LUVTruck.com

i have a 75 chevy luv witha v-8 comversion and a turbo 350 trans and im having a highway driving problem that i dont like. as im doing 60 mph on the highway my rpm's are running right at about 3800 and that fairly high for me and the gas mileage sucks. does anyone know what the stock gear duration is on a 75 rear end and also were i can order a new set of gears that will do me alot better. i did the whole mark the driveline and wheel and then turn the wheel and count how many times the driveline turns and i came to about 4.75ish. some else had told me a couple weeks ago that it seemed like i had a gear set out of a 4 wheel drive so im just curious about the gears and different options

4.56 gears are the norm for 2wd LUVs. 4.10 for the 4X4 and automatic trans trucks. You'd be best off swapping out the axle assy. Somewhere on the site is some info on going with a trooper axle. Most opt for a S-10 axle for a stock engine/V-6/ mild V-8 trucks. With an S-10 unit, you can go with certian Camaro driveshafts that will fit right in.
Ford 9" seems to be the most common axle upgrade for performance. Once you have a Ford 9 installed, you dont have to think about reliability anymore. They're easy to narrow, parts are readily available and ratios can be had from 3.00 to over 5.XX

Im suprised that you haven't grenaded the stock assy with running a V-8. The engine temps with running 4.56 gears on the Hwy must be freaking you out too. Get something better under the truck. A S-10 unit will be easier and faster to do but a Ford 9 will need mods done and it will take all kinds of abuse

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Previous setup: 4.1 Buick V-6/TH 350
Current setup: 400 Small Block Chevy V-8/TH 350
9" ford rear end/short bed/blue
What do Water, Electricity and Humans have in common... They all travel the path of least resistance.

yeah a couple days ago i was on the highway and looked down at the temp gauge and it was sitting at about 240 and i have a 180 thermostat. right now my dad and i are building another luv but this ones only dragrace and were putting a 600 horse sbc with a powerglide and this one were putting the ford 9" i would like to get one of those for my truck but there way to expensive for me. i have a 89 s-10 down in AZ i guess ill have to go rob the rear end ot of it. thanks for the input and hope to hear more about my problem

i hope your s10 is a 2wd, cuz the 4x4 has a wider rear end!

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!!!FINALLY!!!
-1977 Luv mikado

fo sho'
2wd S-10 rear will bolt right in, with only changing the yolk on the driveshaft.
or if you knew where you could find another center "pumpkin" with 3:73 gears you can pull the whole center out and swap it out with your 4:56. most 79 and 80 2wd luvs came with 3:73s.

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03Cobra

3.73 in a stock luv?!? i was under the impression that all luvs had 4.10 or 4.56 depending on whether it was a 4x4 or not, and that the auto luvs had a higher ratio.

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!!!FINALLY!!!
-1977 Luv mikado

yes sir....in the later model luvs they offered a 3:73 ratio.
There was a chart or reference somewhere on the board that stated what ratios were in what year etc....lemme see if I can find it.

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03Cobra

72-75 had 4:56
76-78 had 4:10
79-80 2wd/4spd or auto had 3:73
79-82 4wd had 4:10
81-82 2wd/4spd had 3:42
81-82 2wd/Auto had 4:10

thanks bob, I was on my way back from finding the info.

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03Cobra

no problem.. i had a spreadsheet of info i was gathering for 800xl..

huh.. thanks bob that right there was the clearest info on that topic i have seen!!!



i stand corrected and informed!!

_________________
!!!FINALLY!!!
-1977 Luv mikado

add
81-82 2wd/5spd w/ 3.73 gears

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-Old ride-82 Luv diesel 5spd with some upgrades
-Past rides-82 Sierra, 78 Coupe De'Ville, 91 2dr Blazer, 86 RX7, 86 Porsche 944T (rear-ended and totaled)
-Curr. rides- 1970 Ford LTD 4dr, 390 4Bbl, 2nd owner! With a few Extras 00' Civic beater...

hey guys thanks for all the info i have a 2wd s10 but id rather just swap the 3rd member ourt of the stock rather than driving all the way to AZ for a rear end. just one question is the gears i have and the gears from the later model years use the same pline axel and does anyone ant to trade me some parts for a 3rd member

Finalman... are those numbers for a diesel truck???

Actually, idk, i thought gassers had 5spds w/ 3.73, prob. is for a diesel... Eh, b-day's going so-so now

_________________
-Old ride-82 Luv diesel 5spd with some upgrades
-Past rides-82 Sierra, 78 Coupe De'Ville, 91 2dr Blazer, 86 RX7, 86 Porsche 944T (rear-ended and totaled)
-Curr. rides- 1970 Ford LTD 4dr, 390 4Bbl, 2nd owner! With a few Extras 00' Civic beater...

does anyone know if the 75 rear 3rd member and the later year third members are the same spline axle? i have a 76 rear sitting at my house how much of a difference will swaping 4.56 to 4.10 make on the highway?

they should be the same

thanks bob but do you knwo how much of a difference it will make by swaping gears?

I'm not sure specifically, but your highway rpms would decrease as would your off the line power... but your mpg should improve a fair bit. a buddy of mine went to a 2:73 rear from a 3:42 in an s-10 and upped his mpg about 8.

http://www.idavette.net/tech/ratioc.htm

Click the link above and enter the numbers as best as you can for the setup you have now. Then change the Gear Ratio to the one you want to compare to. This will give you a good ballpark figure.

_________________
Previous setup: 4.1 Buick V-6/TH 350
Current setup: 400 Small Block Chevy V-8/TH 350
9" ford rear end/short bed/blue
What do Water, Electricity and Humans have in common... They all travel the path of least resistance.