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Anyone with a lift + traction bars.....step inside

3K views 27 replies 14 participants last post by  Ray Bennett 
#1 ·
I just got a Icon 2.5 inch leveling kit installed along with a PMF 5 " rear traction block setup. Everything works great except we are having trouble getting the rear drive-train aligned so that it eliminates a moderate vibration/shudder under initial acceleration. We think it is the carrier bearing and have shimmed it which has helped but not eliminated the problem. Has anyone had this same problem before?? What did you do to fix it?Other ideas?? Any help is appreciated. :dunno:
 
#4 ·
I did a 1piece but also cv joints will take care of it as well. Thats a more expensive route then getting a 1 piece made up. You can either have a whole new on built which I did or you can get your 2 piece made into a 1 piece
 
#6 ·
Make sure that the rear pinion angle is correct before you spend the money on the 1 piece shaft. With only the 5" blocks. Thats only 1.5" lift over stock. If the pinion angle is right, the bars "should" hold the pinion perfectly in place. I have a 4" block in the back of mine. I believe I had to drop the carrier bearing about an inch. I don't have any kind of vibrations even running a 310 tune.

I would drop the carrier bearing 0.75-1" to start with. Then set the pinion angle about 2-4 degrees less then the angle of the driveshaft. Which means. If your driveshaft is on a 20 degree angle, Set the pinion at 16-18 degrees.
 
#7 ·
I may try to take it to a specific 4x4 driveline shop and see if they can get it in line before I get a 1 piece driveshaft made. The shudder is not that bad, but once you notice it, its all you can think about. :crazy:
 
#8 ·
Were the traction blocks flat like the stock ones or were they tapered?
 
#10 ·
Hey Ross,
Talked with Vickie some today about the truck and they have a couple more options they are going to try. Although a 1 peice driveshaft will probably fix the problem, there is no reason that it shouldnt be able to be solved without it given the small lift size. As I have told you, Im more than happy to help in any way I can. Feel free to call or have Vickie call me anytime bud...
 
#20 ·
I appreciate it. I am just trying to research other options. I looked under the truck and they only put in 2, 1/4 inch shims so far. It has helped the problem but not eliminated it. That leads me to think that if we add one or two more 1/4 inch shims it should get us close to a smooth drivetrain.

Now, if at that point we are still banging our heads against the wall, we will explore other options like a 1 piece driveshaft, carrier bearing drop, etc.
 
#11 ·
I had the exact problem you are having, I bet your blocks have too much taper and your pinion has too much angle. I had to buy flat blocks and it fixed the problem. our trucks are about the same length. Some companys put a lot of taper on their blocks to fit all the standard cab trucks and extended cab trucks with short beds. Our trucks require little or no taper due to the extra length. One size does not fit all here.
 
#13 ·
I would just keep adjusting your carrier bearing shims. There is no reason a truck with that little of a lift should vibrate. Typically, I've found 1/4" of shim per every 1" you go up in the rear (over stock height) has worked on the 10+ lifted Fords I've owned over the years.

When adjusting, just start with one and work from there. Once you refine it down to your two best scenarios, you can usually take a half size 1/8" for fine adjustment and get it right in between the two best scenarios and it will be dead on.

Good Luck,
 
#14 ·
Thats what I am going to do. I have (2) 1/4 inch shims in there right now and it is still vibrating so, I think im gonna add another 1/4 inch shim, see how she feels and maybe add another 1/4 inch on top of that for a total of 1". Hopefully that should get me close......
 
#21 ·
I agree about the one piece driveshaft. I have had one in the past. However this is completely unnecessary with a small lift. How many times did you shim it? You have to pretty much dial it in through trial and error. I know it took a bunch of tries to get mine right. Every superduty is different though.
 
#22 ·
Didn't read the full thread, but I used to do a little suspension work. I found that the angle on the carrier bearing has as much to do with vibration as the drop on the bearing. Shimming it brings it straight down, and will not keep the driveshaft perpendicular to the bearing. It seems that on the ford you could shim the back side of the factory mount for the carrier bearing by 1/4" and still use the factory studs in it. This angles the carrier bearing to a more perpendicular angle in reference to the driveshaft. It has been some time since I have done suspension, so this may not apply on the new trucks, worth giving it a look though!

If someone has already mentioned this, please disregard my lazyness for not reading the full thread.

Hope this helps!

Oh, and a custom one piece shaft with the correct pinion angle is bar none the best fix for the problem. Last one I had build was about $300 and has been well worth it.
 
#23 ·
I know you think thoes blocks are right for your truck but like I said I went throught the same problem. 5deg of taper is too much for our trucks. I shimed my drive shaft till it was nearly perfectly straight. It helped alot but never got rid of all the vibration. It did not eliminate the problem because your and my pinion is pointing up to much giving you a positive pinion angle. This will always cause vibration under heavy load. In addition the tapered block changes all the angles on the drive line and all thoes angles must be within 3% of each other. Hopefully you will get there by shiming but I never did. If your pinon is pointed upward the same or more than your drive line you are going to have to get flat blocks. You should not have to live with vibration.
 
#24 ·
I have 5.5" Pmf traction blocks with 5* angle started with 1/4" shim then another ended up with 3/4" and it still has a little vib on take off going to add another 1/4" and see what happens just been to cold to play with but you could feel the difference with every shim installed!
Chris
 
#25 ·
I really can't see how 5 degree taper is just right for your truck when I am at a 4" block with no taper. The actual block that was sent to me has a 5 degree taper to it. I had to run a 5 degree spacer to get it back to zero. I should have just sent it back, but I needed to leave on a trip.

I am willing to bet you put a 4-5 degree spacer in there and you will be happy.
 
#26 ·
I don't have a factory block 4in block in front of me but off the top of my head I wanna say it has a 3* taper. In which case why would you want to decrease the amount of pinion angle correction? I don't mean to start an argument with anyone but I don't understand the argument that a flat block is a good thing. Imo you want to divide you difference of joint angle between each joint. This way no intersection encounters more angle than needed. I have run and setup customer trucks with 12" or more of lift and no vibs.....
 
#27 ·
Please don't take anything the wrong way. You make a great product. And if I can't find the time soon to make my own set up, I will be ordering the same set up for my truck.

When I ordered my 4" block from ready lift. They had the option of flat or 5 degree taper. They recommended the 5 degree taper. I should have got the flat block. A factory f-350 comes factory with either a flat or tapered 3.25" block. This depends on cab configuration. Both of the last f-350 CC SB trucks I have had where flat block.

All I was trying to say is some trucks may need different things. My current truck with a 4" block. Needed a 1" carrier drop. I wanted the pinion angle 2 degrees below the drive shafts angle. That took my 5 degree block with a 4.5 degree shim in backwards. All I was saying is if I was to lift my truck another inch, I would only have to change it about a degree after dropping the carrier bearing a little more.

To the original poster. Pick up a $10 magnetic angle finder at your local hardware store and you could check a few things real quick and know whats going on.
 
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