Hi. I have a 1993 960 Wagon that I bought used with 123K miles. Over the past 6 months I have put about 12K miles on it and absolutely love it except for one thing.

If I try to accelerate slowly from 1500 and 2000 RMPs I will experience a very brief knock. This only happens when the car is warmed up and I accelerate slowly. If the car is cold or I step on the gas, this never happens and the car performs great.

The knocking is most noticable when I am driving in traffic on mountain roads. The car shifts into the next gear and idles along going down the hills, and then knocks the instant I ease on the gas for the next uphill. Again, if I step on the gas it doesn't knock.

My mechanic says that this problem sounds like a worn torque converter lock and that the only way to "fix" it is to open the tranny. Given the expense, the fact that the tranny is otherwise working just fine and the age of the car, he recommends that I just live with it. But it is annoying.

I can reduce the number of knocks by using the "S" setting and keeping it out of overdrive by selecting "3" instead of "D", but this reduces the gas mileage. I can also "avoid" the knocks by driving agressively :grin: but traffic and speed limits don't always permit that "fix". :whistling: Any other ideas?

where does that knock eminate from when your driving, infront of you as if the engine or around the area of the gearbox around the center console near the floor?

Do you know when the last time the trans fluid was changed? These transmissions are rather sturdy but having old fluid can cause some problems.

I would flush the trans fluid and replace with a fully synthetic such as Mobil 1.

That may smooth things out, I have had something similar happen a couple of times that was cured with flushing the trans.

My problem was with the lock up, it was not a knocking more like a stuttering, at about 45 mph

DanR '94 964 334,000 miles (100,000 on the new engine)

gotta be careful when flushing it out tho, otherwise silt and stuff thats left in some of the pipes gets dislodged if you connect it up wrongly, and rubbish from the cooling loop into the radiator can come through etc... its still a viable option tho.

It is always difficult to determine where a sound is coming from, but the best that I can tell is that it is coming from underneath the car. I'd describe the "knock" as similar to the sound of hitting a small bump at speed. It could be describe as stuttering. Again, it is difficult to describe sounds.

I bought the car from a small repair shop who told me that they changed the fluids including the tranny fluid before the sale. Of course I checked the fluids before the sale. After 6 months and 12K miles the tranny fluid still looks and feels clean and is not discolored.

Again, I never have any problem under load. If I step on the gas, the wagon behaves as a 960 should and moves nicely. I have absolutely no trouble accelerating up hills at 80+ MPH. The problem only occurs when I drive it passively and I try to slowly apply some gas when idling along at 1500-2000 RPMs.

Thanks for the help.

that sounds like a very similar problem from someone else who i have read about somewhere here ... maybe they are around?

from what i remember they described a series of filters and screens within the gearbox at different stages, and flushing can cause these either to get dis-lodged, or well up the dirt around so it flows around to the next filter.

apparently it caused them all matter of noises and problems shifting and mpg etc...

i would quote me on that as i may have just dreamt it or read it somewhere when googling

Thing is that it shifts fine and doesn't make any noise except in this one situation. There is absolutely no slippage, ever. Gas milage seems about right 22-23 on the highway, high teens around town. This really is more of an annoyance -- like a rattle -- than a real problem. I would like to correct it if it doesn't cost too much.

fair enough, is it a sharp rattle. My 740 has one when hitting hard on the gas using 1st and 2nd usually around 2000-2500rpm ... i have just ignored it as it sounds cool to me, its not doing any damage, i found that it was where the exhaust came off the header there is the cooling lines from the auto box and on that is attached a metal plate to which the warm air feed was connected to. so i just removed this. the noise quietened, but hasn't disapeared.

Matt

Sorry for not replying sooner, but for some reason, I am not getting notifications of posts.

The sound isn't like a rattle that one might hear if there is a loose exhaust. It is more like the sound of worn u-bolts on the driveshaft. It sounds similar to hitting a speed bump or pot hole going a little too fast. Yet the car doesn't experience a jolt as it would if it hit something and it doesn't make a noise easing off the gas as it would with worn U-bolts.

Like I said, it only happens when I drive passively and I try to slowly apply some gas when idling along at 1500-2000 RPMs.

i'm out on this one...

Maybe the sound then is coming from the drive shaft joint at the differential?

I have read where some have found a crack in the rubber boot and the grease has dried out. I causes a unique sound too.

Worth looking into, if caught early enough just regreasing should silence it.

DanR

now u say that, the bearing or something went where the propshaft comes from the gearbox on mine, was awful rattlingknocking noise but when warmed up was fine ... :s i had it changed tho

I'll try to hit it with the grease gun.

Sorry for not replying sooner. I have no idea why I never get notified when there is a new post on this thread.