Intro: and Question

[chip1997]

I have been lurking here for quite some time, but never had the chance to post. Now I am looking at an issue that I have researched, but found not for an answer. I have a 1997 FZJ-80 with 142K on the clock no mods except for and ARB up front. For the last few months I have been experiancing a vibration between 20 and 30 MPH. The vibe shakes the whole vehicle. So far I have Replaced my Shocks with stock, new OME steering dampener, axle job ( whole shooting match bearings, races, etc.), new u-joints (all), New brake pads, front caliper rebuild about 4 years ago & had tire balanced and checked for round.

None of this has eased the vibration. There are two things I have left to do, one is to switch out tires with a Taco or Tundra and see if that eases things. The other is to have the drive shafts balances. In the mean time does anyone have any advice. I find the vibration especially peculiar since it starts at such a low speed.

By the way it is a speed dependant vibration, not related to RPM. When accel. or decel. it is still there. If I shift to netral during the vibe it still continues.

Now for the really weird part, occasionally and I mean very rarely when turning or taking of gingerly I get a much slighter amost none existiant version of the vibe.

Thanks for your help on this.

Chip

 

[DTAYLOR]

Hmm

Try this: At the speed you get the worst vibration, slip the transmission into nuetral and coast. If the vibration goes away, that means you have a "driveline" vibration. Likely a u-joint, possibly (but I doubt) a birf.

If the vibration does not go away, it will most likely be tires.

Let us know.

BTW, welcome, and show us some pics of your rig.

 

[Grench]

Tie rod ends maybe?

 

[chip1997]

I have tried slipping it into neutral, and the vibe is still there. That is why I leaned towards the tires, and possibly the u-joints.

How can I check the tie rod ends?

Thanks.

 

[firetruck41]

I recommend getting your tires balanced on a Hunter GSP9700, it is way more than just a computer balancer, and it has solved similar vibe issues for me before. Next time you buy tires, buy them at a shop that has one of these machines, they can use it on your lifetime free balances, otherwise I have seen them charge $15 per tire,

Find a Hunter GSP9700

 

[Beowulf]

Chip,
Your problem sounds like it is tyre related and Ben is giving you good advice on the balancing and the machine to seek out.

The other thing that I have seen is an out-of-round tyre. Technically, an oval-shaped tyre can be "balanced" but its like driving on an egg and you will get vibrations as you've described.

Have you looked at the rear axle? Does the vibration come through the steering wheel or through the seat?

-B-

 

[chip1997]

Firetruck,

When I had them balanced a month ago I had it done at a shop that uses the Hunter GSP9700. Thanks for the advice.

Anyone in or around Augusta, GA want to swap tires with me for the day?

 

[Beowulf]

Try this: At the speed you get the worst vibration, slip the transmission into nuetral [sic] and coast. If the vibration goes away, that means you have a "driveline" vibration. Likely a u-joint, ...

DTAYLOR,
Chip told us in his first post that the vibration does not go away if he shifts to neutral.

Are you sure about this isolating the problem to a U-joint? The unis continue to spin when the vehicle is moving even if you are in neutral; all 4 of them on our FT 4wd 80s.

-B-

 

[chip1997]

Beowulf,

How can you check for an out of round tire yourself? I feel the vibration mostly through the seat, but you can feel a slight vibe in the steering wheel. It's really hard to describe, but its almost as if the truck vibrates around me, not so much in the seat. I suppose thats because I have a fat arse. I have the parts for the rear axle service, but have yet to do it. Anything specific I should look for while doing it?

 

[chip1997]

I wouldn't think the shift to neutral would isolate a u-joint problem, it would however help isolate a tranny/t-case problem. Since neutral eleminates the load on the drive shaft from the transmission.

 

[Beowulf]

Anything specific I should look for while doing it?

A bad rear wheel bearing would be giving you a loud growl and I don't think you would miss it. I suppose you could have a problem with the rear hub or the bearings that would create this vibration. The FF rear axle is relatively easy compared to the FF front.

A tyre shop can check and correct for out-of-round. Basically, they shave down the high spot(s) but that is something that would move me to buy some new shoes for the truck.

-B-

 

[Beowulf]

I feel the vibration mostly through the seat, but you can feel a slight vibe in the steering wheel.

Does the vibration go away above 30MPH?

-B-

 

[chip1997]

A bad rear wheel bearing would be giving you a loud growl and I don't think you would miss it. I suppose you could have a problem with the rear hub or the bearings that would create this vibration. The FF rear axle is relatively easy compared to the FF front.

A tyre shop can check and correct for out-of-round. Basically, they shave down the high spot(s) but that is something that would move me to buy some new shoes for the truck.

-B-

Yea, I would actually like for it to be the Duelers. Unfortunatly I have had them for five years and they are yet to ware down enough to warrant new ones. I had the Firestone shop check for out of round and they said everything looked good. I suppose my best bet is just to try a set of wheels off of a compatible vehicle. Then I could eleminate the tires being the problem for sure. It may be my imagination, but i could swear that when going very slow on a flat road I can feel the truck slightly loaping from PS Rear to DS Front.

 

[chip1997]

Does the vibration go away above 30MPH?

-B-

Absolutly, that is what puzzles me so much. It seems physics would dictate the vibration would only get worse.

 

[Beowulf]

... when going very slow on a flat road I can feel the truck slightly loaping from PS Rear to DS Front.

This information combined with the facts that the tyres have been checked for out-of-round by a shop, balanced using the Hunter GSP9700, and that the vibration completely goes away above 30MPH has me stumped. I'm done. Let us know how the test goes with another set of wheels and tyres.

-B-

 

[firetruck41]

Firetruck,

When I had them balanced a month ago I had it done at a shop that uses the Hunter GSP9700. Thanks for the advice.

Anyone in or around Augusta, GA want to swap tires with me for the day?

Do you know if they actually used the GSP 9700? Usually they have several Hunter balancers and only one GSP9700. Aso I have heard of techs not knowing how to properly and fully use the machine. I think you may be on the right track with the tires, hopefully someone can do a swap with you, if the shop can't do the job.

 

[chip1997]

Ok Guys, Here's a little update. Upon inspecting my shocks I noticed that the fronts were a little loose. I tightend them up, and it made a difference, however the vibration is still there. Would this indicate that the Vibration was comming from the front? Does this help me rule anything out?

Chip