2nd Gen Non-Engine/Transmission Vibration above 70 without 4x4 engaged

[cmckinney]

Well guys give some input on this.



While driving without 4x4 engaged I have a vibration above 72 and above but when I engage the 4x4 the vibration goes away.



Does anyone have an idea of what this would be?



On my 2002 truck the front driveshaft always spins.



I've had this problem since I put D25 coils on the front, maybe even before this but I don't drive above 70mph often.



When I take the front driveshaft off and drive at the same speeds (70-85mph) I get no vibration so I know it is not the rear driveshaft.



-CM

 

[Bigramguy]

It could be something in the driveshaft,that vibrates when turning,but not under load in 4WD. Bad u-joint,slip yoke,out of balance,etc.



It also could be pinion angle of the front diff. Maybe it's a little out of whack with the taller coils ?

 

[Bigramguy]

It could be something in the driveshaft,that vibrates when turning,but not under load in 4WD. Bad u-joint,slip yoke,out of balance,etc.



It also could be pinion angle of the front diff. Maybe it's a little out of whack with the taller coils ?

 

[jhawkins]

I seem to remember MASSDIESEL had a similar problem don't know if he ever got it fixed.

Jim

 

[CRSmith]

I have to agree with the load/no load opinion. When driving in 4wheel drive there is probably enough bind in the system to keep anything from vibrating. With the shaft free-spinning in 2wd, slack and play show up. Sorry, I don't know how to fix it, other than maybe place a CV joint in the driveline, but that would be a pain.

 

[RustyJC]

If it does it after the lift and didn't (at least you hadn't noticed it) before, one must look at what changed. The balance of the driveshaft didn't, but pinion angle did. That's where I would look first.



Rusty

 

[cmckinney]

Well I may take all my lift off and have the dealer take care of it.



Doesn't make sense why I have a vibration.



-CM

 

[stevek]

Do a search, not too long ago there was a thread on vibration after the D25 coils were installed. Seems its mildly common...

 

[cmckinney]

stevek



That post was probably one I posted a while back.



-CM

 

[CRSmith]

The vibes will probably dissapear when you take the lift off. I think it is happening because of your driveshaft angle at the ujoints. The front shaft on these trucks is kind of short, so when you lift them, the pinion and tcase angles change significantly. Most people w/ lifts can get away with some vibration because their shaft is only turning part time and usually at low speed (below 72mph in 4wd). In fact, most people with lifts probably would have vibration in the front shaft if they went 72 in 4wd, but never do, so they are none the wiser and enjoy their truck for many years. Yours turns all the time, so if the pinion and tcase angles are slightly off from what they were designed for because of the lift, it is entirely probable that some sort of harmonic resonance, or driveline vibes could happen, especially at 72 mph. Unless you decide to take your driveshaft to a shop to have a CV joint installed (if it doesn't already have one) you will probably just have to live with it.



I don't know if your driveshaft came apart at the slip joint when you were installing the lift. If it did, it is possible that you could have put it back together "clocked". The driveshaft needs to be indexed together correctly in order to maintain balance. This is the issue I'm chasing with the 4runner I just lifted.



Maybe another option would be to get longer adjustable control arms from skyjacker. If you bought control arms meant for the 4. 5" lift and put them on a truck with a 2. 5" lift, it would move your front axle forward. This would lengthen your wheel base about an inch to decrease your angles, while still maintainig your caster. When you put bigger tires on these trucks, the tire comes very close to the back of the fender anyway, so you'd be killing two birds w/ one stone. An expensive option.

 

[Bigramguy]

The front shaft has a constant velocity joint (double cardan) at the transfer case end,so you would think it would not vibrate with such a small lift. With this type of setup,the front u-joint angle at the diff should be 0,or straight in line with the pinion. Maybe an alignment,and playing with the caster would help bring the diff back in line ?



Also I wonder if dropping the transfer case a bit would help ?

 

[RustyJC]

Unfortunately, if you try to rotate the back (U-joint) side of the front axle upward, you are going to reduce caster. The less caster, the more tendency to "roadwalk" and wander. Like most things in life, correcting one problem seems to create others. Thus, dropping the front of the transfer case might be the preferred approach to restore correct pinion angle.



Rusty

 

[Bigramguy]

You could set the pinion angle by using the caster adjustment on the lower arm mounting points,to rotate the diff back in line,and then maybe use a caster\camber bushing or offset ball joint to restore the correct caster at the knuckle. I know it can be done on my 97. Not sure on the newer trucks.

 

[cmckinney]

Well I am going to take the D25 coils off the front and see what that does to my vibration.



If it fixes the truck then I'll have a set of D25 coils and add-a-leafs for sale.



I hope this fixes the problem.



Thanks guys for all the responses I don't want to mess with my castor. Anyone notice if it is normal too have a little fluid leak from the shaft of the front pumpkin?



-CM

 

[damon]

Let me know if you decide to sell the D25's.