Longer front shackles, any problems?

[USSkoval]

I put a used (barely) 4in lift on my burb, and the front springs already had shims on them, so I left them. In the rear I went with 4in blocks, 1ton 56's and a 14ff with 1ton hangers. The rear of the burb ended up being 2.5 -3 inches higher than the front, so I would like to level it out a bit. I was thinking longer shackles in the front would be a good idea because the front axle is already shimmed. Just another inch would make me happy, sound good?

 

[cybrfire]

I put a used (barely) 4in lift on my burb, and the front springs already had shims on them, so I left them. In the rear I went with 4in blocks, 1ton 56's and a 14ff with 1ton hangers. The rear of the burb ended up being 2.5 -3 inches higher than the front, so I would like to level it out a bit. I was thinking longer shackles in the front would be a good idea because the front axle is already shimmed. Just another inch would make me happy, sound good?

Longer shackles can give you some more height but could still cause issues. You'd need to know what the shim is there for. Is it correcting and issue with caster? Or causing a problem.... Then, what will the longer shackle do.

 

[USSkoval]

I have no idea why the shims are there, and I don't know the specs of the truck they were on. Longer shackles should compensate for the angle of the shims and put the caster back to stock, I would think. I have driven the truck but it was only lifted in the front at the time so the truck itself was at an angle enough to make up for the shims. Because of this, I'm thinking the burb will drive fine (lifted in the rear too, of course) either with no shims, or longer shackles.

 

[dremu]

As Kert mentions, the shims are there (presumably) to correct castor angle. Changing the length of the shackles will affect the angle, so you might need more or less shimming, depending on which direction the shims are in.

Search for my posts about castor angle and get yourself one of these

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=34214

and you can measure it yourself. Assuming your (new-to-you) front springs were level your angle shouldn't have changed, but it's possible it did. If the angle is slightly off it'll only be mildly unsafe and annoying; if it's way off, the truck becomes damn dear undriveable. Ask me how I know

Another option would be a set of the short length add-a-leafs that bolt to the pack and don't change the spring rate (ORD's "Zero Rates", Kert's "EZ Inch".) You'd leave the shims in, presuming your steering is okay, and voila, an extra inch of lift.

-- A

 

[USSkoval]

I guess I should have mentioned that the springs are BDS springs and I don't think they normally have shims on them. I believe they were added on for one reason or another. They have the pinion angle pointed up (more than stock) and they look to be 5-10 degree shims, just by looking at them but I could be wrong.

The reason I was thinking of leaving the shims in place and going with longer shackles is I don't think the u-bolts I had made are long enough to accommodate a zero rate. I just don't know if longer shackles would cause any stability issues because I've never used them before in the front. If longer shackles aren't good for the street, then I will go with new (again) u-bolts and a zero rate.

Also, what is the stock shackle length on an '88? 4.5? I'm about 30 miles from the truck right now and can't look.

 

[k20]

My BDS springs came with the shims bolted to them. Made my steering somewhat touchy. I had kert make me up a set of 2" extended crosstied shackles (netting 1" of lift) which corrected the angle of the shim, and the touchy feel was gone.

 

[dremu]

I guess I should have mentioned that the springs are BDS springs and I don't think they normally have shims on them. I believe they were added on for one reason or another. They have the pinion angle pointed up (more than stock) and they look to be 5-10 degree shims, just by looking at them but I could be wrong.

The reason I was thinking of leaving the shims in place and going with longer shackles is I don't think the u-bolts I had made are long enough to accommodate a zero rate. I just don't know if longer shackles would cause any stability issues because I've never used them before in the front. If longer shackles aren't good for the street, then I will go with new (again) u-bolts and a zero rate.

Also, what is the stock shackle length on an '88? 4.5? I'm about 30 miles from the truck right now and can't look.

They're there for one reason, to adjust castor angle. (Well, either that or pinion angle, but at the expense of caster.)

Point being there is no one "correct" shim; your springs and their mountings, shackle length, etc all come into play, and the only way to determine what you should be using is to measure it.

10* would be a pretty dang big shim, IIRC.

The longer shackles will not in and of themselves cause any issues. (Well, the skinny stock ones would be a bit worrisome, but any of the aftermarket HD ones are fine.) Changing the caster angle can cause steering problems, and changing the pinion angle can be hard on the front driveshaft.

If you're just looking to change ride height, note that longer shackles won't do so much -- you'd need a 2" longer shackle, IIRC, to get an inch of lift. That much longer a shackle is more likely to cause changes, so I don't know that the shackles are the simple approach. At the very least after changing the shackles you'd want to check the angles.

But if you've just bought U-bolts, yeah, I can see why you wouldn't want to do it again.

It's never simple...

-- A

 

[USSkoval]

OK, thanks fellas. I do know that the pinion is poking up more than stock and I do know I would like to level the truck out a bit, so I'll try the shackle route and go from there.