100 Series clunk and vibration thread

Joined
Mar 6, 2018
Messages
2
Location
South Africa
Hi Guys, I would greatly appreciate some advice on two topics. My 100 series cruiser randomly clunks when moving the gear sellector from Park to drive and also moving from drive to reverse when stationary of course. On the start of one trip this could happen and on the next slightly or even very little. Secondly when I drive and take my foot of the accelerator and then apply power again the car starts to vibrate randomly, if I then take my foot of the accelerator and apply power again there is no vibration. Has anybody experienced this and what is the econimcal remedy?

Cheers NicSA
 
Joined
Mar 6, 2018
Messages
2
Location
South Africa
I have twisted and yanked the driveshaft, there is no play on the u joints so not sure about the clunk coming from there. Could be dry though...will check thanks
 
Joined
Feb 24, 2007
Messages
99
I have twisted and yanked the driveshaft, there is no play on the u joints so not sure about the clunk coming from there. Could be dry though...will check thanks
It really doesn’t take much to generate a vibration on the drive shafts. In an old Land Rover what felt like no play or a simple click when I twisted it was a significant vibration at 35mph.

I have the same clunk when engaging drive/reverse nothing major so I would be interested in there is consensus on that. No vibration or clunk while driving.
 

DirtDawg

"It'd be alot cooler if you did"
Joined
Jun 28, 2013
Messages
1,913
Location
Denver, Colorado
I would check:

-cv axles to hub flange wear
-front differential mount bushings
-rear control arm bushings

Any of those can simulate a clunk when changing gear directions. There is clearly play in the system somewhere there shouldn’t be.
 
Joined
Jan 22, 2010
Messages
246
Location
Spring Hill, TN
I have the same sound on my 100 when I go from reverse to drive. If I go from reverse, to neutral, wait a second, then to drive I don't hear the clunk. It only seems to happen when I go directly from reverse to drive. Any other ideas? I had this happen in my 80 and it was the front pinion that needed replacing.

UPDATE:
Seems to be really good info over in the "official clunk/thunk" thread - will study that and start with over greasing my driveshafts.
 
Last edited:
Joined
Dec 13, 2014
Messages
135
Location
Camryland, KY
I have the clunk/thunk when I put some power on after coasting. I found the thread here- it was pretty useful.

Many oil change places will chassis lube (including the driveshaft u-joints) for nothing extra, but you have to tell them... and tell them the grease to be used and to pump that in until it starts oozing out.

With so many "lifetime lubed" parts in vehicles today, any sort of chassis greasing is usually forgotten.
 
Joined
Jun 23, 2016
Messages
2,546
Location
Wyoming MI
Grease. Grease. Grease. Grease the driveshaft, u-joints, slip yokes...the mid skid plate and hot exhaust make it hard to grease the front u-joint and slip yoke, most quick lubes and even the dealer oil change people are not going to grease those for those reasons.

So, YOU must grease those.

Quick story, last year I went 10,000 miles on a single oil change, around 8,000 miles I developed a slight clunk in the driveline.
I use a heavy duty full synthetic grease.
Change the oil at 10k, greased everything of course, clunk went away.
I have since gone back to 5,000 mile oil changes, I grease everything and no more clunks...ever.
 
Joined
Dec 13, 2014
Messages
135
Location
Camryland, KY
Took it in this afternoon for an oil change and a coolant flush at my local Valvoline. They greased the u-joints, but said they could only find 6 fittings instead of 8, only 2 fittings on the front shaft. So, I expect I will go investigate.

However many there are, the truck is much smoother now. I'm feeling better.

They did find that a family of mice had made a home in the cold air intake, and my battery was below par (both from probably not driving it much).

I have to give them credit though. They spent some time doing it, and even removed a skid plate. I'm glad they loosened those fasteners for me :)
 
Joined
Dec 13, 2014
Messages
135
Location
Camryland, KY
Cool! They did say they greased 6 fittings, so I guess they got them all. I think I'll save them from having to grease the '69 GMC. You should see how much there is on it!
 
Top Bottom