Vibration and Poor Fuel Mileage After Lift.

[jggtjr]

Hey everyone. I have a 3" body lift and a 3" block and key lift for suspension lift. It's 4x4 of course and I'm running 33's. Does anyone know why I would be having a vibration about 70mph? I'm pretty sure it's the cv's, but I'm not positive. Has anyone ever run high angle cv's? Also, what kind of gas mileage do you get, because I'm averaging 11mpg with the 4.0L and 4.10 gearing? Would 4.56's help? Any suggestions to any of these questions will help. Thanks.

And don't say any negative comments about torsion keys because I have gotten enough crap about them from people on here haha. I like them personally because the ride is good and stiff.

 

[railman]

ok, i won't give you a hard way to go on the keys....they are okay for what they are intended for .....

if you "cranked" the keys for 3" then you really need to back down to about 2" of lift, cause you have practically took away all down travel on your suspension not to mention that would put your CV's back into an acceptable angle and be rid of your vibration

also it is easy to "sling" a weight from one of your tires and may just be out of balance ( mine seem to all the time..especially after a good 4x trip )

and yes you need to regear to 4.56 if not 4.88 to get your "power" and some of your mileage back

goin to 33's is adding alot of rotating mass and will allways make mileage suffer, even if you regear, your mileage will allways be worse than in stock form

l8r, John

 

[jggtjr]

Thanks for your response. I actually have pretty good down travel and the keys are barely cranked at all, so that's a plus. Do you know the aproximate cost to regear and is it possible to do it myself (I am pretty mechanically inclined too of coarse haha) to keep the cost down? Thanks

 

[railman]

i wouldn't recommend any "shade tree" mechanic to regear anything, there are so many variables as well as specialized tools needed to do a gear swap to get it right and last

as for cost, expect to pay a pretty penny for it to be done right ( parts alone will run $500-600, and that is just for the gears and master install kits )

if you do regear, now would be the time to install lockers as well since the same steps are needed whether you are just regearing or putting in a locker

l8r, John

 

[jggtjr]

Thanks very much. I appreciate all the info.
John (also haha)

 

[Toms01PSD]

Take out the torsion keys if you think it's the CV's. It may be your ball joints because they are at horrible angles. After I replaced my ball joints I noticed a considerable difference in my steering and it felt like a new truck. I'm not raggin on you because of the torsion keys, but you were warned on what they do to CV axles and ball joints...

 

[JohnnyO]

The front axle is live all the time, meaning that it is spinning even when you're not in 4wd. The dash switch only kicks the transfer case in and out. So the vibration is probably from the CV joints.
Do you seem to feel the vibration more from the steering wheel or from the seat?

 

[jggtjr]

It's mostly from the seat. The vibration certainly isn't the kind that you can't function with, but it's also certainly not "natural". It just hits a point at about 65-70mph and a slight hum (I guess is a good word to describe) starts. And if I just back off the throttle a bit it goes away. My best guess is cv's because I think at that point they are spinning so fast that it's too much. What's the best way to inspect/check your ball joints? And what about a set of those high angle cv's (that claim they can handle 50 degrees at highway speeds)?
Thanks, John

 

[Toms01PSD]

Jack the truck up and wiggle the tires. I've never heard of high angle CV's but i'm sure someone makes them. If they do I can't see them being cheap though...

 

[jggtjr]

Yeah...they are like $1200, so it would be cheaper to keep replacing the stock ones I guess.

 

[Toms01PSD]

CV's and ball joints are going to start adding up quick...

 

[feellnfroggy]

From what I understand, arent all terrains pretty diffucult to accurately balance? And of course bigger tire with more mass, despite the gearing wnd resistance alone iwll affect your mileage, htough I dont know how much.