Need help in sourcing cause of loose frame or drivetrain

[Randall]

Hey guys,
for the last few weeks, my SHO has had a problem that has progressively gotten worse where upon moving from a standing start, or even during low speed downshifts, I feel a very noticeable "thud" in the floorboard, and the shifter is moving around quite a bit.

I recently changed both motor mounts with fresh new ones, the front one is a direct Ford replacement that I re-enforced. The one I replaced was completely shot and the rear had started to tear. So, both those are new. The MTX mount looks like it is a bit worn, but still has not separated at all. I checked the sub frame bushings, and the bolts are all tight, and the bushings are totally intact. I checked the tension strut receivers for cracking or looseness, and they are in excellent condition.

I doubted myself, so I took it to Nick Chrimes, the West Coast SHO expert mechanic, and even he could not find the source of the problem, but he too verified that the shifter and drivetrain are moving far more than they should.

I have no idea what else to check for, and I am a little worried that the constant flexing of the drivetrain will again wear out my exhaust donut and spring bolt assemblies that I just replaced. The motor does not move much at all during the emergency brake test, so it just can't be a motor mount, but I am totally stumped.

Do any of you have any suggestions? I am afraid to drive my SHO aggresively right now as every time I take off even moderately hard or downshift below 30 miles per hour, there is a horrendous noise that sounds like a cement block being dropped from ten feet onto a carpeted mat, (I know that is a weird description, but it is the best I can do for telling you what it sounds like) The noise is accompanied by a huge thud feeling in the floorboard beneath the pedals.

I have not checked the lower ball joints or control arm bushings for that matter, but something is very wrong, and since even Nick Chrimes can't figure this out I need some help.

Thanks for your time!
-Randall

 

[shopartsnw]

Assuming you do not have another bad motor mount, recheck the torque of the motor mount bolts at the block and the subframe. They can work loose as they settle in after a motor mount replacement. I had a broken rear motor mount that sounded like a sledge hammer on the floorboards at a heavy shift at the track.

Second. Recheck the front tension strut rods where they come through the subframe. If you look on the back side of the bushing cups, you might see a crack or some powdered rust. It does not take much to make a "thud". Also check "just joined the broken subframe club"

Third, check the lower ball joints and lower control arms where they connect to the subframe. Jack up the car and shake the wheels at 3/9 and 6/12 to see if you get play. It could also be a loose rack (at the mounting nuts or bad tie rod end).

Fourth, check to make sure the bellhousing bolts are tight. I have seen cars with only two bellhousing bolts in them since a previous "mechanic" did not torque them correctly.

Last, keep us informed, so we know what you find, and we can make further suggestions.

Mike

 

[Randall]

wow! That was one of the most helpful posts I have ever gotten on here! Thank you very much! I will be able to do all the things you suggested on my next day off on wednesday. I will report back to you what I find. In the meantime, I checked the front motor mount's torque and it was perfect, but I think it could be possible that the rear mount is loose as I had a heck of a time getting the new one in, and barely was able to line it up with the hole in the subframe, which makes me think that it is possible it shook loose since then. I also replaced the tie rods a few months back and checked them again this last weekend and they are still in perfect shape. I did do the "shake test" on the wheels as well, looking for a bad tension strut receiver, but there was no play in the wheels. I recently replaced the wheel bearings and hubs with new ones as I did the 11.6 upgrade. I should also note that I have been hearing a lathe like noise coming from the MTX as the movement in the drivetrain occurs as I go from a standing stop to moving forward. It does seem far easier to reproduce the "thud" when I am going from a stop to moving in reverse.

Thanks again for the help, now I have a few things to check that I would not have thought of!!

 

[RAYJAY]

how are the subframe bushing ?? you don't have a subframe moving around

Jeff

 

[NJSHO]

My car was doing this and after many years of reinforcing mounts, torquing bolts 2 and 3 times, and double nutting bolts motor mount bolts, it turned out to be the cups in the subframe that hold the tension rod bushings. Heres a vid showing the problem. It can be diagnosed by putting the parking brake on, car out of gear, and attemping to rotate the front wheel by hand in the normal direction the wheel spins. This is what I found after tightening the snot out of the tension strut nut:
Linky
The solution, hopefully, for me will be the following from rockauto:
MOOG K8737 Crossmember Repair Kit Qty 2
MOOG K8516 Strut Rod Bushing Kit Qty 1
MOOG K8613 Strut Rod Bushing Kit Qty 2

In addition if you dont feel like buying new motor mounts in the near future, I would reinforce them by putting some bolts through them. I dont have a link handy, but if you search you should get the idea. Ill see if I can post a pic later.

 

[93rev2sev]

Pop the hood and pop the clutch a little in first and reverse. You will be able to see if the engine is moving immediately. Have someone sit on the radiator support and watch for where the movement comes from.

You can do this with the parking brake on or ALL 4 wheels choked....you are just trying to load the engine a little...not actually take off down the road.

Do you have working AC? If not, there is a possibility that you have removed your A/C compressor and the bracket(the one that holds the front mount) is broken.

