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02-01-2007, 02:35 AM | #1 |
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Join Date: Jan 2007
Location: Camarillo, CA
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4.10 rear end gears!! Arghhh
Even with the 700R4 locked up, with 295/50/16 BFG's on it, Im turning 2500rpm cruisin on the fwy here, and I pretty much have to stay in the right lane (70mph is WAY slow on the fwy here! So cal!)
Im thinking about switching back to 3.42's.... The problem is... the rear end is new, new Posi, and the rear end built with all new bearings, 5 lug axles, etc.. Thinking about maybe looking for someone to trade out with a tight Posi'd 3.42 or... I dunno Just a bit too short, hell, with the motor in it now, I could run 3.08's with no issue, but cruise would drop way down... 72mph = 2500 rpm - 4.10 72mph = 2100 rpm - 3.42 72mph = 1900 rpm - 3.08 The drawback is that I have a Victor intake with a spacer, and where it has plenty of git, it will be runnign a bit below the torque curve with the lower gear, and with it the loss in mileage... Ideas?? Wanna trade? lol Will
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1970 C10, shortened long bed, Alum Headed full roller 383 (with Victor, 750DP, stainless rockers, behive springs, CNC ported heads) TCI SSF 700R4, 4.10 Posi, Bagged on C-Notch and 2.5 spindles. Air Cond, black out tint, satin black paint, custom interior, rolling low and not so slow... |
02-01-2007, 02:39 AM | #2 |
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Re: 4.10 rear end gears!! Arghhh
cant you take the 3.42 ring a pinion and and put them in your new one so you have the best of both, and i dont think id go lower than that because you do want to have atlest some rpms otherwise the converter will be slipping and heat up to much, but i could be wrong, wouldnt be the first time
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-steven Alte Seele S.S. "Allison" '72 C/10 LWB 350SB/TH350 - DD PITBULL IS NOT A CRIME |
02-01-2007, 10:56 AM | #3 |
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Re: 4.10 rear end gears!! Arghhh
Those numbers do not sound correct. How tall are your tires? 4.10 gears with a 700 in 4th gear become 2.95s before the lock up convertor.
I looked up some stuff, tires must be about 25-26'' tall. try this link for calcs http://www.florida4x4.com/tech/gearcalc.php Last edited by kwmech; 02-01-2007 at 11:05 AM. |
02-01-2007, 03:06 PM | #4 | |
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Re: 4.10 rear end gears!! Arghhh
Quote:
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Chris 74 Custom Deluxe SWB 350/350/3.73’s 99 2wd Silverado RCSB 5.3/4L60/3.90’s http://www.classictrucks.com/feature...short_bed.html |
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02-01-2007, 12:00 PM | #5 |
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Re: 4.10 rear end gears!! Arghhh
I checked it with that calculator too and its right on... 2500 =70mph. Tires are 27.6 tall according to BFG's site..
Guess I could throw taller tires on it, but it kinda kills the "look" lol
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1970 C10, shortened long bed, Alum Headed full roller 383 (with Victor, 750DP, stainless rockers, behive springs, CNC ported heads) TCI SSF 700R4, 4.10 Posi, Bagged on C-Notch and 2.5 spindles. Air Cond, black out tint, satin black paint, custom interior, rolling low and not so slow... |
02-01-2007, 12:24 PM | #6 |
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Re: 4.10 rear end gears!! Arghhh
Personally I think 23-2500 RPM is a good cruise RPM. My problem is that I'm doing 60MPH at 2500,so I definately hug the right and watch my mirrors.
>>My last '69 came with a 3.08 and 33" tires and got lousy freeway mileage. >>Not sure I'd change that set-up of yours.
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'69 GMC C2500 Custom Camper, 8 1/2' bed, New GM 350, NP 435 Close Ratio 4spd. Trans., 3.73 Dana-60 open.Camper and Trailer wiring, PS, PB, AC, tach , three gas tanks, stereo speakers, 2nd owner, Work-Truck supreme. |
02-01-2007, 12:35 PM | #7 |
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Re: 4.10 rear end gears!! Arghhh
my 86 lwb has a 700r4 and 308's from the factory and it does just fine.
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02-01-2007, 03:22 PM | #8 |
Hittin E-Z Street on Mud Tires
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Re: 4.10 rear end gears!! Arghhh
^about 2000 to 2400 seems to be the "happy range" for the 700R in my truck. I have a 3.73 rear.
I have 235/75/15 on my truck and she turns a little more than 2100 rpm at 70. It's really nice
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Jesse James 1967 C10 SWB Stepside: 350/700R4/3.73 1965 Ford Mustang: 289/T5-5spd/3.25 Trac-Loc 1968 Pontiac Firebird: Project Fire Chicken! 2015 Silverado Double Cab 5.3L Z71 2001 Jeep Wrangler Sport 4.0L 5spd 2020 Chevrolet Equinox Premium 2.0L Turbo 2011 Mustang V6 ~ Wife's ride American Born, Country by the Grace of God 1967 CST Shop Truck Rebuild! My 1967 C-10 Build Thread My Vintage Air A/C Install Project "On a Dime" Trying my hand at Home Renovation! 1965 Mustang Modifications! |
02-01-2007, 04:07 PM | #9 |
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Re: 4.10 rear end gears!! Arghhh
try some 373 gears, and a 60 or 65 tire
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1997 pontiac grand prix gt (daily driver) for now; 2004 dodge ram quad cab (wife's truck) 4.7; 2000 pontiac booneville (wife daily driver) 1972 chevy cheyenne 350 bored 40 over 700r trans 373 gears ( posi) soon to be daily driver; 2002 gsxr750 sold |
02-01-2007, 04:15 PM | #10 |
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Re: 4.10 rear end gears!! Arghhh
ive got the stock TH350 with 3.07s and 29ish tall tires (side wall says 31) and i turn i think 3400rpm at 75mph i think i dont really remember
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-steven Alte Seele S.S. "Allison" '72 C/10 LWB 350SB/TH350 - DD PITBULL IS NOT A CRIME |
02-01-2007, 04:43 PM | #11 |
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Re: 4.10 rear end gears!! Arghhh
What rear do you have, 10 bolt or 12bolt? If you can use the same carrier then put some 3.73 in it, that will drop you to about 2100-2200 and then sell the 4.10s on e-bay. If you dont know how to set up gears then it will cost you labor but that is it. If shops in your area want to much to do the swap, ask the techs in back if they do side work.... It shold cost about $300 to do the swap.
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02-02-2007, 12:11 AM | #12 |
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Join Date: Jan 2007
Location: Camarillo, CA
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Re: 4.10 rear end gears!! Arghhh
It has a 12 bolt... I do need the new carrier, but thats part of the deal, no biggie...
Id like to get the cruise RPM about 1900 at 70 mph, as we rarely drive below 80 on the fwy here in SoCal! Dont want to change the tires right now, just about the right stance, so the gears it is.... BTW, anyone need some 20x9.5 torq thrust 2's? Chrome lip with black powdercoated centers? I was at powdercoater today, and they had a deadbeat customer that had them done... they want $1k for the set of 4... PM me if anyone wants the contact info...
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1970 C10, shortened long bed, Alum Headed full roller 383 (with Victor, 750DP, stainless rockers, behive springs, CNC ported heads) TCI SSF 700R4, 4.10 Posi, Bagged on C-Notch and 2.5 spindles. Air Cond, black out tint, satin black paint, custom interior, rolling low and not so slow... |
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