Body lift & MML vibes?

LJDC

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I have an LJ with a 4” suspension lift and no real vibrations. I’m considering a 1” or 1.25” body lift and 1” MML, with it without a “tummy tuck.” (I plan to move to 35s.) How should I think about the possibility of adding vibrations with the high-clearance skid?

I do not want to add expensive driveline parts if I can avoid it. I’m considering the body & motor-mount lift without the high-clearance skid, to decrease wear on the driveline parts. But wouldn’t mind the extra clearance.
 
I have an LJ with a 4” suspension lift and no real vibrations. I’m considering a 1” or 1.25” body lift and 1” MML, with it without a “tummy tuck.” (I plan to move to 35s.) How should I think about the possibility of adding vibrations with the high-clearance skid?

I do not want to add expensive driveline parts if I can avoid it. I’m considering the body & motor-mount lift without the high-clearance skid, to decrease wear on the driveline parts. But wouldn’t mind the extra clearance.

Why even consider the body lift or mml if you’re not going with a high clearance skid. No other reason to really.
 
I have an LJ with a 4” suspension lift and no real vibrations. I’m considering a 1” or 1.25” body lift and 1” MML, with it without a “tummy tuck.” (I plan to move to 35s.) How should I think about the possibility of adding vibrations with the high-clearance skid?

I do not want to add expensive driveline parts if I can avoid it. I’m considering the body & motor-mount lift without the high-clearance skid, to decrease wear on the driveline parts. But wouldn’t mind the extra clearance.

If you don’t have vibrations now, you won’t get them with a BL and MML. The BL is irrelevant to the driveline. The MML will slightly improve the rear driveline angle.

If you do the BL and MML and a high clearance skid you will have to get a SYE/DC and rear control arms (which you should already have).
 
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The body lift is so that I can move to 35s. The MML is for the body lift.

The key question—thanks JMT—is whether the MML would be good or bad for vibrations. My understanding is that it can only reduce them. I don’t notice them now. I thought I did notice a little when I got it… is it possible that the suspension lift settled a bit?
 
you may not need the motor mount lift kit, just add the body lift kit and see if you have vibs…if you don’t you can drop the fan shroud down to accommodate the body lift with no problems..
 
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you may not need the motor mount lift kit, just add the body lift kit and see if you have vibs…if you don’t you can drop the fan shroud down to accommodate the body lift with no problems..

Isn’t there benefit to have better angles, even absent vibrations that I notice, to reduce wear? The lift certainly changed the angles. So I assumed that reducing the angles could only be good. Is that wrong?
 
Isn’t there benefit to have better angles, even absent vibrations that I notice, to reduce wear? The lift certainly changed the angles. So I assumed that reducing the angles could only be good. Is that wrong?

You’re correct the MML will reduce rear driveline angle. It won’t help enough to avoid vibes if you add a high clearance skid.
 
You’re correct the MML will reduce rear driveline angle. It won’t help enough to avoid vibes if you add a high clearance skid.
Thank you. That question was in the back of my mind.

So if I decide to save an inch or so, later in, with a high-clearance skidplate, I should also plan for a SYE and DC drive shaft.

That’ll help with future planning. For me at least, I plan not to do something and then later want to do it.
 
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If you go ahead and install a MML make sure it has good quality RUBBER bushings. Some have polyurethane bushings and some cheap MMLs have cheap rubber bushings that are so stiff they can pass vibrations nearly as well as polyurethane bushings do.

This from M.O.R.E. is is a very high quality MML with good quality rubber bushings that I installed into my previous TJ. It was made with much better quality than a Brown Dog I had plus a previous Currie MML that broke its weld before I learned how to weld so I could have repaired it. https://mountainoffroad.com/collect...f-motor-mount-kit-for-1-lift-97-06-yj-tj-lj-1

It lives up to its Bombproof name.
 
I installed a 3" lift on my LJ and had no vibration problems until I regeared my axles. Since then, I've added a SYE and adjustable upper rear control arms.

What transmission do you have? I have the 42RLE auto and I needed to regear for 32" tires.
 
If you go ahead and install a MML make sure it has good quality RUBBER bushings. Some have polyurethane bushings and some cheap MMLs have cheap rubber bushings that are so stiff they can pass vibrations nearly as well as polyurethane bushings do.

This from M.O.R.E. is is a very high quality MML with good quality rubber bushings that I installed into my previous TJ. It was made with much better quality than a Brown Dog I had plus a previous Currie MML that broke its weld before I learned how to weld so I could have repaired it. https://mountainoffroad.com/collect...f-motor-mount-kit-for-1-lift-97-06-yj-tj-lj-1

It lives up to its Bombproof name.

Thanks. I actually read an earlier thread (from maybe a few years ago) where you strongly recommended the MORE, specifically over the Brown Dog. I added that to my list. I appreciate the reminder.

Poly bushings were actually recommended to me locally, to avoid vibrations. I stayed quiet about it—I don’t have any experience to argue about it. But I’m grateful to learn from the experience of others here.
 
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I installed a 3" lift on my LJ and had no vibration problems until I regeared my axles. Since then, I've added a SYE and adjustable upper rear control arms.

What transmission do you have? I have the 42RLE auto and I needed to regear for 32" tires.

Interesting. I have the manual 6-speed they put on the LJs, running 33s. I haven’t re-geared yet because I plan to move to 35s at the same time.

Why do you think the re-gearing would’ve caused that? It did you add the 32s at the same time as the re-gearing?

Hopefully any vibes that might have emerged in the future will be satiated with the MML.
 
Why do you think the re-gearing would’ve caused that? It did you add the 32s at the same time as the re-gearing?
Re-gearing makes the driveshaft spin faster, any previously mild un-noticed vibes are suddenly noticeable.

You can get a simple metal MML, just a 1" thick block of steel or aluminum, which uses your OEM rubber motor mounts, if they're in good condition. Some people like the complete replacements, some like boosting the OEM mounts.
 
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Why do you think the re-gearing would’ve caused that? It did you add the 32s at the same time as the re-gearing?

My driveshaft now spins faster with 4.88 gearing vs the 3.7ish? OEM. One more revolution for the same speed.
 
Thanks. I actually read an earlier thread (from maybe a few years ago) where you strongly recommended the MORE, specifically over the Brown Dog. I added that to my list. I appreciate the reminder.

Poly bushings were actually recommended to me locally, to avoid vibrations. I stayed quiet about it—I don’t have any experience to argue about it. But I’m grateful to learn from the experience of others here.
I replaced poly engine and transmission mounts with factory style rubber not long ago and was amazed at just how smooth and quiet it made my tj. The whole jeep shook,dash buzzed and rattled and had lots of odd harmonics. Made me feel like i had a cummins 6 instead of the amc 😂
 
How about the MML will give you slightly better driveline angles on a small lift and the BL will give you more tire clearance, plus it makes everythinbg fit better after the
How about the MML will give you slightly better driveline angles on a small lift and the BL will give you more tire clearance, plus it makes everythinbg fit better after the MML.

Agreed, why go through all that and not do a tummy tuck though? If all you’re after is better angles and not worried about clearance, add some spacers for 1/100th of the price. Also if you want more tire clearance, just get the appropriate springs for you tire size choice. Nothing against a good body lift and mml, it just doesn’t add up.