Drive Shaft Lengthen/Spacer (1 Viewer)

[DavidAW]

Hi
Just did a Shackle Reversal (I know, I know) and may need to lengthen the DS.

I've read other posts and figure it should cost between $100-$200 to get it lengthened.

I also see that a couple places make spacers for small length needs. (I havent determined my exact needed length yet)

Anyone every used these, or have any knowledge?

TOYOTA DRIVE LINE SPACERS 1.0 INCH & 1.5 INCH - Longfield Super Axles

4Crawler Offroad Products - Driveshaft Spacers

 

[Cruiserdrew]

Just take your drive shaft to a drive line place with the flange to flange measurement. Tell them you have a reversed shackle situation and they will set the length properly. There is a fairly good chance you will need a long travel kit and they can install that. It involves removing your existing slip joint and welding in a longer splined section.

When I did the front driveshaft on my FJ40 they added a slip joint with 11 inches of travel for $200. I would recommend that because then you don't need to worry about it coming apart, or worse, running out of compression and smashing your transfercase. The long travel slip was a commom Spicer part and heavier duty than the Toyota part it replaced.


Just to give you an idea, changing a drive line length is $80-$100 here, depending on whether you want it balanced or not. Front shaft you don't need to.

 

[Cruzerman]

Like Andrew said, with a SR, the driveshaft now will compress more where before it was expanding. You need to be sure that you do not running out of slip joint, or else you'll bottom out and most likely bust your transfer case.

 

[DavidAW]

Thank to both for the advice.

I'm am still trying to get my head around the DS potential issues.
I assumed that since I have moved the axle away, I wouldnt need to worry about compression as much. I was more worried about it coming apart.

In this pic you can see that the shaft is extended about 2" more than before, the greasy area.

Does the compression bottom out when the yolk hits the smaller part at the arrow on the right?



Thanks
Dave

 

[Mark W]

You never need a shaft balanced if it is straight. The factory does not put the effort into making each shaft perfectly straight. Does not make economic sense. Any shop doing them one at a time should. Few do.

In an SR situation, the dif moves away (forward) from the T/C under droop as it also moves away vertically. In the normal fore shackled arrangement, the diff moved closer (rearward) as it moves down. The two motions go a long way toward offsetting each other. Which is why Cruisers have such short slip joints. In the OEM setup, the pinion also points upward more as the diff droops. in the SR, it points down more. All of this equates to a greater movement at the slip joint as to steeper Ujoint angles.
These are some of the things everyone should understand before undertaking an SR.

If you just lengthen your DS after your lift and SR, You may find that it is a good length when drooped, but that it bottoms out when compressed. Or if it does not bottom out when compressed, it may pull loose under droop.

The spacers you are considering.... result in a steeper Ujoint angle because they effectively shorten the distance between the ends of the DS.

Might work for you.
Might not.


Mark...

 

[DavidAW]

Thanks, I think I have a better understanding of the movement now.

As soon as I get my brake lines in I can flex it and find out what I really have.

I'm not really too concerned about the spacers. I stumbled across them doing searches and couldnt find any information on them here.

Thanks
Dave

 

[Cruiserdrew]

I'm not really too concerned about the spacers. I stumbled across them doing searches and couldnt find any information on them here.

Thanks
Dave

Just remain concerned about the travel in the drive shaft spline. With a shackle reversal you cannot afford to over compress your driveshaft,(which you can easily do because of the geometry and relationships of the leaf springs and shackle). It will do extremely bad things to your transfercase. If there is any doubt, at all, get a longer spline put in there. Remember a spacer re-establishes the right length, but actually takes up some of the compression stroke of the shaft.

Over time I have come to like the SR I did on my 40. I'm not going to bust your chops for that. The approach angle is much better. You just have to accept that spending money on additional required mods is just part of the game.

 

[DavidAW]

Thanks Drew,
Believe me, I am now more deternmined than ever to test this on the driveway.

My only problem now is procedure. I can do the full droop on a jack.
But testing compression is tougher.
I'm open for any ideas there.
I can get 1 wheel stuffed at a time, but not sure how to test the extreme.
Maybe stuffing the PS wheel is enough, since the Diff is on that side.

Again, thanks to All. Good info here.

Dave

 

[lehiguy]

I have eleven or twelve inches if slip yoke on my front DS (Spicer stuff) and I use it all. I'm SOA with the shackles in the rear of the spring. Remember, going forward under a load, the front pinion rotates downward extending the DS even more. I would shoot for a MINIMUM of two inches of engaged splines (or more) at full drop.

