Tranny/Motor Mounts

[kens96]

Think I have a broken motor or tranny mount. I notice just before I come to a slow stop the car pull forward like a soft clunk. Acceleraton and hard stops are fine, just in stop and go traffic is where it is most noticable. Would a broken tranny or motor mount do this?

Also checked Rock Auto and they show 1 front Right motor mount and a Right and Left Tranny mounts, cost for all 3 mounts is under $100.

I've seen in the forum someone saying the front mount was $170. Is there a front Left?

[Cadillac Jim]

Generally the only motor mounts that go bad are the torque wishbones and the front one.

[BodybyFisher]

I replaced my LEFT tranny mount last year, it was torn loose (circled in red). My front mount went shortly thereafter. On hard acceleration especially on turns, I get a thud. More frightening, is the vibration I experience on hard acceleration. The symptoms I experience have, have gotten bad in the last month. I will let you know what I find, I am ordering them this week, I need to get under it to see what is going on.

You could have a bad rear mount allowing the engine to rock forward on braking. What concerns me about what I am experiencing is that this con cause CV joint wear, stress, and misalignment of the axles. My engine looks like it has shifted.

Here is what they look like

[kens96]

Rear Mount is possible. The front was replace about 6 years ago but with a half case leak I'm sure that these are seeing more than their fair share of oil.

Is there some kind of road or driveway test that can be done to be certian. I see the engine rock when I go from forward to reverse standing on the brake with the hood up but it looks normal. Strut mounts were replaced last month. I do notice that when i come to a stop in neutral there is a definite clunk or settling of the motor just before the car reaches a full stop.

[BodybyFisher]

That would be the test, but if I were you, I would have a helper (that you trust) do that, while I put my head in there to see how much its moving.

Take a look at your strut rod bushings, if they are shot or loose, your lower control arm will move fore and aft, and clunk forward on braking.

[kens96]

BBF - Funny you should mention strut rod bushings. Just had the car at the transmission place again. They cannot find anything wrong with the motor or tranny mounts, transmission, or drive train. They recommended a front end guy to take it to.

How difficult are the stut rod bushings for a DIYer ?

[BodybyFisher]

BBF - Funny you should mention strut rod bushings. Just had the car at the transmission place again. They cannot find anything wrong with the motor or tranny mounts, transmission, or drive train. They recommended a front end guy to take it to.

How difficult are the stut rod bushings for a DIYer ?

Not bad at all, just remove the lower control arm. Break the ball joint, disconnect the control arm at the bushings, remove the strut rod nut and pull it out... I used poly bushings, it made my cars directional stability sharp.

[BodybyFisher]

Ill post a photo when I get a chance

[Cadillac Jim]

Make sure that the bolts in the new torque wishbones are really tight. If not, they will slip.

[kens96]

Thanks Jim

Saw what you said in another post and made sure they were tight. Still have the same issue when stopping. Other than the slight "tug" just before the car comes to a full stop it drives and handles fine. No tire wear to indicate anything is loose up front. I was thinking that the last thing I did to the front end was replace the frt wheel bearings.

Is it possible it is something as simple as the rotors sliding back and forth on the new hubs? Lugs were torqued to 110 ft lbs. Also I have never replaced the bushings or bolts on the calipers and they have been on and off an number of times maybe one of them finally gave out?

[Cadillac Jim]

Perhaps it's that last downshift to low gear that is causing this clunk. If the idle speed is high, or if it is slow dropping to 650 RPM, or the throttle cable is sticking, that could do it. What RPM do you see when you get the thunk?

[BodybyFisher]

Ken, here is a photo of my lower control arm, the blue bushings are the strut rod bushings, if they are worn or the nut is loose the control arm will move forward and aft

Here is a photo of it in place

[kens96]

BBF - Thanks for the pictures. Looks like you replaced all the bushing and the ball joint. did you have to take it to a shop to get the bushing pressed in on the control arm?

Jim - I will look and see later today if this issue is a shift problem. With all the work that was done to fix the lean condition 2 weeks ago and the flashing of the PCM to update it, There is a good chance it was over cleaned and something is sticking or a setpoint was changed that should have been left alone.

The issue is intermitant but is obvious when it happens

[BodybyFisher]

I replaced the control arm bushing, ball joint and strut rod bushings.

I took the control are to a machine shop to get the bushing pressed in, they screwed it up the first time and I had to take it back (they used a hammer on it the first time and I went ballistic).

I can't recall, did you replace your strut mounts?

[kens96]

Yes strut mounts were replaced a month ago.

[kens96]

BBF - Thanks for the pictures. Looks like you replaced all the bushing and the ball joint. did you have to take it to a shop to get the bushing pressed in on the control arm?

Jim - I will look and see later today if this issue is a shift problem. With all the work that was done to fix the lean condition 2 weeks ago and the flashing of the PCM to update it, There is a good chance it was over cleaned and something is sticking or a setpoint was changed that should have been left alone.

The issue is intermitant but is obvious when it happens

Jim- I checked the RPM and it is sitting right between 600 and 800 RPM in Drive. Doesn't surge and drops right down when coming to a stop. In Neutral it sits closer to 800RPM. I think its good. Don;t see any manual adjustments for this. Is it all controlled by TPS and IAC.