 

[Randall]

how are the subframe bushing ?? you don't have a subframe moving around

Jeff

Thanks for the idea Jeff, although I did check the bushings and the torque of their bolts and although the bushings look to be a bit dried out, they are completely intact.

My car was doing this and after many years of reinforcing mounts, torquing bolts 2 and 3 times, and double nutting bolts motor mount bolts, it turned out to be the cups in the subframe that hold the tension rod bushings. Heres a vid showing the problem. It can be diagnosed by putting the parking brake on, car out of gear, and attemping to rotate the front wheel by hand in the normal direction the wheel spins.

Thanks a TON for this info, I did check the tension strut receivers, but I didn't really do the procedure the way you outlined it, so I will try that as soon as possible! Your link was very helpful!! I am now thinking this may be my problem too as I have also gone through the same steps you did now!

Pop the hood and pop the clutch a little in first and reverse. You will be able to see if the engine is moving immediately. Have someone sit on the radiator support and watch for where the movement comes from.

You can do this with the parking brake on or ALL 4 wheels choked....you are just trying to load the engine a little...not actually take off down the road.

Do you have working AC?

Thank you too for the great ideas, I did do the parking break test and the motor does move, but it is very slight, and seems to move a little more when I pop the clutch in reverse. Either way it is probably only an inch, which for all I know may even be normal for the new stock Ford mount that is in the rear location. I do still have a very well functioning AC system, so my compressor is still there. I think I will take your advice though and have a second person watch the motor to see where the movement is coming from as I have only been doing the test myself and just watching through the hood opening.


Thanks a lot you guys, I really appreciate the suggestions so far!!:thankyou:

 

[NJSHO]

Even with double reinforced motor mounts, I get a bit of engine movement. Just an FYI

 

[Randall]

OK, here finally is an update, as I actually got a day off today!

I checked the strut rod bushings and receivers several times, several different ways, and they did not budge at all at any time. I re-torqued the motor mounts and subframe bushings, but not surprisingly, they were already within spec. I checked the lower control arms and their attachment points and bushings and they were fine too.

I have no idea what the large deal of movement in my frame could be now, it is VERY bad now when downshifting into second below 30 mph or even into first from 10 mph down as I cruise up to a stop light. The shifter shakes erratically and the "thud" happens a few times, and there definitely is now a sqeaking noise that comes with the movement of the subframe/motor that sounds like it may be coming from the shock towers.

My SHO's strut mounts are only a few months old, but I was wondering if they could be bad and causing all these issues if they are separating? I know that since they were brand new, I get that horrid squeaking noise when the temperature drops below 60 degrees as I steer the car into parking spots or make u-turns.

Anyway, i am getting a bit off subject, and I just wanted to see if you guys could suggest anything else for me to check.

I already ordered new Energy Suspension strut rod bushings, and a great friend of mine shipped me some Gen 3 taurus sub frame bushings to try out, so I am planning on addressing those two possible trouble spots next week by installing the newer parts. In the meantime, I am getting afraid to take turns hard or take off from a stop in a style other than the way a granny would drive because the "thudding" and movement of my drivetrain are alarming.

Thanks for any more help, I appreciate it very much!

-Randall

 

[NJSHO]

When you checked the suspension was everything ie. springs, struts, connected? You may have to disconnect the springs and struts to see any movement since there is no way you are going to be able to move the suspension by hand with the springs in there.

 

[Randall]

yeah, I didn't disconnect or disassemble anything prior to checking the suspension, but I was looking for any signs of excessive play in the bushings, and if they are bad enough to cause the movement of the drivetrain that I am getting, I was pretty confident I would have seen it. I did use a pry bar to try and move the various components around to try and see if the control arms or tension strut rods moved too much. I didn't see anything, so since my NEW strut mounts seem to already have failed, when I go to replace those soon I will check the suspension thoroughly when the springs are out. I hope I can just find what is wrong ASAP though as it seems to get a little worse every day. Thanks for the idea NJSHO, I appreciate it!

 

[sdpatt]

Have you inspected the closeness of the exhaust system to the floor pan? The "seems to move a little more when I pop the clutch in reverse" quote leads me to think that the engine is rocking enough to let the exhaust system contact the structure of the car. A 1" rise at the rear intake plenum would be too much for an intact rear motor mount. With the longer lever arm of the Y-pipe, I would estimate that the cat-back ****** is rising 2" when letting the clutch out in reverse or downshifting and letting the clutch out. That magnitude of movement would certainly lead to the exhaust system banging into something.

 

[shopartsnw]

Have you looked at another "simple" problem of the rod shifter bolts coming loose? If either the two main retaining nuts or the bracket ring came loose, it would allow the rod shifter to move quite dramatically and make a good thump.

I am grasping at straws, but I want to see you solve the problem.

Mike

 

[Randall]

Thanks Scott and Mike!