 

[Mark W]

it is a bit of work and "figurin'", but yiu can get the numbers you need without ever compressing the spring:

Measure along the arc of the spring from the frame mount to the center pin. Then do the same all the way along the spring. Using this second number measure straight back from the frame mounted end of the spring and see how far the shackle has to swing to meet the end point that you measured. This gives you the location of both ends of the spring when it is flat. Using the other measurement (the one to the center pin), you can determine where the center pin will be too. Measure the difference laterally from the front of the spring and you will see how far back the axle is at the furthers shift rearward. Measure the difference in height from the spring pin as the rig sits there and the determined location that you have found by measuring. Now you know how far up the axle will shift.

Apply these two measurements to the location of the pinion flange as the rig sits there and you will know how much the axle will move and how short the drive shaft will be under the maximum rearward shift. IF you springs flex beyond flat the spring arch begins to move the axle back forward.



With some practice it becomes pretty easy to figure this out.... and always add in some safety margin just to be on the safe side.


Mark...

 

[DavidAW]

it is a bit of work and "figurin'", but yiu can get the numbers you need without ever compressing the spring:

Measure along the arc of the spring from the frame mount to the center pin. Then do the same all the way along the spring. Using this second number measure straight back from the frame mounted end of the spring and see how far the shackle has to swing to meet the end point that you measured. This gives you the location of both ends of the spring when it is flat. Using the other measurement (the one to the center pin), you can determine where the center pin will be too. Measure the difference laterally from the front of the spring and you will see how far back the axle is at the furthers shift rearward. Measure the difference in height from the spring pin as the rig sits there and the determined location that you have found by measuring. Now you know how far up the axle will shift.

Apply these two measurements to the location of the pinion flange as the rig sits there and you will know how much the axle will move and how short the drive shaft will be under the maximum rearward shift. IF you springs flex beyond flat the spring arch begins to move the axle back forward.



With some practice it becomes pretty easy to figure this out.... and always add in some safety margin just to be on the safe side.


Mark...

Dang Mark, you are making my brain hurt.

Actually this makes perfect sense after reading and drawing a couple pictures. It should be in the FAQ.

I'm thinking that I should disconnect the DS once I have the measurments so I can put the end right where it would be under full compression. Then I would know for sure where it is bottoming out. And/or how much more compression I would have.


Thanks for all the extra effort on this.

Dave

 

[ntsqd]

[hijack]

snip......

You never need a shaft balanced if it is straight. The factory does not put the effort into making each shaft perfectly straight. Does not make economic sense. Any shop doing them one at a time should. Few do.

My local shop used to subscribe to this thought as well. What they found was that no matter how careful they were there was always some imbalance in the shafts. Some times it was small enough that it did not matter, other times it was bad enough that the shaft had to be balanced. What it came down to was two things that they had no control over. How straight the tube used was, and how consistent the density of the metal in the tube was. A perfectly straight tube isn't as easy to get as it might sound like. Obviously no reputable shop would build a shaft using tube that is visually bent, but a tube that looks straight can still just be not straight enough that it causes balance problems. As odd as it sounds, steel is not consistent in it's density, and that inconsistency can be enough to require balancing. They still shoot for building a shaft that requires no balancing, but also realize that a shaft needing some minor balancing isn't necessarily a failure on their part.[/hijack]

 

[Mark W]

I can accept some balancing occasionally. Especially in higher speed use than a Cruiser normally sees. But shops that automatically sell you balancing as a add on and do not make the effort to make the shaft straight enough to spin true really irritate me. And it is all to common.

My primary DS guy has made over 100 shafts for me and never had to use a weight. They were all true enough that for use under a Cruiser, no vibration was detectable at any speed. Actually 2 needed some attention, and he re worked them a little straighter, but still did not need weights.


Mark...

 

[ntsqd]

Checking and adjusting the balance should be part of the job of building a drive shaft, any drive shaft. I agree, it shouldn't be sold as a separate service. It's not like when getting new tires installed.

 

[DavidAW]

Ready to test DS

OK, got my brake line in and was able to flex it out.

The 2 pics below are both with shocks and sway removed.

First is with DS tire way off the ground, 2nd is at full droop.

I can see splines obviously. But it did not seperate.

Can anyone tell by these pics how much of the male spline part still remains in the shaft?
Or does anyone have a drive shaft laying around that can tell me how many inches of spline are beyond the dust cover?

Thanks
Dave