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newbie with a lot of questions

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by BIG*RED, Mar 14, 2003.

  1. BIG*RED

    BIG*RED 1/2 ton status

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    Hey there, i'm new to this site and new to the 4x4 world..always drove lowered trucks and cars before..yeah i know..its ok i have thick skin, go ahead and make the coments...I guess i should start off by telling you what i know...i bought a 1982 chevy blazer, it has a four inch lift and sits on 35x12.50.15s, it orginally had an inline six..but now has a chevy 350..i ran the casting numbers and came up with 1987 and newer block...it is a fuel injected block and heads (have a electric fuel pump) with an edelbrock performer intake, and an edelbrock performer carb running at 795cfm (so they say) it also has a four speed manual with "granny low"..i have a 12blt rear end with a huge truss type support welded to the bottom of it. and i think i have a dana 44 front axel..still not positive on that, and a np208t-case...ok here are some of my questions..i beleve i have a floating rear axel...what is or how do i figure out my gear ratio...with my foot to the floor i max out at about 53mph going up hill on the freeway..what is a good recomend gear ratio..mainly street driving but i do go out playing in the mud/snow/and climb some rocks..(2) what is the redline for my engine? i seem to peak at 4000rpm..just won't go anymore..(3) should i remove the 4speed and put in an automatic? (4) who makes a good 6inch lift kit..all leafs, i don't want blocks in the rear..well thats all for now, but trust me i have like a hundred..i know nothing about 4x4s..also my truck has new interior top to bottom front to back...i picked it up for $3000.00 and many people have told me i payed too much...what do you think?
     
  2. Z3PR

    Z3PR Banned

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    Welcome to CK5. One thing you may want to try is a search. You won't belive all the information you'll find at this site. Please take a momment to file out your profile if you haven't yet. It'll help us help you.
     
  3. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Welcome to CK5. Yeah you could spend a few hours searching for the info...but that can be a frustrating way to spend your first couple of days here.

    A stock 350 should run out of useable power around 4000-4500. Between the heads and stock cam there isn't much in the way of top end.

    Stock issue if it's a factory 4 speed truck would be 12 bolt rear and 10 bolt front. My 81 Jimmy was a factory 4 speed truck with a 305...and it had 2.73 gears. I'd make a guess you probably have 4.10's because it was a 6 cylinder truck originally.

    53 mph flat out up a hill? What gear? How steep a hill? Is that redlined?

    My advice would be to head to the parts store and pick up some RTV sealant and a few quarts of 90W gear lube and some brake Kleen. Pull the rear cover off, clean the guts and make sure everything is cool. Now rotate the carrier slowly until you see some numbers stamped on the ring gear edge. The first few numbers are part numbers, then there is a pair of numbers like 11-41, or 10-41, and the last few numbers will be the build date (should be sometime in 81 or 82 if it's orginal equipment)

    The smaller number (10, 11, 12) is the number of teeth on the pinion gear, the larger number is the number of teeth on the ring gear. 11-41 is 3.73's, 10-41 is 4.10's, 12-41 is 3.42's...you get the idea.

    It's an easy job that probably needs doing anyways. Diff's are very under serviced...

    The 12 bolt is a half ton semi-floating diff. 8.875" ring gear with C-clips. Not a bad diff, but 35's should be the max tire size. My original 12 bolt blew the spider gears through the cover backing out of a parking spot... /forums/images/graemlins/eek.gif

    The 10 bolt front is a good match for the 12 rear. 8.5" ring gear and also shouldn't see much more than a 35" tire. If you beat the truck hard you'll likely need to upgrade the diff's. They won't spontaneously explode, but the possibilty of trail breakage is there. Many here run the 1/2 ton stuff and swear by it...

    Personally I'd keep the 4" lift...it's pretty easy on the drivelines and helps keep the center of gravity a little lower. If you have clearance problems running the 35's you can trim the fenders a little. Most people would be hard pressed to notice they're trimmed if you do a neat job. You don't need to get too carried away for 35's.

