What's new
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.

Np205 help

C

cadyed

Registered Member
 Premium
Joined
Mar 6, 2025
Posts
6
Reaction score
1
Location
L.h.c.
Just did some mods on t case and have a whining noise on deceleration or coasting at speeds above 40 mph what might cause?
Transfer case info: Figure 8 205 twin stick and large input bearing install behind 480le
 
Case touching the body or frame member not isolated by a bushing ? . . . Also longer driveline and shorter driveshaft the angles will play and make noise .

Whats the specs on your build ?
 
In addition to everything already asked please tell us what ALL mods were made so that we can get a better picture of your situation and condition ?
 
So no I did not run before. I tore down and had machined for larger input bearing and twin sticks installed.
Bearings replaced. The idler shaft had lots of shims. . I'm assuming this is were the noise is.
Definitely not touching floor or anything simple. Drive shafts not long or short, angles are good on joints. Checked those first. it's inside case gear noise if I'm accelerating it goes away and deceleration it comes back
 
My doubler has done the same since I built it. I’ve replaced bearings and done visual internal inspections to no improvement. My sounds like a rattle, as in a gear loose on a shaft type.
 
Multiple shims on the idler shaft is normal for providing proper preload for the two opposing tapered roller bearings that support the idler gear - how many were on your case originally and how many were needed with the new bearings?

When you say that the rear driveshaft angles are good what angles were they and how long is the whole assembly ?
 
to many shims lets the bearings stay loose and gear walk front to back . should be set to zero play up/down in case . first thing to do in the build up .

i had this problem way back not knowing better and had to tear it down and set the lash / preload . took a lot of noise out .
 
When i originally striped it down, the idler shaft had shims on top of bearing and on both sides of spacer. Which was not how manuals illustrated. Otherwise it would have went back how I had found it. So it definitely sounds like its coming out to correct the issue.
 
Yeah that’s definitely not how the shims are intended to go.

Question though - earlier you stated that the bearings were replaced already; was the shim issue delt with at that time and what was the run out on the idler gear at that point ?
 
The reason several of us have asked about the driveline angles is that MANY folks with K5’s have spent a lot of time effort and money chasing other potential possibilities trying to find what they believe is a wine or chatter just as you are describing - the fact that it only occurs at speed and on deceleration is a dead giveaway.

All the internal bearing and shim issues are important but do not dismiss the shaft/joint angles just yet.

Please give us a better picture of what you have as running gear:

What transmission and are you running a range box - and if so what kind ?

Is your 205 a bolt on rear yoke or a slip yoke design ?

How much lift is on this K5 and is the rear all spring, shackle flip, blocks , etc ?

What are the angles of each joint ?

Is there a CV at the case end ?

We can help but we need answers each of these questions - if you don’t know the answers please take pictures and we will go from there.
 
Last edited:
86 k5 ls swap 4l80 2wheel long output cut adapted to figure 8 205 bolted yoke shackle flipped lift no clue no front drive line while diagnosing. 39.5 " drive shaft 3° down at output and 5°up at pinion. Not perfect but good. The noise sounds just like sweetk30's opinion (backlash)very similar to a improperly set rear end. Not also the part i second guessed myself on putting 1 more shim or not and I was to impatient to get good dail gauge set up for accurate reading. Ill link up with wes for a second opinion
 
all that info and NO C/V shaft on rear ...... that sure dont help .

i did a k5 build with a nv4500/205 and 5-6" lift and did a c/v shaft in the rear and dialed in the pinion angle for it and 75mph highay smooth as silk . . took customer for drive and hit 90mph on 37" tires and he said slow down but no vibes . . .

i think you have both problems . shaft angle and lack of C/V on rear for blazer and idler gear to much slack .
 
I might have shaft angle problems. i understand I'm at the edge of needeing a cardon joint but definitely feel the transfer case issue is my pressing issue with summer heat on its way for me. Shaft angle is a quick fix with a call to Tom woods and maybe burning new perchs.
 
It would appear that upon deceleration your pinion angle is even greater with dynamics and no doubt a CV and perch adjustment are in your future - don’t let this go too long as it will kill bearings in the T-case and diff eventually as it’s bad for everything involved.

Keep in mind that it’s not the number of shims that’s important for the idler but the thickness of what’s needed for proper preload.

Hope meeting up with Wes works out good for ya ( good guy ! ) and y’all knock out the possible T-case adjustments so you can move onto towards addressing the rear driveline angle issue.
 
cadyed said:
I might have shaft angle problems. i understand I'm at the edge of needeing a cardon joint but definitely feel the transfer case issue is my pressing issue with summer heat on its way for me. Shaft angle is a quick fix with a call to Tom woods and maybe burning new perchs.
Click to expand...
Look up ford front shaft f250-f550 front shaft swap . Thats what i used and a lot cheeper than others .
 
You must log in or register to reply here.

Latest Posts

Top Bottom