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problems with larger tires

Discussion in 'The Garage' started by mr77k557, Jan 11, 2003.

  1. mr77k557

    mr77k557 Registered Member

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    Location:
    stueben , new york (central new york in hicksville
    I have a 77 blazer 4 speed manual, 383, 4.10 gears and plan on 9 inches of lift and 39in tires

    what problems may i run into for ex
    will they clear,
    will i have to run rims with backspacing,
    will this cause problems with driveline angles and if so how do i compensate for it or fix it,
    will it effect mt speedo and ifso i drive on the road alot so hoe do i fix this one,
    and ant thing else you think i should know about includin tire preference

    im only begining in offroadin but plan on doing it right and so far i am by choosing a blazer
    /forums/images/graemlins/k5.gif
     
  2. heavy4x4

    heavy4x4 1/2 ton status

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    Location:
    Delafield, Wisconsin
    Let me answer what I can from the list of questions you have.
    What problems may you run into...first and foremost, if you've still got 1/2 ton axles (10 bolt front, 12 bolt rear) those have to go (or they will take themselves out with 39" tires). Secondly...the gearing you have setup (doesn't sound stock to me...sm465 w/ granny low, and 4.10's /forums/images/graemlins/confused.gif...was gearing changed at some point?) doesn't sound too bad. I think you'll find yourself using granny to get you going. If you want to mess around with various options in tire size and gearing, go to www.4lo.com and play with the calculators....they're great.
    Will they clear...yeah, they should be o.k. If you get really flexy springs, you may want to hack at the corners of the fenders (at least up front). But that can be decided after the tires go on.
    Do you have to run backspacing? Haven't heard of rims without it to be honest with you. Backspacing is the distance between the wheel-mount-surface and the inner bead-mount surface. You should run anywhere from 3.5" to 4".
    Driveline angle problems...you bet, especially with the short wheelbase of a blazer. First of all, I'm not sure how you plan on getting that 9" of lift, but I suggest 6" springs and 3" body. That will help keep the d-shaft angles lower. With the short manual transmission, you will have more problems sourcing from the front shaft. The rear shaft may also be a problem. As far as a fix....you can buy new driveshafts from Jesse at www.highangledriveline.com with double-cardan joints in them, or if you know a good welder, you can have the spring perches in back repositioned, and the knuckles up front turned in order to get proper driveline angles. None of the options will be cheap.
    Speedo...yes that will be affected. Mess around with the calculators at 4lo.com to see how much. In order to fix...you should have a cable driven speedo, and the gear inside can be replaced with one of a proper size/tooth count. Or, you can always just know how much your speedo's off and compensate...that's what I do /forums/images/graemlins/thumb.gif.
    Tire preference...you said you'd be doing a lot of road driving. In that tire size, you won't find a very good tire-wear tire available. For more radical....gumbo mudders wear better than most. For strictly curb-jumping, go with some Dick Cepek Fun Country's or something along those lines.

    Hope that helps...and welcome aboard, you did pick the best vehicle known to man. /forums/images/graemlins/grin.gif

    WOW, THAT WAS LONG /forums/images/graemlins/thumb.gif
     
  3. Sandman

    Sandman 3/4 ton status Author

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    I had that exact setup for a while. I did have to clear my fenders as it flexes decently. I wasnt to bad to drive around but it sucked for technical driving and was not great in deep mud. I changed to an automatic and it became much more livable. I ended up going to 5.13's anyway.
     
  4. BLUESMAN

    BLUESMAN 1/2 ton status

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    Location:
    Phoenix(but it\'s a dry heat...like an oven!)AZ.
    I have that drivetrain(350/465/208) with 3/4 ton diffs stuffed with 4.10's.Also have the 39.5" TSL's,but with a 4" lift.The motor powers the 39's easily,no need for granny gear until I'm off road.The only problem I see would be your wamting the 9" lift.That will create some bad angles on your driveshafts,I guess you could get an 3" body lift and 6" of suspension and be OK.I always like the lower suspension lifts and sawzall the needed clearance.What kind of off roading are you going to do?You will need stronger diffs.Speedometer can be recalc'd at a good shop(look in your yellow pages).I run my 39's on 8" rims with 3.75" back spacing,the rears are flush with the body,fronts are out by 2"(?).One other thing.....My K/5 has been on a severe weight loss program,so that could be why the 4.10's work for me /forums/images/graemlins/smile.gif.
     
  5. Shaggy

    Shaggy 3/4 ton status

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    <font color="green"> Probably was a 6cyl truck originally, right? That's where the 4.10s would have come from. The major problem I see is that 39s are most likely going to wreak serious havoc on your axles, if you actually do plan on using it offroad. They will be OK for awhile, but as you start trying to tackle more serious trails you'll end up breaking alot of parts. I hate to be the guy that says "go one ton!" since there are alot of people that don't have to go one ton to survive, but in your case I think that you need to in order to keep it reliable. If you're going to stay with the 1/2 ton axles and you want a good measure of reliability (well, borderline at least), then you're going to want to stay with a narrow 37 or a wide 36. 39 is way too much tire for the D44 and 12 bolt. Just my opinion, and I speak from experience (I tried to run 38s on a 12 bolt/D44) </font color>
     
  6. mr77k557

    mr77k557 Registered Member

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    thank it was really helpful.i plan on a 3in body and 6in suspension the 4.10 i put in and i also will probly end up with a set of dana 60's if i can find them. and i was debating on going with highangledriveline but im going to be taking a college welding and machining coures so that may come in useful. this is a full frame up restoration so any way i go it will cost a bundle so any way i can sve money is good but its better to do it right the first time and do it when its already apart than it would be haveing to fix it all the time later. well thanks again
    /forums/images/graemlins/k5.gif
     
  7. mr77k557

    mr77k557 Registered Member

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    no it came stock with a 350 but i completly rebuilt it as for the 4.10's i installed them and will most likely move up to dana 60's even though every thing on this truck was HD from the factory it can with all the factory HD optiond and even the 350 HO and hell yeah i plan on usinf it offroad other wise all the blood , sweat and tears put into it would be absolutly useless i just have to do alot of street driving cause i dont beleave that a perfectly running truck belongs on a trailer plus if i wasnt going to take it off road i should just stop working on it now and go buy some little jap car like most of the kids today and there is as much of a chance of that happening as me winnin the lotto
    /forums/images/graemlins/k5.gif
     

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