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Need advice on this shackle angle (Pics embedded)

handloader90

handloader90

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So this is the shackle angle on my long gone '79 K5.

I used a DIY4X Shackle Flip (flip flopped to the "wrong sides"), 6" Cross-Tied Shackles and 56" long springs.

If I remember correctly that leaf pack is 7 leaves + the overload.

The rear suspension was setup a top of a 14BFF.

I'm getting ready to do another shackle flip (all DIY4X) and looking back at my old pics that shackle angle look somewhat steep to me.

Is that an optimal shackle angle or should I get some shorter shackles say 5" eye to eye or maybe even 4.5" shackles?

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20150704_015946_zpsklboknfu.jpg
 
too steep. I'm looking for the magic thread on this...
 
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i think a longer shackle would decrease the front angle. A longer shackle would move the eye of the springs forward causing the shackle to move forward decreasing the front angle.
 
You also need to take into account the amount of arch in the springs.

Flat springs can use a shorter shackle at a greater angle. They don't grow in length very much as the axle travels. If your springs have alot of arch you run the risk of inverting the shackle under compression.

Now if the shackle is too long it can make the truck feel loose in the rear (I hate a loose rear :whistle:)

To measure for minimum shackle length, you need to figure the theoretical maximum flat length of the spring. Measure from the front attachment point of the spring to the rear and make sure the the shackle would have at least a 25° angle or so at full bumpstop ( | being 90° , -- being 0° )

Now remember that the shorter the shackle the less it will "help" with articulation and travel.

My suggestion is to make your own shackles with 3 or 4 holes and experiment with it. Once you decide on the final length. Make or buy some good cross tied ones.
 
Looks good to me. But it's going to change once it has gas and is bearing full weight and after putting some miles on it. Longer shackles will make it more verticle and shorter will make more of a angle
 
So go to longer shackles?

I have some 7.25" shackles but damn... I really don't wanna put those long fawkers on.

The springs were pulled from the junkyard, they are 56" long and have 7 thinner leaves (maybe 5/16" or 3/8" each) and the overload.

They are stock spring off off a 2WD LWB (I believe that's what I pulled them from). They seem to be in pretty good shape minus some surface crud and they both have a good arch to them, nothing excessive like a lift spring, they're definitely not flat, they both look pretty even to each other when put side to side.

Those pics were taken while the gas tank was still out from installing the shackle flip, the back seat was still bolted in and there was a spare tire sitting in the bed.
 
handloader90 said:
Well I guess when I get the shackle flip on this "new" K5 I'll mock those 7.25" shackles up and see how it looks.

Do 7.25" shackles seem excessively long?
Click to expand...

Nah. Go fast guys run crazy long shackles like 12" all the time.
 
@Deuling hey you think you could brake bend and roll me a tranny tunnel for a '79 K5? Mine is all rusted out and I just found out the P.O. glassed the piss out of it as the rust repair.
 
handloader90 said:
@Deuling hey you think you could brake bend and roll me a tranny tunnel for a '79 K5? Mine is all rusted out and I just found out the P.O. glassed the piss out of it as the rust repair.
Click to expand...

Ill be getting a box and pan brake hopefully in the next 2 weeks. And the english wheel is calling my name....
 
I coud take some measurements, I think their pretty close or maybe exact minuse the '73-'80 having a removeable tranny tunnel cover.
 
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