Removed lowering shackles
#1
Removed lowering shackles
This weekend I wound up removing the Belltech lowering shackles I had installed a few weeks ago because they caused a vibration I couldn't get rid of. Luckily I have access to a machine shop so I was able to make different shim sizes and didn't have to buy shims, but nothing I tried up to 2.75 deg shim would work. With no shims at 2" the vibe was strong. With a 1.5 deg shim it was reduced. Dropping the lift to 1.5" and going to 2 deg reduced it a little more, and more shim beyond that made no difference. I got tired of jacking that beast up, so now I'm back to stock and vibration free again.
I found several websites through a google search about pinion angles. They all said that a vehicle with leaf springs should have a 1.5 - 2 deg angle between the driveshaft and pinion. I measured mine lowered 2" with a 2 deg shim (Belltechs recommended fix) and the driveshaft to pinion angle was 4.5 deg. According to these websites u-joints are only meant to operate with a 1 - 3 deg angle, and anything more will cause possible vibes and premature wear.
I know most of you have lowered without shims and had no problem and shims seem to have fixed the rest. I was wondering if anyone else has encountered a vibe like this and if anyone else has actually measured the pinion/driveshaft angle.
I found several websites through a google search about pinion angles. They all said that a vehicle with leaf springs should have a 1.5 - 2 deg angle between the driveshaft and pinion. I measured mine lowered 2" with a 2 deg shim (Belltechs recommended fix) and the driveshaft to pinion angle was 4.5 deg. According to these websites u-joints are only meant to operate with a 1 - 3 deg angle, and anything more will cause possible vibes and premature wear.
I know most of you have lowered without shims and had no problem and shims seem to have fixed the rest. I was wondering if anyone else has encountered a vibe like this and if anyone else has actually measured the pinion/driveshaft angle.
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I'm sorry for your trouble, but this is interesting. I recently installed the groundforce shackles along with the shims. I had ZERO vibe issues prior to the install so I paid the xtra $ for the shims up front so I would stay vibe free.
After the install (yes the shims are thick end toward the rear) I now have the low speed (20-30mph) vibe. Pi$$ed me off........I called groundforce and they suggested I take the shims out and see what happens. I haven't had time to do it yet, but I may have a set of shims for sale soon.......
Jeff
After the install (yes the shims are thick end toward the rear) I now have the low speed (20-30mph) vibe. Pi$$ed me off........I called groundforce and they suggested I take the shims out and see what happens. I haven't had time to do it yet, but I may have a set of shims for sale soon.......
Jeff
#6
I installed the Suspension Max drop shackles about 2 weeks ago and I've driven about 1500 miles since then ranging from 0-100 mph and never noticed any vibrations but after I installed them I started wondering about how that would affect the pinion angles. How do I measure the angle? Would drop leaf springs be a better option?
#7
If you google "pinion angle shims" you will find several sites that explain this. I found the classicbronco site the most helpful with the measurement and the carcraft.com one explained what the angle should be and why the best.
I measured mine with a machinists level, where you have a flat surface and a rotating center piece with a bubble level that is marked in degrees. I put the flat surface on the drive shaft and found a 3 degree downward tilt to the back.
For the pinion I measured the angle at the flange that where u-joint bolts and found the front to be tilted down 1.5 deg. Added together that gives you a 4.5 deg angle. This was lowered 2" with 2 deg shims installed. I haven't measured it stock.
I measured mine with a machinists level, where you have a flat surface and a rotating center piece with a bubble level that is marked in degrees. I put the flat surface on the drive shaft and found a 3 degree downward tilt to the back.
For the pinion I measured the angle at the flange that where u-joint bolts and found the front to be tilted down 1.5 deg. Added together that gives you a 4.5 deg angle. This was lowered 2" with 2 deg shims installed. I haven't measured it stock.