6/4.5" skyjacker lift....axle clocking

[puff1]

Any one who wants to install a 6/4. 5" please talk to me first. Do not follow the instructions, if you do you will end up doing everything twice possibly 3 times. I now believe that the lift's instructions are for somthing like a ram charger or maybe a short box regular cab. Not a longbox club cab.

First off skyjacker will give you a wedged 4. 5" block to replace the factory 6". The spring pack will come with a degree shim bolted on the bottom. The instructions say to put the wide side of the wedged block towards the rear, if you have the club cab long box disragard this, that will point your pinion way to high. With a two piece drive shaft you can keep the pinion angle factory and lower the steady bearing approx 1/4" per inch of veichle lift. Do it with spacers, I made mine with 1/4" flat bar so I could fine tune (you want no shudder when dragging that duramax). The stupid wedged block might work on a reg-cab long box if you take the degree shim off the the bottom off the spring pack ( make sure you clamp the pack before removing the center bolt)

What I wanted was a flat block and no degree shim on the spring pack, did I get it... ... NO! To make what they sent me work I had to reverse the block, this cancelled out the pinion raise and brought it back to factory.



The front has caused me no end of grief. I followed the instructions completed the lift and went for a test drive. The truck would jump all over the road. I have done everything to correct this, new steering shock, drop stabilizer brackets, ajustable draglink, almost did the kingpins to. The problem is castor! The degree shim bolted on the bottom of the front spring pack is nessesary, I know this because I removed them, the clearences on the front driveshaft are too tight without the shims. The shims or wedges destroy the castor which causes the truck to track like crap..... catch 22. The only way to have this lift, and have the truck drive mint is to clock the axles. I will be doing this starting tomorrow and will take some along the way pics to post. Not sure if I will remove the axle or not.



I really just needed to vent. I don't want anyone to have to go through what i just did. If any one wants to ask about lifting a cummins I might be able to help:-laf

 

[Moab4x4]

Jumpy truck

I know what you mean, I only did a little front lift and have the same issues but probably not as bad. I look forward to seeing you you do the clocking.

I need to get my steering working first though. (another saga for another day) Some days, my truck acts its age. Others it makes me forget mine.

 

[MRitz]

I have the exact same lift and the exact same problems. I removed the rear shims but I still have the wide side of the blocks towards the back and I definetly have axle shudder. I take it you have the block the other way? let me know how the clocking goes because mine is like driving an old hay wagon down the road.



Thanks,

Matt

 

[AKimmel]

Have fun cutting the knuckles loose to be able to turn them. I had to do this on my 89 W350, It has 12" of lift, and the drive shaft was binding even with the wedge blocks under the springs, and I had about 5 degrees of negative caster. So it wondered real bad on the road. I had a whole post on it at chuckstrucks.net, but the site went down the other day and all the old posts were lost. I now have 23 degrees of pinion angle, and 4. 5 degrees of positive caster.

 

[AKimmel]

Here's one last one of it back in the truck.

 

[glhs]

Puff 1;Out of curiosity, how many degrees was that front shim that came with the springs.



Kimmel; That is a lot of lift!

Can the axles tubes be removed from the pumpkin or is that harder to do?

What would a shop charge to reweld and those knuckles... any idea?

 

[KOG]

If you remove axle tubes from housing you have to have a jig to align them straight when you reweld them. And it's not always easy to remove them without damaging something.

Don't try this as home, kids.

 

[AKimmel]

Puff 1;Out of curiosity, how many degrees was that front shim that came with the springs.



Kimmel; That is a lot of lift!

Can the axles tubes be removed from the pumpkin or is that harder to do?

What would a shop charge to reweld and those knuckles... any idea?

I think I figured the shims were about 10 degrees. The springs are 8" skyjacker springs with the spring mounts lowered 4", thats how I got 12" lift. The tubes could be removed from the pumpkin, but they are pressed and plug welded in with nickle rod, which is extremely hard and almost imposible to machine or drill out. To remove the knuckles, I air arc gouged the welds out, then presses the knuckles off. I did it with a 20 ton press, alot of beating, and a good amount of heat. You really need more like a 50 or 75 ton press. I really didn't want to heat the knuckles, but I was already to deep into it to quit. Once the knuckles were removed, I machined them in a lathe to smooth and straighten the weld area before I pressed them back on. If I did this for someone in the future, I would probably have to charge $400 to $500. It is a lot harder than I thought, but If you have the determination and the equipment, I think most people could do it.

 

[AKimmel]

Alot of people wonder what to do with the spring pad cast into the chunk. This is what I made.

