Can Can
Pusher Man
Would swapping out the stock 4" front spring shackles in exchange for 6" greasable ORD shackles alter the caster enough to bring on driveability issues on a 1989 V3500? If so, what's the fix?
CK5
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can extended front shackles affect caster THAT MUCH???
- Thread starter Can Can
- Start date
CanmoreK5 said:
The fix would be to install shims to point the pinion back up. Why not just run the ones that are like 4.5" (which happen to be the same length as the ones you currently have) and are greasable? Going longer is also going to make your nonexistent shackle angle worse and make the truck ride crappier...
Can Can
Pusher Man
This question is hypothetical, brother. I have to make some measurements before I continue with this line of thinking, but I wanted to learn some stuff in the meantime.
Just trying to give you some all around info... As for driveablity isuse i couldnt tell ya as i dont have anything to go by, wish i could help ya more thoughCanmoreK5 said:
Just wondering though, why go that much longer?
Can Can
Pusher Man
My thoughts exactly...... PM headed your way.
Well I just got to take my truck for a longer drive and had a DW issue for the first time in over three years. Steering felt much more vague than I can ever recall.
The only thing that has changed is I went from front shackles that were 4.5" long (47" springs and front shackle mount in stock location) to 7.25" long shackles and the shackle hanger moved up/forward. This did move the spring eye about 2" below the frame and seems to have affected caster enough to cause a bit of DW in my case.
I'll take some measurements tomorrow and make some shorter shackles.
So, I would say it is possible if you have longer than stock front shackles it could contribute to DW issues.
Rene
The only thing that has changed is I went from front shackles that were 4.5" long (47" springs and front shackle mount in stock location) to 7.25" long shackles and the shackle hanger moved up/forward. This did move the spring eye about 2" below the frame and seems to have affected caster enough to cause a bit of DW in my case.
I'll take some measurements tomorrow and make some shorter shackles.
So, I would say it is possible if you have longer than stock front shackles it could contribute to DW issues.
Rene
Your steering geometry would be all hosed and would put a wrong constant load on the ball joints and just a bad idea IMO.
Course I'm considered in many circles to be an idiot so.........
Course I'm considered in many circles to be an idiot so.........
justhorsinaround said:
The shackle being 2" longer than stock will lift the truck 1". It will affect caster angle but it won't affect his "ball joints" because a 1 ton has king pins.
4X4HIGH said:The shackle being 2" longer than stock will lift the truck 1". It will affect caster angle but it won't affect his "ball joints" because a 1 ton has king pins.
Shut up ya know it all!!!
i put HILL4WD shackles on my suburban and developed a death wobble out of it... and the steering felt funny too.
justhorsinaround said:Shut up ya know it all!!!
Had to bust someones balls tonight. With a post count like yours you certainly aren't a noob and i would've expected more from you.
Yea well.
You're just a big meany and I flat didn't draw the line between 3500 and 60.
So shoot me!
Meany.
You're just a big meany and I flat didn't draw the line between 3500 and 60.
So shoot me!
Meany.
Yep, same here. It was a lot more difficult to hold in a straight line on the highway. It had no "centered" feel. I'm guessing shims could have helped me.muddysub said:
As mentioned, he has a Dana 60. Isn't there something that needs done (to the spring plates?) to use shims because of the two bolts that thread into the axle housing?
.
You can get away with 4* but anything more will want to bind the bolts.
beater_k20
Banned
shims and angled spring plates. i'm thinking shims on both sides of the spring pack isnt a good idea for some reason or another. 
I was looking at doing the shackle angle/move the frame hanger thing this weekend. Based on the measurements I took you would probably between 5 & 6" shackles. That's with my 2.5" lift front springs.tRustyK5 said:
I think the 7.25" shackles are for the 52" swap where the spring is longer and hence the need for longer shackles than you would with stock length springs.
This is the best explanation I've found for figuring shackle length:
rcurrier44 said:
Canmore, I think you'd need to move the frame hangar to accomplish what you are after.
Yeah, I probably forgot to note that I'm running 49" long Alcan's up front. Measuring from the center of the old shackle hanger hole down to the lower bolt on the new shackle I'm running the equivalent of 5.5" shackles.
I'm now thinking I need to shim the front diff.
