Big Blue's Transformation

[ArdWrknTrk]

Yes, I think I'd better do that.

I'll measure the articulation and figure out how much farther the spline will move with the additional 1 5/8" of movement that the shocks will allow. And, I'll put the yoke and see how long the splines are. That should tell me how close to coming out the stub will be at full travel.

As I think about it, the best bet for the stub not bottoming in the yoke when the suspension bottoms is when the stub almost comes out at full extension. Right?

Well if the wheels are in the air the spline doesn't have to transmit much torque!

[Nothing Special]

Yes, I think I'd better do that.

I'll measure the articulation and figure out how much farther the spline will move with the additional 1 5/8" of movement that the shocks will allow. And, I'll put the yoke and see how long the splines are. That should tell me how close to coming out the stub will be at full travel.

As I think about it, the best bet for the stub not bottoming in the yoke when the suspension bottoms is when the stub almost comes out at full extension. Right?

You don't want the spline coming out at full droop. That's a pretty messy thing to happen. But you REALLY don't want the slip joint to bottom. That breaks the transfer case casting and you need to be towed home.

You can add limit straps to keep it from falling apart if necessary. Or better yet, add one limit strap in the center of the axle. That will keep the driveshaft from coming apart but won't affect articulation much, if any.

[Gary Lewis]

You don't want the spline coming out at full droop. That's a pretty messy thing to happen. But you REALLY don't want the slip joint to bottom. That breaks the transfer case casting and you need to be towed home.

You can add limit straps to keep it from falling apart if necessary. Or better yet, add one limit strap in the center of the axle. That will keep the driveshaft from coming apart but won't affect articulation much, if any.

Jim - Yes, I'd thought about that.

Bob - I wondered if the worst possible case was bottoming rather than coming out. Seemed like it might be.

I hope to find that the driveshaft I have is "just right", meaning it won't come out nor bottom. And here's my plan to find out:

• Install the shocks. This needs to be done I was waiting until I had enough weight on the front end to get the axle in the proper position. Looks like I'm there, and the shock towers just need to have the extra two holes drilled and the bolts put in.

• Mark & measure the max depth before bottoming

• Mark & measure the max extension before falling out

• Determine the max droop, and see if I can simulate it with weight hanging from the axle to pull the shocks to full extension, and then see where the stub is.

• Determine the max compression, and see if I can simulate it. I think this may take installing the bumper and then placing my five 50 lb bags of blast medium on top of the bumper. And even if I can't get to full compression I should at least be able to measure the compression and the movement of the splines and extrapolate from there.

Upgrades to the plan? Better ideas?

[ArdWrknTrk]

Jim - Yes, I'd thought about that.

Bob - I wondered if the worst possible case was bottoming rather than coming out. Seemed like it might be.

I hope to find that the driveshaft I have is "just right", meaning it won't come out nor bottom. And here's my plan to find out:

• Install the shocks. This needs to be done I was waiting until I had enough weight on the front end to get the axle in the proper position. Looks like I'm there, and the shock towers just need to have the extra two holes drilled and the bolts put in.

• Mark & measure the max depth before bottoming

• Mark & measure the max extension before falling out

• Determine the max droop, and see if I can simulate it with weight hanging from the axle to pull the shocks to full extension, and then see where the stub is.

• Determine the max compression, and see if I can simulate it. I think this may take installing the bumper and then placing my five 50 lb bags of blast medium on top of the bumper. And even if I can't get to full compression I should at least be able to measure the compression and the movement of the splines and extrapolate from there.

Upgrades to the plan? Better ideas?

6) cinch up a zip tie around the spline and drop BB off the lift from 6'

400 Lbs isn't going to do it.

It's not easy, because now you have rear shackles and the arch of the spring flattening out.

You're going to have to swing an arc from the front spring eye that gets longer as the springs flatten.

To model it I think you need a circle that remains tangent at that point, but the circumference unwinds.

At least that's how my autistic mind visualizes it.

Though with CAD you could probably flatten the curve instead of using a straight line to model the spring.

[Gary Lewis]

6) cinch up a zip tie around the spline and drop BB off the lift from 6'

400 Lbs isn't going to do it.

It's not easy, because now you have rear shackles and the arch of the spring flattening out.

You're going to have to swing an arc from the front spring eye that gets longer as the springs flatten.

To model it I think you need a circle that remains tangent at that point, but the circumference unwinds.

At least that's how my autistic mind visualizes it.

Though with CAD you could probably flatten the curve instead of using a straight line to model the spring.

I like the zip tie idea. But the lift doesn't come down fast enough to effectively "drop" it. I can bounce it by hand once it is on the ground, although that won't do much if the brand new Bilsteins are on there. Perhaps doing that with the extra weight on the bumper might?

But you are right about the arc of the springs and the shackle, which is what is causing the axle to move rearward. So any modeling I do of articulation vs driveshaft movement should really be a chart and I could approximate articulation that I can't measure.

Saying it another way, if I measure the articulation every inch that I can and plot that against driveshaft position I'll have a curve. On the droop end I'll know the limit from the shock's range and can extend the curve there. And, assuming the shocks allow travel to the bump stops, I can measure how much farther the suspension can compress from the resting position and eyeball the curve to approximate that.

