Vibration coming from something....

[Stovebolter]

Guys, this is unrelated to hot rods but would appreciate the help.

A little history: 91 Jeep Wrangler 2.5 4cyl 5 speed manual
A lot of miles. Just hit 170,000.

I'm just not sure where to start and if I take her to a shop...well that'll delay the 36 quite a bit longer. So I'd like to try to do this myself.

This ole girl hasnt been abused....oil changed often...no oil leaks....no blow by. But the engine is starting to show its age with mileage. Tick tick tick...or is that a light knock. For a very long time now, 3 years, I have had the indicator of a clutch problem. If I don't give a decent hesitation between shifts it will have a slight grind when going into the next gear. I usually can drive it without a single grinding gear on a up shift. On a down shift it always grinds no matter how long I engage the clutch. Same old story....I've been very easy on her to make her last. She's probably due for some serious work.

Tonights scenario. I was on the way home after work....at about 10 miles I had to stop to make a turn....upshift from 1rst to 2nd....smooth....upshift from 2nd to 3rd....smooth...until about 1600 RPM's then it has a moderate vibration....upshift from 3rd to 4rth.....again at around 1600 Rpms it vibrates all the way up to 2500 when I shift into 5th.....and again at 1600 a vibration.
I can duplicate this each and every time and the transition from 1rst to 2nd and 2nd to 3rd is fine. When it is vibrating the most .....if I engage the clutch the vibration is gone....indicating to me that the transmission and u-joints would be fine. When I rev the motor to 3000 rpms I feel no noticable vibration in the engine. I know it probably wants a rebuild but I just dont thing its the engine.

I know nothing about manual transmissions. Had at least 4 350 tubos, a 400 turbo, and 2 700r4's that I did a shadetree rebuild on. But I know nothing about clutches. Could my clutch be missing a chunk out of it which would thow it off balance? And if so....wouldnt it vibrate in 1rst and 2nd also?

Moderators. I hope this is where it should be. If not I apologize.

Thanks. Any help will be appreciated.

Dave G

[Stovebolter]

Tick...Tick...sounds like the tune of just high miles, and wear. Oil pressure ok ?

Try double clutching on the downshifts. That helps to sync it. Just like in the old days...

No, actually, when you take the load off, and it gets smooth. That would indicate a drive shaft, Probably a U-joint problem. Check those U-joints right away, or you might be walking...

ps: If you want to test this...when you are on the gas lightly, or until the vibration starts...ease up, and almost coast, and then back on the gas. You should feel the vibration get lighter, or quit, and then come back again when you go back on the gas.

LOL's. Yeah Denny. She's fussing a bit in the valve train. Oil pressure is a-okay. Since I use to drive trucks for a wholesale outfit that was the first thing I tried....double clutching just doesnt help. I tried what you said in your ps: driving normal up to shift range the vibration does get worse....let off on throttle and its still there until you get in the lower rpms...so yes...the vibration does start to go away....and back on the throttle vibrations starts getting worse. I honestly didnt think it would be the u-joints because it stops when the clutch pedal is pressed. I'll go out and check them after supper.

Thanks Denny!

Dave G

[Dave Severson]

Is there an inspection cover on the bottom of the bellhousing??? If so, you can remove it and check to see if there's any pieces of the disc laying in the pan, or visibly missing from the disc..... you can rotate the engine with a socket and breaker bar on the crank bolt and with a good inspection light you should be able to see at least the outer portion of the disc....

Could also be the throwout bearing starting to self destruct.... While you're under there, have someone push the clutch pedal in and watch inside to see if things are working correctly....

I've had diaphragm clutches break a finger sometimes and make a similar vibration, no idea what kind of clutch your jeep has......

As for the grinding on shifts, could be something as simple as the adjustment.... might want to check a service manual for specific adjustment procedures on your jeep.

[Stovebolter]

One other thing. When checking them U-joints. They aren't always loose, like ready to fall out. They can be just plain old dry, and have needle bearing indents. By that I mean, you may even have to take the drive shaft loose, so you can move it around, and or check the joint for tight, catchy spots. This will give a snappy reaction.

On that double clutching...do you give the engine a rev, to speed up the main shaft as you do the double clutch ? I use to play, and not use a clutch to shift. Only the engine speed to the shift. It didn't matter if it had syncros or not. I used to be pretty good at at...

Denny,

I'll take the drive shaft out tomorrow after work....that way I'll have a pair on hand. I'm sure they are in need of replacing. I was going to anyway a month ago when I was doing a general all over....getting ready for winter. Yes on the double clutching and rev. I was told the pressure plate was probably weak from heat?? My RX8 shifts real nice without the clutch....rarely ever have trouble shifting.

Thanks so much for the help Denny.

Dave G

Is there an inspection cover on the bottom of the bellhousing??? If so, you can remove it and check to see if there's any pieces of the disc laying in the pan, or visibly missing from the disc..... you can rotate the engine with a socket and breaker bar on the crank bolt and with a good inspection light you should be able to see at least the outer portion of the disc....

