I have been to 3 places and have gotten 3 responses. I have a 85 bronco C6 and NP208 case. I get the Cha-*****/Clunk when going from Reverse to Drive and Back again. The sound comes from under the center cabinet between the seats and under the driver seat.
1 place said, U-Joints, all three replace
2 place said, Drive Chain in Transfer case needs replacment
3 place said, Tranny Rubber Mount on brace bar, need new one.

This is what I know, Transfer case is full and good, Ujoints on the double Cardan not making noise when I twisted the shaft. Rubber is pretty chewed up and weathered for tranny mount.

351/C6 has a lot of torque when you shift, could a bad tranny mount cause this kind of backlash? What would you experienced guys do?

Tim

 

I don't know about causing a clunking noise but, a bad tranny mount can cause a bad vibration at speeds of 30 or more. It causes the driveline to change its angles. Hope others can help with the clunking noise, Good Luck,

Rick
86 302 EFI, bored 60 over, AOD,
Headman Headers, Flowmaster 40 series,
2 inch dual exhaust, MSD ignition

 

Ah Yes, The infamous ford clunk in the driveline.
Take the rear driveshaft off and put some high temp wheel bearing greas inside the driveshaft splines.
This quiets the driveline and doesn't do any harm.
No More CLUNK.


[font color=red]Dennis

Calgary,Alberta,Canada[/font]


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[font color=blue]78 F-150 429CJ,Silver,Explorer Pkg.
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[updated:LAST EDITED ON 14-Jun-02 AT 12:18 PM (EST)]I had the same thing happening in my '97 Tahoe when I had it, and it ended up being the U-Joints. I replaced them and the clunk was gone. I'm not saying that is what is wrong on yours, but you may want to double check them!

 

I'd 1) remove the d/s from the truck and carefully check all u-joints, can be near impossible to detect play in the double cardan while it's on the truck, even if in neutral. 2) replace the tranny mount 'cause it's cheap and easy to do and looks worn according to your description, 3) hope the t-case is not the problem.

 

Thanks for all your help and suggestions. It seems for the moment to be the worst of all 3. My transfer Case Chain is slipping. Tranny place said they would drop it and fix it for about $410. Lets hope nothing else is screwed up inside it. 4x4 works great and clunk goes away when its engaged. Ujoints were tight to satisfy mechanics so at least the place was honest about not needing them. Sound is surely resonating from T-Case. I let you know what I find out.

Tim