I have '99 4runner with a 2.5 in Pro comp poly lift. I dropped the diff 3/4 of an inch and my cv's still vibrate between 55-65 mph, no leakage though. Next week I'm going on a 600 mile back country trip and was wondering if this vibration shouldn't be too concerning or should it? It's only been lifted about a month and a half, If that matters.

 

how do you know its the cv's?

could be driveshaft or wheel alignment.

 

When was the last time you had your wheels balanced? Every time I have had an issue with a vibration at that speed it's been a balance problem.

 

if you havent had a wheel alignment since the lift, then that woulld be the best place to start.

 

I had the alignment done, however that doesn't mean it was done right! I suppose it could be the tires but I don't think so because it started right after it was lifted. I expected some cv vibration and installed a drop kit which helped some but didn't completely eliminate it, but I'm not sure if they do. Do they?

 

it should because it lowers the cv angles more towards stock.

 

It would be a good idea to replace your steering rack bushings too...
http://www.wheelersoffroad.com/96024runner.htm

 

Should I have dropped it more than 3/4 of an inch?

 

What did you end up using to drop the diff? I had a Daystar 2.5 inch spacer lift on my rig for a long time and never had problem 1 with vibration. It's most likely something else.

 

Thanks for the help. I was wonderin' this though, my brother has a rough country 2.5 in spacer lift on his 2000 Taco and his cv angles are quite a bit less steep than mine. Am I comparing apples to oranges here? Basically the front ends are the same and the lifts are the same except for the brand. Were '99 4runners made differently?

 

Okay I just went over to my brother's to take some measurements and this is what I have found. His Taco sits at 12 5/8 at the back of his skid plate and mine is 14 1/4. He is running 32 in Pro Comp A/T's and I am running 265/75/16
BFG A/T's (roughly 32inches) his tires have a little more tread than mine but not too much and his coils look more compressed than mine. Is there anyone with a stock '99 4runner with 265/75/16 BFG's to measure against? I just don't see how there could be an inch + difference between them.

 

Did you get the printout of the alignment or take a look at teh computer screens. If the just straightened out your ride and did not check the other adjustments then that may be it.

Wheel balance is the number one source of vibration...

 

I got the print out on the alignment job although I must admit I'm not sure what to make of it. Left side so many degrees right side so many degrees and so on, so again I'm not sure. I went ahead and dropped the diff another 3/8 of an inch and gave her a good run up a hill and I think it helped but to soon to tell if it's cured. So this is pretty much a 1 1/4 diff drop is there draw backs to that?
I used the ALL PRO 3/4 in. and this evening I added some washers.

 

99s are taller

 

I was wondering if they were. Do you know how much taller they are?

Thanks!

 

Yeah, an entire coil wrap more.

 

All seems fine now but I hate doing hack jobs like stacking washers under my spacers but, oh well it's working for now. I will purchase a whole different set when I get back from my trip in Eastern Oregon this weekend.
Thanks for all yer help!