Hello,

On my 960 sedan, I have an issue I've been puzzled about for awhile. When driving at around 40-45 MPH maybe up to almost 50 MPH, only at low RPM cruising, the transmission or the torque converter in the transmission will struggle to smoothly transition from either third to fourth gear or perhaps more likely the torque converter locking and unlocking. It shifts kind of rough and almost slams back and forth a bit as it's trying to settle in on one state or the other. It was rare that it happened but it's getting a little bit more noticeable now so I want to get it fixed.

This often occurs when I'm going on level ground or very slight uphill grade and at this particular speed range. It acts like the car isn't sure which gear it wants to be in because it kind of bounces back and forth between 2 states. Immediately I back off the throttle or more often I give it a little more throttle to make it downshift from fourth to third or to unlock the torque converter, whichever is happening. Fluid was flushed about 25K miles ago as a routine maintenance item. I've owned the car for a little over a year and almost 30K miles. It's been doing this ever so slightly for awhile now but concerned it's getting more noticeable. Under normal or moderate acceleration it always shifts perfectly through all 4 gears. Current mileage is 183K.

Previously when I first got the car in December 2017 there was a bad vibration when the car was under load, which turned out to be the transmission mount. This was replaced a good 15K miles ago and eliminated the vibration. But that problem existed when I got the car and who knows how long it was run like that by a previous owner. This car had a great body but maintenance was somewhat neglected by previous owner(s). It had a failing head gasket causing a miss when I bought it, but that's beside the point.

The car always shifts smoothly all the way to fourth gear under normal to moderate acceleration. I never drive it hard. Downshifts under other conditions are always normal, like pressing the accelerator pedal to kick it down to a lower gear to pass someone or going uphill on the highway or whatever. It's this cruising along at a particular speed when it wants to change states from fourth to third gear or as I say more likely torque converter locking/unlocking, that this slamming back and forth occurs.

Any thoughts on whether this could be the torque converter or a solenoid or the transmission itself? Fluid level is fine and not really dirty.

I used to own a notorious 2002 Volvo V70 XC and after the fluid got fully hot, the transmission started slamming when upshifting from third to fourth gear (5 speed automatic). This isn't that severe but it has gotten to where I want to fix it. And I can't say that it's only after the fluid is hot. Cooling system is in good shape, I've had cooling system flushed and the radiator is newer i.e. not original to the car.

Thanks,
Tom

 

I'd change the fluid and see what happens. "Not really dirty" is not good enough, when was it last changed? Besides the fluid change, not much else to do without getting pricey.

 

 

I wouldn't use synthetic, it wasn't designed for it. Also, don't flush it, just change it-power flushing seems unhealthy for older cars especially. Although, since changed so recently, you probably won't see any difference. I'd live with it the way it is, not really worth it sinking lots of cash in this car unless you really love it beyond reason.

 

Thank you for all of your advice. I appreciate it. Just to clarify, the flushing I was referring to is when you disconnect the return hose and use the transmission itself to pump some/most of the fluid out before refilling, then repeating until clean fluid comes out; this being as opposed to connecting a machine to force fluid through the transmission to flush it out.

I am kind of invested in this car to keep it long term if possible. If all else fails I found a transmission within about 120 miles of me for $100 out of a 960 whose timing belt broke. It's a bit more of a drive than I'd like to make but the price is right.

 

Yeah, a flush is power flush change of fluid, what you do is just a change which is fine.
If you have a chance to get a good tranny for $100, go for it, just make sure they changed the fluid once or twice...