Christopher FENTON

I put 1.5 inch lift shackles on my truck after I built a flat bed for the truck. After the shackles went on I get a shudder in the back while accelerating and decreasing speed from 0 to 10mph and 10 to 0mph. Could my shocks need replacing for a longer throw? They are brand new shocks before the lift. Never happened until shackles went on. U joints, brakes...all check out fine.

mountainmanjoe

Possibly shocks. You may also be experiencing axle wrap. The extended shackles could be exacerbating it.

You could try stiffer springs, or shocks arranged in a opposing configuration.

To give people a better idea, you should post photos of your suspension.

Christopher FENTON

Thanks for your time.

Christopher FENTON

The shocks seem like they are fully stroked.

mountainmanjoe

If possible, mount the shocks on opposite sides of the axle.

Christopher FENTON

That would be tough. I have a welder and work at a fab shop for the brackets so that would be easy. The only tough part is that I have no crossmember to handle the shock going forward. I thought about maybe just getting the ZR2 factory shocks and see what happens.

mountainmanjoe

it looks like on the passenger side you can bolt to the frame rail. Possible with a piece of square tube or something as spacer.

Maybe you could tape a phone camera or something down there to record a video of what's going on.

Christopher FENTON

Guess I could weld a stud or just throw a bolt through the frame. You have any suggestions on shocks? Brand?

mountainmanjoe

Any reputable brand. Monroe, Gabriel, KYB, Rancho. Monotube design is more durable. I had Rancho RS5000s on my offroad vehicle and they were great.

I just had another thought. By extending the shackles, you could have changed your pinion angle. If the rotation of the axle pinion and the transmission slip-yoke aren't in the same plane, it will cause driveline vibration. An angle finder can be used to test this. The easiest fix is to shim the leaf spring mounts.