Old Transmission Mount Cause Of Vibration

stevenva · Jan 23, 2020

2 Years ago I had to replace by driveshaft assembly because the rubber bushing holding the center carrier bearing weakened causing severe vibrations. When that started to fail on me it only took a hundred miles or so from first vibration to thinking your transmission is bad. Lucky it was "only" the $500 driveshaft. It was better after replacement but still had a faint vibration if you floored it. I read elsewhere in this forum of some poor guy having to replace his driveshaft 2 years after doing a new one. Turned out for him it was the transmission mount as a possible root cause. Due to age it became softer, flexing more than designed, forcing the center carrier driveshaft bushing to flex more than designed.
Mine looked OK but was actually sagging. Look how the center castle bushing is no longer flush with crossmember.

The new mount has stiff rubber while the old one looks perfect but can be twisted a bit just by hand. Replacement is not hard and the part costs less than half tank of gas. No more vibration while stomping it. I do not want to buy a $500 driveshaft because of a $15 trans mount.
The after shows the castle bushing flush with crossmember. It's bolt thread depth is limited and the nut only screws on so far.

jwrezz · Jan 23, 2020

Again, I'll refer to @traildogck don't you make/sell trans mounts?

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stevenva · Jan 23, 2020

He makes inserts only I believe. I'm not a fan of driveline poly, or whatever, bushing inserts. I have Whiteline diff inserts and now the diff whine transmits into the car. I hate em. Not to mention the fact that there is no noticeable benefit to me. Just my experience with that one product turned me off driveline bushing inserts of all makers.

jwrezz · Jan 23, 2020

Gotcha. I get that.

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kiwisix · Jan 23, 2020

Thanks for sharing with photos @stevenva I’m glad the vibration has gone. Did you need to switch or adjust the pitch stop mount top front of the transmission ?

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stevenva · Jan 23, 2020

I didn't do anything to the pitch stop

Brucey · Jan 23, 2020

I don't think the insert would help if the mount had failed completely.

It just stiffens up the factory one.

traildogck · Jan 24, 2020

The OPs pics just show how much the mount can collapse. And, In a little bit, after the mount breaks in it will have about a 1/8" space at the safety washer. Because I have a new mount in Cherry, well I mean I had yo put one in. And I had a 1/8" space when I took a picture on a thread @cardoc was posting similar pics.

Once the transmission weight is on it for a couple hundy miles. There is movement there.

kiwisix · Jan 29, 2020

traildogck said:
The OPs pics just show how much the mount can collapse. And, In a little bit, after the mount breaks in it will have about a 1/8" space at the safety washer. Because I have a new mount in Cherry, well I mean I had yo put one in. And I had a 1/8" space when I took a picture on a thread @cardoc was posting similar pics.

Once the transmission weight is on it for a couple hundy miles. There is movement there.

Is the safety washer item #4 on the pic, perhaps kind of a backstop should the trans mount break ? Will the 1/8" gap occur after installing the CKE SSP medium transmission mount insert with 1" raised rear king springs ? I noticed the safety washer on mine is still flush on the cross member but it's only been a couple 100 km since installing the insert.

jwrezz · Jan 24, 2020

What is this "pitch stop" y'all are mentioning?

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jwrezz · Jan 24, 2020

Ok so it stops the engine and trans from pitching fore and aft.

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Plastixx · Jan 24, 2020

For anyone interested in the pitch stop poly insert kit, it's Whiteline W92832. Bought from ebay for $24. Install took maybe 15 minutes. I was worried that once the bolts were removed that the engine would shift and make it difficult to get them back in, but that wasn't the case.

atchipmunk · Jan 30, 2020

@stevenva Thanks for this post. I recently started noticing a slight vibration under lighter acceleration on my '09 OBW 2.5i. Seems to go away at higher RPM's and under heavier acceleration...but haven't had a chance to try to diagnose it. After seeing this post, I climbed under my car to take a quick peek at the castle bushing under the trans crossmember, and sure enough...it's sagging much like your before pic. Guess I should go pick up a new tranny mount for my 4EAT...

kiwisix · Feb 5, 2020

With a new transmission mount and the CKE SSP insert my castle stopper was touching the mount hardware (similar to second pic, first post) to cause noise and vibration whilst driving and at idle, even after 500km of travel. The mount insert makes the fitting more rigid so more contact with the stopper.

Temporarily removed the castle stopper which has greatly helped with the noise and vibration, I'll put it back on with some sort of spacer to allow the mount and insert to do their thing.

I figure the castle stopper is to stop the transmission dropping if the mount rubber rips and is not designed to be in permanent physical contact hence the shoulder on the stopper bolt piece. But this is definitely more noticeable with the mount insert.

Duncan Heinz · Nov 25, 2020

Reviving a somewhat old thread...
After researching the pitch stop, I ordered the kit from Whiteline.
Black Friday pricing and free shipping sealed the deal.
Install and review will have to wait until spring.

stevenva · Nov 25, 2020

I must amend a false statement I made about noise after installing diff inserts. It was a bad wheel hub.

Old Transmission Mount Cause Of Vibration

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