The Alcan's have about 2-3" of loaded arch and the center pin is 1.5" forward of center. I'm thinking the more forward location along the arch of the spring has tipped my pinion down...
At any rate it is pretty squirrelly right now.
I'll have to bust out my angle finder and see what the caster angle now is and go from there. IIRC stock is supposed to be 8 degrees?
Rene
I'm now thinking I need to shim the front diff.
The Alcan's have about 2-3" of loaded arch and the center pin is 1.5" forward of center. I'm thinking the more forward location along the arch of the spring has tipped my pinion down...
At any rate it is pretty squirrelly right now.
I'll have to bust out my angle finder and see what the caster angle now is and go from there. IIRC stock is supposed to be 8 degrees?
Rene
Shims on a front axle scares me. I know it's illegal in NJ. Measure the castor, do the mods and relocate the spring perches back to the original castor angle. Do it right the first time.
"Originally Posted by justhorsinaround
Your steering geometry would be all hosed and would put a wrong constant load on the ball joints and just a bad idea IMO.
Course I'm considered in many circles to be an idiot so........."
Ball joints/kingpins, whatever. The centerline thru them is supposed to be at a certain angle so the steering is balanced (Not heavy or light feel). It should be to the manufactures specs.
"Originally Posted by justhorsinaround
Your steering geometry would be all hosed and would put a wrong constant load on the ball joints and just a bad idea IMO.
Course I'm considered in many circles to be an idiot so........."
Ball joints/kingpins, whatever. The centerline thru them is supposed to be at a certain angle so the steering is balanced (Not heavy or light feel). It should be to the manufactures specs.
It's not like you can just 'move the perches' on a d60. You could move the drivers side, but the passenger side the perch is part of the center section.
Doing a search I found this gem by Greg72
He is running Alcan's and a D60 front as well.
Rene
Doing a search I found this gem by Greg72
Greg72 said:OK, first of all let's get straightened out on the terminology:
Caster is the imaginary line drawn between the upper and lower balljoints (or kingpins) and is measured in degrees. If the front of your truck is facing the left side of this page (looking at the drivers side) then:
/ would represent "positive" caster
\ would represent "negative" caster
| would be zero caster.
You want positive caster, and 4 - 6 degrees is probably what the factory manual will show as a "stock" specification for your truck. Even with a lift, you'd like to still aim for that number.
SO....looking at those crude diagrams, if you have negative caster now, and you rotate the pumkpin (with shims)...then you should be able to see how the pinion will start angling downward.
The reason I wanted you to have an angle finder (and a cheap $10 will work fine) is that the top surface of the knuckle (if it's flat) will be exactly 90* off from the caster number you want to find. That will make the math easy.
My own truck isn't really a good example because of some weirdness caused by the custom springs, but I'll tell you the story to at least show you the problem solving process.....
My (4" Lift) front springs were made 1" longer than stock, and the spring pin was offset 1" further forward over stock. That meant that my axle was sitting further up the "smile" of the spring, and was actally rotating the pinion DOWN automatically. My D60 steering arms are nice and flat, so I was able to get a measurement easily....but it showed 10* of positive caster! I only wanted 4* of positive caster which meant that I needed to rotate my pinion UP (not down, like most people) to get rid of the excess positive caster. I added a 6* shim under each spring (and also had to use some spherical washers on the side with the cast-in perch to avoid putting 6* of "tweak" in the U-Bolt plate bolts.
Anyway. The result was that I got to 4* postive caster and the truck ended up driving better afterwards.
Conceptually, that's what you want to achieve....but again, the steps you will need to take are going to depend on your own caster measurements.
He is running Alcan's and a D60 front as well.
Rene
Well, I am at 11 degrees positive caster right now...
As for what the caster should be I've seen everything from 4 degrees all the way up to 8 degrees mentioned as being the correct spec. Judging by the way my truck handles right now I'd say too much caster is just as bad as not enough.
I think tomorrow I'll pick up some 4 degree steel shims and see how much difference it makes.
Rene
As for what the caster should be I've seen everything from 4 degrees all the way up to 8 degrees mentioned as being the correct spec. Judging by the way my truck handles right now I'd say too much caster is just as bad as not enough.
I think tomorrow I'll pick up some 4 degree steel shims and see how much difference it makes.
Rene
