Jeep Enthusiast Forums banner

BL questions and unintended consequences (planning)

2K views 32 replies 10 participants last post by  Denzien 
#1 ·
I have a 1.25" JKS BL and a 1" Brown Dog MML waiting to be installed, but as much as I've read, I'm still fuzzy on a few details. A Novak cable shifter is in my future, so we'll ignore issues with xfer case linkage for now.

Also, yes - I tend to over-think things. I can't help it and I don't need it pointed out :D

Here is what I think I know:

  1. The transmission is mounted to the skid plate, so installing the BL will result in the transmission being that much further away from the body.
    Having a 6-speed, this might result in difficulty either accessing gears 2, 4, 6 and R or staying in gear without trimming the console.
  2. If I install the MML, the driveline angle will change exacerbating the issue above.
    Short of buying a TT skid plate for now, what are my options to also raise the transmission to correct the in-cabin shifter issue? Washers between the transmission and skid plate?
    I like the Savvy Underarmor kit, but I feel I've spent too much money recently and want to let the dust settle on my finances before pulling that trigger....however, it looks like I can purchase the transmission cross member from the kit a la carte. Would this allow me to raise the transmission 1" and free it from the skid plate all at the same time, do I also need other pieces from that kit, or is this just inviting other problems like dealing with the exhaust?
  3. Since I have about 3.5" of lift (give or take) on an LJ, would raising both the engine and transmission likely result in driveline vibrations, requiring an SYE and double cardan driveshaft?
    I seem to recall that 4.5" was a "maybe it will, maybe it won't" height for LJs.
  4. I have a replacement fuel filler hose per the fuel overflow fix thread that I have not installed, so I shouldn't have to worry about that. It would go on after the BL.

Are there any other concerns I haven't thought about? Brake lines or differential vent lines, etc? All of that stuff is either stock or how the Jeep came to me - which I'm pretty sure is all stock. (I have not had issues with any of this stuff as-yet).

Finally, in researching tummy tucks, I've come across some very confusing language on the UCF site regarding their LoPro transmission mount:
Move your transfer case down into your skid plate to reduce driveline angles or allow you to install a TT without a body lift.
[...]
The new mount is a direct replacement for the factory transmission mount on the '03-'06 model TJ and LJ. It is almost 1" shorter than the factory piece. This lowers the transfer case down into the skid plate by the same amount. That 1" of extra clearance can go far toward reducing metal-on-metal vibration and avoiding body lifts. Some increase in felt drivetrain vibration should be expected with this transmission mount.
I don't understand how lowering the transfer case will allow you to install a high clearance skid. Can someone disabuse me of whatever notion I'm holding onto that is causing this statement to break my head?

Thanks everyone for indulging my inquiries.
 
See less See more
#2 ·
I have a 1.25" JKS BL and a 1" Brown Dog MML waiting to be installed, but as much as I've read, I'm still fuzzy on a few details. A Novak cable shifter is in my future, so we'll ignore issues with xfer case linkage for now.

Also, yes - I tend to over-think things. I can't help it and I don't need it pointed out :D

Here is what I think I know:

  1. The transmission is mounted to the skid plate, so installing the BL will result in the transmission being that much further away from the body. Yes
    Having a 6-speed, this might result in difficulty either accessing gears 2, 4, 6 and R or staying in gear without trimming the console. This is true, some people have this issue
  2. If I install the MML, the driveline angle will change exacerbating the issue above.It may in fact actually do the opposite and help the issue
    Short of buying a TT skid plate for now, what are my options to also raise the transmission to correct the in-cabin shifter issue? Washers between the transmission and skid plate? I suppose any 1" spacer under the mount would work
    I like the Savvy Underarmor kit, but I feel I've spent too much money recently and want to let the dust settle on my finances before pulling that trigger....however, it looks like I can purchase the transmission cross member from the kit a la carte. Would this allow me to raise the transmission 1" and free it from the skid plate all at the same time, do I also need other pieces from that kit, or is this just inviting other problems like dealing with the exhaust? If you order the crossmember you will get a new mount. It will raise it more than 1"
  3. Since I have about 3.5" of lift (give or take) on an LJ, would raising both the engine and transmission likely result in driveline vibrations, requiring an SYE and double cardan driveshaft?Most likely
    I seem to recall that 4.5" was a "maybe it will, maybe it won't" height for LJs.
  4. I have a replacement fuel filler hose per the fuel overflow fix thread that I have not installed, so I shouldn't have to worry about that. It would go on after the BL.

