A bad case of shudders - after a day of fun.

[TJ]

Hi All,

A big thanks to Peter Vahry for following me all the way from the farm where we were to near our house to make sure my family and I got back in one piece. Thanks very much Peter, you are a kind man.

Went out with our club (Auckland 4wd Club) for a Christmas do today, had a blast. Track was easy family oriented sand / grassy. Nothing complicated. Everything was fine in the morning and during the day. But when I got back on the road and got to 50 km/hour, my steering started to vibrate (more like shudder - as in when you go over those judder bars). I thought that was odd, so slowed down and everything was fine. Sped up again, same problem. I could barely manage to do 60 km/hour. So stopped and a few people had a look at the steering components while I turned from lock to lock, nothing out of ordinary. Eveything seemed straight and tight.

Started driving again, this time when the shudder came about at 50 km/hour, I sped up and then put it in Neutral and all the shuderring went away (slight vibration was still there). Seems its not tyre related. What else could it be?

I did another test, on a straight bit of road where I knew there was no chance of damaging part time 4wd, at 60 km/hour I put it into 4H and then sped up - no shakes/shudders or they were markedly reduced. Got up to 70/75 km/hour and went back in to 2wd, kept that speed and everything was relatively okay (minor shaking). But whenever I was under load (uphill / speeding up), the shakes would come back and markedly go away when I took the foot off the accelerator.

I have had the universal joints replaced about six weeks ago as a preventative maintenance. New replacements were Dana pieces as well.

What can it be? I know its a long post, but wanted to give as much information as possible to people to give me ideas?

Thanks for all your help in advance. And no its not a Jeep thing and I do understand (before anybody else says anything).

[dazza85]

I think that it is unlikely as you were only on grass / sand
but have you picked up a clump of muddy grass in one rim throwing it out of balance ??

[TJ]

I think that it is unlikely as you were only on grass / sand
but have you picked up a clump of muddy grass in one rim throwing it out of balance ??

Looked under the whole thing in rain after coming back. Nothing stuck anywhere. Rims are clean and don't seem to be missing any weights.

Besides, the shakes were only when under load. As soon as I went in Neutral and doing 60 km/hr, shakes go away. An unbalanced tyre wouldn't do that, would it?

I am leaning towards one of the new u-joints has ceased or was not fitted properly by the shop.

[Petemcc]

Is it possible it's the engine missing. Most things that would shudder would not go away when not under load i would think. (ie if the diff or gearbox was bad enough to do it then i wouldn't think it would go away) check your spark plug leads lol.

Does it make any difference what gear you are in? My mates auto v8 kingswood would shudder at about 40k's some times and turned out that it was running on 7.

Pete

[TJ]

Engine not missing, idles fine and revs up nicely. Also, on a 2000+ Wrangler (i.e. TJ) there are no spark plug leads. There is one coil pack for two cylinders (a total of three coil packs and six cylinders).

Do you think it might be something in the auto transmission? Any ideas how I can test this theory?

[lilpigzuk]

missus nailed a high speed hump with out old falcon, bent the trans mount, made it vibrate like a mofo. All you engine,gearbox,transfer mounts sweet??

[TJ]

missus nailed a high speed hump with out old falcon, bent the trans mount, made it vibrate like a mofo. All you engine,gearbox,transfer mounts sweet??

Hmmmm, engine mount seems okay. There are no transfer case mounts. Auto mount - good thinking, I might have to investigate that one. Logically makes sense.

[xj]

balance weight off the driveshaft??????????? (clutching at straws)

[TJ]

balance weight off the driveshaft??????????? (clutching at straws)

Its too dark outside, another good candidate.

[TJ]

UPDATE:

Well its final, I have managed to bend the rear output shaft on my transfer case! Its bad enough to cause all the jerks I am feeling.

Oh well, time to give myself a Christmas gift. I'll import a slip yoke eminator kit and a double cardan rear driveshaft to fix the poor factory design. Important thing is, nobody was injured or harmed in the process.

JB Conversion Super Shorty, here I come.