Bad Vibrations between 35-45 MPH

[HOrnbrod]

One friend said try fastening a stainless steel hose clamp around each end of the driveshaft just to see if things change, and attempt to do a redneck balance by moving them in or out. Don't know about that. But many thanks for your words of wisdom, and I feel like I'm finally zeroing in on the problem.

 

Thats a good idea (wish I would have thought of it years ago). Getting it to balance that way probably won't happen but if putting a few clamps on the shaft changes your vibration it would be an indicator that you are on the right track. opsled

 

I picked up a couple of new U-joints this afternoon, and will install tomorrow. WTH, it can't hurt. The guy at the driveshaft shop said since the vibes are happening at kind of low speeds (35-45 MPH), U-joints are most likely the cause. According to him, normally an unbalanced shaft shows vibes at 55+, and has harmonics further up the MPH range. My vibes are strictly at 35-45, and I can go on up to 95 MPH w. no more vibes. If the new U-joints do not cure the vibes, I try the hose clamp trick. Dayem, what a PITA

[JeepcoMJ]

I picked up a couple of new U-joints this afternoon, and will install tomorrow. WTH, it can't hurt. The guy at the driveshaft shop said since the vibes are happening at kind of low speeds (35-45 MPH), U-joints are most likely the cause. According to him, normally an unbalanced shaft shows vibes at 55+, and has harmonics further up the MPH range. My vibes are strictly at 35-45, and I can go on up to 95 MPH w. no more vibes. If the new U-joints do not cure the vibes, I try the hose clamp trick. Dayem, what a PITA

 

ya kno, no offense, but honestly at this point...I would have the place that does driveshafts just do your ujoints and balance it. just doing the ujoints is taking a risk and possibly wasting them. the driveshaft shop will do everything correctly and you'll be done with it.

[rockhardzj]

I've always done Ujoints on my own, and never had a problem. Only problem's with ujoints Ive ever had come back to me were due to driver stupidity... :roll:

[JeepcoMJ]

I've always done Ujoints on my own, and never had a problem. Only problem's with ujoints Ive ever had come back to me were due to driver stupidity... :roll:

 

yea, but you've never had a potentially out of balance driveshaft issue have you? best to get everything covered now.

[86FUBAR]

I still say tires...New doesn't automatically mean right or fixed or eliminate them as the problem.

 

Tires begin to need to be balanced at + - 35MPH. that's where your problem begins....notice a trend?

 

Try OTHER tires, got a buddie you could try his for a trip doen the road?

 

CW

Nope. New isn't necessarily perfect. Manufacturer defects, and the occasional one that didn't have as superior of a build quality, but it's not visible when leaving the factory.

 

My buddy's TJ, all the sudden, one day, it would ride fine till about 35mph, and then all hell would break loose for vibration. Threw it up on a lift, balanced and rotated the tires, tightened any bolt you could set your eyes on underneath, shook everything checking for worn out bushings or anything, seemed perfectly fine. take it out for a test drive, did it again, but slightly different feeling, about the same speed. Back on the lift, pull all the tires, road force balance them, and quickly notice one is a little egg shaped. a section of tire, the entire width of the tire, and about 15-18 inches long was about 1/4" higher than the rest of the tire. Put that on the spare tire carrier, balanced the spare before installing, threw all the tires back on and handed the keys to my buddy. He was quite happy. When he asked what the problem was, I showed him the tire on the carrier, and he was quite surprised. The tires had under 2500 miles on them when this all happened.

 

Only thing I miss about college was the 2 post lifts and the road force balancer... :cry:

Thought id share this ., its a set of 38-14.50-15 thornbirds a budy gave me and when i de-mounted them , i quickly figured out why he had the shakes so bad, we just chalked it up to be because of the tire size but it was an inner tire seperation.

not that i believe hornbrod's problem is this , just thought everyone might want to see that it does happen

[HOrnbrod]

Pulled the driveshaft this morning and the rear U-joint was binding on the bearings of the driveshaft yoke. Removed the joint and the bearing cups were well greased. So I pressed in a new joint and cracked my Craftsman vice at the cast iron base while doing so and had to finish up with a BFH and a big brass punch. The new joint was good and tight with no binding. Reinstalled the driveshaft the same way it came out and went for a spin. The vibes are all but gone. There are still some very minor vibes at the same 35-45 MPH band, but you really have to strain to feel them. So all-in-all about an 80% improvement. But am still going to the driveshaft shop next Tuesday to spin the shaft. So a definite driveline problem.........

