since it makes its torque lower in the power band.
 
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