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#1 |
Registered User
Join Date: Feb 2005
Location: Texas
Posts: 581
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What is the best rear gear for??
What is the best rear end gear for a 402 w/ a 400th transmission? right now i am running a 373 rear end gear ratio but I I am thinking of a 355 or 342 posi any Ideas? what would you go with with this setup?
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1972 Cheyenne 402 LWB 2005 Silverado X-Cab 5.3L 2004 John Deere L120 20HP B&S Last edited by 72 Cheyenne402; 06-21-2006 at 10:51 PM. |
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#2 |
its all about the +6 inches
Join Date: Jan 2001
Location: Hilliard Ohio
Posts: 2,693
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Re: What is the best rear gear for??
depends on what you want out of the truck, and if the engine is built up or not.
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#3 |
Registered User
Join Date: Mar 2005
Location: 10-Uh-See
Posts: 5,609
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Re: What is the best rear gear for??
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#4 |
Registered User
Join Date: Feb 2005
Location: Texas
Posts: 581
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Re: What is the best rear gear for??
The engine was built about 5 years ago Crane Fast bleed lifters - low end rv cam - 427 crank (because I couldn't find a 396 crank) - Crane chromollly pushrods - Crane steel stamped rockers - bored 40 thousands over (if I remember correctly) - High dome pistons - The heads were reworked with new valve job, valves, and valve seats for unleaded fuel. I thing reworking the heads costed almostr as much as rebuilding the engine. I almost bought some new BB aluminum heads.- Aluminum intake and AFB 750 carb- 3" 3 chamber flow masters 3" exaust all the way back to 4" tips.
Any Ideas?? I am still leaning to the 355 posi. This truck is a crusier anymore and the engine is not ratical just a good build
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1972 Cheyenne 402 LWB 2005 Silverado X-Cab 5.3L 2004 John Deere L120 20HP B&S |
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#5 | |
Global warming is a myth
Join Date: Apr 2003
Location: Henderson, NV
Posts: 208
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![]() Quote:
Swapping the gears would definitely be cheaper, but you could always do that or the trans swap afterward. For me, I'd swap in a t-56 6-speed from a camaro or corvette. I like to row my own gears. Later, Buddy
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Henderson, NV 1972 K5 - Lifelong project - Needs Time, Place, Help & Parts!! 1990 K5 with 37's 2003 Discovery SE7 - Wife's |
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#6 |
Registered User
Join Date: Mar 2005
Location: 10-Uh-See
Posts: 5,609
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Re: What is the best rear gear for??
I don't think you can get 3.55 gears if it's a truck 12-bolt. 3.42 is the only choice, which will work well also. Do you know what kind of rearend you have? The OD tranny is a good idea if you want to spend the money. If you want to get by on a budget, put a set of 3.42's in it.
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#7 |
its all about the +6 inches
Join Date: Jan 2001
Location: Hilliard Ohio
Posts: 2,693
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Re: What is the best rear gear for??
that sucker should have plenty of grunt. Myself, i'd say screw the overdrive, and just go with a 3.08 gear. You'll ned up with a good cruise RPM, maybe a couple hundred revs more than wanted, but not much, and the low end torque should walk right over that gear. Plus, this would be WAY cheaper, and more reliable than any GM overdrive with the exception of the 4L80E, but the cost of that swap would be as much as your motor was.
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#8 | |
Hittin E-Z Street on Mud Tires
![]() Join Date: Nov 2004
Location: Greenville, SC
Posts: 23,090
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Re: What is the best rear gear for??
Quote:
![]() AND you're more likely to find a 3.08 than a 3.42. 3.42's were rare for these trucks right? If you can find a good 3.08 you can swap the whole axle directly (as long as its a leaf rear with a lear rear or a coil rear with a coil rear, otherwise you'll have to swap the mounting blocks.) If you do decide to go OD I'd leave the 3.73 in the truck.
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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! |
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#9 |
Iron Thunder
Join Date: Nov 2003
Location: Phoenix Arizona
Posts: 377
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Re: What is the best rear gear for??
i like 411s,350/th350
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#10 |
Registered User
Join Date: Feb 2005
Location: Texas
Posts: 581
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Re: What is the best rear gear for??
