Drive shafts too short after 4inch TC lift

[dhenderz]

Got around to installing the rebuilt front & rear drive shafts in to the 77 K10 (see pics on rebuild thread). The truck has a 4 inch Tuff Country lift. Now both front and rear drive shafts are too short. I was able to get the rear shaft installed by tilting the rear of transfer case down a bit (push the front of the transmission up a bit). Not sure if this is the right position or not since the engine is not yet in the chassis. So the rear is in although it is at its slip yoke limit and is presenting holding the transfer case/transmission in place. Went to install the front shaft - no way, its at least an inch too short. I expect I could possibly unhook the rear shaft and tilt the transfer case & transmission forward and connect the front shaft. But there is no way both will hook up.

Is this something any of you have experienced? I cannot believe a 4 inch lift requires new/longer drive shafts. Thoughts?

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[eskimomann209]

I have tilted the output at the trans to make it work before
But you may get vibrations if your “operating angles” are too extreme.
I could give you a rundown but there is a lot of info out there.
Your biggest issue is if the shaft is too short and you step on it it WILL yank out.
I recommend a retube usually 120 ish in my area.
Then you need to decide if you’re going to go with CV or standard joints .
But since you have no engine in and there’s no load on your springs you’re technically a few inches taller than you will be with the body and engine on the frame
So you’ll need to wait to really know anyways

 

[dhenderz]

Yes, I was thinking the same thing. But then I was also considering the fact that at the moment it isn't even at full droop/extension. I have the jack stands under the axles (not the frame). So the weight of the frame, transmission & transfer case are loading the springs. They are new springs and certainly they will settle (in addition to the extra weight of the body & engine). But even after all of that, if the truck ever gets lifted by the frame and goes into full droop, I think it will destroy the axles.

I was thinking of starting with moving the cross member spacers to the top side (between cross member and frame). And then it necessary, maybe consider a spacer for the front drive shaft. I am hoping either or certainly both of these steps might be enough. I am still questioning all of this with only a 4inch lift. I installed a 4 inch (Rough Country) lift on a 94 F150 with no drive shaft issues.

 

[dhenderz]

OK, I believe I've figured out the issue with the rear drive shaft. And yes, it was as usual a simple/stupid mistake on my part. Seems the springs are not symmetrical about the u-bolt rivet. There is a proper orientation for front of spring vs rear of spring. So it would appear that I mistakenly installed them backwards (front facing to the rear). I will rotate them today. Based on my measurements it should shift the axle about 1.5 inches forward. This, I believe, will resolve the rear shaft issue. Will have to see about the front. I expect that one might need to be lengthened or a 1 inch spacer added.

PS - this now explains why I was also having an issue with the parking brake cables being too short. I had a separate post some weeks back with this issue. I ended up making drop brackets to get them hooked up. I expect now I could remove the drop brackets!

 

[78C10BigTen]

Good thing to keep in mind for reference.

 

[dhenderz]

Got the rear springs rotated 180 degrees. Sure enough. Drive shaft fits now. Plus I was able to remove the drop brackets I fabricated for the parking brake cables. Now they fit correctly as well.

It does still look like I will need a 1 inch spacer for the front drive shaft.

 

[77 K20]

Got the rear springs rotated 180 degrees. Sure enough. Drive shaft fits now. Plus I was able to remove the drop brackets I fabricated for the parking brake cables. Now they fit correctly as well.

It does still look like I will need a 1 inch spacer for the front drive shaft.

Perhaps not 100% ideal- but it can be a quick fix to get you going Superlift does make a 1" spacer.

https://www.summitracing.com/parts/slf-4310

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I'm running one right now. I had a custom made Tom Woods driveshaft made for when I had a 3" lift. But now I have a 5" lift with long travel suspension. And I might push my front axle out 1"... so if/when I get all my ducks in a row I'll have a long travel front driveshaft made and I'll eliminate this spacer. In the meantime it has worked for the last 8 months or so just fine.

 

[Craig 85]

I only did a 3" lift on my K30 and had to add to the front driveshaft. Luckily the slip yoke was worn out and by adding a the new one that was a little longer, I didn't have to modify the tubes.

 

[dhenderz]

Where did you get the rebuild kit from? Or did you have it done?

I was also wondering if they make longer yokes (diff end of the shaft) that could be assembled into the shaft, thus effectively lengthening the drive shaft without needing to retube.

 

[Craig 85]

Where did you get the rebuild kit from? Or did you have it done?

I was also wondering if they make longer yokes (diff end of the shaft) that could be assembled into the shaft, thus effectively lengthening the drive shaft without needing to retube.

I think that is what they did with mine. It was $305 parts and labor, but those are California prices.