frantic29

Getting ready to order all the stuff I need for my floorboards and exhaust manifold. Know I need to change out the motor mounts as well. My passenger side I know needs a new motor bracket as 1 of the bolts is broken off. The driver side is good and I have changed out all the bolts with new. This is a DD that will see very little off road and I am just torn between ordering just the mounts and passenger bracket and using the OEM driver bracket or just going all the way and getting the full kit. Guess I could also just get the one bracket and go with OEM mounts but I would rather not be replacing mounts in 2 years again. What do you guys think? 1996 XJ country, 4.0, auto.

Atmos

I used to spend all this money on my engine too. but I've yet to have any problems with regular old rubber mounts in the stock brackets. do whatever is cheapest, I say

frantic29

Kind of where I am leaning. I going to do the passenger side mount definitely. But the more I look at how my xj is used the more I'm leaning toward stock MM. Wish someone made good middle of the road mounts. But it seems like they just jump from like $30 to $100 with really nothing in between.

884x4

I went through a new drivers side mount in 6 months from autozone.
I got brown dogs and am very happy with them

apac020

I bought the Brown Dog motor mounts and motor mount brackets super kit. I had 2 sheared bolts in my block and it was either that or dismantle and drop the whole engine to get the bolts out.

Pros:
Very well built, great performance, vibes not bad at speed.

Cons:
Lots more vibrations at idle. Sitting at a light will rattle every loose panel. You get used to it, but it's definitely noticeable.

s1xty7

Was that the poly or rubber kit? I have a set of the super brackets with the rubber mounts waiting to be installed. I heard the rubber ones take about 500 miles to soften.

SteveMongr

From my experience, mounts from Napa, AutoZone and the others all seem to be crap compared to factory motor mounts. Mounts from Napa last me one year (Anchor brand).
Factory mounts, the sleeve sits lower in the mount with 1/2" or more rubber encasing it. Anchor,DEA, and Omix all sit the sleeve at top of mount with 1/8" - 1/4" of rubber wrap.

apac020

Rubber. I've got about 1000 miles on them and they softened a little bit, but I still definitely have more idle vibes. If you look at the mounts there is a lot less rubber than OEM style, so it's not that surprising.

The flip side to the vibes is the throttle response is excellent. There's a lot less engine movement.

cruiser54

Here's WHY the bolt(s) broke.

From Jon Kelley aka 5-90 @ www.kelleyswip.com



This is a known issue.

1) Unless you're going to get silly with the skinny pedal, 2xSAE8 screws on one side won't be a huge problem. You'd be better off with three, but if you don't get silly you'll be okeh.

2) The Brown Dog engine mounts use two or three additional holes on each side, and spread the mount/clamping force over more of the block. This is invariably a good idea, and I'll probably be doing it as I refit my 88.

3) The primary reason that the screws snap is because, sometimes, the screw holes in the block aren't drilled & tapped deeply enough. This causes the screw to bottom out in the hole, so you end up torquing against the bottom of the hole instead of stretching the screw (as you're supposed to do. Not your fault - you aren't doing anything wrong.) The screw is not stretched properly, and the head is not butted up against the bracket, so there's some room to move there. Vibration then causes wear cycles on the screw, which generally leads to rupture.

The easy/cheap fix? When you replace the screws (3/8"-16x1.25", as I recall,) put two flat washers under the head before you screw it into the hole.

The check? Take a feeler gage (.003" to .005") and try to slide it under the head of the screw. You'll be able to get under the corners (look at the hex head, and you'll see that the surfaces curve toward each other slightly) if it's a standard hex head - if it's a flanged hex head, you should not be able to get under the head anywhere. If you can slip the gage under the head, you have a problem. If you can touch the shank of the screw, you have a big problem!

In no case should you reuse the screws after you take them out - they'll be stressed under the head, and you'll have a significant reduction in strength. Replace them outright, putting washers under the head as I mentioned before. The washers will make up for the slight lack of depth in the hole (two of them will be about 0.125" or so,) and allow the screw to be preloaded properly.

apac020

This isn't always necessarily the case. Mine backed out and sheared because the factory loc-tite on the bolts was too close to the bolt head and didn't even touch the threads in the block. No loc-tite = bolts slowly vibed their way lose.

My mechanic verified that the bolt holes were deep enough, but was aware of that problem as well.

frantic29

I went ahead and just ordered the passenger side bracket and MM from Brown Dog. I had done all the reading on why they broke and just decided I didn't like the idea of only having two bolts. I did go ahead and do what you said with the washers when I first found the issue back in December.

I will be posting more on the general subject as I am going to have a big week coming up doing all this stuff. Going to be looking for a general order of operation. Going to be doing the MM, exhaust from the motor to the muffler, putting new floors in the passenger compartment and installing a wire kit from 5-90.