Front end vibration (2 Viewers)

[BuckeyeFZJ]

I just got finished with a full knuckle rebuild all new bearings and seals. Had 3rd members re geared to 4:88 and ARBs installed at a shop. Took it on a test drive and I am getting a pretty good vibration in the front end around 55-60mph mostly on deceleration, gets a little better without front driveshaft but is still there. No vibration before work was done. Any thoughts?

 

[landtank]

What is your lift height and caster correction? The regear and subsequent rpm change can exasperate drive line vibes

 

[Rusty Marlin]

OH man have I played this game!
What Land tank said. We need info.

 

[Moonglow96]

I’ve had similar issues. 3” icon lift, caster correction bushings, new pan hards, links and steering box. Mickey T MTs 35”. Before the gear box was replaced it was more pronounced, turning and decelerating around 35-40 for me. I’ve been told the tires are hard to balance and I’d have to live widdit. Hope to figure it out at some point.

 

[landtank]

I’ve had similar issues. 3” icon lift, caster correction bushings, new pan hards, links and steering box. Mickey T MTs 35”. Before the gear box was replaced it was more pronounced, turning and decelerating around 35-40 for me. I’ve been told the tires are hard to balance and I’d have to live widdit. Hope to figure it out at some point.

You really should have more caster correction than the bushings. As for the tires, see if you can find a shop that can road force balance them. Someone here will know the machine used for that. A friend had issues and with the road force machine it was determined that 2 of his tires where out of manufacturing spec. Company replaced the tires and everything was smooth.

 

[Moonglow96]

You really should have more caster correction than the bushings. As for the tires, see if you can find a shop that can road force balance them. Someone here will know the machine used for that. A friend had issues and with the road force machine it was determined that 2 of his tires where out of manufacturing spec. Company replaced the tires and everything was smooth.

I actually did have one that was out of spec on the rear and they replaced it. Pretty sure they used a road force machine.

I have wondered about more caster correction but at 3” I was hoping the bushings were enough. The shop felt like they were plenty. Idk.

Originally it was a back end wobble that got my attention. I put a delta panhard bracket on and had them check the balance. They found the out of spec tire and replaced. That fixed the wobble.

The only original bushings left that I know of are the rear upper and lower trailing arms and that’s on my short list to replace. I’m looking at Dobinsons for those. Seem reasonably priced compared to other brands. Still spendy though.

 

[ppc]

I have wondered about more caster correction but at 3” I was hoping the bushings were enough. The shop felt like they were plenty. Idk.

Stop guessing and have an alignment done. Bushings and a 3" lift is not sufficient even if they were installed properly.

 

[JoeCova]

You don’t need an alignment to determine if it’s driveline vibes. You can use a cheap digital angle finder to determine that. I dont disagree that you need more caster for pure drivability but don't chase caster, chase pinion angle.

Unless the dude is on stock tires regearing won’t necessarily exacerbate vibrations either, in fact many regears simply put the rpms closer to stock levels because of the increase in tire size. The difference in driveshaft rpms with 31" tires and 4.1s and 35" tires and 4.88s is 5% if he's on 37s its exactly the same.

I regeared to 4.88 on a 3” with -2 caster on corrective bushing to +3 with correction arms never experienced any vibrations.

The fact that you had a completely knuckle rebuild may open the door to other things like loose wheel bearings or loose pinion bearings etc. and if the vibes were still there after the front driveshaft was removed then it's likely not driveline related but axle related.

People’s perception of vibrations are all different so it’s hard to say without specific details.