new strange noise?

[rucr8z2]

Let me start by saying this noise was not there before I installed a RCD lift on my 1999 yukon 4dr.
Now the noise I'm hearing sounds like a front wheel bearing but doesn't change when turn to left or right. I jacked it up and turn both wheels and there quiet with no play. I've check all the ujoints front shaft and rear for play. There also is a (very small) vibration felt in the steering wheel and the floor board that goes with the noise(up front). Now this is a autotrac vehicle but with the RCD kit you should not need the new front shaft... The noise comes in at around 30MPH and comes and goes with throttle. All along this has been in 2wd and wasn't present until the lift was added. Sometimes its there and sometimes it takes 10 min. to appear and sometimes it comes and goes>
Do you think that a ujoint that has spent most of its time at one angle then made to be at a steeper angle could make noise or perhaps driveshaft yoke vibrating in tailshaft????

Sorry the truck is a 99 yukon 6"rcd +3"bl and 325-60-18 atzs

 

[992door]

take the front driveshaft out and drive down the road it is probably your driveshaft that would be my guess. Because even with like a 4" lift you need a new driveshaft if you have autotrac

Why do you say that with the RCD lift you dont need a new driveshaft?

 

[rucr8z2]

Well most spindle kits put the rear of the front diff at an angle to lessen the joint angle. I have installed multiple rcd and fabtech lifts on autotracs and never had a problem- This is the first one on a four door yukon. I'll try to take out the shaft tomorrow and see.

 

[992door]

It is not the angle at the front diff that is normally the issue it is where it comes out of the t-case

 

[rucr8z2]

If removing the shaft stops the noise etc... who has the better front shaft?

 

[992door]

I have always heard that you need a dual cardan front driveshaft other that than i dont know who has a better shaft

 

[rucr8z2]

I'll price out the pro comp one because its also a slip yoke eliminator.
If its required. I have pulled the front diff back out and replaced the output needle bearings and seals and pulled the screw in vent off and looked at the gears and spyders and they look fine. I bought this truck 6 months ago and never looked at the transfer case fluid, but today I looked at it and it was red dexron III and I thought autotracs take a bluish green autrac II fluid?

 

[992door]

Was that it?

 

[rucr8z2]

I haven't been able to get to it yet. By the time I finish everyone elses cars I'm tired and ready for a shower but tomorrow I'll pull it at lunch and report back latter that night. It did change pitch today when the suspension went over a big bump so I did recheck wheel bearings for the 5th time and still no play or noise????. Definitely from up front and have never heard a cv axle sound bearingish??? So I'll pull the front shaft...I'll also post some pics of my truck.

 

[rucr8z2]

Pulled front driveshaft out at lunch and on the way home NO NOISE!!!
I'm just glad that it wasn't anything more expensive...
Thanks 992door - good call