I had a 3.08 posi in it stock the gear just wore out so I went with the 3.73 which cam from another 72 truck it works well and will nearly throw your head through the rear window. I just run hi rmp's at 70-75 MPH. I'm thinking a different gear may help out. I don't want to lose any power or off the line speed???
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1972 Cheyenne 402 LWB 2005 Silverado X-Cab 5.3L 2004 John Deere L120 20HP B&S |
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#11 |
Fabricate till you "puke"
Join Date: Jun 2002
Location: Ill
Posts: 9,403
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Re: What is the best rear gear for??
I like a mid 3's gear with a BB or big inch sb.......that said, I agree with Andy, that sucker will pull a 3.08 just fine
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69 longhorn,4" chop,3/5 drop, 1/2 ton suspension/disc brakes,1 1/2" body drop,steel tilt clip, 5.3/Edelbrock rpm intake/600 carb, Hooker streetrod shorties,2 1/2" exhaust/ H pipe/50's Flows , 6 spd Richmond trans,12 bolt/ 3.40 gears.... |
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#12 |
its all about the +6 inches
Join Date: Jan 2001
Location: Hilliard Ohio
Posts: 2,693
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Re: What is the best rear gear for??
3.42 was never found in these trucks, so there would be no simple axle swap.
I can't believe I said 3.08.... and no one jumped on me for it. (I always tell ppl it's not 3.08, ot's a 3.07) |
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#13 |
Registered User
Join Date: Feb 2005
Location: Texas
Posts: 581
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Re: What is the best rear gear for??
Right now I am running 15x10 with 295-50-15 on the rear and a 15x8 265-60-15 in the front I have been looking at moving up to a 17x10 on the rear with 285-40-17 and on the front 17x8 with a 245-40-17. I'd like to see how this combination works out. Maybe going with a bigger wheel could make all the difference
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1972 Cheyenne 402 LWB 2005 Silverado X-Cab 5.3L 2004 John Deere L120 20HP B&S |
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#14 | |
Hittin E-Z Street on Mud Tires
![]() Join Date: Nov 2004
Location: Greenville, SC
Posts: 23,090
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Re: What is the best rear gear for??
Quote:
I can't ever remember which is the correct one (3.07 or 3.08), I'm lysdexic so it don't matter anyways! I was shown a book at a junkyard with rear axle codes for 67-72 chevy trucks and some of the listings I remember were 3.07, 3.42, 3.73, 4.11, and 4.56. Maybe the 3.42 was used in vans or something? Maybe I was looking at the wrong years, maybe it was for a car? I just remember thinking, "man! if I could get a 3.42 with my 700R4 that would be awesome!" Yup, larger diameter tires (overall larger height) will effectively give you a higher gear ratio. There's lots of online calculators out there, just google it and find one that uses a 1:1 ratio or you can find one and play with the tire/gear/OD ratios (a 700R4 uses a .70)
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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! Last edited by 67ChevyRedneck; 06-22-2006 at 05:31 PM. |
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#15 |
its all about the +6 inches
Join Date: Jan 2001
Location: Hilliard Ohio
Posts: 2,693
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Re: What is the best rear gear for??
3.07 is correct.
The 3.42 wasn't offered, not as a RPO anyways. I'm sure it was used in cars, and maybe vans, but I know for ertian it was not an RPO on the 67 - 72 10 - 30 trucks. |
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#16 |
State of Confusion!
![]() ![]() Join Date: Jul 2002
Location: Gulfport, MS USA
Posts: 46,904
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Re: What is the best rear gear for??
I agree with Andy. With a BB get the 3.07 or 3.08. Unless this is being used as a serious work/pulling/racing truck, that will give you the best overall driving ratio.
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Bill 1970 Chevy Custom/10 LWB Fleetside 2010 Toyota Tacoma PreRunner SR5 Double Cab - DD Member of Louisiana Classic Truck Club (LCTC) Bill's Gallery Life isn't tied with a bow, but it's still a gift. Live simply. Love generously. Care deeply. Speak kindly. Leave the rest to God! |
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#17 |
Fabricate till you "puke"
Join Date: Jun 2002
Location: Ill
Posts: 9,403
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Re: What is the best rear gear for??
The 3.42 gears are available aftermarket (Richmond, ect). The 75 12 bolt under my truck actually has e 3.40 gear.....
