Lets Play, Name That Sound!!

[jakbob]

ok so heres the deal...i installed my rustys 3 " lift and afterwards when im off the throttle coasting it sounds like a train going over tracks (20 mph = dunk dunk dunk dunk) and it gets faster as speed increases....my theory is that its because the rear springs haven't sagged yet so its more like 4.5 in the rear and its just the slip yolk..any other theories and what not would be greatly appreciated....

 

[TwistedCU]

Could be driveline vibes, did you lower the transfer case? if not how does your rear pinion angle look?

or

Is the front driveshaft hitting the exhaust header?

 

[Utah_jeepster]

Drive line!
If nothing changed except the your drive line angles...
Drive lines, also check the U-Joints might have messed one up installing the lift.

 

[jakbob]

no i didnt install a tcase drop...it was only 3 inches, springs havent sagged...but how would i check the pinion angle and what would a a bad u-joint look like?

 

[Saurian]

Grab the driveshaft and try to twist it back and forth, there should be no play at the point of the U-joints, if it's moving back and forth, U-joints are headed south... Front driveshaft, same deal, look near the wheels to see if the yokes are able to move a little bit, with all 4 wheels sitting on the ground, that driveshaft shouldn't be able to slap around at all...

On the driveshaft where it meets the transfercase, look at the yokes for evidence of SHINY metal; if it is binding, it'll be shinier than the rest due to the contact of metal to metal...

Hope this helps...

 

[jakbob]

yeah i did that and atleast my ujoints are still good...but there is evidence of binding on the rear output shaft on the tcase...so heres the next question...is there a solution other than an SYE? cause they be expensive...

 

[Saurian]

I am new to this, but you have a few options...

SYE, yes, but as you said, expensive...

CV Driveshaft, again, expensive...

Transfer case drop, not sure on expense, don't think that bad...

Grind out the yokes to gain more clearance... I would NOT recommend this one, because you will burn through U-joints like no tomorrow, not to mention weakening the yoke, which is already the weakest point in the driveshaft system...

 

[jakbob]

yeah sounds like the best alternative is the tc drop..thanks for the help guys...

 

[TwistedCU]

Get yourself a Skyjacker transfer case lowering kit. Skyjacker because you won't have to extract a stubborn stud that you would have to deal with if you went with any other TC drop. The install is easy and not very time consuming. An afternoon is more than enough time for even the novice.

The reason I asked about the front DS hitting the exhaust header is I had that problem when my front axle was not centered properly for lack of an adjustable trackbar and the pinion was rotated up slightly for lack of adjustable control arms. It only happened when the front suspension was compressed (over hard bumps).

 

[TwistedCU]

The other option would be a SYE and CV driveshaft, but is much more $$$.

 

[TwistedCU]

Did you get those tires on yet???

 

[exjay33]

I have installed several of rustys kits (3) never had a vibration I think you have a u joint starting to go or frt wheel bearing pack starting to go . Change the rear u joints first if one cap is bad you won't feel it buy trying to move it buy hand .

 

[jakbob]

Did you get those tires on yet???

no but i will have some wheel adapters coming in today so then i will, and as for the rustys 3" lift, i got like 4.5" in the rear...i think its cause of me having the 2 door model...my jeeps light...and there is signs of metal rubbing metal on the output shaft of the transfer case on the rear driveshaft...

 

[jakbob]

ok ok...you guys gotta check this out...the noise i was talking about, it dissapeared after i put the 31's i got from TC on...so here is MY theory (proceed to slap some sense into me if i am wrong)



so the little green men in... (j/k)

during the many times i took off my stock tires before and after the lift (random things, i.e. brakes, studs, what not) and the process of putting them back on, i over tightened them unknowingly ( i dont have a torque wrench) and in doing so, made the hole for the stud that passes through the rim to go from a circle to an oval, which would cause the vibration like this....


wheel wants to travel the same speed as the road because of the tire, BUT normally is restricted by the drivetrain...when the hole in the rim became an oval (on all five) it allowed movement from the rim to differentiate from what it would normally do (easy way to explain this would be...worn u joints...i.e. the driveshaft can move back and forth while what it is connected to doesn't...which would explain why the noise only happens when i am off the throttle....



SO IN SHORT

my problem ceased because i put on rims that had not worn ovals instead of circles allowing the wheel not to do whatever it wanted and to do what it is supposed to do...any questions?


PICTURES OF NEW JEEP TO COME SOON!!

 

[currupt4130]

SYE, yes, but as you said, expensive...

CV Driveshaft, again, expensive...

Just so you know, most people don't do one without the other. I suppose you could do the SYE and not buy a CV shaft but then you defeat the purpose of putting in a fixed yoke.

 

[Saurian]

Hmm, good point... I got lucky with mine, there's the slightest vibration, but no evidence of binding anywhere, so I'm running stock driveshafts with the 1" TC drop, all is well