Driveline clunk
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New User
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Driveline clunk
Fellas,
The other day my 78 F-150 4x4 started clunking when I would take off from a stop. It felt like one or more universal joints were starting to let go. So, I replaced all three in the rear drive shaft and it is still doing the same thing. It is definitely a slip and clunk type feeling, so it probably is not a bushing or anything (they are all new anyways). Therefore the only other things it could be are the clutch, NP435, NP205, or the differential. The tranny and transfer case have been rebuilt within the past 5 years and they are pretty stout. Any thoughts? Thanks.
The other day my 78 F-150 4x4 started clunking when I would take off from a stop. It felt like one or more universal joints were starting to let go. So, I replaced all three in the rear drive shaft and it is still doing the same thing. It is definitely a slip and clunk type feeling, so it probably is not a bushing or anything (they are all new anyways). Therefore the only other things it could be are the clutch, NP435, NP205, or the differential. The tranny and transfer case have been rebuilt within the past 5 years and they are pretty stout. Any thoughts? Thanks.
Senior User
Joined: Mar 2002
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From: detroit, michigan
Driveline clunk
where is the sound coming from the back of truck or the middle of truck if it's the back of truck you might want to check ring and pinion and spider gears in the carrier if it's the middle it could be as simple as a trans mount does the clutch seem fine when you take off (no slipping)was the clutch replaced when trans and transfer case was rebuilt hope this helps
Junior User
Joined: Jan 2003
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Driveline clunk
my two wheel drive does the same thing. the mechanic told me it was slack in the rear end. i've got a 9" rear end and haven't taken the time to look into what might need fixing.
it is aggravating to hear that clunk whenever i let off the brake and start off.
it is aggravating to hear that clunk whenever i let off the brake and start off.
Posting Guru
Joined: Aug 2000
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Driveline clunk
It might also be the slip-yoke on the driveshaft. When they bind, they make a clunk that can be felt, and sounds like what you describe. Try a Teflon based grease in the slip-yoke housing, and see if that helps.
Elder User
Joined: Apr 2003
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From: Cheney, Wa
Driveline clunk
i have that same thing with my front drive line, what it is is in the double cardan joint by the t case there is a spring block that holds the wrist tight, if its worn out it will let the wrist wobble which causes the clunking, it a 50 buck part that wears out as often as the ujoints and should be changed with ujoints aswell according to my napa guy. what you can do is roll under there and see if the wrist wobbles....if it does its probably that part.
btw i don't know the official name but there are 3 parts to the joint the "h block" which is the big peice that holds both crosses and then the crosses and the other spring block thing....forgot what he called it. but thats the part.
btw i don't know the official name but there are 3 parts to the joint the "h block" which is the big peice that holds both crosses and then the crosses and the other spring block thing....forgot what he called it. but thats the part.
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Joined: Feb 2003
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From: Boise, ID
Driveline clunk
I see lots of good ideas for things to check so far.
I'll add another. Are the U bolts for the rear diff tight?
I'll add another. Are the U bolts for the rear diff tight?
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New User
Joined: Jan 2008
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Driveline clunk
Moneranger has the best idea.
I have been putting Hightemp wheel bearing grease for 20 years to get rid of this problem.
I put the grease in every 4 years.
I have been putting Hightemp wheel bearing grease for 20 years to get rid of this problem.
I put the grease in every 4 years.
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Driveline clunk
Dennis, I read a post a while back that you mentioned this "fix," but are you referring to the slip yokes on the two-piece drive shafts? I'm really hesitant to throw a gob of grease in the slip yoke on my single piece drive shaft (where it connects to the output shaft). Would the grease make it's way inside the tranny? I have the same problem with the clunking, and have suspected the third member as a tech told me the shims for the pinion bearing tend to disintegrate over time - but I know nothing about third members...