Could also be the throwout bearing starting to self destruct.... While you're under there, have someone push the clutch pedal in and watch inside to see if things are working correctly....

I've had diaphragm clutches break a finger sometimes and make a similar vibration, no idea what kind of clutch your jeep has......

As for the grinding on shifts, could be something as simple as the adjustment.... might want to check a service manual for specific adjustment procedures on your jeep.

Dave,

I dont think it has an inspection cover. I remember thinking about that while I was under it a month ago doing routine maintenance. I'm going to replace the u-joints tomorrow and shouldve a month ago. I'm sure they are worn. I'm also going to plan a clutch replacement this weekend. Shucks. I've been making this thing work for 3 years now without any repairs. At a 170,000 I guess I'm lucky I've done nothing but replace the throttle position switch. The guy I bought it from must have taken good care of it. Winter sneaking up....and the distance of winding backroads with hills that I have to travel to work.....I just dont think I can make without the Jeep. I was told buy an old GM mechanic to stay away from the reman units unless I was prepared to make a trip back for a different one....so I'm going to try to find a heavier duty unit. I guess I opened this thread because I just needed someone to re-inforce what I was already thinking. As far as clutch replacement....I'll try not to sweat it....but its a whole new thing for me. I noticed you sent me some of that artic air down my way. Brrrr. Time to buck up and just get after it I suppose.

Thanks so much Dave,

Dave G

[firebird77clone]

if the U joints have grease zerks, shoot some lube in 'em. If not, hose them down liberally with some liquid wrench and see if the vibration goes away.

[Stovebolter]

I will check that first before dismantling everything. This has me baffles. It only does it in gears 3rd and up. Throw it out of gear while its doing it and its fine. I thought ujoints (typically above 40 mph) would indicate they are in trouble even when throwing it out of gear.

Lets face it...my ole girl is tired.

Thanks,
Dave G

[jerry clayton]

Harmonic dampner

[jerry clayton]

And on 4 cylinders---motor mounts

[ted dehaan]

had a problem on a friend of mine jeep a few years back wanted to grind between gears and had vibration problems think his was an 89 or 90 same motor and trans we put a new clutch resurface fly wheel to brg same problem it had a hydrolic clutch sys no adjustment so we replaced the slave and m/c no help so we finaly figured out the clutch pedal has an arm at the pivot point and it was cracked replaced it with new oem part the dealer said they had alot problems with them worked fine for about 6 mo. and did it agean so I took it out bent it back and welded and reinforced it no more problems might want to check this as for the vibration turned out the alternator bracket had broken and the pivot bolt had worn the alt. case hole egg shaped big time funny thing is you could rev the eng and no vib and you could not see the problem but when you drove it felt just like u joints some times these things can fool ya good luck....ted

[jerry clayton]

So will a crossfeed between plug wires where they are close together

[Stovebolter]

Hi fellas. Well, I gave all of the u-joints a few shots....and took it for a spin. Remembering it is cold right now I assumed I would have to give it time to warm up. 1rst 4 miles....same scenario. Next 4....the vibration literally disappeared. Turned around and by the time I got back to the house it came back but not as bad as it was.

Shame on you Denny.....are you picking on my pile o Jeep? Come on....I thought these things were suppose to last forever. Just teasing ya.

I feel the vibration in the steering wheel and thru the floor....all over. But seems to be forward of the front seats mostly.

I plan on replacing the u-joints tomorrow. I'll check for visible problems....such as front mounted drive assesories, dampner, etc.

Tires are fine. Checked them first thing...still have all of their wheel weights in same place.

Thanks,
Dave G

[Stovebolter]

I was just sitting here thinking, and is the ignition system, plugs, and wires ok ? A cracked porcelin, under load, will cause a miss, or a wire. The miss can cause the vibration feel also. Is the power feeling ok ?

Oh, and do you feel the vibration in the seat, or the steering wheel ? Or just all over ?

Honestly Denny, it may be in need of plug wires and plugs. I really dont know what the fella before me had done. No service records.....just an assurance that it was serviced according to manufacturer suggestions. I'll give the plugs and wires a good check over.

LOL's. Is the power feeling ok? Let me tell you....dont ever!!! buy a 2.5 Jeep. I wish I had waiting for a 4.0 ltr 6....much more power and just a hair better on the gas mileage. I have two friends with 4.0 ltr Jeeps and they have proved it to me on more than one occasion. This thing just wasnt meant for used in our hills. But I really dont notice any difference in power. Just seems like the motor may be hurting a little more now under load....mid rpms.

Thanks,
Dave G

[Stovebolter]

Got an update. Definitely had a bad u-joint. I am really suprised it didnt explode before now. One....and only one cap was dry. Nothing but dust in the one cap. The rest were well greased.

I replaced the offending part....and shabang....drives fine.

Now I may make a thread about the grinding shifts issue.

I never wouldve thought the u-joints would be the problem. Live and learn.

Thanks everyone,
Dave G