Vibrating above ~55mph

Duckhat · 04-18-2008, 09:34 AM

Hello again all, I'm having yet another problem with my little toy. It seems that when I drive my wrangler above 55mph or so, there is a terrible vibration. The thing that confuses me is that if I take my foot off of the gas and coast at these speeds the ride is relatively smooth.

The vibration only comes when the engine is revving. I have a 4cyl 1991 Wrangler. I have not taken this in anywhere yet to get it checked out but I am wondering if anyone else knows what this could be. Thanks!

**MLJeeper** · 04-18-2008, 09:38 AM

more details please, is it lifted? etc

Duckhat · 04-18-2008, 09:42 AM

It has a 3" suspension lift and a 3/4" shackle lift and 33" tires. I figured it would be any of these things because it doesn't vibrate when its coasting.

On a possibly related note, there is a tube that runs from the air filter box to the top of the motor (some sort of silver thing, I obviously know nothing about engines) that seems to be duck taped together. I hope thats not too important...

Let me know if you need anything else

**RockWoRM** · 04-18-2008, 10:06 AM

If the vibes go away when taking your foot off the gas, its likely the DL u-joints. Check them for play and/or if the straps are loose, or have a shop look at it.

WRM

Duckhat · 04-18-2008, 10:10 AM

Forgive me for my ignorance, but what is a DL u-joint?

Now that I think about it, I was told a little ways back that some sort of u-joint would need to be replaced in the future but I forgot about it since then. If this is the case, have I completely screwed my jeep?

**RockWoRM** · 04-18-2008, 10:17 AM

DL = drive line
check the FAQ for more Jeep terms
when U let off the gas, your releasing the torque from the DL, so the u-joints won't vibe as much. with my old stock DL and lift, I would go through joints almost every 6 months.
installing a SYE (slip yoke eleminator) and CV style DL took care of that. good investment for any lifted Jeep, IMHO.

WRM

**MLJeeper** · 04-18-2008, 10:17 AM

he beat me to it lol

Duckhat · 04-18-2008, 10:20 AM

Thank you so much! I will get this checked out ASAP. Yet again Jeepforum saves the day!

**sebastian22** · 04-18-2008, 10:21 AM

if i were you i would beg a fellow jeeper from this site in your area to come by and take a look at it. most guys are eager to help and will probably do it for free and teach you a thing or two in the process.

Marine_Mike · 04-18-2008, 05:28 PM

check your balancer on the engine. Mine went.... looked like it puked its guts out. Sound like the same prob I had. when my bud changed it the vibe went away... much to my wife's dismay.... lol

**laybackman** · 04-18-2008, 07:46 PM

THe fluid damper on the front of the engine is a good candidtae for the vibes just like a bad U joint.

Once I had a vibe only under load above a certain speed. Turns out one the rear brake springs popped off and that shoe was rubbing against the drum under load but the second I touched the brakes it stopped.