I know there is now a banging noise too that does sound like the exhaust moving into the floorboard, but this really only started happening last night. There still is a worrisome "thud" that literally can be felt throughout the car, so it has to be the motor or subframe moving since it definitely is something very heavy by the feel of it. Oh, and I did check the shifter's hardware and there is some slop, but the shifter is tight and all the bolts and linkage are on solid. I have almost given up as I just can't seem to source this problem out. I want to say that it could be the transmission mount, but I am unsure of how to isolate that and test it without removing it.

Next week I will be able to visit my friend Nick Chrimes and I am sure he will let me put my SHO on the lift so I can check through the car again. I still am planning on replacing the strut rod bushings and welding the receiver cups either way, and I also am planning on installing some gen three subframe bushings too. Hopefully the problem is related to one of these things. In the meantime though, I am bothered by this a lot as this has been a nightmare to diagnose. It almost feels (although visually I can't verify) that the rear motor mount may not be on all the way, kind of like it is traveling in and out of the subframe's mounting hole as if the mounting nut isn't on all the way. I did try to tighten that nut on with a three foot long wrench, and it didn't budge, so who knows.

I do know that if I get on the gas in first gear as I am rolling, even just moderately, and then suddenly let off the gas pedal, I hear the banging noise now a few times as the car shakes and also feel the thudding in the floorboard, but it feels like a very heavy thudding that just can't be the exhaust as the shifter moves at least an inch back and forth.

If you guys have any more suggestions, I would love to hear them, otherwise I guess I will just wait til next week on tuesday when I have access to the lift to do a thorough inspection.

thanks a ton for all the ideas so far!!!

 

[NotSoSlowSHO]

Before the noise and shifter movement.... you didnt happen to have the front sway bar out did you?

 

[naval-avi8or]

Place floor jack with short piece of 2X4 under rear of oil pan and slightly apply some lifting pressure and see if the rear mount rises at the subframe or at the insulator. This can determine if the rear mount is properly tightened or seperated.

 

[whiteman_01]

Has the rear subframe recall been done on this car? It was never done on my 92 and it ended up dropping the passenger rear corner due to it rusting out. Hopfully not it, but somthing to check.

 

[Randall]

Before the noise and shifter movement.... you didnt happen to have the front sway bar out did you?

No, I have never even touched the sway bar aside from replacing the end links when I did the suspension. I also did check the sway bar to see if it is moving, and it is all buttoned in nice and tight, and it even looks like I have a 26mm sway bar, which I thought ended in '91, but that is a whole different topic.

Place floor jack with short piece of 2X4 under rear of oil pan and slightly apply some lifting pressure and see if the rear mount rises at the subframe or at the insulator. This can determine if the rear mount is properly tightened or seperated.

Thanks for the tip, but I already did this and when I jacked up the oil pan, the whole car began to move upward, and I didn't see any gap between the mount and subframe, but I was mostly watching the front mount in all honesty, so I may try this again.

Has the rear subframe recall been done on this car? It was never done on my 92 and it ended up dropping the passenger rear corner due to it rusting out. Hopfully not it, but somthing to check.

I read your post and went to Ford's site to check my VIN in their recall verification page, and it says there are no outstanding recalls for my car, so I guess that means the subframe recall was done. Structurally, when I inspected the subframe recently, it looked perfect, no rust anywhere and no cracks or bends either.

If I jack the car up by the MTX with a block of wood between it and the jack, will that show me if the MTX mount is bad?

I think I will also try jacking the oil pan up again and paying closer attention to the rear mount. I will have time Sunday for this, but I still think it is something else. When I put the old SHO on the rack on tuesday, I will completely check the subframe though as well to make sure it isn't broken.

Thanks again for the suggestions guys, it is very helpful to me!

 

[Phoenix]

No, I have never even touched the sway bar aside from replacing the end links when I did the suspension. I also did check the sway bar to see if it is moving, and it is all buttoned in nice and tight, and it even looks like I have a 26mm sway bar, which I thought ended in '91, but that is a whole different topic.



Thanks for the tip, but I already did this and when I jacked up the oil pan, the whole car began to move upward, and I didn't see any gap between the mount and subframe, but I was mostly watching the front mount in all honesty, so I may try this again.



I read your post and went to Ford's site to check my VIN in their recall verification page, and it says there are no outstanding recalls for my car, so I guess that means the subframe recall was done. Structurally, when I inspected the subframe recently, it looked perfect, no rust anywhere and no cracks or bends either.

If I jack the car up by the MTX with a block of wood between it and the jack, will that show me if the MTX mount is bad?

I think I will also try jacking the oil pan up again and paying closer attention to the rear mount. I will have time Sunday for this, but I still think it is something else. When I put the old SHO on the rack on tuesday, I will completely check the subframe though as well to make sure it isn't broken.

Thanks again for the suggestions guys, it is very helpful to me!

If you really want to know if the recall was done physicaly ( not through Ford's cheesy recall site) just lift floors carpet where your feet are at when you drive (you can check on the passenger side as well) you should see a 2 1/2" black rubber grommet in the floor. If you don't, it was not done.

 

[NJSHO]

Before the noise and shifter movement.... you didnt happen to have the front sway bar out did you?

Ive done that before, just for reference an upside down front sway bar will push on you rod shifter linkage on dips in the road.