Most 2" kits only come with rear bump stop extensions. I assume the same applies for the 2.5" kits.
Diagnosing TJ after 2.5 inch Rancho lift kit install
- Thread starter GrandpaJeepTJ
- Start date
Most 2" kits only come with rear bump stop extensions. I assume the same applies for the 2.5" kits.
Even so,my rancho shocks that work with a 2.5" lift needed extra front bumpstop
The vibration is definitely a common after-effect from installing a suspension lift like your 2.5" from Rancho. It's caused by the u-joints on the rear driveshaft vibrating due to the excessive angle they are now working into with the rear driveshaft's now steeper angle.
There are possible three fixes depending on your budget and mechanical skills. From lowest cost and easiest to install to highest cost and most complexity. Of course the order of desirability also goes in the same order.
1) Install a transfer case lowering kit which consists of six spacers that are inserted between the skid plate under your transfer case and the frame, the six mounting bolts pass through them. Looks like this, and they are not expensive. This works by reducing the angle of the rear driveshaft which reduces the excessive angle the driveshaft's u-joints have to work into which stops them from vibrating. This also of course causes a 1" loss of ground clearance beneath the skidplate... if that's important to you as it is to most offroaders.
View attachment 406166
The next most desirable fix is a pair of motor mount lifts. They lift the front of the engine 1" which tips the engine/transmission/transfer case angle a bit to lower the rear transfer case output shaft the rear driveshaft connects to. It works to reduces the angles much like a transfer case drop but without the resulting loss of ground clearance. This also gives the engine's oil pan 1" more ground clearance, a very good thing. You can buy motor mount spacers from https://savvyoffroad.com/product/sav-mmltj/ or if your motor mount rubber bushings are getting old you can get a pair of complete motor mounts with the 1" lift benefit from https://mountainoffroad.com/collect...f-motor-mount-kit-for-1-lift-97-06-yj-tj-lj-1
Best of all but also most expensive is to install a SYE (slip yoke eliminator) kit into the transfer case and replace the rear factory driveshaft with an aftermarket double-cardan driveshaft. It also requires new adjustable length control arms in the rear because the rear axle's pinion angle has to be raised up significantly to match the requirements of the new rear DC driveshaft. This is what those of us with 4" or taller suspension lifts run. Fortunately, cost and labor-wise, this is not really needed for just a 2.5" lift but if you ever get to 4" of suspension lift then it would be required.
Personally, I'd go with motor mount lift blocks if your existing motor mounts are in good condition. This is a good solid fix that doesn't lose ground clearance. Good luck with it all!
I am having the same issues on my TJ after a 4" lift, line drive vibration. shaft joint seems to be fine but i will double check, I also have the transfer case drop installed which i hate . my question is, If I install a SYE and a motor mount lift will i be able to eliminate the TC spacers ? thank you
Yes,you should remove the spacers with an sye.you need a double cardan driveshaft and adjustable rear control arms with an sye.
Without a body lift idk if I'd do a motor mount lift. Pushing the motor up makes it tough to get to bellhousing bolts,crank trigger,etc without one.
Vibrations are normal with a 4" suspension lift even after installing a transfer case drop. Best would be to install a SYE and DC driveshaft which also requires adjustable length rear control arms. This would allow the transfer case drop spacers to be removed.
Or, and this would be a second place choice, would be to install a pair of 1" motor mount spacers or 1" taller motor mount lifts like from Mountain Offroad Enterprises. This would require the tcase lowering kit remain in place which of course causes a loss of ground clearance.
Or, and this would be a second place choice, would be to install a pair of 1" motor mount spacers or 1" taller motor mount lifts like from Mountain Offroad Enterprises. This would require the tcase lowering kit remain in place which of course causes a loss of ground clearance.
When you get your new tires installed, check the air pressure. Many (most?) tire shops will put WAY too much pressure in them. For 33-inchers on a TJ, 26 or 27 PSI is about right. If it feels wonky on the way home, it might feel a lot better after you set the correct pressure (for both steering and ride).
got it , Thank you, will definitely go with SYE, DC shaft and adjustable rear uppers, ill do anything to get rid of those ugly purpose defeating TC bars.
thank you , definitely going with your advise on the SYE and DC
@GrandpaJeepTJ When replacing the motormounts with a MML.... get NEW hardware. Do not re-use the bolts that attach the mount to the engine.
