Vibration - just appeared ! (1 Viewer)

[robnicko]

Hi,

My 80 has developed a vibration which is driving me crazy so am looking for some ideas.

It is a shudder upon acceleraion but not from a standing start. Its almost like a rumble that shakes the car

Once it gets to about 40km/h it feels like a shudder and if I back off the throttle the shudder is still there but fades away once speed reduces.

What I have done so far is,

Checked and repacked all wheel bearings, there was a tiny amount of play in the front ones and one rear however the bearing surfaces (both cup & race) were perfect so cleaned,, repacked and adjusted.
Checked and adjusted handbrake
Replaced both uni joints on rear tailshaft (transfer end uni had a minute bit of play, had been meaning to change for a while)
Checked front shaft, uni's appear fine (no play) - greased for good measure
Tyres are balanced fine so no probs there. No flat spots or anything (less than 1 year old)
front discs are in need of replacing however the shudder doesnt get worse if I apply brakes
Confirmed that none of the brake calipers are sticking
removed rear tailshaft and locked centre diff & took for drive........still a shudder
All suspension bushes are fine, shocks great and no broken springs

Im going to remove the front tailshaft tomorrow and try a drive as rear wheel drive.

Note, the shudder just appeared out of nowhere

Ive only ever had a uni joint fail immediately so want to ask if they can start to create vibrations and yet still show no signs of play?

Im at wits end so hoping someone might have some ideas?

thanks
rob

 

[baldilocks]

Can you remove the front shaft and use, if installed, the center diff lock switch so you can isolate the drive shafts for troubleshooting purposes? Did you replace the uni’s yourself or was it done by a shop and did they check the shaft for straightness and balance? Any driveline shop worth their salt does this. Make sure the slip end splines are not warn and that the yokes are in phase. Is there some of that “down under” mud stuck to the inside of a wheel maybe?

 

[robnicko]

Im going to remove the front shaft tomorrow and try driving wth the CDL engaged (RWD)

I changed the unis myself (have done a few in my time & marked & ensured yokes and shaft put back together as it was prior.) new uni's on rear shaft are very smooth and no play in them so am sure theyre fine as when driving without the rear shaft the shudder wasnt any better(or less I should say)
Yokes definitly in phase and slip splines are like new, no movement and slides easily. Front shaft is out of phase (OEM setup)
Wheels all clean (havent been offroad for a while) This car doesnt get driven during the week, only weekends so its got me stuffed
I have a feeling im gonna find something out when I remove the front shaft. Although there is no axial movement or no visible play Im hoping the movement of the uni bearings will be the issue (rough or the like)
Ive always kept the grease up to the uni's and one or two pumps into the slip every oil change so its really got me stuffed

only positive is I can tear down a steering knuckle in a few minutes now !!

 

[baldilocks]

How about suspension bushings? Bad bushings will allow the axle housing to wrap up changing pinion angle under load.

 

[bigredmachine]

does the vibration get better or worse when your over 40k

 

[robnicko]

it seems to get better but if I back off the throttle and accel again it comes back at different rates.
its very inconsistent and cause its there im being mindful of it and cautious

I may even pull the CV's out and see.

Ive had the car since new and the CV's are original and I last pulled them out for a clean and regrease about 2 years back.

I did notice that when driving as a front wheel drive there was a clicking sound coming when on full lock which sounds like CV clicking but I guess I'll see when I rip em out

 

[bigredmachine]

it seems to get better but if I back off the throttle and accel again it comes back at different rates.
its very inconsistent and cause its there im being mindful of it and cautious

I may even pull the CV's out and see.

Ive had the car since new and the CV's are original and I last pulled them out for a clean and regrease about 2 years back.

I did notice that when driving as a front wheel drive there was a clicking sound coming when on full lock which sounds like CV clicking but I guess I'll see when I rip em out

sounds like the birfs may be an issue, usually the clicking is a sign that they are on the way out. im assuming that theres plenty of grease in the knuckles

 

[Heckraiser]

I've had u-joint vibes start small and increase over time, so could still be your front u-joints. I've also had bad u-joints that didn't show any sign of play tested. Vibes that are related/specific to vehicle speed also point to u-joints, IMO. Just my $.02

 

[Cruzerman]

does the vibration get better or worse when your over 40k

Either that cruiser has a very high redline or is extremely fast!

