Larry Meyer

automatic transmission shudder - torque mount fix

4 posts in this topic

I have a 2007 V70R (with 114k) which began to have this problem late this summer. Specifically after about 30 minutes of driving, after being stopped, the transmission (Geartronic 6 speed) would thunk when shifted from P, N, R, D. Afterwards, sometimes when the car shifted from 2nd to 3rd, or from 3rd down to 2nd (when slowing and braking), the shift would be harsh and clunking.

But both these problems were sporadic. Ninety-nine % of the time the trannie was just fine.

After reading many posts, suggesting everything from new trannie, fluid flush, software upgrade,  coolant contamination, failing valve bodies, etc., I decided replacing that the lower transmission torque mount, a known defect, was the place to start. It was the cheapest fix. I had already replaced the upper engine mount, another known defect. If the upper engine mounts were under-engineered, then likely so was the lower transmission torque mount. As the car needed to be warmed up before the problems occurred, this could be explained by the fact that the torque mount’s rubber bushings softened up with heat from the engine.

I ordered  IPD’s HD Billet & Polyurethane Transmission Torque Mount and had my mechanic install it. WOW what an immediate difference! The original torque mount was a mess. It’s just a metal frame. The bushings were seriously degraded. About 95% of the front-end clunckiness was gone: I had been thinking I was overdue for serious suspension work.

(It’s just possible that this fixed also resolved an intermittent “Chassis Service Settings” warning light I had been getting.)

I am not an engineer, or even a mechanic, but it’s just common sense that if the transmission housing is not firmly anchored to the subframe, it’s not going to do its job very well.

On the editorial side, it seems ridiculous that Volvo is going to all the expense of setting up a 4C suspension system, with all the sensors and so on, and then so seriously under-designing something as fundamental as the torque and engine mounts. It’s like building a mansion on a sand foundation.                

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Agreed, but on the other hand, those two torque mounts have two roles; isolating engine vibrations from the chassis and preventing the engine from rotating. Over 10 years and 100k miles from rubber bushings seem pretty reasonable and they are easy to replace. I wish the control arm bushings were that easy to replace.  Mine all failed at about 110k miles.

Are you getting much in terms of vibration with the poly transmission torque mount?  I installed Pro Part Sweden's, which got rid of the clunk but has the side effect of increased vibration.

GLM

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Very slight additional vibration. I’m actually shocked at the overall performance improvement. Handling, ride, acceleration all conspicuously better. It’s like night and day   It got rid of a big clunk too.  

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Just to be clear there were two kinds of clunks that were gone after installation of the torque mount. One seemed to be “suspension” related; it occurred running over road bumps and holes at any speed. This was due I now think to the engine not being strongly enough supported by the torque mount.

The second clunk was related to gear shifts through P, N, R, D when stopped and after the car was warmed up. These were clutch slippage (shudder) in the trannie. I think this occurred only when the car was warmed up because engine heat softened the rubber bushings. When the ambient temperatures were cold, the bushings were firmed up just enough to overcome clutch slippage.

At speed the trannie ran fine.

So if you’ve got these two problems a new torque mount is the way to go.

In addition to degraded bushing I think there was some metal fatigue in the mount framework. The IPD mount is solid, not just a metal frame.

Looking back at my history driving the car I think the failing torque mount has been affecting the car’s performance for some years now. It would not be unwise to replace the mount before it gets to this stage, say at about 75k.          

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