LB7: LB7 Gear change

jmaz268

jmaz268

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May 20, 2010
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So been doing alot of thinking on that I wanna try out some new gearing. Obviously if I pull apart the difs, I will prob do new lockers as well.

I will be running PYOs with some M and Hs and will prob go with some 3.42s. Any of you guys running that gear set with same size tires?

In my mind I foresee it launching a bit better and staying gear slightly longer than the 3.73s, possibly allowing more a load on the motor and staying in the sweet spot longer.

Or am I wrong?

What would you guys suggest?
 
THEFERMANATOR

THEFERMANATOR

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Feb 16, 2009
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I don't race mine, but I have 3.42 gears in my BURB with the stock 245/75/16 tires. They work out great except for when I'm towing. I think they actually helped the power a bit as it is loaded better when empty, and it isn't trying to shift so dang fast with them like the donor truck did with 3.73's. I personally for racing would use a MPH to RPM calculator, and go with the gear ratio that is going to have you close to redline in whichever gear you want once you have reached your trap speed. When I watch teh diesel races Idon't understand why the trucks aren't geared to run out the back door. SO many guys out there are just hitting top gear a 100 feet before the trap, and to me this is a waste. I drag raced gassers for years, and you could see a noticeable gain by regearing so that you would be running high gear out by the end of the track VS still having some RPM's left.
 
jmaz268

jmaz268

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THEFERMANATOR said:
I don't race mine, but I have 3.42 gears in my BURB with the stock 245/75/16 tires. They work out great except for when I'm towing. I think they actually helped the power a bit as it is loaded better when empty, and it isn't trying to shift so dang fast with them like the donor truck did with 3.73's. I personally for racing would use a MPH to RPM calculator, and go with the gear ratio that is going to have you close to redline in whichever gear you want once you have reached your trap speed. When I watch teh diesel races Idon't understand why the trucks aren't geared to run out the back door. SO many guys out there are just hitting top gear a 100 feet before the trap, and to me this is a waste. I drag raced gassers for years, and you could see a noticeable gain by regearing so that you would be running high gear out by the end of the track VS still having some RPM's left.
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Yeah thats about how I am now, I shift into 5th 100-200 ft before the finish. Would much rather either stay in 4th or be in 5th for alot longer.

I would just extend out the shifts on my trans tune, but I think changing gearing will net much better results in the first half of the track as well.
 
THEFERMANATOR

THEFERMANATOR

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It seems to me from teh few diesel races I have been to, that the guys who are winding out pretty good in 5th at the end, are launching in 2nd. I always wondered why they didn't go to a taller gear and use 1st to launch and wind out in 4th at the end. I've only drag raced gasser's, so I don't know if this holds true with diesels or not. But we always found winding it out in OD at the end would cost you some ET rather than gearing to wind her out in direct.
 
DMAXchris

DMAXchris

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Apr 28, 2009
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John, have you ever tried holding 4th through the trap? I would try that before I started playing with gearing. Do you have a trans tune?
 
05_LLY

05_LLY

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jmaz268 said:
Yeah thats about how I am now, I shift into 5th 100-200 ft before the finish. Would much rather either stay in 4th or be in 5th for alot longer.

I would just extend out the shifts on my trans tune, but I think changing gearing will net much better results in the first half of the track as well.
Click to expand...

1/8th mile?
 
jmaz268

jmaz268

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Yeah I've tried it and just seemed it died at the end and wasn't making anymore power, then the shit and it would. that is with a 3550rpm shit point.

I think I could swap the gear and drop it back down to stockish rpm and it run much better with a better ET.

I would like to know how it will affect 60 ft times, if at any. Hard to tell when you take off in 1st if I'm shifting into 2nd before or after, I am assuming I am shifting shortly before I hit that stage.
 
Evan@InglewoodTrans

Evan@InglewoodTrans

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Aug 5, 2010
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jmaz268 said:
Yeah I've tried it and just seemed it died at the end and wasn't making anymore power, then the shit and it would. that is with a 3550rpm shit point.

I think I could swap the gear and drop it back down to stockish rpm and it run much better with a better ET.

I would like to know how it will affect 60 ft times, if at any. Hard to tell when you take off in 1st if I'm shifting into 2nd before or after, I am assuming I am shifting shortly before I hit that stage.
Click to expand...

Those shits will get you everytime John :joker:
 
05_LLY

05_LLY

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My self id wait and see where your other new mods get youtime wise and shifting wise on the track befor making the decision!
 
jmaz268

jmaz268

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05_LLY said:
My self id wait and see where your other new mods get youtime wise and shifting wise on the track befor making the decision!
Click to expand...

Yeah Caleb, I figured I wouldn't have much of a choice on that one anyway. Cause if the Dif is coming apart new lockers are going in too.
 
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