[CWLONGSHOT]

Glad you found it!!

 

CW

[HOrnbrod]

Pulled the driveshaft this morning and the rear U-joint was binding on the bearings of the driveshaft yoke. Removed the joint and the bearing cups were well greased. So I pressed in a new joint and cracked my Craftsman vice at the cast iron base while doing so and had to finish up with a BFH and a big brass punch. The new joint was good and tight with no binding. Reinstalled the driveshaft the same way it came out and went for a spin. The vibes are all but gone. There are still some very minor vibes at the same 35-45 MPH band, but you really have to strain to feel them. So all-in-all about an 80% improvement. But am still going to the driveshaft shop next Tuesday to spin the shaft. So a definite driveline problem.........

 

I picked up a YJ slip yoke which I was going to install to get the extra 1/2" spline length (or so I thought) before I brought my driveshaft to be balanced. The YJ yoke is actually 5/8" shorter than the yoke I have on my 2WD w. AW4 now, which measures 4-5/8" from the base of the "Y" to the end of the slip shaft. The YJ yoke measurement is 4". WTF?? Does anyone have any slip yokes laying around with a measurement greater than 4-5/8"? Thanks

 

 

[HOrnbrod]

Here's a better pic comparing the two:

 

Image Not Found

[rockhardzj]

I have like 3 or 4 at home, but yea, that's a 12hr drive away... I'lllet you know their lengths in about 2 weeks.

[HOrnbrod]

I have like 3 or 4 at home, but yea, that's a 12hr drive away... I'lllet you know their lengths in about 2 weeks.

 

Thanks Joel. The measured lengths from the center of the yoke U-joint hole to the end of the slip shaft are:

 

MJ Yoke: 6-1/8"

YJ Yoke: 5-3/4"

[rockhardzj]

Well, I know I have at least 1 XJ slip yoke floatring around, an MJ one, and a few YJ ones as well.

[HOrnbrod]

One friend said try fastening a stainless steel hose clamp around each end of the driveshaft just to see if things change, and attempt to do a redneck balance by moving them in or out. Don't know about that. But many thanks for your words of wisdom, and I feel like I'm finally zeroing in on the problem.

 

I lied, the vibes continue. Same crap, on at 35, off at 45, the worst vibes are under acceleration. No vibes at any other speed. No handling problems. The seat-of-the-pants vibes are basically unchanged since I started on this problem. Here's what I've done since my last post:

 

1. New drive shaft: The local drive shaft shop had trouble balancing my old one, so I had a new one made (Tom Woods). Helped very little.

2. Transmission/TC drop: Installed a 1" drop on the tranny, which had no effect. Pulled the shims off and am now back to normal with no drop.

3. Replaced the LCAs w. WJ LCAs: Worked great reducing body roll, did nothing for the vibes.

 

What gets me is that I ran vibe-free for over a year post-lift until I regeared the diff. The new gears run quietly and smooth. I know I mentioned I had some very slight vibes prior to the regear, but the regearing made the vibes worse. Regearing can't change driveline angles, right? Also I have kept a close sag watch on the new Metric Ton rear leaf pack that's been there for over a year. Maybe the body settled 1/4" lower if that, basically no sag happened. So my driveline angles haven't changed. Sorry for the rant, but I'm getting discouraged and don't know what to try next.

[HOrnbrod]

Oh, and the title of this thread "Bad Vibrations between 35-45 MPH" is not really true. The vibes are not BAD bad, more like annoying as hell. :mad: I'm not losing mirrors and other body pieces because of them. If anyone can figure this put for me, you will receive a case or 12 of your favorite brew. :cheers:

[86FUBAR]

have u tried to put the truck on jack stands and replicate the vibes ,that might help eliminate the problem . also just because the gears run quiet doesent mean they couldnt be messed up try taking it to shop ( preferably a different shop than the one that did the anitial install) and have them double check the pattern on the gears. also when u did the gears did u replace the bearings in the rearend (all of them)?