 

[robnicko]

update

removed front tailshaft and took for drive---still vibrating, Unis in front shaft as I thought are in perfect cond and slip joint perfect as well
with front tail shaft out I removed drive flanges so front wheels rolling on bearings only and front diff not moving- still happening
put new wheel bearings in rear as I had them anyway- still happening

checked fluid in transmission, clear as a bell and sweet smelling, no burnt smell and at correct level
checking suspension bushes again and cannot see anything out of the ordinary
engine mounts and trans mounts all fine
transfer output flange are firm and no play
auto transmission shifts normally and cannot feel vibration on the auto selector when holding it whilst driving, vibration is felt through the steering wheel / seat / floor and mirrors are shaking

Its definitly a motion vibration as giving the car a rev in neutral is smooth as silk and idles perfectly. It feelk like driving with the handbrake on but its not on and if I pull up the handbrake whilst driving doesnt get any worse or better when releasing
The vibration does not happen from take off, it comes in at about 40 KM/h and stays in varying degrees of shuddering, sometimes more other times less and if putting in neutral is still there whilst coasting along

going to drain and refill rear diff oil next and back off handbrake (its set at the 7 click hold as per FSM)

my 80 has a 2" lift with ARB castor correction bushes however has been like this since 2001 so its really got me buggered as it just started a few days back

 

[FJP971]

This may be way off but any chance this is engine related like a misfire or vacuum leak that only shows under load/speed? Just throwing darts here. Sounds like you've been through the drivetrain pretty thoroughly. Next thought would be transmission internals... Hope that's not the case. Good luck.

 

[robnicko]

Im going to change the auto tranny fluid and see if that makes a difference.

I have a bad feeling it may be the torque converter slipping or something in there.

Might try some of that shudder additive as well

Transmission goes through all gears fine, doesnt appear to be slipping and locks up iine.

Fluid is transparent red and no hint of burnt smell and level perfect

Its really annoying cause it comes & goes sometimes heavy shudder other times light and then nothing.
taking off from a stop there is nothing and once up to about 40Km it appears

no vacuum leaks are evident and no misfiring either....

 

[robnicko]

I dumped the tranny fluid and refilled (5.5lt came out)
Id say the vibration has dissapeared about 80%
it still comes back on & off but much less severe and not as often
I think im on the right track so will dump again, change filter and refill
the drain plug had a small amount of crud but nothing out of the ordinary or excessive

 

[bigredmachine]

Im going to change the auto tranny fluid and see if that makes a difference.

I have a bad feeling it may be the torque converter slipping or something in there.

Might try some of that shudder additive as well

Transmission goes through all gears fine, doesnt appear to be slipping and locks up iine.

Fluid is transparent red and no hint of burnt smell and level perfect

Its really annoying cause it comes & goes sometimes heavy shudder other times light and then nothing.
taking off from a stop there is nothing and once up to about 40Km it appears

no vacuum leaks are evident and no misfiring either....

so just thinking it out here and if its the torque converter that's shuddering I would expect that to happen at a higher speed, usually it will shudder during lock up. are you driving with the power button on or off? power button off will lead to an earlier lock up but at 40k/mh I think that that may be a very low speed for lock up, but I could be wrong and off on my math trying to go from km to mi.

does the shudder happen at heavy load or light load? can you make it go away by down shifting or taking it out of overdrive? about when did it start happening and how long has it been happening?

I know its the stupid thing to say but make sure that your using the right atf, incorrect fluid can cause issues in the trans.

 

[robnicko]

It started late last week so just a few days now
It would happen at light load and moderate loads and when coasting would come & go
OD on or off made no difference & same with the power mode
took it on the freeway tonight and up to 120km/h and it had minimal vibration at that speed and then cleared up.
upon stopping and taking off again the shudder came back but very slight, gave more gas and it dissappeared
Its shifintg through all gears perfectly and no wierd noises or the like and after the fluid change shifts noticeably smoother than before however it never shifted rough
its not consistent but after changing the fluid has made a big difference so I think I'll persist with a few more drain / refill cycles
Im using Dexron 3 which is compatible with Dex 2 so all good there
I also have a tube of that DrTranny additive but want to see if the fluid changes make a difference first which it looks like it is

 

[bigredmachine]

so if its happening with the od off than I don't think that its the torque converter, going out of od will unlock the converter. you also ty[ically feel the shudder only under lighter loads and not while coasting.

I djust keep doing the drain and fills for a while to see how that works. do a drain an fill, drive for a week or so and repeat

 

[BILT4ME]

Instead of drain/refill 4QT at a time, can you do a fluid exchange (pump it out through the cooler in front?) I did 20 qt through mine and it made it smooth shifting again.

It's a bit expensive all at once, but you get a better job of changing it all instead of continuous mixing.

 

[robnicko]

well i'll be damned !

out of frustration I removed both tailshafsts, separated the slip joints, cleaned with de-greaser and put back together with a light coat of grease on the splines (used a small brush and painted it on)

took car for a drive and all is well. Took on freeway up to 130km/h and smooth as silk

What gets me is there was no binding in the slip yokes prior or excessive buildup of grease
next time they need greasing I think I will do the same procedure

In hindsight I guess I did a major service.......the hard & frustrating way !!

 

[bigredmachine]

we at least you know your drive line is good to go. when you took the d-shaft apart how much grease was in the slip joint cavity?

 

[robnicko]

there was not an excessive amount in there which is the surprising thing as its usually too much grease that causes issues