I lifted my '02 F250 w/ F350 axel blocks (2" taller). I have been trying to eliminate the vibration on drive away. I am going to fab some angle shims for the rear axel to correct the increased drive shaft angle. Can anyone tell me how many degrees of angle I need to make these shims. Any help would be appreciated. Thank You !

 

What config is the truck? how did you lift it? stack blocks? new springs?

 

Just 2 inches? Have you lowered the carrier bearing housing? That might be the culprit.

 

I agree...with a 2" lift, I would highly doubt shims will be needed. Lower the carrier bearing and this should fix the problem.

 

if you decide that you need shims, dont angle up,angle down. the u-joints need to be at equal and opposite angles.

 

My truck is a long bed extended cab, 5.4 L , 4wd with a 2 peice drive shaft. I used a Pro Comp 2" leveling kit on the front which basicly consited of new springs and I changed out all four shocks. For the back I simply just changed the factory F250 blocks for factory F350 blocks which are 2" taller, that's where my problem began. I am going crazy try to eliminate this vibration. I have shimed the mid bearing straight down in 1/4" incriments from 1/4" - 1 3/4" with no luck. the vibration only changed to either worse or just different but did not fix the problem. In the process of all my shimming I wasted a u joint and ruined my mid bearing. Now with the u joint and mid bearing replaced I am back to square one. So I thought I would try the angle shims. So if anyone could shed some light on how to do that I would be grateful. I can make the shims I just don't know what angle or which way to go. I would love some expertice before spending more time and money on fabricating shims. I know it seems crazy that just a 2" lift could cause so much vibrations. CAN ANYONE HELP ?

 

Superlift and others make a bracket called the Carrier Bearing Drop Bracket. Basically bolts up where the carrier bearing joins the two halves of the driveshafts together, and it is angled for proper installation, probably part of the reason you are still having problems with just regular shims. For 2" of lift I think you need to drop the carrier bearing 1" to level it out (my 6" lift needed a 3" drop). Even with the bracket installed I found out later (after my vibration continued) that it needs to be properly aligned. Your local shop can do it pretty easily, that should take care of any remaining vibrations.

 

check under a 350 specd like your truck and see what is diferent. some people have gone with a 1 piece driveshaft to eliminate the vibration. do a search and there is some info on it.

 

if you have 3 u-joints, the first one from back of tranny needs to straight. If you have to lower the mid bearing, youll have to lower the tranny too to keep it straight.
Measure u-joint angle by using an inclomineter (sp?) and measure u-joint, the turn it 90 degrees and measure again. subtract smaller angle from larger one and that is the u-joing angle. That is the first angle. Do the same for the j-joint at final drive and shim as necessary to correct any difference. OBTW, truck should be on ground in operating conditions.

 

two inches should not make much of a variance with your drive shaft. I agree with the others that a slight drop in the carrier bearing would be my first step.

Another consideration is that the vibration you feel may be axle hop if it is only happening at take off with a heavy foot. If you used a 2 inch block it allows the axle more leverage against the spring. if it is a u-joint binding it should happen at certain speed when it starts to resonate.

 

I've done the same block swap on my truck, with the same results. I get a slight vibration on drive away, but no-where else. I feels like axle wrap, but I would like to get rid of it if I can. My truck is also a 04' extended cab, long bed, FX4 package 4x4. Correct me if I'm wrong, but doesn't the pinion angle change depending on the amount of weight in the bed? More weight would make the truck squat, or is this just absorbed by the slip yoke? I've had this swap in for about 2 months now, and like the looks, but don't really care for the vibration. I didn't notice it as much when I had my truck camper in, but it weighed about 2000lbs. I put the blocks in because with the severe service springs (snowplow package), it really looked like crap with the camper in. It looked like I was overloading it. Now the truck camper is gone, and the fifth wheel is on the way. Depending on clearance issues, I may have to take the blocks off.
Anybody out there ever measure their pinion angle before mods, like I WANTED to and forgot? I'd like to know where I am now as opposed to what it used to be.
Alan

 

It sounds like axle wrap. I would shim down abot 4 to 6 degrees... But it definately sounds like axle wrap...

Get track bars. They look cool and will stop the vibration!

 

xc600 - you didn’t say how large the rear blocks are. I would guess 2" if you were compensating for the frond spring. I would say 2 to 4 degrees would be sufficient. If you have a two piece axle you may want to drop your carrier bearing an inch or so with a shim.

When you put in a block it will increase axle wrap because of the extra leverage against the springs. I highly recommend traction/ladder bars. If you are pulling a trailer and you takeoff from a stop or uphill you can wrap the axle enough to bind the u-joint. With no load I ripped the axle and bend my pinion. Lots of money. A lot more than $400-$700 for a set of ladder bars.

 

Wish I would have thought of that!

 

Did you get the tapered or non-tapered 350 blocks? I believe for your truck you need the non tapered blocks.