[HOrnbrod]

have u tried to put the truck on jack stands and replicate the vibes ,that might help eliminate the problem . also just because the gears run quiet doesent mean they couldnt be messed up try taking it to shop ( preferably a different shop than the one that did the anitial install) and have them double check the pattern on the gears. also when u did the gears did u replace the bearings in the rearend (all of them)?

 

Did put the truck up on jack stands, went slowly up to 85 MPH letting the auto tranny shift up to OD, zero vibes. Especially concentrated on the 35-45 MPH range. All the bearings were replaced during the install as I had the master rebuild kit along w. the new Yukon R&P 4.11 gears. Had a problem getting consistent patterns finally traced to a weird crush sleeve that would not crush properly during the pinion setup, so ended up re-using the original crush sleeve. Can regearing the diff cause driveline vibes? I searched hard and not found anything on it.

[Oizarod115]

i can't imagine you having a pinion angle related vibration unless its WAYYY off. like eyeballing it and it looks way off off.

 

its a LB manche, which means the shaft is a good 50"ish right?

[HOrnbrod]

i can't imagine you having a pinion angle related vibration unless its WAYYY off. like eyeballing it and it looks way off off.

its a LB manche, which means the shaft is a good 50"ish right?

 

More like 60" u-joint to u-joint. Eyeballing both angles looks good, but I'm going to pick up an angle finder to be sure. This one really has me buffaloed.

[Duner]

Ok, your probally just about crazy at this point and even contemplating selling your MJ. All I can tell you is take one more thorough look around under truck from the fron to the back.

 

Start at the harmonic balancer, check the tranny to engine block bolts, remove the inspection cover and check torque converter bolts, flex plate and bolt mounts, check tailshaft of trans, new driveshaft did they handle the slip yoke or did you remove it before they worked on it? if they did it move on to the rear yoke on your diff - its possible that its cracked or it has been slightly bent.

 

The vibration as you described it is typical for the driveline. If you had a 4wd you would need to check out the t-case but since its 2wd I would concentrate on the flexplate converter area of your aw4. Again given that the vibration is consistent between 35 to 45 and worse during acceleration than deceleration. That stroker engine may have cracked your flexplate.

[HOrnbrod]

Ok, your probally just about crazy at this point and even contemplating selling your MJ. All I can tell you is take one more thorough look around under truck from the fron to the back.

 

Start at the harmonic balancer, check the tranny to engine block bolts, remove the inspection cover and check torque converter bolts, flex plate and bolt mounts, check tailshaft of trans, new driveshaft did they handle the slip yoke or did you remove it before they worked on it? if they did it move on to the rear yoke on your diff - its possible that its cracked or it has been slightly bent.

 

The vibration as you described it is typical for the driveline. If you had a 4wd you would need to check out the t-case but since its 2wd I would concentrate on the flexplate converter area of your aw4. Again given that the vibration is consistent between 35 to 45 and worse during acceleration than deceleration. That stroker engine may have cracked your flexplate.

 

No, not contemplating selling it, but it's definitely getting to be a PITA. The new drive shaft came complete with Spicer greasable u-joints and a new YJ slip yoke. Hadn't thought about a loose or cracked flexplate as I don't have any random clanking noises, but I get on that tomorrow. I'll also check the read diff yoke closely, since the vibes got worse when we changed diff gears. I have a new OEM tranny mount coming. It still has the original, so I'm hoping that will help. Put new engine mounts and harmonic balancer on when the stroker went in a couple of years ago.

 

Just for kicks and grins, I went to the local Chevy dealer today. They have a new Hunter road force wheel balancer. Awesome machine, and it the vibes seem to be a little less than before, but of course they are still there. Thanks for everyones comments; sooner or later I'll stumble on to the solution. But I'm nearly positive it's a driveline issue.

[MiNi Beast]

have u pulled your diff cover off and looked at your gears at all? Just a thought thought if they are slightly off they will leave some wear. I had bad vibe with my old D35, thought was an worn out u joint so replaced it but still there, got worse as I drove it being dd, so brother had me check the diff and found 10 teeth missing from the ring. not saying you have missing teeth, but would check at least, being last major fix, have to watch that gear lash.

