The Official Tummy Tuck FAQ Thread

My question is this: for a largely street and fire trail Jeep with a 2" suspension lift and 31s (maybe 33s when the 31s die and after a BL and MML), would the Teraflex or UCF plates (needing only a MML or BL, respectively, which were likely going on anyway) be a viable option for increasing ground clearance without necessitating the purchase of a new driveshaft, SYE, adjustable control arms, and and and or would all the other stuff be needed anyway?
Terrible answer but, maybe.

You really won't know until you get it on. At the very least I'd guess you'd need adjustable upper or lower rear control arms. Remember the jeep doesn't know if you're adding height due to springs or a tuck. So if you raise the jeep 2" and then raise the belly 2" (total guess on height gain) as far as the TC is considered it's a 4" lift. Now the good thing is if you add a tuck such as the UCF and run into vibrations you can always lower it down with spacers or washers until the supporting mods are installed if needed.
 
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All that said though for a mostly street/fire road jeep I don't see a tuck, mild or not, being needed. I say start taking it on the trails you want to go on and you'll figure out quick if you're getting stuck on the belly. @Thunderhead ran the rubicon with us when his rubicon was on a 2" budget boost and 32s. I won't say it was always pretty since it was deemed the snow plow for rocks durning that trip but it did everything exect Lil sluice and didnt take any damage. Just banged up the stock skids and tube bumpers. These Jeeps are really capable out of the box.
 
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Terrible answer but, maybe.

You really won't know until you get it on. At the very least I'd guess you'd need adjustable upper or lower rear control arms. Remember the jeep doesn't know if you're adding height due to springs or a tuck. So if you raise the jeep 2" and then raise the belly 2" (total guess on height gain) as far as the TC is considered it's a 4" lift. Now the good thing is if you add a tuck such as the UCF and run into vibrations you can always lower it down with spacers or washers until the supporting mods are installed if needed.

I think I see it now. The Teraflex "All you need to do to correct driveline angle is a MML" and UCF's "All you need to do to correct driveline angle is a BL" is predicated on the angle being "OK" before shoving the transfer case up another X inches? I'm guessing 2" springs with 1.25" BL with a ~2" TC tuck (via plates) isn't going to leave the driveline at an optimal angle.

Bear with me: it take me awhile to get there, but I will get there.
 
All that said though for a mostly street/fire road jeep I don't see a tuck, mild or not, being needed. I say start taking it on the trails you want to go on and you'll figure out quick if you're getting stuck on the belly. @Thunderhead ran the rubicon with us when his rubicon was on a 2" budget boost and 32s. I won't say it was always pretty since it was deemed the snow plow for rocks durning that trip but it did everything exect Lil sluice and didnt take any damage. Just banged up the stock skids and tube bumpers. These Jeeps are really capable out of the box.

Good to know. If some is good, however.. well, you know.
 
I think I see it now. The Teraflex "All you need to do to correct driveline angle is a MML" and UCF's "All you need to do to correct driveline angle is a BL" is predicated on the angle being "OK" before shoving the transfer case up another X inches? I'm guessing 2" springs with 1.25" BL with a ~2" TC tuck (via plates) isn't going to leave the driveline at an optimal angle.

Bear with me: it take me awhile to get there, but I will get there.
You’re thinking right. If the TCase is seeing 4” of lift your driveline is not going to be happy. After a BL and MML, all that would be required would be rear CA’s, DC, and SYE.

EDIT: You cant fix the driveline angle caused by 4" lift with a MML.
 
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Mine starts to bind at about 5.5" of droop from ride height. That seems to be where it happens. My answer was to add a center limit strap between the diff and shock mount crossmember.
I just created a quick drawing, explaining something regarding limit straps for a guy so I decided it might be a good idea to use that drawing to add to any other conversations about limit straps. In case someone looking for answers stumbles upon this thread in the future.

Here's the deal with limit straps, they don't need to limit your wheel travel. If you put just a single limit strap over the differential as mentioned by jjvw above, that will prevent the drive shaft from binding but still allow the axle to see-saw and give you full independent wheel articulation. The attached drawing illustrates this.

LIMIT STRAP.png
 
What if the limit straps keep the springs in? What if the limit straps prevent the shock from breaking off the mount? I don't know, I don't run them but I didn't think their only purpose was protecting the driveshaft from over extension.
 
What if the limit straps keep the springs in? What if the limit straps prevent the shock from breaking off the mount? I don't know, I don't run them but I didn't think their only purpose was protecting the driveshaft from over extension.
I think he’s pointing out a limit strap doesn’t have to limit flex.

If you run straps for another reason, that’s a different story.
 
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What if the limit straps keep the springs in? What if the limit straps prevent the shock from breaking off the mount? I don't know, I don't run them but I didn't think their only purpose was protecting the driveshaft from over extension.
Good point/question. I have a habit of looking at things through the lens of the drive shaft so when I tell someone they need a limit strap it's to prevent binding on the drive shaft. Usually I'll bring up this center strap axle see-saw thing because people get cagey when they think I'm telling them they need to limit the down-travel on the big expensive coil-overs they just installed. There are other reasons to run limit straps though and some of those reasons would necessitate putting two straps out closer to the wheels.
 
