Driveline noises

Hello anyone have any ideas at all on this?

92 S83P. 43thousand km. Drove it for 4 thousand km and it was fine.

- I put a 2 inch lift on it made noises when you were driving 60 km hours. Sounded like front CVs. So

- I dropped the front diff 2 inches with square tubing. The noises were not as bad. But at 60 km/h when you let off it made really bad noises the same. While the driveline was under load it was fine, driveline not under load noisey. So I am thinking U joints.

- I replaced the back 2 even tho they seemed fine. Thought they could be dry no grease zerks. Noise was not as bad but still there after replacing the back. Was feaking terrible before.

- I check the front driveline and notice the front driveline is being driven at all times and the diff locks up with vaccumm when 4 wd is engages. The front U joints were hooped both. The front pinion u joint was worse. I replaced both. And it is not as bad after but now from 80 km/hour or faster if I let off the gas it makes the same kind of bearing noise in 4th or 5th, but not all the time. Put my foot on the clutch and it goes away.

-My fears are tranny, or differential bearings.

What do you guys think???

 

Yup your front drive shaft is what is making the noise. Your back vac pot must not be moving. When I was playing with my 4x4 trying to fix it. I unplugged my front pot. And hit the 4x4 and yes when the front drive shaft free spins you will hear it. You will have 2 little 6” vac lines on your back pot most likely one of them has a hair line crack.

 

That is awesome to hear that will be a easy fix. I was thinking bearing in the transfercase/tranny. Thank you very much.

 

let me know if it works out.

 

I may be wrong but from my experience that sounds like worn teeth in your differential. Ujoints clunk ,bearings and gear teeth whine. Possible as Starpuss said its a partially engaged front axle

 

i've been through a lot of drive train vibes and noises. it's usually easiest to eliminate sources.

pull the front drive shaft (as long as it has a fixed yoke) to eliminate the u-joint noises. if it continues then pull each c/v axle, left first, then right (or the other way around, just not both at once).

just because the noise goes away with a c/v axle pulled doesn't mean it was the c/v... i could be the diff still. you have to pull them each at a time, then both at once.

if it goes away with only the left (or right) but not the right (or left) then i would say it's a damaged c/v joint. if it goes away with either axle pulled or both pulled i would say it's the R&P

 

Thanks for your replies guys.

I think the problem is the actuator on the transfercase is hooped.

1) The lift made the bad u-joints sound worse (Problem fixed new U joints) And with new u-joints the sound is not that bad, but still troubles me.

2) The front axle is disengaging & ingaging

3) The transfercase is not disengaging and at 80-110 km/hour (when I let off it is the only time it makes the noise, but not as bad or at all with a second 200lb passenger, possibly closer to the way the driveline angle was before the lift?)in a small truck with the front driveshaft spinning at that speed it would be about the same as putting a full size truck in 4wd with hubs or front differential unlocked and driving 140-160 km/hour I am thinking. Not something they were meant to do.
I replaced the vac lines on the transfercase and it has not made any difference front driveshaft does not disengage, the front axle still does. And I believe from what I have read from Greg & StarrPuss the transfercase should disengage the front driveshaft.

However I have been wrong before haha. I will let you know what I find out, and drive it slowly until then.

Or maybe the driveline is out of ballance and I screwed it up when I changed ujoints? I took care as to not let this happen I don't believe it is the case.

 

I may be wrong again (it's been known to happen ) But the transfer case does not disengage the front driveshaft..these are very basic vehicles and as far as I can tell only the front diff engages or disengages .Mine is the same as yours always spinning front shaft. The transfer case is only for low/nuetral/high range..Hope I'm right or something is knackered in mine too

 

Grrrrr now I gotta start checking mine..never noticed the actuator on the transfer case

 

Colour me corrected my front driveshaft rotates only in 4wd (helps if you dont have it in low range which automatically turns on 4wd when you check) I sometimes wonder how I manage to feed myself

 

Ah stuff happens part of the learning experience. I could be wrong but the first time you pull your CVs and put the wheels on the ground you have destroyed your wheel bearings I have a brother that was through that once with a VW (he rolled it on and off a dolley with no CVs.

My driveshaft does turn in 2wd. But when I stopped and put my finger on the driveshaft and drove in 1st or reverse with the passenger seat up I could hold the driveshaft from turning(I DID NOT PUT MY FINGERS NEAR THE UJOINT). Not something totally out to lunch but other peoples driveshafts are completly stopped while in 2wd. Is my vac actuator not completly disengaging?

 

i say take a rope. or some thing rope up your driveshaft and take it for a spin and see if there is a noise?

 

I am not that crazy lol. I would have to be going over 80km/hour and then let off before it makes the noise and with a rope on the driveline, well you get the picture. You cannot disconnect the driveshafts and drive it becase the output shaft spline in the transfercase prevents all the oil from coming out.

I have a email into a guy in Texas "Mini Truck Supply" and I will see what he can think of.

Maybe with a 2 inch lift, and dropping the front differential 2 inches with square tubing to help out the CVs @ over 80 km/hour you get nasty noises?

Or maybe it is something to do with the front drive shaft spinning where other peoples are completely still in 2wd? or???????????

 

Starrpuss I will think about that. op:

 

I figured out what the problem is. After changing a few of the vac lines on the transfer case and the front differential that made no difference. (ran out of vaccumm line the little town I am living in at the time has some on back order)

I switched the vaccumm lines on the differential actuator. Flipped it into 4 wd then back to 2wd, and then flipped the vaccuum lines on the differential back to where they should be. Now when you drive in 2wd the front driveshaft still turns but barely at all, not even close to the speed of the rear diff. So I am thinking the elcectronic valve that switches the vaccumm actuator to unlock the front diff is faulty. Looked like there was 4 of them they are just to the right of the shifter underneath the seat. I am guessing 2 do the front axle in and out & 2 do the transfercase in & out?

110 km/hour plus and there is no noise.

 

Bang on.

Thanks for your help everyone. Hopefully things are ok from here on and I have not hooped my front differential too badly. I will order up the electrical switch thingy tomorrow.

 

Dropped the back of the transmission 1/2 inch fixxed it.

My 2 cents if you want to wreck your truck lift it.

I dropped the back of the transmission 1/2 inch with 2x 1/4 inch steel plates on both sides that fixed it.

Big difference if you are going to drive it offroad fine at slow speeds. But this truck does both, majority onroad.

Hopefully everything works good from here on.

The fact that the differential pinwheels alittle is not a big deal. I replaced the majority of the vac lines on the truck, and all the vac lines on the 4wd system.

The readings were 14 mmHg on a vaccumm gauge on the transfercase & differential ingaging and disengaging. Everything consistant and good.

I spoke to a friend that is a dodge mechanic and has lots of problems with lifted trucks. First thing he said was drop the back of the engine to lessen the driveline angle.

 

What was the u joint number that you used?