How streetable are 4.88's vs 4.10's?

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bubba_pa

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The truck sees 10 - 20 miles daily on highway into small town. Rarely makes long trips. At most 90 - 100 miles for local pulls. I don't mind not going fast but want to try and compete better at pulls (10 - 12 per year).

Can't do the truck as dedicated puller yet so have to keep options open. By my calculations it looks like 65 mph is 2250 rpm's with 33" tires. Truck has a 66/71/16 turbo, pump work, 5 X 0.16's, stock cam, Goerends auto and runs pretty well but need the extra rpm's to make more power.

Any body actually run 4.88's on the highway please let me know if I'm crazy or if it would work. Do you have to change anything with the tranny (shift points, etc.) with the 4.88's? Thanks for help.
 
This is a good question and something I have been contemplating. I need to add either set to my DD/Hauler and I was leaning toward 4.10's but they do run 4.88's in f-450's etc. and I know they run high rpm's on the highway but the stock tires are what near to 33" and I am running 35's so I'm not sure which set to go with.
 
by my math the rpm @ 65 will be 3,230. with a 1.1 gear and no slippage in the trans. i wouldent try to run that much gear kn the street.
 
Fuel milage will drop in your rpms will go up alot running highway speed. But short trips shouldnt be to bad.
 
BenM said:
that's what i thought untill i got it on the highway and the 4.88 sucked. rpm is 2300/2400 at 65-70. if i could change them back i would.
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Most of my driving is 55 - 65 mph. Rare interstate at 70. What was the worst part - mileage, rpm's, noise???? do you still have the 4.88's? Also what size tire do you have?


stuckey_272002 said:
by my math the rpm @ 65 will be 3,230. with a 1.1 gear and no slippage in the trans. i wouldent try to run that much gear kn the street.
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That's true with a 35" tire in Drive (1:1 ratio) but overdrive drops to 0.69 so I think that is where BenM gets his 65 - 70 mph at 2300 - 2400.
 
BenM said:
that's what i thought untill i got it on the highway and the 4.88 sucked. rpm is 2300/2400 at 65-70. if i could change them back i would.
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Ben -

did you have to change anything with the tranny? I'm assuming you run an auto not manual?
 
305/70-16s(roughly a 33) with 4.10s in 5th(OD) im at 22-2250 at 65.

all the calculators im looking at online are showing it to be about a 10mph(roughly, at 2250rpm) difference at the same rpm comparing 4.10-4.88.

i cant imagine driving 4.88s on the street unless i was running 37s.

Garrett
 
SSpeeDEMONSS said:
305/70-16s(roughly a 33) with 4.10s in 5th(OD) im at 22-2250 at 65.

all the calculators im looking at online are showing it to be about a 10mph(roughly, at 2250rpm) difference at the same rpm comparing 4.10-4.88.

i cant imagine driving 4.88s on the street unless i was running 37s.

Garrett
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What's the final ratio for a manual 5th gear? Your numbers seem kind of high for rpm's? Did you recalibrate the speedo with the 305's?
 
bubba_pa said:
What's the final ratio for a manual 5th gear? Your numbers seem kind of high for rpm's? Did you recalibrate the speedo with the 305's?
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5th gear for the NV4500 is .73.

my number for my truck is GPS mph, not speedo mph. i think it might be a little off with my memory but im pretty sure thats right. maybe 2300 for 65mph.

Garrett
 
SSpeeDEMONSS said:
5th gear for the NV4500 is .73.

my number for my truck is GPS mph, not speedo mph. i think it might be a little off with my memory but im pretty sure thats right. maybe 2300 for 65mph.

Garrett
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0.69 to 0.73 would probably make the difference. I'm right around 1800 - 2000 for 60+ mph.

It seems the best answer may lie in how you drive the truck. If you want highway speed then the 4.88's wouldn't work but if willing to give up a bit they might be drivable. I'm just trying to get the best idea before I drop $2000 to make the switch (assuming $500 for rear, $400 for front and a new locker up front $800+as I'll need a new carrier anyway and why stay with a limited slip). That's a lot a green backs to find out later it didn't work.

Thanks for help so far, keep the comments/recommendations coming.
 
Get a second set of tires/rims that are taller for your daily driving and use the 33's for the pulls... that way you can run that gearing.
 
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