 

[Tippin Spotted Cow]

Are those knuckles splined inside, or how do you make sure theyre parallel to each other on the tubes?

 

[therabbittree]

no splines. . you measure twice before tacking, then measure more

 

[Tippin Spotted Cow]

Thats an issue of angles though, I feel like that'd be hard to line up right.

 

[AKimmel]

I just used a regular old angle finder, you can see it in the last picture. It reads down to half degrees, and I checked the frontend before I cut it apart, and it wasn't very acurate from the factory. The left side had more caster than the right, and it should be the other way around to correct for the crown of the road. I put it back at 4 degress on the left side and 4. 5 on the right, not that it matters, this truck only sees mud. Also I forgot to mention before, the knuckles are pressed on with a . 006" press fit, for those who know, that a lot, and thats why they ar so hard to get on and off.

 

[puff1]

The axle clocking went really awsome I did it all with diff in place. I have not welded the knuckles yet because I am doing a little research about castor. So far I have found out that the passenger side should have . 75 degrees more castor then the drivers side for road crown, this allows your truck to drive straight instead of veering into the ditch. I am trying to got the right number for my truck with the lift, I may go more than factory, I think the most you would want to go is 4. 5 on the passenger side, this means you would go 3. 75 on the drivers. More castor = more stability, but at some point it will get harder to steer and take more room to turn around. It's like a motor bike if you took out the rake in the fork and put the fork straight up and down it would be very hard to keep it in a straight line.

Anyways I am waiting on a King Pin rebuild kit from 4wdfactory.com I will weld the the knuckles on after I get it. I will be doing a write-up with pictures in about a week.

 

[puff1]

Puff 1;Out of curiosity, how many degrees was that front shim that came with the springs.



Glhs; the shim that came with the 6/4. 5 lift is a 5 degree one, it gives you pretty good pinion angle. I may go up a little more because when the diff is all the way down the cv binds slightly. I may just grind the nubs a little in the center of cv joint on the driveshaft. It's all a balance between proper driveshaft angle (without shudde) and castor. Now is the time to figure it all out. I may even just tack the knuckles on then test drive. All the strength is in the the machined fit ( about 2 inches of overlap) the weld mostly stops rotation of the knuckles. One square inch of perfect weld can hold 70,000 pounds. I want my truck perfect.

 

[Tippin Spotted Cow]

. 006" interference fit? I'm guessing those are somewhat hardened, thats a mile if they are.

 

[AKimmel]

I want to see how you got the knuckles off with it still in the truck. I went with a 1/2 degree split, because I have a buddy that does alignment work, and he said thats how much puts in when he aligns vehicles. As far as the 4 or 4. 5 degrees of caster, actually made my truck easier to steer than the way it was before. My truck turns sharper also on 44's than my other two trucks do with close to normal size tires.

 

[Tippin Spotted Cow]

I want an 8" skyjacker system for my Ramcharger when I get it running, so I'll probably be looking for you guys then.



Sounds like I got my work cut out for me.

 

[glhs]

Good info. guys.

I'm just learning about pinion and driveshaft angles and it looks like mine has been off since new. I would imagine the front pinion goes down another 1* when I have my foot in it going down the track.

My FSM says it is set from the factory at +2* and the acceptable range is +1/2* to +3 1/2*.

I may consider doing this since a 2* shim would ruin my caster if it's like the FSM says it is.

 

[puff1]

Once I had the knuckles exposed It took an hour a side solid work to get the knuckles free and rotated. This does not include cooling time. Mind you there was alot of smokes and coffee but I know I could rotate one in an hour. It may not be the most professional way but I'm too lazy to take it right out. Also it's nice to have an 8000 lb work bench attached to the axle to hold it in place. I live in the city and don't have a shop just a 14' wide garage. The key to getting the knuckles rotated was heat. most people would heat the knuckle, maybe they would pound it when hot, this is a good way to cause distortion. I would recommend avoiding this.

I concentrated the heat from an oxy/acet torch onto the very end of the axle tube untill I could see a dark glow stay briefly. After this I let it cool completely, you can hear some pinging as the cooling takes place. If you heat somthing it will expand, but in this case the expansion is restricted to elongation as the knuckle is so tight on the axle tube. You wouldn't want to beat on the knuckle with the axle tube hot or with the knuckle hot..... anyways as the tube was heated it grew slightly longer because of restriction and upon cooling the diameter ends up slightly smaller because the growth was latteral but shrinkage is not. This is why the the knuckles even moved at all