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#1 |
Registered User
Join Date: Mar 2011
Location: Denver Colorado
Posts: 32
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Help.. gearing stupidity
Ok so I've never changed out gearing and want to know A.how much trouble I'm getting myself into...... or B: which ratio works well for you.
Bought a manual 350, 71 K5 earlier this year and it currently has 3.08. It feels dog slow off the line but has great power once rpm's are up. I'm currently running 33's w 4 in. suspention lift. I really don't want to get totally into rock crawling since the truck a fun family 4wheeling\camping type machine. So if I want to possibly run 35's in the future, but still have some type of highway capability; would you all recommend 4.11 or 4.56? |
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#2 |
Registered User
Join Date: Apr 2010
Location: AK
Posts: 198
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Re: Help.. gearing stupidity
I have 33's with 3.73's and turn ~2800 rpm at 65. I would think 4.56 would eliminate reasonable highway driving even with 35's.
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#3 |
SKINNY TIRES RULE!
Join Date: Sep 2001
Location: Bothell, WA
Posts: 11,049
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Re: Help.. gearing stupidity
I've had three blazers, each with different gears. My first had a 4" lift with 35's and 3.73's. It was sluggish off the line. My second had 6" lift with 35's and 4.10s. It seemed better suited to the tires. My current truck has the 3.07s and tires approx 31.5" tall. It is by far the most drivable.
__________________
bouncytruck 1972 K5 The Hauler 1994 K1500 Suburban The Daily2010 Kia Soul Wife's Ride2014 Fiat 500L |
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#4 |
Senior Member
![]() Join Date: Jan 2001
Location: Orem, Utah
Posts: 7,908
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Re: Help.. gearing stupidity
I would agree. I have the same setup, 33s and 3.73 ratio, and I think it's a good compromise between highway driveability and some mild off-roading.
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#5 |
Rollin in my K5 toaster
Join Date: Oct 2010
Location: Pacific Northwest
Posts: 254
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Re: Help.. gearing stupidity
As much as I like to drive the streets. 4.10 is as low as I would go for a truck with 33/35 and a trany with a 1:1 3rd. If it will never see the free way or Hwy 4.88 would be cool to have. If you have the money you can put a 4 speed over drive in it and go low with no prob.
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#6 |
Registered User
Join Date: Mar 2011
Location: Denver Colorado
Posts: 32
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Re: Help.. gearing stupidity
Ok so next part of the question is, how hard is it to replace the gearing? special tools?
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#7 |
Registered User
Join Date: Mar 2007
Location: Oakland, Ca
Posts: 1,382
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Re: Help.. gearing stupidity
Special tooling yes and a lot of patience getting the bearing preload and backlash correct.
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#8 |
Registered User
Join Date: Jan 2008
Location: PENDLETON,INDIANA
Posts: 271
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Re: Help.. gearing stupidity
Get a book or somebody who has done it
lots of patience in and out multiple times and adjusting backlash and tooth depth as far as tools goes i dont remember much special. .bearing pressed on to the pinion gear if memory serves me |
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#9 |
Registered User
Join Date: Mar 2007
Location: Oakland, Ca
Posts: 1,382
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Re: Help.. gearing stupidity
Press, setup bearings (make them yourself), dial indicator, accurate 1/2" torque wrench, seal driver, locktite...That should cover 95% of it.
Maybe a pinion depth tool and a case spreader... |
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#10 |
Not a bad nut after all..
Join Date: Dec 2000
Location: ND
Posts: 1,756
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Re: Help.. gearing stupidity
It may be cheaper for you to find a different set of axles and swap them in. If you are looking for another 12-bolt rear axle you are limited to '69-'72 4x4 to get the correct spring perches and shock mounts. For the front axle you can use any '71-'76 GM truck Dana 44; a '77-'91 corporate 10 bolt front axle could also be used with a driveshaft length modification.
__________________
'05 Chevy 2500HD 4x4 '72 GMC LWB 4x2 driver '72 Chevy LWB 4x4 plow truck '71 Blazer 4x4 driver '70 GMC LWB trailer |
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axles, blazer, gearing, ratio |
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