SurgeGT

first off, i've already done a search and couldn't really find what i was looking for so i'll give this a shot. when my 96 SR5 2WD auto 4runner is at speed (usually around 55+mph) and i let off the throttle i get a deep rumble sound with a faint vibrating feeling. nothing seems to be different at slow speeds or while accelerating, just deccelerating...

also, i'm not sure if its related but when i put the tranny in R then D and just play with it going back and forth, (not rapidly...just casually, as if normally shifting the lever) as the tranny engages i get a clunk (not always but often, like if we sat in the truck at any given time i could get it to do it at least a couple times) but like a pretty hefty clunk and sometimes it will engage really smooth.

so, ok..play. somthings got some play. what do you guys think are my most likely culprits? i've only had the time to get under there and try and shake things around to see if i have any obvious slack. nothing as far as that goes.

anyone else have this happen to them? what was the fix? now i hear the 2WD had maintainence free universals on the drive shafts or something along those lines? the yoke maybe? what should i look for in advance?

and i know y ou guys can't possibly know exactly what it is off hand...but what are average costs of repairs for whatever you might suggest it is? i just had the motor out of my other car rebuilt and i was hoping for longer than a week to recoupe from the bills!!!! :cry:

thanks guys!

Flamedx4

Have you done anything like lift the rear? Had the driveshaft disconnected and reconnected lately? Classic description on pinion angle problem - the angle of the front ujoint being a lot different from the angle of the rear u-joint sort of thing. Typically get a vibration at or above a certain speed, typically either on accelleration or decelleration, rarely at coasting.

89_4runner

SurgeGT,

You're not alone, I have had the same rumble/vibration on my 4Runner for a little over a year. When it first started I had 6" rear springs and 35" tires. I thought it was pinion angle, so I tried measuring the driveshaft with an angle gauge and played with angle shims under the rear springs without any change. So, last August I removed the original 4-6" front and rear lift and currently run cranked torsion bars and 2" Rancho rear springs. Guess what, I still have the noise and vibration at highway speed when accelerating and decelerating. I don't think it's just the rear springs because I ran them 10 years ago without any vibration.

I also tend to have more vibration than expected driving on the highway and don't think it's the tires since I rotate them front and back and don't notice a difference (steering wheel <-> seat of pants). Plus the vibration didn't change when downsizing from 35" BFG MTs to 31" BFG ATs.

The clunk or smooth engagement of the transmission could be related to engine RPMs when shifting between R-N-D. High RPM (2k) -> clunk, low RPM (800) -> smooth. Or, it could be the u-joints or axle wrap.

Could the u-joint(s) on the rear driveshaft be going out and creating this vibration? Is it possibly a problem with the bearing on the transfer case output? Last time I checked everything felt fairly tight. I plan to place the rear axle on jackstands, fire the engine up and look for driveshaft vibration.

Anyone's help or experience with driveline vibration is welcome...

li_runner

I'd venture to guess it's the u-joints. Just because there maintenance free doesn't mean they are infallible. I had the same wierd vibration at around 110K miles and that is what it turned out to be. Quick jaunt to a drive-shaft shop and it was fixed.

FingerMan20

I have a friend with a '99 Formula 1 Firebird, and she had problems very similar to yours, and upon inspection we found 2 of her tranny mounts to be snapped. So just inspect your mounts, and trans-to-engine mount bolts, and torque the aforementioned bolts to specifications, while you're at it .

89_4runner

The u-joints on my 89 have zerks, but I still think they're the #1 culprit. I have greased and re-greased them to see if there are differences in the vibration and it doesn't change so I thought they were ok. Since my u-joints have 180k on them, it's probably simplest to just swap them out. I hate to just blindly replace parts though. But if it fixes the problem.

4Crawler

iTrader: (3)

Check the angles on the rear driveshaft as well as the u-joint phasing:

http://www.4crawler.com/4x4/CheapTri...l#Measurements

http://www.4crawler.com/4x4/CheapTri....shtml#Phasing

kaiberg

putting grease in the zerks is good but if the "needle bearings" inside the u-joints are shot then greasing wont do any good...sounds like you need to replace the u-joints...do the front and rear while you are at it because it is easier to just to take out the driveshaft and put it in a vise to work on it..since its out the parts are not that expensive...

SurgeGT

you guys are freaking RAD!

i was thinking my tranny mounts..i was gonna try that. i dont feel any play...but i'll do like you guys suggested.

now i'm not sure if i've always had this...i mean...i KNOW it's never been this noticable, but i may have had it but its gotten progressively worse.

my rig isn't lifted,,,well, i guess it is, its a 2WD lifted with 99 4WD springs. so its mild.

my schedule is hectic and i hate just dropping her off at joe mechanics...so i'll try that stuff first..but it may be a few days..do you guys think i have to worry about it locking on me on the freeway?