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Driveline clunk
Fellas,
I have personally restored this vehicle and I have already verified that the bushings, suspension, et al are all within spec. When I grab the driveshaft, it seems to turn quite a bit and I am suspecting that it is in the third member. A long while back, the carrier bearings went, but those where the originals. Not to say that they couldn't have gone again, but that is where I am leaning towards. If it where the motor, tranny, or transfer mounts, I would get vibration at speed, but this is not the case. Right now I plan to run it until it breaks. Also, it does it if you let off of the gas and then get back on it from a roll. It definitely feels like it would be the u-joints, but I just replaced them. So, that's where we stand today.
I have personally restored this vehicle and I have already verified that the bushings, suspension, et al are all within spec. When I grab the driveshaft, it seems to turn quite a bit and I am suspecting that it is in the third member. A long while back, the carrier bearings went, but those where the originals. Not to say that they couldn't have gone again, but that is where I am leaning towards. If it where the motor, tranny, or transfer mounts, I would get vibration at speed, but this is not the case. Right now I plan to run it until it breaks. Also, it does it if you let off of the gas and then get back on it from a roll. It definitely feels like it would be the u-joints, but I just replaced them. So, that's where we stand today.
Elder User
Joined: Apr 2003
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From: Cheney, Wa
Driveline clunk
you have to replace the spring thing in the double cardan joint too.....when you gas it, it clunks right...but then when you are just coasting it isn't as bad? if so samething i had and i just took it into the shop...they have to use the press to get the ujoints out..i don't have one so i was out 30 bucks for labor..and another fifty for the part
this guy posted a very similiar problem https://www.ford-trucks.com/dcforum/bigbronco/1828.html
check it out see if it helps.
but you should let us know what it is when you finally figure it out
this guy posted a very similiar problem https://www.ford-trucks.com/dcforum/bigbronco/1828.html
check it out see if it helps.
but you should let us know what it is when you finally figure it out
Last edited by superswamper; Apr 9, 2003 at 12:21 PM.
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Driveline clunk
It is more than just a clunk. I know what you are talking about in terms of the set-up for the double carden. All is well with this piece. I can feel an actual slip in the drive train, as if something is slipping into place. I am going to set the park brake and from a little distance, have my wife let the clutch out while in gear and see if I can see where it is coming from. If the shaft tightens and then I see a shudder at the differential yoke, then I think it will be solved. If not, then more digging.
Elder User
Joined: Dec 2002
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From: Quaker Hill ,CT U.S.A.
Driveline clunk
I had a np435-4 speed loosen up from where it bolts to the bell housing and it did just what yours is doing you might want to check those bolts, and everything that bolts the engine to the tranny tranny to the truck . Look at the motor mounts ,,just give it a good lookover. Move things around, shake things, gently pry on things (mounts) with a pry bar!
let us know what you find
let us know what you find
Lead Driver
Joined: Oct 1999
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From: Kalispell, MT
Driveline clunk
If you're sure it's in the rear end, here's another possibility. My 86 150 4x4 with a ltd slip carrier destroyed axle/side gear splines. Twice. This was in a 9" rear. With both incidents I got slop back there before it let go.
When it let go the second time I swapped in a standard carrier. I miss the locker, but its not as hard on axle splines.
When it let go the second time I swapped in a standard carrier. I miss the locker, but its not as hard on axle splines.
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Driveline clunk
quote:
Dennis, I read a post a while back that you mentioned this "fix," but are you referring to the slip yokes on the two-piece drive shafts.
Actually Tet,not even a hand full placed inside the receiver part of tbe drive shaft that slides onto the splines coming out of the tranny.It doesn't seem to even come out of the end never mind going into the trans seal.
Just enough to take the clunk out.
Dennis, I read a post a while back that you mentioned this "fix," but are you referring to the slip yokes on the two-piece drive shafts.
Actually Tet,not even a hand full placed inside the receiver part of tbe drive shaft that slides onto the splines coming out of the tranny.It doesn't seem to even come out of the end never mind going into the trans seal.
Just enough to take the clunk out.