I was told this by 2x different mechanics, one was a certified jeep mechanic in Reno; while I was 10k feet into the mountains with my engine dragging on the ground.
My motor mounts sheared off. One of the lessons learned was that the stock bolts were meant to be used once and not removed. If removed then reused... they lose their shear strength.
I was told this by 2x different mechanics, one was a certified jeep mechanic in Reno; while I was 10k feet into the mountains with my engine dragging on the ground.
My motor mounts sheared off. One of the lessons learned was that the stock bolts were meant to be used once and not removed. If removed then reused... they lose their shear strength.
You need the cup and jounce up top, and you need bumpstop on the lower perch. At 2.5” you’ll need about 2” of bumpstop. I use hockey pucks. You drill and tap a hole in the lower perch. Then get appropriate length grade 5 bolt and bolt them on.
These companies that package lifts can totally suck. They sell you an incomplete kit under the guise it’s complete, then up sell you into more stuff to complete it. Jerks.
OP
Are you talking the pass through bolts that go through the motor mount bracket and thru the engine mount? Or the 3 bolts that hold the bracket to the engine block?
OP
Ok. Perfect I just went and found these. They came with locktight or anti seize on them from jeep dealer, not sure. Still torque to 45 ft lbs?
That sounds about right, the FSM doesn't specify the torque for those particular bolts or at least I couldn't find it. I certainly wouldn't go any tighter than that.
Using regular bolts is an option. I get rid of torque to yield fasteners on all my rigs when advisable.
3x bolts that go into the engine block.
btw.. Cedarburg? Beautiful town. Brings back memories... when I was living in Muskego/Franklin.
OP
Guys! The 1” body lift and 1” motor mount lift did wonders! No more vibration over 50 mph. I also no longer hear any clanking during turns, so I attribute that to either the new, longer sway bar links torqued to the right spec (found the old were pretty much all very lose) or the MML/BLs. I put some new 15” wheels with 33” x 10.5 A/T bf goodrich tires and did alignment. The Jeep feels lighter and handles a lot more like how I remember - great!
Next up: hockey puck bump stop spacers. In the summer, plan on cleaning out the frame and painting the entire underside.
Question (I’m full of them if you haven’t already noticed: I’ve not used the shifting linkage adapter bracket that came with my 1” BL and the 2.5” suspension lift. What exactly does this do and what would be a result of not using? I see a lot of people replace with a cable type shifting system and call the OEM “one of the worst inventions ever.”
Thanks a bunch for all your guys’ help getting this baby back riding like it should be!
Next up: hockey puck bump stop spacers. In the summer, plan on cleaning out the frame and painting the entire underside.
Question (I’m full of them if you haven’t already noticed
: I’ve not used the shifting linkage adapter bracket that came with my 1” BL and the 2.5” suspension lift. What exactly does this do and what would be a result of not using? I see a lot of people replace with a cable type shifting system and call the OEM “one of the worst inventions ever.”Thanks a bunch for all your guys’ help getting this baby back riding like it should be!
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OP
Thanks. I found some of these and installed this weekend. All the videos I watched replacing that mounting bracket just used the old ones, so if it wasn’t for you, I would have done the same. Thanks!
yep, cedarburg is a great small town. I moved here 6 months ago. Originally from the Racine area. Had a stint out in lake forest ca for a couple years. Couldn’t let go of the 4 seasons I guess and ended up back here! Ha
I did a similar lift to you... and had to replace the stock shifter linkage with a cable shifter. It solved a problem of the transfer case popping outta 4lo into neutral. Do you have a manual? If so, you may need to adjust back 1/2 inch the shifter bezel/cup holder/arm rest thingy.
I hear ya about the 4 seasons! San Diego has a lot to offer.. but the four seasons (and people) of Wisconsin are missed. Not the humidity and mosquitos tho.