89_4runner

Hi Roger,
The angle still may be a problem, but we're only talking 2" lift rear springs. I honestly never checked the angles after removing the 6" springs, but it used to be something like 15 degs. I've driven the truck for 15 years and it only had the stock suspension setup for the first 9 months. I ran the same 2" Rancho springs 10 years ago without this strange vibration. It seems that something is wearing out (u-joint, tailshaft bushing, etc.).

The phasing shouldn't be a problem because I've never removed the driveshaft, but I can double check it. I had the truck towed a couple of years ago when I was having starting problems (by the way, I haven't had any since installing the relay that you recommended). Maybe the tow truck driver removed the driveshaft for some strange reason.

89_4runner

Kaiberg,
You're probably right, the u-joints are relatively cheap and not that difficult to change. They've never been changed, and years with 4" and 6" rear lift probably took a toll on them. While I'm at it I'll check the angles and phase as Roger suggested. It may take a few days before I can dig into this.

SurgeGT,
If your vibration and noise is anything like mine, I wouldn't worry. Mine has been doing this for months. On the other hand use good common sense since you know the exact situation first hand. If everything feels/looks tight around the driveshaft you should be ok in the short run. If the vibration gets bad, just pull over.

4RunnerBuddha

Surge,

I have a 99 2wd, and I just took mine into the mechanic for the same problem! Mine seems like it has to do with the O/D, but I'll have the mechanics check the u-joints as well....

4Crawler

iTrader: (3)

Easy to check the angles, its not so much the angle of the shaft but the relative angles at the flanges. Also check that the flanges are tight, no play. With driveshaft vibes, you need to make sure everything is good, as one problem can shake some other part loose or wear out a u-joint, so you can still have vibrations after fixing the initial problem.

89_4runner

Well, the u-joints feel tight to me, but the transfer case flange has roughly .010"-.020" of play in the vertical direction. I don't notice any play in the horizontal direction. I'm guessing that vertical play is causing the vibration. Any ideas on what must be replaced since this is an A340H A/T (entire x-fer case )? The FSM is not real clear how the rear output shaft is supported, but I don't see a simple bearing in the rear chain cover. Seems like a bad idea to have such a long unsupported shaft.

Is there any chance the play is acceptable?

bikeguy18974

89 4runner

i had same problem as you with my 86. I had 3.5" lift springs but when new gave me almost 6" of lift. I actually got the angles dead on at the pinion and t-case but they were too steep based on info from rogers site.

I got a double cardan driveshaft off a 2000 regular cab tacoma. The pinion flange had the same bolt pattern, and on the tcase I had to just widen the holes a bit. Mine cost $100 from a junkyard, but other non-local places had some for as low as $35. The u joints were all good as far as i could tell.

Installed that, reset the pinion angle for that type of shaft (once again thanks to the 4crawler site) and I've been vibration free ever since.

ugadawg95

see this thread:

https://www.yotatech.com/forums/f2/ome-lift-installed-driveshaft-vibration-51725/

4Crawler

iTrader: (3)

Yes, if a single cardan shaft is run at too steep an angle, even if perfectly aligned, you can still get vibrations. This is due to the incomplete cancellation of one u-joint's non-linear rotation by the opposite u-joint. The angle where this happens depends on many factors, but I found on my '85 happened in the 12-15 degree range. Also went to a double-cardan (CV) shaft and it's been much better since then.

Play in the t-case output flange may be due to a loose nut holding it in place. You could try unstaking the nut and then crank it down to 90 ft.lbs. or so (if it moves) and restake it. If that helps, that was the problem.

Tato97T100

I would say it was definately the u-joints although you said it vibrates after you let off the pedal. It if were the u-joints its more likely to vibrate when you stomp on the pedal (or just push---doesn't have to be stomp)

And i wouldn't say changeing out the u-joint is so easy. If that driveshaft gets stuck--which it sometimes does, you are going to have something good waiting for you.

But it is true they are cheap--if i remember, about $12 a peice.

The next most likely would be the mounts--since letting go of the pedals would cause it to do more "resting" on the mounts, but if thats not it, beats me.

The weird thing is that it vibrates after letting go of the pedal

good luck...keep us posted

4Crawler

iTrader: (3)

Two possibilities for vibrating while coasting:

#1 is something loose, worn u-joint, slip yoke, loose flange, etc. Vibrates more when the is no pressure on it.

#2 is if the pinion angle is too low. Pinion flange wants to tip up under load, so the angle gets closer to the proper alignment, vibration lessens. Let off the gas, pinion tips back down, alignment gets worse and vibration increases.

Flamedx4

This has been a great thread.
The tip about the trans mounts reminded me of something that happened to me once in my 85. I was getting more noise/vibration/harshness than ever before (normally none!) and I *eventually* noticed a ROCK absolutely wedged between the crossmember and the transfer case. I had to break it with a chisel to remove it. Vibration gone! Wierd things happen.