Vibrations after tummy tuck - is this normal?

[DaveC]

Just got the TJ back from having a TT done and I'm wondering if what I'm experiencing is normal as it definitely doesn't feel like it did before.

1. It's fine while driving, but when stopped and in gear (like at a red light), I've got pretty bad vibrations and it sounds 'rough' - very different than when driving/under active acceleration. I'd say it's like things are bound up when the TJ isn't accelerating, but they loosen up and go back to normal under acceleration/once moving again. When the TJ is first started in park, there are no vibes/rough sounds; it's only after going into gear.
2. Both the vibrations and change in sound go away if I shift out of gear and into neutral, and the TJ almost seems to settle or relax when going into neutral. Prior to the tuck, there had never been any noticeable difference in feeling between being in neutral vs. in drive.
3. Once I shift back into gear, the roughness and vibes comes back and it almost feels like the rear end wants to climb/come up a tad (like climbing over a small obstacle) - as if I were hitting the gas while holding the brake with the other foot - but this is with no gas applied, just shifting from neutral to drive with a foot on the brake and the TJ running.
4. Tight turns (i.e. U-turn in a driveway) are now choppy; almost like I'm in 4wd or even 4lo.

2006 auto with the 42RLE trans, SYE, DCDS and adjustable control arms had all been in place for +1 yr and the TJ driving, running and performing flawlessly. Here's the work that was just done:

1. High clearance belly skid
2. Stand alone trans crossmember
3. Brown Dog 1" Ultra Flex MML
4. Daystar 1" BL

This was done at a one of the top off-road shops in the area, where I've had all other work done with no issues. I brought the issues up after I got home and they've said that what I'm experiencing is normal as the new motor and transmission mounts are poly and thus more solid than the old rubber style. I plan to take it back to have the issues checked because if they were related to the new bushings, it seems they'd be consistent and not vary based on whether or not the vehicle is in gear, accelerating, etc. I'd appreciate any input as I'd like to be armed with this to compare to what the shop says if necessary.

 

[Jerry Bransford]

Polyurethane body lift mounts transmit more vibrations into the cab, and comments I've read about Brown Dog's rubber motor mounts say the rubber is so stiff they're almost as bad as polyurethane motor mounts where passing vibrations are concerned. I'm not saying those are the cause of all the vibrations but...

Also, belly-ups increase the angles the driveshaft works into so that can be contributing to the vibes too. What u-joints did you go with in your rear driveshaft? 1310? 1330? 1350? 1350 u-joints are known to cause more vibrations when their angles get a little steep.

 

[DaveC]

Polyurethane body lift mounts transmit more vibrations into the cab, and comments I've read about Brown Dog's rubber motor mounts say the rubber is so stiff they're almost as bad as polyurethane motor mounts where passing vibrations are concerned. I'm not saying those are the cause of all the vibrations but...

Also, belly-ups increase the angles the driveshaft works into so that can be contributing to the vibes too. What u-joints did you go with in your rear driveshaft? 1310? 1330? 1350? 1350 u-joints are known to cause more vibrations when their angles get a little steep.

Frustrating on the choice of mounts as one thing I was adamant on was retaining the 'streetability'/stock feel. Sadly, I can't answer the question on the driveshaft as that detail isn't listed on my work order - but it's one I'll bring up when I take it back to have them ride with me and investigate the causes. Appreciate the comments and direction!

 

[Vasq]

Does the stand alone trans crossmember utilize the factory rubber mount? If they used some kind of lo-pro mount, that will transfer much more vibrations.

As far as brown dog mounts, i have them. My M.O.R.E. mounts are arriving today, as they have MUCH more rubber (in the pictures) so i'll try to remember to report back if that was a waste of money or not I believe taylormade(?) recently switched from his BD 1" rubber mounts to the MORE one's and it was an improvement.

If you have an angle finder i would double check your pinion is in line with your driveshafts.
I've heard the same about the poly mounts but have no experience with that.

 

[Moglocker]

Frustrating on the choice of mounts as one thing I was adamant on was retaining the 'streetability'/stock feel. Sadly, I can't answer the question on the driveshaft as that detail isn't listed on my work order - but it's one I'll bring up when I take it back to have them ride with me and investigate the causes. Appreciate the comments and direction!

It’s the brown dog mounts compare them to your stock ones that float around in there frame,it’s on there web on the questions

 

[DaveC]

Polyurethane body lift mounts transmit more vibrations into the cab, and comments I've read about Brown Dog's rubber motor mounts say the rubber is so stiff they're almost as bad as polyurethane motor mounts where passing vibrations are concerned. I'm not saying those are the cause of all the vibrations but...

Also, belly-ups increase the angles the driveshaft works into so that can be contributing to the vibes too. What u-joints did you go with in your rear driveshaft? 1310? 1330? 1350? 1350 u-joints are known to cause more vibrations when their angles get a little steep.

Does the stand alone trans crossmember utilize the factory rubber mount? If they used some kind of lo-pro mount, that will transfer much more vibrations.

As far as brown dog mounts, i have them. My M.O.R.E. mounts are arriving today, as they have MUCH more rubber (in the pictures) so i'll try to remember to report back if that was a waste of money or not I believe taylormade(?) recently switched from his BD 1" rubber mounts to the MORE one's and it was an improvement.

If you have an angle finder i would double check your pinion is in line with your driveshafts.
I've heard the same about the poly mounts but have no experience with that.

Good questions I can't answer but now have in my 'tool box' for when I take it in. The work order says ultraflex, which look to be the rubber bushings on the website but in my e-mail exchange, they referenced poly. They did mention having to adjust pinion angle, but I do have an angle finder, so will check that myself. Thank you!

 

[Farmergreg]

I've got the MORE mounts and the UCF Lo-Pro trans mount which is just two plate of metal with a thin piece of rubber between. Ive slight vibes at idle and just above. I've heard using OEM motor mounts and spacers might be a better route.

PS: How about a pic?

 

[DaveC]

I've got the MORE mounts and the UCF Lo-Pro trans mount which is just two plate of metal with a thin piece of rubber between. Ive slight vibes at idle and just above. I've heard using OEM motor mounts and spacers might be a better route.

PS: How about a pic?

Need to get one in better light

 

[DaveC]

Need to get one in better light View attachment 250403

Went from tubby to svelte

 

[Farmergreg]

Went from tubby to svelte

Looks very clean.
You're on the merry-go-round now, I think @RINC needs to join you!
Did you decide on a tire?

 

[DaveC]

Looks very clean.
You're on the merry-go-round now, I think @RINC needs to join you!
Did you decide on a tire?

Given it's typically 1-3 hours on the freeway to get to the trails and the fact that mud is a rarity for us, 98% sure it'll be the KO2s. The crappy cheap ATs I've been running have done far better than I ever expected (both in traction and durability), so I'm sure a top notch AT like that will do well.