It will all be approximate, but it'll be far better than nothing.

Thanks for the ideas, I think the plan for after church is evolving.

[ArdWrknTrk]

I like the zip tie idea. But the lift doesn't come down fast enough to effectively "drop" it. I can bounce it by hand once it is on the ground, although that won't do much if the brand new Bilsteins are on there. Perhaps doing that with the extra weight on the bumper might?

But you are right about the arc of the springs and the shackle, which is what is causing the axle to move rearward. So any modeling I do of articulation vs driveshaft movement should really be a chart and I could approximate articulation that I can't measure.

Saying it another way, if I measure the articulation every inch that I can and plot that against driveshaft position I'll have a curve. On the droop end I'll know the limit from the shock's range and can extend the curve there. And, assuming the shocks allow travel to the bump stops, I can measure how much farther the suspension can compress from the resting position and eyeball the curve to approximate that.

It will all be approximate, but it'll be far better than nothing.

Thanks for the ideas, I think the plan for after church is evolving.

No, I really meant drop it.

[Gary Lewis]

No, I really meant drop it.

Can't and don't want to do that, Jim.

Anyway, didn't get as much done as I'd hoped. The first thing I did was to measure the splines, and there are 2 1/4" of splines. So at the max droop I can get, which has 1 1/4" of splines out, there's only 1" of splines in the yoke. And, you might ask how I got the max droop. Well, I don't know how much my tool box weighs, but with a full set of 1/2", 3/8", and 1/4" sockets, both shallow and deep, extensions and ratchets in all sizes, full sets of metric and SAE wrenches, both box/open and ratcheting, and lots of screwdrivers I'd say it is heavy. But, it didn't move the driveshaft whatsoever.

Then I moved on to the shocks. I got the shock towers on, which took longer than anticipated due to having to drill four holes in the frame since the F350 towers have four bolts vs the F250's two bolts.

And I got the shocks in. However, I think they are upside down in spite of the writing being right-side up this way.

Next up was the bumper. I'd hoped that I could just put it back on with the brackets still on the bumper, but that wasn't happening as the bumper was 1" too far to the driver's side and didn't want to move. So I pulled the brackets and put them on the truck. Part of the reason it didn't want to move was that the Sky inside bracket limits the bolt length and my longer bolts were hanging up on it. So I put in shorter bolts, but I still had to move the lock washer on the lower bolt to under the head of the bolt instead of under the nut due to the lack of space. This is the passenger's side:

But I got the brackets on. But it turned out that the DS bracket is about 3/8" low, so has to come up. However, I ran out of time so will fix that tomorrow - I hope.

 

[Rembrant]

Can't and don't want to do that, Jim.

Anyway, didn't get as much done as I'd hoped. The first thing I did was to measure the splines, and there are 2 1/4" of splines. So at the max droop I can get, which has 1 1/4" of splines out, there's only 1" of splines in the yoke. And, you might ask how I got the max droop. Well, I don't know how much my tool box weighs, but with a full set of 1/2", 3/8", and 1/4" sockets, both shallow and deep, extensions and ratchets in all sizes, full sets of metric and SAE wrenches, both box/open and ratcheting, and lots of screwdrivers I'd say it is heavy. But, it didn't move the driveshaft whatsoever.

Then I moved on to the shocks. I got the shock towers on, which took longer than anticipated due to having to drill four holes in the frame since the F350 towers have four bolts vs the F250's two bolts.

And I got the shocks in. However, I think they are upside down in spite of the writing being right-side up this way.

Next up was the bumper. I'd hoped that I could just put it back on with the brackets still on the bumper, but that wasn't happening as the bumper was 1" too far to the driver's side and didn't want to move. So I pulled the brackets and put them on the truck. Part of the reason it didn't want to move was that the Sky inside bracket limits the bolt length and my longer bolts were hanging up on it. So I put in shorter bolts, but I still had to move the lock washer on the lower bolt to under the head of the bolt instead of under the nut due to the lack of space. This is the passenger's side:

But I got the brackets on. But it turned out that the DS bracket is about 3/8" low, so has to come up. However, I ran out of time so will fix that tomorrow - I hope.

Nice idea on the toolbox Gary.

[Gary Lewis]

Nice idea on the toolbox Gary.

Thanks, Cory! I was surprised that the driveshaft didn't come out any more at all when I picked the toolbox up. I'm wondering if I should load it up with the blast media and pick that up and see what happens.

And, when I get the bumper on I can load it up with the blast media and see how far that pushes the splines in.

[85lebaront2]

Thanks, Cory! I was surprised that the driveshaft didn't come out any more at all when I picked the toolbox up. I'm wondering if I should load it up with the blast media and pick that up and see what happens.

And, when I get the bumper on I can load it up with the blast media and see how far that pushes the splines in.

Gary, two items, first, as the truck loads the front springs, the axle will move slightly forward as it goes up so it is not just a straight vertical motion, rear is going to be the same except as the axle goes up it will move slightly back so in both cases the springs flexing will somewhat extend the driveshafts. It won't be much, but it may help with the spline travel.