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69 longhorn,4" chop,3/5 drop, 1/2 ton suspension/disc brakes,1 1/2" body drop,steel tilt clip, 5.3/Edelbrock rpm intake/600 carb, Hooker streetrod shorties,2 1/2" exhaust/ H pipe/50's Flows , 6 spd Richmond trans,12 bolt/ 3.40 gears.... |
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#18 |
Registered User
Join Date: Jan 2006
Location: Houston
Posts: 434
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Re: What is the best rear gear for??
Longhorn Man
When you do the calculation isn't it something like 3.07692307692. It's so close I think you can get away with either 3.07 or 3.08. |
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#19 |
Gone Fishing
Join Date: Aug 2005
Location: Fort Worth, Texas 76135
Posts: 12,361
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Re: What is the best rear gear for??
With that setup I would run 3.08's
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68 Chevy Short Fleetside LSX Swap Under Way 3.73 posi 2.5/4 drop ![]() 2022 Hyundai Tucson Limited 2019 Chevy Traverse Redline Edition Wifes Ride Build Thread http://67-72chevytrucks.com/vboard/s...=1#post3483616 |
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#20 |
its all about the +6 inches
Join Date: Jan 2001
Location: Hilliard Ohio
Posts: 2,693
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Re: What is the best rear gear for??
There was a reason for the 3.07 and the 3.08 gears. The 12 bolt in our truck is not the same as the 12 bolt for a car. This way, back in the day, there was no confusion when a tach ordered gears. If he ordered 3.07...it was a truck, if he ordered 3.08, then it was a car.
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#21 |
Senior Member
![]() Join Date: Nov 2005
Location: Spokane , Wash.
Posts: 790
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Re: What is the best rear gear for??
I love my 3.73's in my 68 bb t400 c10 . I like being able to outrun the new trucks , at least stoplight to stoplight . Especially those v8 ricer wannabe's .
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Can-Am Motorsports 37 Chev Coupe 331 4 speed 5.13 posi . ex-gasser . 64 Biscayne 409 2x4 4 speed 4.11 posi 65 Nova Wagon Drag Car 383 t400 (Dragin-Wagon) 68 c10 cst 396 t400 a/c buckets lwb 4.11 posi (SOLD) |
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#22 |
Thats the Hillbilly way
Join Date: Jul 2001
Location: Torrance,Ca
Posts: 5,980
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Re: What is the best rear gear for??
I went with 3.54 for the Dana rear , it works out great for city and freeway driving .
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BILL Torrance Calif 90504 Member DUF Club Member Old Farts Club 72 3/4ton Custom Camper BB402/400 trans Dynomax Cerama-coat headers , Hei distributor ,Edelbrock 1411 air,ps,pb,leafsprings ,98 chevy 60/40 seat,S10 shoulder belts tilt,3.54 Dana 60 rear. 16" Eagle wheels with LT265/75 16 tires,Gaylord Lid,H4 headlights with 100W relay conversion. " If I knew I was going to live this long I would have taken better care of myself " Marriage changes passion...suddenly you're in bed with a relative. A GUY'S PRAYER.... Lord, I pray for a nympho with huge boobs who owns a liquor store and likes to fish and hunt and has a Harley .Amen , |
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#23 |
Registered User
Join Date: Feb 2005
Location: Texas
Posts: 581
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Re: What is the best rear gear for??
I think I may just go with some bigger wheels maybe some 17" or 18" and see how that works out. I planed on going bigger on the wheels anyway. Can't beat that 3.73/400 trans/402 from one stoplight to the next. I used to take the old 5.0L Mustang's in Houston. You should have seen the anger on there faces. it was great!!
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1972 Cheyenne 402 LWB 2005 Silverado X-Cab 5.3L 2004 John Deere L120 20HP B&S |
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#24 |
Registered User
Join Date: Mar 2005
Location: 10-Uh-See
Posts: 5,609
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Re: What is the best rear gear for??
The 275/40/17 tires won't help you. They are actually a smaller diameter tire. The 295/50/15's are 26.6" tall. The 275/40/17's are 25.7" tall. It would actually be like going to a lower gear and higher revs. If you go with a 275/50/17 or 275/55/17, that would help a little. The 3.42 gears would still work well, a good mix between good off-the-line acceleration and still turn lower rpms at highway speeds.
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#25 | |
Registered User
Join Date: Aug 2005
Location: Pasadena,Tx /Pto Pta DR
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Re: What is the best rear gear for??
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