Can you find the vibration???

[Gmelahn]

I would like to start off saying that this is my first post on this forum but I have been here for a few months now. What a great site!!!

I have a 1972 K10 new motor(stock w/ rv cam), a 4" Rancho lift, rebuilt posi 3.73, turbo 350, np203. Truck sat for a while(was my dads) but has a rebuilt transmission. I also just had the driveline straightened and balanced, the rear-end rebuilt, the transfer case had the coupler and transfer case spline replaced and new tires 33x12.5x15 with less than 200 miles.

Problem:

I get a bad vibration at freeway speeds, the vibration is constant but is strong for a few seconds then it gets lighter. The vibration has a consistent tempo that lasts until I am under about 45-50 mph. There is also noticeable vibration(while not as strong) under some accelerations. Also when I let off the gas and then reapply the gas quickly there is a noticeable clunking coming from the transfer case/transmission. I can control the clunking by feathering on and off the throttle.

The engine was just checked out by our Mechanic today and he said the vibration is not engine related. He did however recommend new transmission and transfer case mounts, which are now on order.

I have searched as many different combinations of words to try and figure out what else the vibration could be, I have had a lot of good tips but I am sick of throwing money at this problem.

What should I look for, Torque converter? Fly wheel? Wheel bearings? PLEASE HELP!!!

Thanks,

[2tons of fun]

ujoints.

who did the rear end?

new or old diff?
new or old bearings?

how much lift?
driveline angles?

[Rack Man]

My first thought was u-joints too...

[LONGHAIR]

You stated that this truck has a NP203 transfer case, it is still "full-time"? or has it been converted?

There is a chain drive that works the front drive shaft, slack there can make all kinds of noises and/or vibrations.
This could very well be your "clunking".
There is also a fairly thin stamped drive ring that can cause problems in there too.

You didn't say if you could feel this vibration through the steering, but if so....I could be front axle-joint stiffness. This is very common too. A thorough front end servicing is probably in order anyway.

[Gmelahn]

Thanks guys,

U-joints were replaced with Spicer when the driveline was straightened and balanced by a driveline shop. The driveline shop wants me to bring the truck back so they could check the driveline angles.

Bearings need to be checked..

The Transfer case is a part time transfer case....

The rear end was rebuilt by a transmission/drivetrain shop owned by my fathers buddy.... I'll have him check the rest of the transfer case as well.

The vibration is not really felt through the steering(at least not primarily).

Just had the front ball joints checked and one replaced. I guess I could check the rest of the front end.


I will be replacing the mounts today, I'll keep everyone updated thanks for your replies! I hate chasing down problems by throwing money at it. I need a mechanic that can actually diagnose problems. haha

Garrett

[Gmelahn]

So while I didn't get the opportunity to replace the mounts today, I found something else out that may be causing the problem. I was under another K10 we have and I noticed something was different, something was missing on my truck. Here is a pic, can you tell me what I'm missing?

[2tons of fun]

the unecessary portion of the cross member?

the unecessary strut bar from the tcase to the bell housing?

[Rack Man]

Torque Mount....

[Gmelahn]

winner! winner!

so now my question is.... will this cause the vibration I'm experiencing? or is the the cause of the clunking I hear?

And an even bigger question.... Where can I buy one? I have looked everywhere!!!!

Thanks guys

[2tons of fun]

no.

[Gmelahn]

Originally Posted by 2tons of fun

no.

"no" this wont cause the vibration? or "no" you don't know where to find one?

[Gmelahn]

This is what I'm looking for...

[LONGHAIR]

Though I would not call it "un-necessary", the lack of that mount will not cause your vibration.

45-50 MPH also points to wheel balance. Have you done anything about that? Try swaping them around to see if it changes anything?

[Gmelahn]

Originally Posted by LONGHAIR

Though I would not call it "un-necessary", the lack of that mount will not cause your vibration.

45-50 MPH also points to wheel balance. Have you done anything about that? Try swaping them around to see if it changes anything?

Well I was hoping that would be the problem. I had the wheel/tires mounted and balanced a month ago but I'll switch them around and see if that helps.

Also I found out its a 205 Transfer case, kinda weird though because the speedo cable is on the drivers side?????

[2tons of fun]

so which is it, a 203 or a 205, from your pic there is now way to tell.

the mount you posted is a 205 mount but you could use it on a 203.

a 203 uses a rod that mounts to the same to bolts then runs all the way up to the back of the bell housing.


and yes, no it wont make it vibrate and no i dont know where to find one.

[Gmelahn]

Originally Posted by 2tons of fun

so which is it, a 203 or a 205, from your pic there is now way to tell.

the mount you posted is a 205 mount but you could use it on a 203.

a 203 uses a rod that mounts to the same to bolts then runs all the way up to the back of the bell housing.


and yes, no it wont make it vibrate and no i dont know where to find one.

My Dad who I bought the truck from says its a 205, "all gears inside" is what he said. Funny thing.... the speedo cable is on the drivers side. I thought only the 203 had the speedo cable on the drivers side. I'll get a pic tomorrow.

I already bought a mount from one of the other members. But I still need to chase down this vibration. I work weekends but tomorrow I will rotate the tires and I have an appointment with the mechanic who worked on the trans transfer and rear end.

I'll post more when I find out what the problem is.

Thanks,

Garrett

[Gmelahn]

So the transmission/drivetrain Mechanic said it was not drivetrain related and to look at the flexplate. I also need new exhaust and he said that could be a source of the vibration because the hangers were all trash and metal on metal.

On another note I took a picture of my 205 and noticed that where the speedo cable enters the transfer case is on the wrong side. First how is this possible and second woud this cause any of my problems???

[84 400]

Don't quote me on this but I think the tail cone could be rotated?? My truck has a factory NP203 and does NOT have the tourqe arm. It looks like you definatly have a np205 tho because it has the lower drain plug which my np203 does not have.

Wish i could be more help

[Gmelahn]

Originally Posted by 84 400

Don't quote me on this but I think the tail cone could be rotated?? My truck has a factory NP203 and does NOT have the tourqe arm. It looks like you definatly have a np205 tho because it has the lower drain plug which my np203 does not have.

Wish i could be more help

It is a np205 say so on the metal 1"x2" tab. plus the mechanic said its all gears inside. Would this cause a vibration? Should I turn it around asap?

[2tons of fun]

no it wont and some of them are on the d side, not a big deal.

with a full pic now you can tell its a 205, the small round metal cover in the middle is the idler shaft retainer and is only on the 205.

you CANNOT rotate the housings because the goofy bump on the upper right side of the housing is the shifter rail cover/seal and you piss oil out.

[Gmelahn]

the transmission guy also said the transfer case should run tranny fluid?? From what I have read this is WRONG! 10w40 is what should be in there...

[2tons of fun]

or 80-90

you can run whatever you want, the atf isnt supposed to be as protective fo rthe gears but it was spec'd in dodges.

[2tons of fun]

fwiw i have always ran 80-90 + mud and water.

[Gmelahn]

Originally Posted by 2tons of fun

fwiw i have always ran 80-90 + mud and water.

haha, I think I'll change it. There is a slight noise when i let off the the throttle and then get back on it lightly, the trans guy said it normal play in the gears with big tires.

Any experience with that?

[Oilbrnr]

Has the pinion angle been ruled out yet?