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Noise when decelerating

K5-CJ5

K5-CJ5

1/2 ton status
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I was driving my 84 k30 today and noticed, when radio off, a rotational noise when I let up off the gas. As soon as I barely touch the gas it goes away. Im not getting any vibration etc just a minimal growl. This is the first 205 I have had with an auto and never noticed any noise on my sm465 np205 setup on the blazer, but the sm465 is already louder.

My setup that is making noise is a th400/np205 combo. It sounds as if coming form the t-case area. The u joints, pinion etc feel good. The carrier seems ok. Any thoughts? Does the np205 always have a low growl (not loud just noticeable) similiar to a throwout bearing.
 
I have a similar noise in my K5. Mine isn't the transfer case though and wasn't shocked when I first heard the growl either. Mine is caused by too much angle at the slip yoke of my driveline. I have 11" of lift on my K5, and being cheap I decided against a CV shaft :doah:. It only growls/vibrates at a certain MPH when I let off the gas as well (around 40-45 MPH) and goes away as soon as I apply throttle. I know there is a number of variables when it comes to these trucks as far as tranny/t-case setup, lift, wheelbase, etc. Just thought I would share as to what mine is caused by, maybe something you could look into on your truck as well. :waytogo:
 
I have a TH350 / NP205 combo with 6in lift. Just fought the same issue. Do you have the Tcase drop kit? I put on new spacers from Tuff country ( slightly longer) and it seems to fix my issue.
Also check your shift linkage …. Make sure it tight. I put a new spacer in the linkage where if bolts to the case.

side note - could also be the rear end making the noise…
 
The truck doesn't have a lift to tcase/driveline angles are not the issue. Ive checked the rear end and the noise is def. coming from the tcase/carrier bearing area. Carrier bearing appears to be ok. No vibration at all.
 
K5-CJ5 said:
The truck doesn't have a lift to tcase/driveline angles are not the issue. Ive checked the rear end and the noise is def. coming from the tcase/carrier bearing area. Carrier bearing appears to be ok. No vibration at all.
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Did you check the fluid level in the 205?
It could also be the Ujoint on the rear output on the tcase.
 
I just dealt with this on my blazer TH400/205 and found the bolt holding the shifter was loose into the TC. Pulled the trans hump and removed it and cleaned it up added one extra washer and tightened it up that stopped the noise for me.
 
After riding int he back of the truck while my wife was driving, I found the noise coming form the carrier bearing, and the u joints have a little play. Pinion is tight so carrier and u joints are in my future!
 
K5-CJ5 said:
I know but I had to figure out the noise:woot: No shes a great driver.:waytogo:
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hahaha always use the seatbelt!!!:waytogo:
I found a similar noise under my truck but havent really found out what causes it, i jacked it up the other day and had my dad give it gas i was under it with a hose trying to find the damn noise and nothing.... so i thought it was noise from the tires/what ever coming in to the cab cause i have a cage done... if you find the issue pleasse let us know.
 
bot0611 said:
hahaha always use the seatbelt!!!:waytogo:
I found a similar noise under my truck but havent really found out what causes it, i jacked it up the other day and had my dad give it gas i was under it with a hose trying to find the damn noise and nothing.... so i thought it was noise from the tires/what ever coming in to the cab cause i have a cage done... if you find the issue pleasse let us know.
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Im going to replace the carrier bearing in the next couple days and Ill let you know if it was the problem (I suspect it is)
 
Yup! Carrier bearing replaced and noise is gone! Much smoother now without the slight vibration also!
 
You only have have a carrier bearing with the long wheelbase vehicles. For a 2-piece driveshaft, the carrier bearing is what holds the front section of the driveshaft up.
 
I was going to say it was due to a lift also, but guess not. I'm glad you got yours fixed.

I have a similar noise on my K5. 700r4, np208 just cleaned up and installed and in great shape, 10b rebuilt. We dropped the tcase an inch, by putting the spacers between the frame and cross member instead of below the cross member. Today we added some 2.5 degree shims to the rear. I have 6" lift blocks that the previous owner installed. I haven't had a chance to take it on the freeway yet to check the noise issue. A local shop quoted me $650 for a CV drive shaft that would work with my 208. I could still try some bigger shims if need be, to adjust the angle.

Any opinions in my case?
 
CGT80 said:
I was going to say it was due to a lift also, but guess not. I'm glad you got yours fixed.

I have a similar noise on my K5. 700r4, np208 just cleaned up and installed and in great shape, 10b rebuilt. We dropped the tcase an inch, by putting the spacers between the frame and cross member instead of below the cross member. Today we added some 2.5 degree shims to the rear. I have 6" lift blocks that the previous owner installed. I haven't had a chance to take it on the freeway yet to check the noise issue. A local shop quoted me $650 for a CV drive shaft that would work with my 208. I could still try some bigger shims if need be, to adjust the angle.

Any opinions in my case?
Click to expand...

If your getting vibration definitely go with a cv shaft and proper rear end shims. I would do that and remove the tcase drop spacers.
 
I test drove my K5 with the 2.5 degree shims. It seemed to help but there is still some noise/slop in the drive shaft. My mechanic (at my uncle's shop) says the U joints are good. He held the brake and applied the throttle in gear, and you can see the drive shaft flex. We suspect it is just from the amount of angle with the 6" lift.

I am going to swap out the shims for something more like a 7 degree, and see what happens. I don't have the extra money for a cv drive shaft right now. If the shims don't work, I'll save up for the drive shaft. My K5 may become my daily driver, so I need it to be comfortable, reliable, and somewhat quiet.
 
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