Are there any other concerns I haven't thought about? Brake lines or differential vent lines, etc? All of that stuff is either stock or how the Jeep came to me - which I'm pretty sure is all stock. (I have not had issues with any of this stuff as-yet).
You may have to do something with some vent lines, very minor and very easy to fix

Finally, in researching tummy tucks, I've come across some very confusing language on the UCF site regarding their LoPro transmission mount:
I don't understand how lowering the transfer case will allow you to install a high clearance skid. Can someone disabuse me of whatever notion I'm holding onto that is causing this statement to break my head?

It's "lowering" the transfer case in relation to the skid.
If you use the mount with a stock skid it will actually lower the t-case.
Using if with a raised skid reduces the amount that it (the raised skid) raises the t-case.

Thanks everyone for indulging my inquiries.
If you want the Savvy UA I would suggest doing their crossmember and mount along with the 1.25" BL and 1" spacer type MML. Then you will know if you have any vibration or shifter issues to deal with. That is, funds allowing, of course.
 
#3 ·
Hmm...seems like the cost of their cross member and transmission mount together are the majority of the cost of basic TT kit.

Also, why a spacer type MML?
 
#8 ·
I had the Brown Dog rubber mounts. Took them out and went back to OEM with lift blocks, gave away the Brown Dog mounts to someone who convinced themselves they wanted them.

For my 6 speed TJ, BL + MML meant no issues shifting. BL alone meant issues. But with the MML, it corrected the issues. And the Novak shifter cables were a fantastic upgrade regardless of BL/MML stuff, and I'm glad I went with them. Adjust them to ensure proper dis/engagement, and you're good to go. Buttery smooth and eliminated any spacing concerns.
 
#9 ·
I'm so glad I don't over-think. I've done BL's and MML's by themselves and never had a shifting or any other problem. I just did a BL without a MML and it still shifts like butta ( tranny and t case). :shhh:
 
#15 ·
I used the Energy Suspension motor mounts, which basically takes a set of stock motor mounts and replaces the rubber with poly (soft poly, not the hard stuff), put them on a 1" block MML (Savvy), and paired them with the Energy Suspension poly transmission mount. Had increased vibes for a couple days, until the mounts settled in, now feels similar to stock.
 
#16 ·
That's interesting to note that all poly results in better vibrations - almost like the issue was a different resonating frequency between the rubber and poly. (technical terms pulled out of my butt, inspired by Star Trek)


As far as replacement body mounts, it looks like Savvy has a full set of OEM-looking mounts, or there's the prothane poly mounts for a bit less. The local auto stores look like they're selling OEM style mounts for ~$60 per mount, which I think is insane. Thoughts on the replacement stock-height mounts?
 
#17 ·
That's interesting to note that all poly results in better vibrations - almost like the issue was a different resonating frequency between the rubber and poly. (technical terms pulled out of my butt, inspired by Star Trek)
Yep, pretty much. You also need to consider that poly comes in different durometers (hardness). I have seen some poly bushings that are harder than the stock rubber (I currently have these on the axle-side of my track bar), I suspect that these are what Brown Dog uses on their poly engine mounts, leading to all the complaints about them. The poly used in my motor and transmission mounts (all by Energy Suspension) is the more "squishy" poly that feels softer than stock rubber.

As far as replacement body mounts, it looks like Savvy has a full set of OEM-looking mounts, or there's the prothane poly mounts for a bit less. The local auto stores look like they're selling OEM style mounts for ~$60 per mount, which I think is insane. Thoughts on the replacement stock-height mounts?
I don't recall anyone saying "Don't buy xxx-brand/style body mounts, I have them and they are bad because..." People will steer you one way or another for various reasons, but I think you'll be fine whichever style you choose, I just wouldn't try mixing styles.
 
#20 ·
I did a 1" poly mml from currie.
I did a prothane poly trans mount.
I got an energy suspension 1" poly body lift.
i have the factory transfer case skid plate(shovel)
I am using the stock transfer case shifter and linkage, with no adjustment needed.
i did not have to adjust the fan shroud.
i dont have a manual trans, so im no help there.

I do have a little more vibration, but its only felt at a stop in gear.
It dont bother me, so im ok with it.
If you dont want a little more vibration, go factory rubber everything.

I got a rubicon lj, so im no help on the sye either, but i bet u would need one, if you add a tt

Good luck
 
#23 ·
Ok, I'll get those up a bit later.

I do get a clunk vibration under my left foot when I hit a bump. Could that be a body mount, or the upper control arm I haven't gotten around to replacing?
 
#26 ·
Failed body mounts will be cracked and torn and generally falling apart.
If they're starting to fail, you will see cracks and splitting in the rubber.
 
#32 ·
Clunking I would also check your TC linkage as part of the linkage can fail and bangs against the tub. Personally if you are doing a TT, I wouldn't do it without a cable shifter it makes it so much better. The lopro tc mount from UCF does cause vibes but only at idle. They are really minor.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top