DIY: Weld-in transmission cross-member and transfer case skid

sjalkian said:
I bought this kit at the same time as my Atlas, but waiting to install for a buddy to help me weld it up:

https://www.tmrcustoms.com/products...MIvLKmitXJ7gIVl-azCh1R5g1zEAQYASABEgKM3fD_BwE
Hopefully this works as is.
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I'm sure you can make it work. I did go a step down in diameter 1.5/1.25 and that helped me get it as high as possible. You'll prob have to remake the long side tabs without bolt holes so you can adapt to the sloping frame width. Use the ones in the kit as the short side.
 
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Nice work! I am looking to add a crossmember to my LJ now so I can drop the belly up skid without supporting everything.
 
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NskLJ said:
Nice work! I am looking to add a crossmember to my LJ now so I can drop the belly up skid without supporting everything.
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Let me tell you, having a crossmember is a game changer.
 
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B00mb00m said:
It really is an incredibly functional modification. Recommend to anyone not just rock crawlers.
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Functional is a great description. My crossmember allowed me to drop my output a full 1 1/4" which greatly reduces my driveshaft angle. Now I have to rework the rear suspension to take advantage of that.
 
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B00mb00m said:
The main reason that I wanted a separate transmission support cross-member from my transfer case skid is so I can pull my driveshaft without supporting the drive train. While I was adding a cross-member I knew I had to strengthen the skid. I have been bending my current skid (3/16 steel) every time I wheel at my local ORV area. I did what everyone should do in this situation... I talked to the Wizard.

The reason why I wanted to DIY this instead of purchase the Savvy kit or Genright X-member+skid combo was three-fold.
  1. First, given my experience with the UCF skid I was currently running, the holes on these frames are not accurate and require slots in the skids and I even had to open the slots an addition 1/2" with a dremel tool. I also wanted the new skid to for sure work with my UCF engine skid. The beauty of DIY is you can build it perfect, don't have to accomodate anyone's tolerances except that of yourself. Of course it also means you can f**k it up all on your own also.
  2. Secondly, i had recently got some JL control arms for free and I wanted to try to hack one up and make a cross-member on the cheap. At some point, I think this happens to a lot of people, you start enjoying the process more than the result. I like building somewhat, i mean I'd like it more if I was better at the fabrication processes, but I really like designing.
  3. Finally, I had yet to draw up any parst on my jeep in CAD. I use 3D modeling software at work most days of my life. I thought it was kind of odd I hadn't drawn up anything or really designed any parts besides like on-the-fly brackets and what not. This is the first of three things I wanted to design with bent up aluminum plate. So i used this opportunity to find a local fabricator I could work with to bend stuff for me.
Things you should probably do first:
  1. SYE / Body Lift / Motor mount lift. This will give you the clearance to pick your drivetrain up so you can get the cross-member as high as possible.
  2. With a body lift you can now move your fuel lines and rear brake line on top of the driver side frame rail. I think this is well-documented in Savvy Midarm installation, but if any one has questions I can show how I did it also. You must move your lines in some manner so you can weld the tabs to hold the cross-member on your driver side frame rail.
  3. *Maybe the rubicrawler for those 42RLE folks. I do want to add the rubicrawer in future. That part does replace the part you currently mount to. I'm hoping it's the same, but it would be smart to do the rubicrawler before you build a mount for that bolt-pattern. ya'll know me, tho, I LOVE doing things 3 times.
Supplies you need:
  1. qty 2 Bushings - these provide vibration isolation between your drivetrain and your frame.
    1. I did buy a set of 1.75" Bushing Assembly (BA175) from Autofab.
    2. I chose to use JL control arm bushings as they felt more compliant.
  2. QTY 4 - Tabs - make your own or purchase. I bought low hanging tabs from Autofab.
    1. Bushing Tab - T106
  3. Cross-member telescoping steel tube:
    1. ~14" of 1.5" OD x .120" wall DOM (no weld inside)
    2. ~3' of 1.0 X .120" HREW or DOM.
    3. Maybe 1.5" holesaw for mount.
    4. Pipemaster 1.25" od coping tool. I used this style tool on my coilover hoops and its awesome! It made the compound angle cope easy (though I still messed it up). I got mine from Summitracing PFR-P-T125
  4. Some sort of skid.

Prep Work:
- Take measurements of your current setup. I recorded front drive shaft angle, transmission pan height, skid to floor height, and rear driveline angle. This will help you with a place to start or return to the old setup if you end up moving things around. Also reach on top of the transmission near the bell housing and find out where your closest point of contact is. This will be your limiting factor of how far up you can move the drivetrain (if you so desire).
- Support drivetrain. I used a floor jack and a piece of 2x6 under the transmission pan as close to the existing skid as possible. I also kept a back up jack stand under the end of transfer case when i was working under neath.
-Remove nuts attaching transmission mount to the transfer case skid.
- Drop skid.

Now you should have a view like this:

View attachment 156392

That giant can on the passenger side frame rail is going to be a problem. Temporarily remove it from this volume so you can mock up and install the cross-member.

Get a rough measurement here with how far up you can push the 1.5" tube and not contact transmission or transfer case.

Then get a measurement of how far out you will want to mount the tube center considering the item you need to avoid is the driveshaft at full droop. If you mount the tube center under the front UJ yoke, it's very unlikely you will have contact (if you leave the cross-member straight). Those of you with bent ends on the tubes (Genright esque) will have to position that respectively. Its in the 3.5-4 ballpark, and I chose 3.75" approximately.

View attachment 156393

Now that you have an idea of where things need to be it's time to start the creative process (the fun part).
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@B00mb00m the parts list has 1.0” tubing did you use 1.25” tubing it looks like a snug fit in the 1.5 .120 wall.
 
NskLJ said:
@B00mb00m the parts list has 1.0” tubing did you use 1.25” tubing it looks like a snug fit in the 1.5 .120 wall.
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I'll have to check what I actually used. You're right there is an error there somewhere. Either 1.25 x .120 for the sleeve with 1.0" sliders or 1.5x.120 wall sleeve with 1.25 OD sliders. I'm guessing I used 1.5 for center and 1.25 for ends.
 
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can i cliff note this thread.? you where bending/flexing ithe stock skid plate? (rock crawling?) to stop this you raised the trany/transfer case with a cross member and put a higher aluminum skid plate on?
have you had any engine or cooling problems since? are you bending/scaring the aluminum skid? did you think of putting UHMW on it? did you change the angles of your front and rear axles? any driveline vibration?
 
Bald Fat Dad said:
can i cliff note this thread.? you where bending/flexing ithe stock skid plate? (rock crawling?) to stop this you raised the trany/transfer case with a cross member and put a higher aluminum skid plate on?
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Yes

Bald Fat Dad said:
have you had any engine or cooling problems since?
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No

Bald Fat Dad said:
are you bending/scaring the aluminum skid?
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Bending no, scratches definitely but looks sustainable.

Bald Fat Dad said:
did you think of putting UHMW on it?
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UHMW is softer than 6061-t6 if I was going to skin the skid in something I’d want to use something harder than the base.
Bald Fat Dad said:
did you change the angles of your front and rear axles? any driveline vibration?
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My situation isn’t relevant to most given I ended up redoing it with an atlas and already had JK axles. Yes it can change your pinion angles and you may have to readjust. If your angles are too great you could get vibes.
 
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