is there a test to see if MTX mount is bad?

[Randall]

Hey Guys,
Is there a test to see if the transmission mount has gone bad? I have a 92 MTX and I checked the front and rear motor mounts visually and by trying to move forward in first and back in reverse with the parking brake on, and there is some movement but nothing major. I suspected the mounts because I am hearing a loud frame clunking, epsecially if I am not smooth on the clutch, and especially in first gear. The shifter actually moves too if you try to downshift into first at low speeds or just let off in first gear in stop and go traffic. I am not sure what else to check, but all the front suspension is newer, and I mean ALL of it, and the noise just began a few weeks ago with what was first a creaking type of noise with some shifter movement, and has gotten worse since. Any ideas how to diagnose this further? Thanks!

 

[SHObill]

First check your SubFrame Bushings=SFB! Esp with the shifter movement Its prolly the SFB's! You can check The SFB's by jacking up the car using the support rails under the frt seats just behind the rear SF bolts. Put a 4X4 across both & lift car & support on jack stands. Then see if there is any clearance between the body & SFB's. Use the floor jack right under each SF mount & check for movement up. Then get a 3/4" rod & insert at frt driver SF alignment hole to body. Rod should be verticle if SF in in proper location. Use rod to pry sidways to see if SF moves. If any tests show slop SFB's are shot. Then support front of car using SF then apply floor jack with block of wood under oil pan on each side to see how much frt & rear Motor mounts move & then tranny mount. You could have a combo of all.

 

[ShadetreeSHOguy]

First check your SubFrame Bushings=SFB! Esp with the shifter movement Its prolly the SFB's! You can check The SFB's by jacking up the car using the support rails under the frt seats just behind the rear SF bolts. Put a 4X4 across both & lift car & support on jack stands. Then see if there is any clearance between the body & SFB's. Use the floor jack right under each SF mount & check for movement up. Then get a 3/4" rod & insert at frt driver SF alignment hole to body. Rod should be verticle if SF in in proper location. Use rod to pry sidways to see if SF moves. If any tests show slop SFB's are shot. Then support front of car using SF then apply floor jack with block of wood under oil pan on each side to see how much frt & rear Motor mounts move & then tranny mount. You could have a combo of all.

cant you also turn the steering wheel to the left and right, and if the engin moves to the left and right the SFB's are bad too?

 

[Randall]

Wow, SHOBill, thanks!!! That is exactly what I was looking for, I will go do that test now and see what happens. I did check the subframe bushings a few weeks ago when i replaced the rod bearings, and they seemed fine as I did a similar test to what you described by jacking up the subframe and unibody separately and looking for a gap. I will post back in a bit to tell you what I found, but maybe I will just take a video of how much the motor moves when I do the parking brake method so it can be seen if the movement is normal. Thanks for the help!

 

[Randall]

OK, I did the test you described by jacking the car up and putting a pry bar into the subframe alignment holes and checking for slop, and I did get a little! I was able to tighten the driver's side bolt almost a half turn more. I then drove the car around the block hoping the problem would be gone, and it wasn't. Maybe I ran through the procedure too quickly, but it's dark now and I will have to wait until tomorrow as I accidentally lowered the car onto my Craftsman light unit and crushed it beyond repair! First time I have ever done something stupid like that in years of wrenching! Anyway, is there anything else I can check or more tests to see what is causing my problem? I will have access to a hydraulic lift on wednesday night or thursday morning, so I may wait until then to really look at the subframe bushings, and I thank you again for the suggestion SHOBill! I breifly looked at the MTX mount and saw a line running through the middle of it, but I remember my other SHO has this tear like line in it too, and it never had the problem of the shifter moving and clunking in the front end, so i am unclear on the mount still. Thanks for any further help!

 

[93rev2sev]

Jack and support vehicle(Jackstands should be under the subframe...not the unibody).
Place jack under drivers side of transmission(use 3/4" plywood pad).

snug the jack under the tranny then give it 2 slow pumps. Inspect tranny mount for separation.

Removal of drivers tire and inner fender lining may be needed to get a clear view of the mount.

 

[Randall]

I didn't even think of this, but of course! This is probably the best way to see if the mount is still good, thanks for the post 93rev2sev!!