v12mac

Suspension binding popping sound, sticky bushing?

While I am digging around with the car I have one odd ball issue that I am trying to track down. It seems that I have something in the suspension that sounds like it is binding and popping as the suspension moves up and down. I can repeat the sound by dropping the suspension from the H position to the L but I can’t figure out what is hanging up. As it moves I get a whurrrr from the pump as the height changes then pop…..pop… pop..pop..

Any trouble spots to look for?

vcheng

When was the last time the front and rear propellor shaft zirk fittings were greased? I'd start with those as the likely culprit, and only if exlcuded look to other components.

v12mac

I would guess it has been quite a while.. or never.

vcheng

Then that's the place to start.

There are three zirk fittings on each propellor shaft, one on the sliding yoke and two on the universal joint at the differential ends of the shafts.

The rear ones are easy to get to, and it is possible to get to the front ones with a flexible attachment to the grease gun.

However, the whole job, although simple, is messy and uncomfortable. You may want to take it your repair shop, dealer or not, is up to you.

v12mac

Nope, that wasn't it.

Any chance a shock could be going bad? How could I isolate it to trouble shoot?

vcheng

Well then, assuming that the lubrication has been done properly and the issue persists, then the suspension would be the next logical place to look for a binding in a bushing or a linkage.

One way to troubleshoot would be to raise the vehicle on a lift and then compress suspension on each corner with a separate jack to see where the noise might be coming from.

I would still go back to the propellor shafts. The sliding yoke issue is well known as a cause of the symptoms you are describing. Who did the lube job and how many pumps were needed for the yokes?

v12mac

I had the truck over at mechanic for a T belt and they spent several hours trying to track the noise down. They said they lubed everything that had fittings. I am going to get under there this weekend and see if they might have missed something.

I can hear this sound when the suspension moves (the rear) and when I take off from a red light.

v12mac

How many pumps should I hit the shafts with?

vcheng

"Lubed everything" sounds fishy to me. How many zirks did they hit? There are exactly SIX, no more, no less.

The two zirks near the back end of the rear shaft and the front end of the front shaft (i.e. the ends close to differentials) are easy. One or two pumps should be enough.

The sliding yokes are more tricky. The manual says to pump enough grease until it comes out the sliding seal. However, there are reports of the seals being so tight that one can cause a hydraulic lock.

So, what I would suggest is three pumps at first and go from there. Please clean off the fittings first (of course) and then keep a close eye on the sliding portion. If you see the shaft extending with no grease coming out, that is too much grease. You may have to take the entire fitting off and let the excess grease come out when you lower the truck. Cleaning and lubing the exposed sliding portion may also be a good idea.

Also, once the lube has been done, you may need to move the suspension a few times before the grease works in everywhere.

One PITA is access to the front shaft zirks. You may want to take off the front underbody shield to get better access. Safety glassess and other precautions of course are essential.

Once this has been done properly, your issue should be fixed. If not, then looking at other components is in order. The rear suspension bushings would be good place to start.

Good Luck!

v12mac

Thanks! I am going to print this out and head under there with my grease gun.

v12mac

I found and hit all 6. They look like no one has greased them in many years.

I thought I had it on my last test run until I parked on the drive way (up slight hill) and the noise came back. It is coming from the rear. So I went back and Hit the slip yoke fitting with another 5 pumps. The thing is that I didn't see any grease on the drive shaft where it slips back in to the other part. (Still very dry) Should I keep hitting that fitting till some seeps out?

Mac

vcheng

Assuming that a lack of lubrication over the long term has not damaged the prop shafts, I'd add more grease, no more than three pumps at a time until grease oozes out or until the yoke is forced to slide due to overfill and then relieve the pressure by removing the zirk and puting the truck suspension in low, and then see if the noise goes away.

The fact that the greasing the shaft zirks has made a difference, albeit temporarily, is a hint that this indeed is the right track for troubleshooting.

Also, clean off the sliding portion of any loose rust or other build up and spray some WD-40 to help the seal.

v12mac

Will do, thanks again for the info.

Just a thought is there any down side to pulling the drive shaft and running the susp just to be sure that is the problem?

vcheng

Other than the hassle, no that is actually a good idea if you want to go that route. However, just be careful with proper scratch marks so that you can put the shaft back in the same location rotationally speaking, thereby avoiding any problems with balance.

Also, when you have the shafts off, check all joints including the U-joints for any damage, binding or execessive play.

Whatever you do, play it SAFE!