Geometry / Driveshaft Question

[Intimnasc]

So been working on my build thread and came across a problem I need help with. I bought the Jeep with 4" suspension lift and a 1" transmission drop (realized this when adding the body lift). So now I've added a 1.25" body lift and 1" motor mount lift and the shifter started hitting again, I modified the plastic and if I hold down on 2, 4, and R it works but if not it sometimes pops out. If I remove the transfer case drop I think it will get me going. In January I plan on getting the UCF intermediate tummy tuck (Not sure I wanna try to dent the tunnel to make things fit) and plan on ordering a drive shaft from Tom Woods. What are my risks driving for a month? Am I going to tear up my driveshaft or rear diff if the shaft is a little short? Any help from the geometry tummy tuck guys here is appreciated

 

[TheBoogieman]

Remove the larger drop and use thick washers to drop it just enough to get rid of any vibes. I did that on two of my Jeeps with zero issues.
p.s. I've got 3" springs/1.25" BL on my Rubicon with no MML or t-case drop. I bought a fake leather shift boot to replace the thick rubber one. That fixed my issue with mine popping out of reverse or grinding. Best $9 I've ever spent.

 

[macleanflood]

Might even be a good with a lite tummy tuck skid plate. Up an inch or so.

-Mac

 

[Intimnasc]

Tummy tuck I'm prolly doing is 2.5 so I'm good with getting a new drive shaft I am just trying to relieve the problem long enough for me to go out of town come back and order everything.

 

[05rubi]

Remove the larger drop and use thick washers to drop it just enough to get rid of any vibes. I did that on two of my Jeeps with zero issues.
p.s. I've got 3" springs/1.25" BL on my Rubicon with no MML or t-case drop. I bought a fake leather shift boot to replace the thick rubber one. That fixed my issue with mine popping out of reverse or grinding. Best $9 I've ever spent.
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sorry little late to the thread but how long have you been running this? i got a 2.5” lift and 1” tc drop on my rubicon (bought it that way) and was wanting to delete the drop and go to 3.5” lift (willing to do a mml if needed don’t wanna do BL tho) just not sure what best option is for geometry and trying to make driveshafts last im trying to avoid going double cardan incase i go bigger in the future don’t wanna have to resize again

 

[JMT]

sorry little late to the thread but how long have you been running this? i got a 2.5” lift and 1” tc drop on my rubicon (bought it that way) and was wanting to delete the drop and go to 3.5” lift (willing to do a mml if needed don’t wanna do BL tho) just not sure what best option is for geometry and trying to make driveshafts last im trying to avoid going double cardan incase i go bigger in the future don’t wanna have to resize again

You don’t need another DC. You have one with your Rubicon. What you need is adjustable control arms. If you go to 3.5” you may need to get the DC shaft lengthened, or it may be fine. You just want enough spline engagement that it doesn’t slide out when the axle droops.

 

[jjvw]

You don’t need another DC. You have one with your Rubicon. What you need is adjustable control arms. If you go to 3.5” you may need to get the DC shaft lengthened, or it may be fine. You just want enough spline engagement that it doesn’t slide out when the axle droops.

From the factory, the only double cardan driveshaft the Rubicon came with was in the front.

 

[JMT]

From the factory, the only double cardan driveshaft the Rubicon came with was in the front.

I think that’s like the second time I’ve posted that. NO need for an SYE! I’ll stop!

 

[GoldenGorilla]

sorry little late to the thread but how long have you been running this? i got a 2.5” lift and 1” tc drop on my rubicon (bought it that way) and was wanting to delete the drop and go to 3.5” lift (willing to do a mml if needed don’t wanna do BL tho) just not sure what best option is for geometry and trying to make driveshafts last im trying to avoid going double cardan incase i go bigger in the future don’t wanna have to resize again

The Rubi driveshaft is shorter due to the length of the 241TC which can make the angles pretty steep. 3.5" is pushing it. The TC drop is probably there for a reason.

