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help needed at the rear axle

Discussion in '1969-1972 K5 Blazer | Truck | Suburban' started by jello, Apr 3, 2001.

  1. jello

    jello Registered Member

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    Ok I've got a six inch lifted rear springs over the back axle and I am wondering how great of an angled shim can be installed on top of the spring perch. I heard that to much of an angle results in oil starvation inside the pumkin. So whats the word on this? I will be machining the angle into a one inch add aleaf from ORD. Steve at ORD was kind of unclear (or my interpretation of what he had to say was). So I thought I'd ask the question here and pick some brains. Thanks for your responses.
     
  2. Steve_Chin

    Steve_Chin 1/2 ton status

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    That kind of depends. The insides of the pumpkin are pretty much unaffected by the angle of the pinion, but the pinion bearings might be affected (especially the front pinion bearing). General rule of thumb is not to alter the angle by more than 4 degrees up unless you're taking steps to increase the oil level in the differential above the bottom of the fill hole in the side of the pinion housing. If you do increase the fill level, don't go too high or you will end up leaking oil out of the axle seals. A couple of ounces should be enough for most sane angles.

    Question: How are you going to machine this angle into an add-a-leaf? Leaves are typically kind of thin and machining some of their thickness away will reduce the rate and load rating of the leaf...
     
  3. jello

    jello Registered Member

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    Steve thanks for responding.

    The "add -a-leafs" are the one inch blocks of mild steel sold by ORD they bolt up to the bottom of the spring packs and sit ontop of the perches. My neighbor is a machinist and says he can taper the top of them to any incline on one of his machines. So I was thinking..... the lift I mentioned above Tuff Country 4"front and 6"rear came with angled shims that I beleive compensate for the angle of the rear drive line. My plans were to do away with the shims and have the new add-a-leafs cut with that angle or greater. My thought was that I could possibly increase the angle and improve the driveline geometry. What do you think?
     
  4. Steve_Chin

    Steve_Chin 1/2 ton status

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    Ahhh... I see. They're not really add-a-leafs (an add-a-leaf is literally another spring leaf that you add to the spring pack to increase the spring load capacity and spring rate, and usually modifies the unladen curvature of the pack). They're blocks... I think that it's OK to angle-cut the blocks as long as you don't get too happy with the angle milling. Milling any amount at an angle off of the top of the block will change the angle of the pinion, but it will also move the centerline of the rear axle forward a little. The more angle you mill into the top, the more the axle moves forward. A few degrees shouldn't make a noticeable bit of difference in axle location and typically, that's all you need to make your driveline geometry correct. I would suggest you mock up all of the pieces and measure the yoke angles at the transfer case and at the pinion before deciding on how much angle to put into the blocks. Cut just enough to make the angle of the pinion agree with the angle at the transfer case.
     
  5. jello

    jello Registered Member

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    Hey thanks again for responding that advice sounds -sound.

    I think ORD calls the ('bolt to the springs') blocks add -a- leafs because of certain laws. In some states maybe they forbid blocks?
     
  6. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    ORD calls them '0' spring rate add-a-leafs because they bolt to the spring pack. A block is just sandwiched between the leaf pack and the perch. The center bolt goes through them just like a leaf, this one happens to be very short and does not alter the ride quality at all...

    Rene

    [​IMG]<A target="_blank" HREF=http://jules.coloradok5.com>http://jules.coloradok5.com</A>
     
  7. Rasberry

    Rasberry 1/2 ton status

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    If the lift Kit comes with shims why would you take them off and replace them. I have a 6 inch lift that came with shims and my drive train geometry is just fine. It sounds to me like your buying a cake, scraping off Iceing and putting on your own. Unless maybe your looking for that 3/4 of an inch extra lift or something. Maybe I'm just missing something?

    http://www.geocities.com/71blazer
     
  8. jello

    jello Registered Member

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    Yeah I can see how it looks like that. After installing the Tuff Country springs (4" front and 6" rear) the truck STILL sags in the butt - just over 1". This was disappointing!! So Im attempting to correct this, as well as, changing out the u bolts to the later style-- so the nuts and bolt portrude up above the axle and not down below where they hang up on whatever. While Im at it, why not and try to improve the angles a bit?
     
  9. Rasberry

    Rasberry 1/2 ton status

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    I'm amazed at how many people have had problems with keeping there ride level after lifting it. My Softride(which isn't very soft) 6 inch skyjackerlift(springs all the way around) is very level without any addon's other than the kit.

    Is this just certian brands?

    Rasberry 71' K/5 Blazer
    http://www.geocities.com/71blazer
     
  10. Sledge

    Sledge Registered Member

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    Rasberry,

    That's weird, I have the 6" Skyjacker Softride kit like you in my '72 Jimmy, but I would consider mine to ride pretty soft and I have the usual rear-end sag. I've had the lift on for almost four years, how old is yours?

    Sledge
     
  11. Rasberry

    Rasberry 1/2 ton status

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    I think I've had my lift about 3 years. There has been almost no sag in the back. If anything the front has come down a little. I'm not saying the ride is hard, hard. Just saying it rides like a truck, unlike the coil spring Fords which is easy to get sea sick in. But all in all the truck has stayed level.

    Rasberry 71' K/5 Blazer
    http://www.geocities.com/71blazer
     
  12. Sledge

    Sledge Registered Member

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    That's pretty strange. You're from Florida, right? Maybe I've had my hardtop on more here in Oregon? Odd stuff!

    I'm planning to "fix" mine by doing a 4" shackle flip in the rear and getting a new set of 8" front springs.
     
  13. Steve_Chin

    Steve_Chin 1/2 ton status

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    OK, if the bolt goes through the block, you can't angle-cut the top of the block because yuo will create a misalignment. You will need to angle-cut the bottom of the block and then counterbore the bolt land so that it rides correctly in the block. Too much hassle. Use the shims.
     
  14. californiak5

    californiak5 1/2 ton status

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    For a machine shop this would be no hassel at all. A simple set up and 10 min. machine time and it's done.

    [​IMG] Born to Drive My K5 [​IMG]
     

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