    Keep the 4 speed...it's bullet proof and great for crawling!! I love my 4 speed!

    Hard to say on the price...too many variables. 3K should have got you a decent truck though.

    Rene
     
  4. Blazinaire

    Blazinaire 1/2 ton status

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    [ QUOTE ]
    I'd make a guess you probably have 4.10's because it was a 6 cylinder truck originally.

    Rene

    [/ QUOTE ] And if this is the case then you would be in about the right rpm range for your 35'' tires being that you do not have overdrive. If that is the case and you feel that you still need more low end power you could change the gears to 4.56 but you will lose a little top speed (but better climbing power and acceleration.)

    As for the transmission, your 4 spd is about as strong as they come and is great for crawling due to its low first gear.

    I agree that you will be better off all around if you stick with the 4'' lift being that it will ride better than a taller lift, keep driveline angles reasonable, and keep the vehicles center of gravity lower. If you really want to get rid of the blocks in the rear there are a few things that you could do: shackle flip from www.offroaddesign.com this will basically flip your rear shackle over to gain 4'' of lift with stock springs and no blocks. The benefits of this are that you keep your stock springs for a better ride and you won't have blocks that cause axle wrap and this method is cheaper than new springs.The downside is that it can be difficult to install. Or you could just replace the rear springs with some 4'' lift springs from most any lift manufacturer. +: easier install with less axle wrap. -: stiffer ride, more $$$.

    and most importantly: WELCOME TO CK5! /forums/images/graemlins/laugh.gif
     
  5. pismorat

    pismorat 1/2 ton status

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    welcome, can you get a pic of your rear axle online, i am curious what your truss looks like. /forums/images/graemlins/truck.gif
     
  6. BIG*RED

    BIG*RED 1/2 ton status

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    thanks guys for all of the help and info...
    at 53mph up hill, i am in 4th gear at about 2800rpm with my foot to the floor, if i shift down to 3rd gear the truck screems at runs at 4500rpm, so i go back into 4th and crawl up the hill, the hill is not that steep goes about 700ft in elevation over the cousre of 9miles..
    as for the pics, i have a couple at http://photos.yahoo.com/scr8pngmc
    they are not that reat but once the rain stops and the sun comes out i will get some better ones
     
  7. pismorat

    pismorat 1/2 ton status

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    thanks a lot for the pics, just a thought, could your t-case be in a different mode or something? maybe someone just put really tall gears in it. /forums/images/graemlins/truck.gif
     
  8. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    53 mph in 4th at 2800 rpm on 35's says you have a wonky speedo. Or you have 5.13's...

    mph x final drive ratio x 336 / tire diameter

    53 x 5.13 x 336 / 34 (true diameter) = 2686 rpm

    I'd say either your tach or your speedo is off by a fair bit...

    Rene
     
  9. BIG*RED

    BIG*RED 1/2 ton status

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    Well I have a slight update on that, I went to go get a new muffler put on, and when the old muffler was cut out we noticed that the cat convertor was all melted inside, so we just cut the cat out and replaced it with a straight pipe, and magnaflow muffler (which is so illegal living here in cali, but hey i've got two years before i have to smog it again)..i took it up that same hill on the freeway after removing the cat and now after makeing the run three times each time i ran about 68mph at approx 3000rpm up the hill in fourth with the foot to the floor.. /forums/images/graemlins/grin.gif but i still would like to figure out my ratio one of these days..
     
  10. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Pull the cover.

    What kind of tach do you have? How accurate is your speedo?

    With a 4 speed the drivetrain has no slip like an auto so throttle position doesn't change the rpm versus speed.

    The new numbers tell me 4.56 gears...so either your approximations are off or something is screwy. I suspect the speedo is reading slower than true (prolly 12-15% slow) and you have 4.10's.

    Rene
     

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