SAS driveshafts? New driveshafts?

[ArdWrknTrk]

Pythagorean theorem isn't trig, and it isn't difficult at all with the calculator in your phone.

You need to measure from the center of the universal joint axis.

How far horizontally, and how far vertically.

Obviously vertical changes from fully on the bump stops to full droop.

Then you solve for the hypotenuse.

You can use sin cos=tan, or you can do A2+B2, root=C

 

[Littlebeefy]

Hi guys,

@Jim - Just an engineer joking about the math. Of course I'll do the correct measurements once that front and rear axle completes installation. I guess the original question around that was does a half inch longer shaft really make a difference (if I did need a new shaft, I'm assuming it would be because it needs to be significantly longer than the original). I know I'm opening up myself to quite a few jokes here, so feel free to take advantage of the gentle lob.

@Gary - I had poured through the Driveshafts tab last weekend. Incredibly detailed and useful stuff. Literally spent hours on it. What I'm confused about is a little more basic. Various models have different types of Ujoints. Some have cardan, some don't. Also, they used 1310, 1330, etc but had varying Ujoint measurements within the same "standard". Given that my bronco has 1330 yolks at the TC and diffs, what options do I have to use (or shorten) a Ford truck driveshaft at the salvage to get something slightly longer than what I've got? My current driveshafts use type 35 and type 42 Ujoints (Ford codes) so does that mean I have to stick with that or can I use anything that has 1330 at both ends? Since I currently have a cardan on the rear at the transfer case, do I have to keep a cardan joint there? Again, I'm only trying to "get by" until I do the powertrain swap later in the year. I know these seem like basic questions but I lack some of the basic knowledge of Ujoint and 1 piece/2 piece shaft interchangeability.

[Gary Lewis]

Hi guys,

@Jim - Just an engineer joking about the math. Of course I'll do the correct measurements once that front and rear axle completes installation. I guess the original question around that was does a half inch longer shaft really make a difference (if I did need a new shaft, I'm assuming it would be because it needs to be significantly longer than the original). I know I'm opening up myself to quite a few jokes here, so feel free to take advantage of the gentle lob.

@Gary - I had poured through the Driveshafts tab last weekend. Incredibly detailed and useful stuff. Literally spent hours on it. What I'm confused about is a little more basic. Various models have different types of Ujoints. Some have cardan, some don't. Also, they used 1310, 1330, etc but had varying Ujoint measurements within the same "standard". Given that my bronco has 1330 yolks at the TC and diffs, what options do I have to use (or shorten) a Ford truck driveshaft at the salvage to get something slightly longer than what I've got? My current driveshafts use type 35 and type 42 Ujoints (Ford codes) so does that mean I have to stick with that or can I use anything that has 1330 at both ends? Since I currently have a cardan on the rear at the transfer case, do I have to keep a cardan joint there? Again, I'm only trying to "get by" until I do the powertrain swap later in the year. I know these seem like basic questions but I lack some of the basic knowledge of Ujoint and 1 piece/2 piece shaft interchangeability.

Chad - I'm not the best guy to answer those questions as I just have a smattering of theory and very little experience.

But if I understand correctly the Broncos had double-cardan rear shafts due to the short length of the shaft and the angle that created. Ditto the F350's on the front shaft.

As for u-joints, I think you can use any shaft that has u-joints that fit into your yokes. But, there are crossover u-joints that have different sized caps on one axis than on the other. So I think you could adapt just about any shaft if it is the appropriate length. That may not be the "best" approach from a strength standpoint, but since you said it is only temporary.

And on terminology, u-joint capacity, and driveline angles, you might want to read up on that. One source is FourWheeler, which says this:

Most drivelines have two opposing yokes with a single U-joint at each end, referred to as “single cardan,” where the joints are set 90 degrees apart. The joints in the transfer case end and axle end should operate on parallel planes with a single cardan joint in order to cancel out the phasing when one joint speeds up and the other slows down. This occurs because the U-joint is at an angle as it spins, as opposed to being straight up and down.

Some drivelines use a “double cardan,” or constant velocity (CV), with two joints at one end (typically the transfer case) and a single joint at the other end. The two joints split the angle, allowing for greater angularity. With this type of driveline the pinion should be pointed up at the transfer case.

