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Signs of bad motor/tranny mounts?

M

mattbred

NAXJA Forum User
Location
Canada
I have an '89 Cherokee 4.0 Litre with a Peugeot BA/10 manual transmission and I was wondering if any of these signs point to bad mounts somewhere.

When I'm driving in a torquey gear, say second, and I let go of the gas, the whole jeep rocks back and forth, and you can see the shifter move forward and backwards as well. The same thing happens if I step on the gas, no matter how softly I try it. Once the slack is picked up, it feels absolutely fine. This is pretty nauseating after a while and hard on passengers.

What's bothering me is it seems like there is excessive drive line slack. The U-joints seem fairly new and I can't find any play in them, however if I push on the rear drive shaft, it does move the transfer case and transmission pretty good.

Any ideas?
 
take a flashlight and look at the motor mounts, you can almost always see what kind of condition the rubber is in. it sounds like a tranny mount, but to be honest i've only had them go bad in my f-150, never in an xj so take it for what its worth.
 
the drivers side mount is the one that takes most of the abuse. It usually fails first.

easy way to check is to pop the hood and snap the throttle a few times. The motr should rock a bit, but it shouldn't be excessive.
If it moves more than a few inches the mounts are probably shot.
 
tranny mount for the peugot is expensive and weak in general. when i would hit a pothole or speedbump the shifter would move all over the place. i got mine at the dealer but there are some jeep sites that may have it.

i replaced mine a few years ago. the tranny still moved a bit more than i liked. to get some of the slop out, i pryed the tranny up a bit and inserted sway bar link bushings between the tranny and the mount. no extra movement and still flexs enough. i also run daystar poly engine mounts. they vibed at first but the vibes went away.

for the engine mounts, the driverside mount needs to be ground down slightly to fit and the oil adapter(replace the orings while its off) needs to be removed during installation to get the passengerside mount on.
 
89xj said:
tranny mount for the peugot is expensive and weak in general. when i would hit a pothole or speedbump the shifter would move all over the place. i got mine at the dealer but there are some jeep sites that may have it.

i replaced mine a few years ago. the tranny still moved a bit more than i liked. to get some of the slop out, i pryed the tranny up a bit and inserted sway bar link bushings between the tranny and the mount. no extra movement and still flexs enough. i also run daystar poly engine mounts. they vibed at first but the vibes went away.

for the engine mounts, the driverside mount needs to be ground down slightly to fit and the oil adapter(replace the orings while its off) needs to be removed during installation to get the passengerside mount on.
Click to expand...

Don't start grinding your mounts until you try to fit them. Some do need to be ground but not all.....measure twice cut once.

It is however a good idea to do the oil filter o-rings while you are in there though.
 
Jess said:
Don't start grinding your mounts until you try to fit them. Some do need to be ground but not all.....measure twice cut once.

It is however a good idea to do the oil filter o-rings while you are in there though.
Click to expand...

let me restate, with the daystar poly mounts from rustys, i had to grind.

who would grind them before dry fitting them??? how would they know where to grind and how much?
 
Ok I'll check the motor mounts. I took it for a drive today and really payed attention and damn its really really jerky. Not a single jerk either, it rocks back and forth a good 3 times before settling down on the torque. this is both letting off the gas, and getting on the gas. Also, I listened well and every time it rocked I heard a popping sound from underneath the floor pan. Transmission I'm guessing.
 
Mine does it, and I have a 98 with the ax-15. I replaced my motor AND tranny mounts... still does it. Cant figure it out yet... though it was the motor mounts but replaced those then i did the tranny mounts and still... oh well. it runs good.
 
The tranny mount on my 99 was shot when I replaced it last year. My drivers side motor mount had basically no rubber left, and the left mount was bent. :gee:

the mounts are likely your problem
 
My 89 five speed jerks and shimmies sometimes on take off or in a bind like going over a small hump real slow. Every now and again if I'm shifting hard, I will hear a banging sound. Other than that it is smooth on the highway and everywhere else.
I will try the cracking the throttle at the throttle body and watch for excessive motor movement.
 
1989, 5sp(peugot) with poly engine mounts and after reinforcing the weak tranny mount, i now get no movement over bumps or hard throttles and no vibs. it does have enough movement so nothing breaks. i dealt with the loose tranny mounts for years untill i reinforced it.
 
I have the same problems. Just ordered a Crown replacement trans mount
I'm also going to look into M.O.R.E. rubber mounts for more permanent solution
I've been rubbing front driveshaft on header downtube(have a new piece redesigned from pacesetter to replace self clearenced piece)
 
Last edited:
one of the biggest signs is your fan going through the rad.

at least it was for me
 
selarep said:
Mine does it, and I have a 98 with the ax-15. I replaced my motor AND tranny mounts... still does it. Cant figure it out yet... though it was the motor mounts but replaced those then i did the tranny mounts and still... oh well. it runs good.
Click to expand...

yeah, the 5spds behave weird sometimes at really low speeds, people look at me like i'm nuts in the parking lot.
 
mattbred said:
Can you describe exactly how you reinforced it? Also can you take pictures? I'd love to fix this annoyingness.
Click to expand...

on the peugot, the mount for the tranny is v-shaped. there is nothing holding the tranny up in the middle where it is flat. i used poly sway bar end link bushings to reinforce it. pry the tranny up and slide the bushings(1 on each side) between the flat spot of the tranny and mount.
 
Last edited:
For my motor mounts they looked like this.

On the left you have the M.O.R.E mount and on the right you have the stock mounts

P9150008_Piggig.jpg


As you can see the drivers side mount was torn nearly in half. The passengers side was super soft and mushy.
 
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