1985 Pickup Shackle Help

[jah__volunteer]

Ive got a solid front axle 85 pickup and am trying to get the ride height maybe 1-2in higher than it sits now (Stock leafs and shackles)
I know extended shackles can be a half ass way to lift a truck, but just need something before i can get something better.
How much longer than the stock shackles can you get away with before you feel the negative side effects? Would I be able to get way with running stock sized shocks?
I am aware that a shackle that is 3 inches longer than stock will give about a 1.5 inch lift, but is this too much longer to daily drive and road trip with?
Thanks ahead, for any advice.

 

[DaveInDenver]

In the back the main issue is rotating the differential pinion. This causes a couple of potential issues. One is starving the pinion bearing of gear oil and leading to an early demise. The other is moving the u-joints in the driveshaft out of phase, which leads to vibrations.

In the front longer shackles can cause these same issues but additionally rotates the trunion bearings in the knuckles and throws the caster all out of wack. In a solid axle there's no way to align the front end to correct it and makes the steering unstable. There can be an oscillation that starts called a death wobble.

You can correct the angle with shims between the axle perch and the leaf spring. In the back this is a legit and common solution.

In front it's not, though, since it raises the risk of the axle shearing or moving to have anything other than the truck springs sitting solidly on the axle with the center pin fully inside with the spring perch. So large shims (or lift blocks) are not usually advised in front. The safe way to lift the front of leaf sprung truck significantly is lift springs and a shackle that matches them. A small shim can be OK but a 3" shackle is quite a lot.

 

[jah__volunteer]

In the back the main issue is rotating the differential pinion. This causes a couple of potential issues. One is starving the pinion bearing of gear oil and leading to an early demise. The other is moving the u-joints in the driveshaft out of phase, which leads to vibrations.

In the front longer shackles can cause these same issues but additionally rotates the trunion bearings in the knuckles and throws the caster all out of wack. In a solid axle there's no way to align the front end to correct it and makes the steering unstable. There can be an oscillation that starts called a death wobble.

You can correct the angle with shims between the axle perch and the leaf spring. In the back this is a legit and common solution.

In front it's not, though, since it raises the risk of the axle shearing or moving to have anything other than the truck springs sitting solidly on the axle with the center pin fully inside with the spring perch. So large shims (or lift blocks) are not usually advised in front. The safe way to lift the front of leaf sprung truck significantly is lift springs and a shackle that matches them. A small shim can be OK but a 3" shackle is quite a lot.

That all is very helpful, thank you.
Do you have an experience or advice on whether or not just a 1.5" longer shackle would be doable, only in the back to try and help level it out with a load on already somewhat sagging leafs?

 

[DaveInDenver]

That all is very helpful, thank you.
Do you have an experience or advice on whether or not just a 1.5" longer shackle would be doable, only in the back to try and help level it out with a load on already somewhat sagging leafs?

Longer shackles in the back isn't a problem. It's not going to fix the issue of insufficient spring rate and may cause the leafs to over compress. It's hard on them to go beyond flat into negative arch, which longer shackles make easier to happen. So you should lower your bump stops to be safe.

BTW, I should have mentioned on the Toyota mini trucks the front shackle is trailing (fixed eye is forward) so the alignment problem is slightly different. The pinion tends to rotate down too much with longer shackles and the caster slackens.

 

[bkg]

If stock springs, you’ve got almost 35 years of wear and sag... I personally wouldn’t do shackles for the reasons mentioned above. Not a cheap option, but I’d do an OME 2” lift....

 

[Arktikos]

Ive got a solid front axle 85 pickup and am trying to get the ride height maybe 1-2in higher than it sits now (Stock leafs and shackles)
I know extended shackles can be a half ass way to lift a truck, but just need something before i can get something better.
How much longer than the stock shackles can you get away with before you feel the negative side effects? Would I be able to get way with running stock sized shocks?
I am aware that a shackle that is 3 inches longer than stock will give about a 1.5 inch lift, but is this too much longer to daily drive and road trip with?
Thanks ahead, for any advice.

One thing to consider is how much your springs are currently sagging. I bought 1 1/2 to 2 inch lift shackles for my TLC and they probably provided 1" at most over actual stock ride height with no adverse effects over many years.
https://www.4crawler.com/4x4/ForSale/Shackles.shtml is where I'd go for your pickup. OME lift springs provide a bit too much lift for my needs, which are the same as yours. Custom leaves with less lift would be ideal, IMO, for your pickup-albeit spendy.

 

[jah__volunteer]

Longer shackles in the back isn't a problem. It's not going to fix the issue of insufficient spring rate and may cause the leafs to over compress. It's hard on them to go beyond flat into negative arch, which longer shackles make easier to happen. So you should lower your bump stops to be safe.

BTW, I should have mentioned on the Toyota mini trucks the front shackle is trailing (fixed eye is forward) so the alignment problem is slightly different. The pinion tends to rotate down too much with longer shackles and the caster slackens.

got it, thanks for the help

 

[jah__volunteer]

If stock springs, you’ve got almost 35 years of wear and sag... I personally wouldn’t do shackles for the reasons mentioned above. Not a cheap option, but I’d do an OME 2” lift....

This is what I will be doing in about a year. just trying to find something in the meantime, and the sag is by no means bad at all

 

[DaveInDenver]

This is what I will be doing in about a year. just trying to find something in the meantime, and the sag is by no means bad at all

I think a better solution would be to put in an extra leaf or two, either get an add-a-leaf kit or just take leafs from a used set of packs. Finding used springs would be cheap (maybe free). You'd just need new u-bolts.

 

[Arktikos]

For a daily driver and road trip truck I don't understand the urgency in lifting it. Or lifting it at all, for that matter.
Will you be carrying a lot of weight in the rear? If the sag isn't bad and you don't have plans for a great deal of weight remember that more leaves/stiffer springs typically produce a worse ride.

 

[Clawhammer]

If stock springs, you’ve got almost 35 years of wear and sag... I personally wouldn’t do shackles for the reasons mentioned above. Not a cheap option, but I’d do an OME 2” lift....

This is what I was going to say. The springs are probably so worn out that you'd get two inches of lift from where you are now just by going with an aftermarket "stock ride height" set up. (I went with a full OME suspension in my Taco and have absolutely no regrets. Expensive, yes, but so much better than stock. New leaf springs, shocks, longer shackles, all stuff that's worn out on your truck. And I'm about 2" over stock, which is at least 3" over where I was).

I wouldn't worry about a stop-gap solution right now if you're going to be replacing everything in a year. Just save up, do it right once and be done with it.

 

[bkg]

This is what I will be doing in about a year. just trying to find something in the meantime, and the sag is by no means bad at all

I'm going to challenge that last portion.

 

[jah__volunteer]

Thanks to all for the info!! I will keep it all in mind


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