[HOrnbrod]

Start at the harmonic balancer, check the tranny to engine block bolts, remove the inspection cover and check torque converter bolts, flex plate and bolt mounts, check tailshaft of trans, new driveshaft did they handle the slip yoke or did you remove it before they worked on it? if they did it move on to the rear yoke on your diff - its possible that its cracked or it has been slightly bent.

 

The vibration as you described it is typical for the driveline. If you had a 4wd you would need to check out the t-case but since its 2wd I would concentrate on the flexplate converter area of your aw4. Again given that the vibration is consistent between 35 to 45 and worse during acceleration than deceleration. That stroker engine may have cracked your flexplate..

 

Took a peek and the flexplate bolts were all tight and the plate looked good.

 

have u pulled your diff cover off and looked at your gears at all? Just a thought thought if they are slightly off they will leave some wear. I had bad vibe with my old D35, thought was an worn out u joint so replaced it but still there, got worse as I drove it being dd, so brother had me check the diff and found 10 teeth missing from the ring. not saying you have missing teeth, but would check at least, being last major fix, have to watch that gear lash.

 

Yes, this is next. I am going to wait until I get the new tranny mount on just in case I luck out and this fixes it. If not, will pull the cover and do a detailed rectal exam on the diff. Also will try to borrow a dial indicator and check out the trueness of the pinion yoke since we had such a hard time with the new crush sleeve that didn't want to crush.

[MiNi Beast]

I can tell you right now it won't be the tranny mount. But check this before throwing more parts at this. Rule of thumb is if figure out problem area then first check area of last area you fixed. Get it? A gimme that things where out, but doing a major job like this and that be the area the problem arises in whold have been the first place to check. I didn't check mine being never messed with gears but you have so. But hope it isn't the problem due to time and money if it is the problem but would check there.

[HOrnbrod]

I can tell you right now it won't be the tranny mount. But check this before throwing more parts at this. Rule of thumb is if figure out problem area then first check area of last area you fixed. Get it? A gimme that things where out, but doing a major job like this and that be the area the problem arises in whold have been the first place to check. I didn't check mine being never messed with gears but you have so. But hope it isn't the problem due to time and money if it is the problem but would check there.

 

Yes, I know that's the first thing you do when troubleshooting; go back to when the problem first started. But I did have these same vibes before the gear install, although very faint. The gear install made the vibes worse, but did not change their freq or the 35-45 MPH range where they showed up. And they are very quiet during accel, coast, and when braking. Course I know that sometimes doesn't mean squat either. :mad:

[HOrnbrod]

I can tell you right now it won't be the tranny mount. But check this before throwing more parts at this. Rule of thumb is if figure out problem area then first check area of last area you fixed. Get it? A gimme that things where out, but doing a major job like this and that be the area the problem arises in whold have been the first place to check. I didn't check mine being never messed with gears but you have so. But hope it isn't the problem due to time and money if it is the problem but would check there.

 

Yes, I know that's the first thing you do when troubleshooting; go back to when the problem first started. But I did have these same vibes before the gear install, although very faint. The gear install made the vibes worse, but did not change their freq or the 35-45 MPH range where they showed up. And they are very quiet during accel, coast, and when braking. Course I know that sometimes doesn't mean squat either. :mad:

 

Draggin' this up again to report the vibes are finally GONE!!! In the very first post when I started this thread, I said the vibes started when we regeared, but like a dumbass I had to try EVERYTHING before I went back in the diff like I should have done originally - you were right roger21maynard. Most everyone said the diff couldn't/shouldn't cause low speed driveline vibes like I had, but it dayem sure did. The problem was pinion backlash - there was none. On the original install we could not get the crush sleeve to crush, so we re-used the original and tightened the crap out of the pinion. This week we looked at the pattern, and although there was very little metal in the diff, you could see where the pinion and ring gears had tiny dents in it caused by chattering 'cause it was too close to the ring gear, which caused the vibes. At first I only had vibes under acceleration, then it progressed to deceleration, then to coast during the 35-55 MPH speed range. And the strange thing is that the diff was very quiet during the whole time - made NO noise. This was a strange one and I thought I'd pass it on. Expensive hard-learned lesson :mad:

 

But anyhow, I learned a lot about driveline angles, slip yokes, u-joints, drive shafts, alignment, and DIFFERENTIALS. Everything's right now, and I'm happy. :cheers: