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Rubbing 39.5 TSL on 15x10 with 4 1/8 backspacing on 14bFF

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by BorregoK5, Jan 21, 2002.

  1. BorregoK5

    BorregoK5 1/2 ton status

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    Would anyone have any input on the 39.5 15" wide tire on a 15x10" rim running on a 1 ton 14 bolt and inner fender well rub? I know that 4 1/4" backspacing will clear the 15" axle drums but the width of the tire may require even more offset in the rear to clear the inner wheel wells. While I'm concerned with bearing wear, I'm more concerned with tire rub! Anyone?

    I started with nothing and I still have most of that left! - <a target="_blank" href=http://24.55.50.76:81/k5/> Pictures</a><P ID="edit"><FONT class="small">Edited by BorregoK5 on 01/21/02 09:38 PM.</FONT></P>
     
  2. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    Borrego,

    Just to paint a complete picture here....Are you talking about a 14BFF? Is it the "standard" one, or one of those special VAN ones that's the same track width as the front axle?

    Here's my take....FWIW:

    The 14BFF is about the strongest axle out there. I personally wouldn't worry about bearing life as an issue under a Blazer....I don't think the amount of weight on it will even make it sweat! That axle was designed to be underneath much heavier and tougher equipment.

    I am planning on getting the T-6061 (?) 1.5" spacers to make the track width identical between the front and rear. Mostly a "look" thing, but if you do the spacers you won't need weird offset wheels (most of the ones I'm seeing at least in 16.5" are all 4.75" backspace) and you may still have adequate clearance on the inner fenderwell.

    Anyway, I'm just brainstorming a little. I can't give you any BTDT advice for another month or so....I'm working on my own 14BFF swap as we speak....! [​IMG]

    I'm going to try for 38 x 15.50 x 16.5" under the stock fenders with only 6" of lift......I'm in for some FUN!!!! [​IMG]

    Good Luck..



    -Greg72

    '72 K5 Blazer - 427BB/TH350/NP205/6" Lift/35x12.50's
    <font color=blue>See it here: </font color=blue><a target="_blank" href=http://coloradok5.com/gallery/albun38>http://coloradok5.com/gallery/albun38</a>
     
  3. zakk

    zakk 1/2 ton status

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    Greg, why do you need the offset? if they are the same track width front and back then...???

    My three brain cells do not seem to be cooperating tonight...

    -zakk

    '77 1-Ton K5
    World's Ugliest Lawn Ornament
    [​IMG] CK5's Moab 2002 or Bust!! [​IMG]
     
  4. BorregoK5

    BorregoK5 1/2 ton status

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    I've already purchased a 1 ton diesel rear from a 78 k20 if I remember right. The track width was realatively the same at the backing plates but ended up a little wider at the lugs due to those massive drums. I've had the perches relocated and rotated for a 1350 CV style shaft but it hasn't been installed yet. My worry is running a backspacing which would not just complement the huge drums (even though I'm going disk later.. or sooner.. whichever) but also leave room for a little flex tuck into the wheel well without ripping lugs into the bed. What I don't want to do is space them out so far as to put unneccesary leverage on the axle bearings. Is this even an issue with a full floater?

    I started with nothing and I still have most of that left! - <a target="_blank" href=http://24.55.50.76:81/k5/> Pictures</a>
     
  5. wayne

    wayne 3/4 ton status

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    I have 35x14.50's on the same wheel pattern you are talking about. I have 4 1/8" backspacing. Now granted mine are only 35's but I have stuffed them pretty good with no problem hitting the wheel well in the back. Not knowing how much lift you have but if you have 6+ inches I will say you should be ok. I am planning to run the 5" lift I have now with a 1" body lift and 38.5x14.50's on the same wheels I have now.

    See <a target="_blank" href=http://coloradok5.com/gallery/Waynes-Toy>Project Mighty Mouse</a> here.
    <font color=blue>Wayne<font color=blue>
    <font color=blue>Happy Trails<font color=blue>
     
  6. BorregoK5

    BorregoK5 1/2 ton status

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    I'm currently running 4" of lift, plan on cutting the fenders considerably to keep my center of gravity low and have a 3" body lift waiting in the wings for emergency sake but would rather only do it if I have to. I'd rather tray a smaller body lift if possible, only raise enough to clear... got to keep it airborne capable!

    I started with nothing and I still have most of that left! - <a target="_blank" href=http://24.55.50.76:81/k5/> Pictures</a>
     
  7. wayne

    wayne 3/4 ton status

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    With just a 4" lift it might rub. You could alway make the wheel wells bigger if you want to get creative. BTW the 415 looks good.[​IMG][​IMG]

    See <a target="_blank" href=http://coloradok5.com/gallery/Waynes-Toy>Project Mighty Mouse</a> here.
    <font color=blue>Wayne<font color=blue>
    <font color=blue>Happy Trails<font color=blue>
     
  8. BorregoK5

    BorregoK5 1/2 ton status

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    Thanks on the 415, there is about a years worth of planning in to making it, specificly to push some big rubber. The breakin is the hardest part... I've had over a year of immediate satisfaction in an on demand type of manner with it and all I can do now is baby it and wonder what it will be like when its ready. I'm looking for some excuses to put some easy miles on it! [​IMG]

    I started with nothing and I still have most of that left! - <a target="_blank" href=http://24.55.50.76:81/k5/> Pictures</a>
     
  9. wayne

    wayne 3/4 ton status

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    I always had that problem with new engines. I don't think I ever broke an engine in the way you are supposed to.

    See <a target="_blank" href=http://coloradok5.com/gallery/Waynes-Toy>Project Mighty Mouse</a> here.
    <font color=blue>Wayne<font color=blue>
    <font color=blue>Happy Trails<font color=blue>
     
  10. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    Zakk-man,



    From everthing I've read, all Blazers were built deliberately with a 3" narrower track at the rear. Something about being able to have the rear tires run slightly to the inside of the ruts that the fronts would make when offroading...

    The 14BFF is also about 3" narrower....the only exception I'm aware of is the ones from vans, where for some reason, they are almost identical width to the front. There are a couple of tech articles on OFFROAD.COM about the wheel spacers...I think there's also one on CK5, because Steve Fox uses them on his "UAV".

    Personally, I'm going to measure everything first to found out what my exact measurements are, and then order the correct spacers to get the front and rear tracks identical.

    [​IMG]



    -Greg72

    '72 K5 Blazer - 427BB/TH350/NP205/6" Lift/35x12.50's
    <font color=blue>See it here: </font color=blue><a target="_blank" href=http://coloradok5.com/gallery/albun38>http://coloradok5.com/gallery/albun38</a>
     
  11. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    Borrego,

    Well I don't know......I've seen a lot of pics of trucks with the 1-Ton axles and 13" Drums, and the 15" wheels have always seems to fit over them OK. From that perspective, standard offset wheels seem like a solution that has worked for a number of people already.

    The other thing to consider if you are going to get wheels with more offset (moving the wheel inside the well) is that the problems will probably be in the front axle! I'm assuming you are going to buy 4 identical wheels for the truck.....(not 2 custom offsets, and two regular ones!). You may end up with more interferences up front due to the fact that the tires are further underneath, and when turning they are going to want to rub all over the inner fenderwell.

    You know it's funny, we are planning quite similar trucks.....I am trying for the same "small lift, big tire" thing that you are....4" spring lift, 2" body lift, 38.5" TSLs, and the least amount of cutting possible! I am supremely concerned about getting the offsets PERFECT so that I don't have too much space left over on either in "inside" of the wheelwell or the "outside".

    Be sure to post pics as you start test-fitting this stuff....I'm very curious to see how crazy this is going to get!!! [​IMG]



    -Greg72

    '72 K5 Blazer - 427BB/TH350/NP205/6" Lift/35x12.50's
    <font color=blue>See it here: </font color=blue><a target="_blank" href=http://coloradok5.com/gallery/albun38>http://coloradok5.com/gallery/albun38</a>
     
  12. pcorssmit

    pcorssmit 1/2 ton status

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    I have those exact tires and wheels on a '77 K20 rear end (14FF). They rub a little, but its on a smooth area, so all it does is wear off the paint on the inside of the fenderwell, no damage at all to the tires. My old 35 x 12.50s rubbed there, too. I wouldn't worry about it, and would do it again.

    BTW,
    <blockquote><font class="small">In reply to:</font><hr>

    I've already purchased a 1 ton diesel rear from a 78 k20 if I remember right.

    <hr></blockquote>

    A k20 is a 3/4 ton,
    The first year for diesels was '79, but AFIK they only came in C10s,
    The first year for a K20/K30 diesel was '82.

    Pete

    '83 K5, 350 TBI (ex 6.2), 700R4, NP208, Dana 60/14 bolt, 4.56s, Detroits, 3" lift, 15-39.5x15 TSLs
    '97 Dodge 2500 4x4 CC LB Sport, Cummins 5 spd
     
  13. BorregoK5

    BorregoK5 1/2 ton status

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    I'm probably wrong about the donor vehicle then, I really can't remember too much other than tearing the rear end out of it and I thought I grabbed the hydraboost from the same truck. It's definately the large drum Full Floater though, the drum measures 15" in diameter at the backing plate and the hubs protrude a good 4 to 5 inches. I'm not so concerned with getting a rim to fit on the drum as I am making sure the width of the tire is properly accomodated at the offset. I'm thinking less than 4" of offset may be in order but as stated above the front end is where this becomes a problem. The further I move the center mount of the rim to the inside, them less equal the pivot, meaning the tire no longer rotates from the center when turning but arc's around the hub. This would mean more trimming to the front and rear of the front fender would be necessary for every inch I move the wheel out. I don't mind a larger trac width either for stability, hey, its a fullsize thing! As for your setup, you say your running 39.5's on a 4 1/4" backspacing now... same lift? I wonder if therear wells are the same distance from the center of the rim as my K5...

    I started with nothing and I still have most of that left! - <a target="_blank" href=http://24.55.50.76:81/k5/> Pictures</a>
     
  14. pcorssmit

    pcorssmit 1/2 ton status

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    Guess I wasn't clear. The truck is an '83 K5, 3" lift. The axle is from a '77 K20. If your axle's spring perches lined up with your Blazer's, then its a 3/4 ton rear. If they were too close together (on the axle), then its a 1 ton rear. The only real difference is the brakes, either one will work fine.

    Gas 1 tons had Hydroboost (not sure if all did or just some). Maybe thats why you were thinking it was diesel.

    Pete

    '83 K5, 350 TBI (ex 6.2), 700R4, NP208, Dana 60/14 bolt, 4.56s, Detroits, 3" lift, 15-39.5x15 TSLs
    '97 Dodge 2500 4x4 CC LB Sport, Cummins 5 spd
     
  15. BorregoK5

    BorregoK5 1/2 ton status

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    Yeah, had to move the spring perches out. Well, maybe I can get away with 4 1/4 after all, thanks for the info... got pics?

    I started with nothing and I still have most of that left! - <a target="_blank" href=http://24.55.50.76:81/k5/> Pictures</a>
     

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