Do 1" lifted shackles make vibes worse?

hoobness · #1 (**permalink**) 03-29-2005, 10:12 PM

Do 1" lifted shackles make vibes worse? If I have 1" shackles to my rig, am I making the driveline vibes worse? (rear)

I want 35x13.5s under there so Im trying to figure out the most cost effective way...

Junkpile · #2 (**permalink**) 03-29-2005, 10:21 PM

Longer shackles only move one end of the spring. On a factory SWB Jeep the shackle end is opposite the pinion side of both axles. So, by dropping that end of the spring down with longer shackles, you are rotating the pinion upwards. It can actually help with the vibes.....you just don't want to rotate the pinion too far, so you may need to remove or change any shims you may have installed with the suspension lift.

There are also issues with steering and spring fatigue that can come up, but with your 4" springs, you would be fine with up to a 1" shackle.

TwistedCopper · #3 (**permalink**) 03-30-2005, 05:40 PM

4" lift and another inch in shackles your driveshaft will be too short. Pinion angle or not.

I put lift shackles on the back of my XJ to help with vibes, and they work great.

If you had a 2.5" or 3" lift I'd say go for it. Heck try it if you want, they're easy enough to swap, but look at your TC output when they're on

Junkpile · #4 (**permalink**) 03-30-2005, 09:16 PM

I wasn't even thinking about the driveshafts. TC is right, it will be too short.

Bounty__Hunter · #5 (**permalink**) 04-05-2005, 10:52 AM

Not necessarily. The lift springs often pull the slipyoke out a bit, for the driveshaft. The shackles point the pinion up slightly more, thus pushing that slipyoke back in a bit.

My money is on using a body lift, or installing TJ flares. For me the TJ flares and fender trimming involved have been the best bang for the buck.

TwistedCopper · #6 (**permalink**) 04-05-2005, 07:59 PM

Quote:

Originally Posted by Bounty__Hunter

Not necessarily. The lift springs often pull the slipyoke out a bit, for the driveshaft. The shackles point the pinion up slightly more, thus pushing that slipyoke back in a bit.

They will lift a vehicle already 4" high to 5". A correct angle will compensate somewhat but 5" of lift is 5" of lift. It's asking for problems (like the yoke slipping out altogether

)
If you just want to correct the pinion angle, shim the axle.

yjdave · #7 (**permalink**) 04-05-2005, 08:25 PM

If you want 35's you are going to have to have al least 6 inches of lift however you get it. Even if you run bfg's or similar that measure small you will need 5-6 inches. I have 35" mtrs and boggers and have a 4 inch spring lift 1 1/2 inch shackle and 2 inch body lift and TJ flares and cut fenders and still rub at full flex. As far as vibrations just spend the money and get the short shaft kit and suck that belly pan up for more clearance...

TwistedCopper · #8 (**permalink**) 04-05-2005, 08:27 PM

good point.

hoobness · #9 (**permalink**) 04-06-2005, 01:00 PM

thanks!

Bounty__Hunter · #10 (**permalink**) 04-06-2005, 11:00 PM

yjdave, that's an awful lot of clearance to still rub with 35", you sure those springs aren't sagged or otherwise worn out?

yjdave · #11 (**permalink**) 04-07-2005, 12:35 AM

lots of flex...brand new skyjackers last summer.........