[ArdWrknTrk]

Hi guys,

@Jim - Just an engineer joking about the math. Of course I'll do the correct measurements once that front and rear axle completes installation. I guess the original question around that was does a half inch longer shaft really make a difference (if I did need a new shaft, I'm assuming it would be because it needs to be significantly longer than the original). I know I'm opening up myself to quite a few jokes here, so feel free to take advantage of the gentle lob.

@Gary - I had poured through the Driveshafts tab last weekend. Incredibly detailed and useful stuff. Literally spent hours on it. What I'm confused about is a little more basic. Various models have different types of Ujoints. Some have cardan, some don't. Also, they used 1310, 1330, etc but had varying Ujoint measurements within the same "standard". Given that my bronco has 1330 yolks at the TC and diffs, what options do I have to use (or shorten) a Ford truck driveshaft at the salvage to get something slightly longer than what I've got? My current driveshafts use type 35 and type 42 Ujoints (Ford codes) so does that mean I have to stick with that or can I use anything that has 1330 at both ends? Since I currently have a cardan on the rear at the transfer case, do I have to keep a cardan joint there? Again, I'm only trying to "get by" until I do the powertrain swap later in the year. I know these seem like basic questions but I lack some of the basic knowledge of Ujoint and 1 piece/2 piece shaft interchangeability.

This is a family friendly forum!

I guess my autism has me thinking too literally.

I probably would have said. "Maths is hard! :nabble_smiley_teeth:"

But geometry and trig are pretty easy for me. Integral calculus... not so much.

[Gary Lewis]

This is a family friendly forum!

I guess my autism has me thinking too literally.

I probably would have said. "Maths is hard! :nabble_smiley_teeth:"

But geometry and trig are pretty easy for me. Integral calculus... not so much.

I have a degree in Math, and I hated Calc and DiffE.

[Littlebeefy]

I have a degree in Math, and I hated Calc and DiffE.

The axles and suspension are now fully installed under the truck and I can confirm, definitively, the rear drive shaft is definitely too short. I've checked around for stock applications and the best option is a 78 Bronco, but those aren't very easy to find and it's maybe half an inch too long.

I need an interim solution to get me by until I switch out the rest of the powertrain and get custom shafts.

Tell me if this seems like a reasonably cheap (and especially fast!) solution for getting this resolved. I have a set of driveshafts off an 89 Bronco with the M5OD, so it's a super long front shaft and short rear shaft with double cardan; I'd like to cut the double cardan off the rear, cut the front tube to length, and then weld on the double cardan. Effectively, that is the same as shortening a drive shaft and shouldn't be that expensive, right?

The measurement on the gap between the diff and the tranny is 35" at rest (u-joint cap center-to-center). I have no way of knowing what the measurement is with the suspension compressed hahaha. It appears that the stock drive shafts have 2 3/4" of travel. Am I safe just getting a replacement shaft made to a resting length of 35" just like I'm describing?

 

[Gary Lewis]

The axles and suspension are now fully installed under the truck and I can confirm, definitively, the rear drive shaft is definitely too short. I've checked around for stock applications and the best option is a 78 Bronco, but those aren't very easy to find and it's maybe half an inch too long.

I need an interim solution to get me by until I switch out the rest of the powertrain and get custom shafts.

Tell me if this seems like a reasonably cheap (and especially fast!) solution for getting this resolved. I have a set of driveshafts off an 89 Bronco with the M5OD, so it's a super long front shaft and short rear shaft with double cardan; I'd like to cut the double cardan off the rear, cut the front tube to length, and then weld on the double cardan. Effectively, that is the same as shortening a drive shaft and shouldn't be that expensive, right?

The measurement on the gap between the diff and the tranny is 35" at rest (u-joint cap center-to-center). I have no way of knowing what the measurement is with the suspension compressed hahaha. It appears that the stock drive shafts have 2 3/4" of travel. Am I safe just getting a replacement shaft made to a resting length of 35" just like I'm describing?

Chad - I've noticed on both my F150's and F250 that with the truck on the lift the driveshaft is really hard to get in. In fact, the other day when I reinstalled the rear shaft on Big Blue I had to use a small pry bar to get it in.

So I think I'd jack the rear up and measure in that condition and make the shaft slightly less than that. Doing so will give you the maximum extension when the weight comes down on the truck, ensuring the shaft won't come apart.