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What if the limit straps keep the springs in? What if the limit straps prevent the shock from breaking off the mount? I don't know, I don't run them but I didn't think their only purpose was protecting the driveshaft from over extension.
It is in my case. My shocks are the limit to droop, but that puts the rear driveshaft into bind. So I added a center strap as pictured.

But no one is saying a limit strap can't be used for other purposes. Nothing is stopping me from adding an additional straps to limit the shocks, except that I believe it to be unnecessary.
 
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Here's the deal with limit straps, they don't need to limit your wheel travel. If you put just a single limit strap over the differential as mentioned by jjvw above, that will prevent the drive shaft from binding but still allow the axle to see-saw and give you full independent wheel articulation. The attached drawing illustrates this.

View attachment 329788

I'm sure you're right about what you posted but I don't think you chose the best wording that I changed to red. If full independent, one side going down wouldn't force the other side up, down or anywhere. I'm just saying that for anyone seeing this that might not know enough about suspensions to realize what exactly is what.


Now after looking at your 2nd picture while typing that, I'm wondering if anyone has ever rotated the big Cs and steering knuckles on each end of a front axle a good 90 degrees or so, installed it in the rear and used some heavy ass tie rods to connect each knuckle to the frame to keep those tires perpendicular to the world below them and away from the stuff beside them (frame, springs, whatevers). Oh, and ditch the ball joints (now on their sides) for king pins and.... Oops, sorry I'm already just wondering too deep into a rabbit hole of craziness that isn't needed but at least I'm glad I didn't wander into.
 
I'm sure you're right about what you posted but I don't think you chose the best wording that I changed to red. If full independent, one side going down wouldn't force the other side up, down or anywhere. I'm just saying that for anyone seeing this that might not know enough about suspensions to realize what exactly is what.


Now after looking at your 2nd picture while typing that, I'm wondering if anyone has ever rotated the big Cs and steering knuckles on each end of a front axle a good 90 degrees or so, installed it in the rear and used some heavy ass tie rods to connect each knuckle to the frame to keep those tires perpendicular to the world below them and away from the stuff beside them (frame, springs, whatevers). Oh, and ditch the ball joints (now on their sides) for king pins and.... Oops, sorry I'm already just wondering too deep into a rabbit hole of craziness that isn't needed but at least I'm glad I didn't wander into.

You are absolutely right, by definition the wheel travel on one side is actually dependent on the other side. For one side to go down to max droop the other side will have to go up some. It's not independent suspension. Of course what I mean and what I hope most people understand is that limit straps don't have to limit suspension travel as much as most people would imagine. In most real world scenarios for one tire to droop out full the other one gets stuffed anyway so the center strap doesn't limit suspension travel in the most slow speed scenarios. Jumps or whoops are a different story though.

In my second picture, the only reason the tires are perpendicular to the ground simply because it was a 5 minute Microsoft paint drawing, I didn't have the tools nor the time to change the angle of the tires. In real life of course the tires would stay perpendicular to the axles and would tip to the side, on a rear axle at least. I also wonder if anyone has figured out a way to keep the front tires perpendicular.
 
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Hope I can describe this right as my brother has my LJ and can’t seem to get him to dig out his account here.

‘05 LJ 6sp 4”Currie lift Savvy BL BrownDog MML

Finished up Savvy crossmember and tranny mount quick test drive all fine. Parked for whatever reason on tire on edge of gravel pile. Now when start can is rubbing bottom of shroud but can find anything that seemed to have moved, was loose, etc. Any idea where should be looking or that maybe installed wrong?
 
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Hope I can describe this right as my brother has my LJ and can’t seem to get him to dig out his account here.

‘05 LJ 6sp 4”Currie lift Savvy BL BrownDog MML

Finished up Savvy crossmember and tranny mount quick test drive all fine. Parked for whatever reason on tire on edge of gravel pile. Now when start can is rubbing bottom of shroud but can find anything that seemed to have moved, was loose, etc. Any idea where should be looking or that maybe installed wrong?

The frames on these Jeeps flex, so it's likely the clearance was enough that it doesn't hit on level ground. When one tire is on something like a gravel pile, it must be twisting the frame just enough to make the fan hit the shroud. You'll need to check the clearance on level ground and adjust the shroud accordingly.
 
The frames on these Jeeps flex, so it's likely the clearance was enough that it doesn't hit on level ground. When one tire is on something like a gravel pile, it must be twisting the frame just enough to make the fan hit the shroud. You'll need to check the clearance on level ground and adjust the shroud accordingly.

He has had it back on level ground, on lift, etc. Still seems to rub. Like you said almost as if tweaked something parked like that but can’t seem find it. Almost like he is overthinking it just needs focus on trying adjust shroud as think he went back through tranny mount etc.
 
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Hope I can describe this right as my brother has my LJ and can’t seem to get him to dig out his account here.

‘05 LJ 6sp 4”Currie lift Savvy BL BrownDog MML

Finished up Savvy crossmember and tranny mount quick test drive all fine. Parked for whatever reason on tire on edge of gravel pile. Now when start can is rubbing bottom of shroud but can find anything that seemed to have moved, was loose, etc. Any idea where should be looking or that maybe installed wrong?

X2, when you raised the TCase for the TT it tilted the engine down, so it’s rubbing the fan shroud again. 1 change begets another.
 
Does anyone know if the savvy tummy tuck is still being produced or has it been discontinued?
 
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