Clunks in 4x4 while driving
 

I have a 2006 Ford Ranger Sport 4.0L 4x4 5-spd, it has 93000kms. It has the electric shift transfer case. When driving at speed (50+ km/h) in 4x4 (both while accelerating and cruising), in good or medium traction situations, there is a kind of clunk that occurs. It feels kinda like a very small surge of power, or clunking in and out of gear in the transfer case, it doesn't really make a noise, but feels like hitting a small pothole. The transfer case seems to work fine with no noises when in very bad traction (6" or more snow) or sheer ice. I am not sure what the issue could be, but it seems like it has to be transfer case or front end as there is no noise when in 2 wheel drive.

When i first bought the truck (a month ago) it had really worn down back tires, and at first i though the issue was different sized front and back tires (due to excessive wear) putting added stress on the 4x4 system, but a week ago i replaced them with new tires and rims (Dick Cepek DC-2's and Goodyear Wrangler Duratracs), and it made no difference with the symptoms.

Any ideas or suggestions would be greatly appreciated!

Re: Clunks in 4x4 while driving
 

4x4 is not meant to be used on certain surfaces like tarred roads. You'll get hopping and clunking if you drive on surfaces like tarred roads and other hard/firm surfaces in 4x4. It works in the snow cause that is a surface meant for 4x4 use. Also make sure with 4x4 that the truck has the same size tires all round.

Re: Clunks in 4x4 while driving
 

Yeah, i dont use 4x4 on pavement (unless ice or snow present), but the situation i notice this the most in is gravel roads with patches of ice (even completely snow covered surfaces it happens. As far as i know, gravel has bad enough traction that it wont cause issues using 4x4, but even driving on ice i get these symtoms. I used to have a 2002 Ford Ranger 4x4, and it never did this on any surface. And yes, all four tires are identical (31/10.5/15's with ~10000kms)

Re: Clunks in 4x4 while driving
 

you earlier said this was happening in good or medium traction situations but was fine on bad traction areas like ice or 6" of snow. Hard packed gravel can be as bad as driving w/4x4 on tar if the gravel is hard packed enough. Why are you using 4x4 on a gravel road?

Re: Clunks in 4x4 while driving
 

Does the clunk happen when turning or driving straight or both? Sounds like you know how to use a 4x4 truck so driving conditions dont sound like an issue. Have you inspected teh front driveshaft and CV axles for play in the joints?

Re: Clunks in 4x4 while driving
 

Correction: when i say good conditions i mean good as in 4x4 isnt needed, but it helps to keep the back end from fish-tailing (ie: loose gravel, wet gravel, slush etc). I dont use the 4x4 unless it will help with driving and keeping control of the vehicle. This is my second ranger, so i have a pretty good idea of what conditions are needed to make the tires skip when in 4x4. The symptoms occur in semi slippery conditions, where a 2WD would have no problem getting through, it gives no issues when the 4x4 is needed (lots of snow or mud).

I have only noticed it while in a straight line, i have not noticed it while turning. It is sometime tough to tell when it is doing it, as it feels so similar to a small bump in the road, but it becomes obvious when driving on a smooth icy road, or smooth wet gravel. I have only had the truck for a month, and i have only been using the 4x4 for the last week since it started snowing/raining. I havent checked the CV joints yet, but i will do that when i have a free minute.

Re: Clunks in 4x4 while driving
 

Sorry for the double post, but i was just thinking that if it was a CV joint or the front drive shaft, that i would get the symtoms when in heavy snow or mud. This is where i am kind of at a loss as to what could be causing the problem... unless it is in the transfer case itself. Hopefully its a cheap fix whatever it is.

I checked the CV joints on the front end, and the universal joints on the front driveshaft, and they are all good, no play and no tears in the boots. Kinda looking like its a transfer case issue... Any thoughts?

Re: Clunks in 4x4 while driving
 

Any Suggestions?

Re: Clunks in 4x4 while driving
 

I got the same problem with my 06 fx4 lvl2...its like its slipping in and out of fwd....hope someone can help us out with this issue

Re: Clunks in 4x4 while driving
 

Hey gibby, same problem here. 07 level II with 110,000km. Have you figured anything out? I read on another forum that it could be the slip yoke needs greasing but I have no idea if that will solve it. I'm just going to keep running in 2wd until I can get mine to a shop. Ujoints and CV's are fine on mine as well but I do have about an inch of play in my front driveshaft, is that normal?

I have not for sure figured out what the problem is, I also saw the site that said the slip yoke, but I don't understand how that could be the problem because it should act up in 2wd also if that's the issue.
One inch of play seems like quite a bit, that could cause some issues, mine is tight, no more than an 1/8th of an inch of play. I do have some ideas, I just don't have the money to work on it right now, I found a website that has a few suggestions that could cause the problem, I don't have the link on me, but I will post it in a bit. According to the website (it was one of those that you pay for an expert to answer your question), it says there is a spring inside the transfer case that keeps the transfer case in gear, and it suggests that it could be broken.
I haven't figured out what the issue is yet, but I sure cant find anything wrong external, so I figure it has to be internal to the transfer case.

Re: Clunks in 4x4 while driving
 

Thanks man. Have you had any problems just driving it in 2wd?

Re: Clunks in 4x4 while driving
 

No, i have no issues in 2wd, it only seems to be in 4hi, i have tried a couple times and cant make it happen in 4low. Here is the the link i was talking about before:
http://www.justanswer.com/ford/6zd3s...-4wd-just.html

My truck also made the noise for a while but then I noticed that there is a bracket on the backside of the front differential housing that the bolts felt tight but allowed the diff to jump up when underload.
So I took a big ratchet and tightened the bolts real good and tight and the noise stopped, so it might be worth it to check those bolts.

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