You might be able to help it with a motor mount lift. But if you want that clearance now, a motor mount and body lift may let you get rid of the TC drop, end up at the same height while costing much less.

For context I have an 04 Rubi with 2.5" lift and when I installed a Barnes no-lift skid it moved the transmission up 1/2" but the tail of the 241OR a bit higher. The DS was not OK with it and I used some drop spacers for the summer. I'm just now installing the DC and getting it dialed in with a DC.

The rear DC shaft can be +-1/2" and as you go up you'll be rotating the pinion up, bring the points closer.

 

[Intimnasc]

So when I added the 1" MML it made a huge difference. I was able to totally remove the T-case drop and no problems as yet. I'm on a 4 inch lift, 1" MML, and 1.25" body lift with T-case back in stock position. I call Tom Woods and spoke to their main guy about when my control arms get here and I do the 2.5" tummy tuck and he said most likey I'll be fine for the week or so it takes to get my new drive shaft. But with stock height T-case been driving for several weeks now and no issues. Not that over time I won't get issues which is why I ordered the Savvy control arms and will measure drive shaft as soon as everything else is done. Worst case of it causes a problem I can drive on the front shaft for the week it takes to get a new rear

 

[TheBoogieman]

sorry little late to the thread but how long have you been running this? i got a 2.5” lift and 1” tc drop on my rubicon (bought it that way) and was wanting to delete the drop and go to 3.5” lift (willing to do a mml if needed don’t wanna do BL tho) just not sure what best option is for geometry and trying to make driveshafts last im trying to avoid going double cardan incase i go bigger in the future don’t wanna have to resize again

Almost 8 years on this setup. You don't need a BL to do a MML. You just have to relocate the fan shroud.

 

[05rubi]

You don’t need another DC. You have one with your Rubicon. What you need is adjustable control arms. If you go to 3.5” you may need to get the DC shaft lengthened, or it may be fine. You just want enough spline engagement that it doesn’t slide out when the axle droops.

sorry i do have 8 adjustable control arms already in shoulda mentioned that

 

[GoldenGorilla]

sorry i do have 8 adjustable control arms already in shoulda mentioned that

incase i go bigger in the future don’t wanna have to resize again

You've got what you need to get started and go.

If you contact Tom Woods, they'll tell you most of their Rubicon DC driveshafts are between 16" and 17". For my Barnes no-lift skid + Rancho 2.5" spring with no BL and no MML I needed a 16.5" partly because the output shaft is turned up slightly from stock by my skid. A MML would shorten that and I have one on hand if I need it. I also have some 1/2" aluminum spacers or can run down to Ace for some thick washers in case I want to lower the T-case slightly. I'm dialing in the control arms/pinion angle right now.

If you look at a diagram of how the DC shaft is setup and think about the way you need to rotate the pinion up with a DC shaft as you lift you'll kinda see why the range of lengths is relatively small. Again, TW has some good demonstrations of this. If you are currently going to measure 16.5" and think you might go up 1-1.5" lift in the future and you buy your driveshaft at 16.75", that'll put you currently well within it's +/-1/2" range now and give you up to 17.25" on the long end, which should be plenty of flexibility. It's best to install the lift, set the pinion to point to the output and get a good measure before your order. You can drive your Rubi in FWD by putting it in 4Hi with no rear driveshaft even though it feels very strange and can be a bit clicky when turning on dry pavement.

Eventually you will end up outside the range the driveshaft can operate within and you'll just have to suck it up and buy a longer one, but there is probably more flexibility than you think.

 

[Intimnasc]

Eventually you will end up outside the range the driveshaft can operate within and you'll just have to suck it up and buy a longer one, but there is probably more flexibility than you think.

That is basically what the guy from Tom Woods told me on the phone. As long as you don't get vibration you are probably ok. I was concerned about doing without the jeep while I waited on the new shaft and he said as long as I call him on Monday morning it will almost always be delivered by Friday. The guys at Tom Woods are freaking awesome.