Lockup vs Non-Lockup

Lockup allows lower revs at highway speeds and removes a source of loss (the slippage of the torque convertor). Both of these lower transmission temperature (good) and improve fuel economy. On the con side, you have one more thing to go wrong, and everything else being equal, the transmission won't respond as quickly to downshift demands. All in all, I'd say the balance is overwhelmingly positive for having this feature.

Thanks Mike

Murphy's Law = of course I have the transmission without Lockup. I have noticed that it shifts a little hard and is slightly slow responding between park and drive. (110,000 miles, American car rescued into Canada)

I plan to change fluid this weekend, perhaps a flush if all goes well.

One thing I am worried about is that the car rolls backward on a hill if one lets off the brake when in drive. Not a good sign uh? or is this also indicative of non-lockup?

I'm not entirely sure if that has to do with lockup or not, but I've come to notice that cars with rear wheel drive generally only go in the direction they are set in (i.e., set in drive, doesn't roll back; set in reverse, doesn't roll forward) and front wheel drive cars roll all over...but I could be wrong.

Anyway, how do you know whether you have lockup or non-lockup? I've noticed that my 1993 Volvo 940 seems to shift a little hard and gets fuel economy in the high teens/low twenties...could this be because it is non-lockup?

From the Volvo Brickboard: " Product Plate Number Coding. The Product Plate is located on the passenger's side of the front radiator cross brace and has the following additional information in the five lines on the right of the label: "

Line 2 Digit 2 refers to the Transmission. If the code is 6 you have AW 70L/71L/72L with lockup If the code is 7 you have AW 70/71/72 without lockup

down the same page it says 940 normally aspirated had the AW 72L and the turbo had AW 71L. So you should have lockup.

So Robert

Did you check if you had lockup or not? (thanks Andrew) I am interested to know now since you mentioned that your 93 940 seems to shift a little hard.

Sorry being from across the pond I think I'm in a boots/trunks bonnets/hoods thing please what is a "lockup"? Thanks Bosun

On an automatic transmission with lockup, there is a clutch built into the torque convertor. At highway speeds this locks the input and output shafts of the torque convertor together, which eliminates the slippage in this fluid coupling. At light throttle settings as you accelerate through the lockup point, you can feel something like an upshift.

Just checked...the car indeed does have a lockup transmission, so I'm not sure exactly what is going on. It's not a terrible shift, so it could be normal and I just never noticed it; but my 1998 V70XC is a whole lot smoother when it comes to shifting...that may have to do with increased horsepower, though.

I'm not too worried about it...but it's definitely not a lockup/non-lockup thing.

Thank you, yes I to have "lockup"with my 1997 850 GLT I just didn't know it! Thanks again Bosun

Well I had half the fluid changed in my non-lockup 945 with 110,000 miles on it.

Everything seems ok, shifts a little hard, I could do better myself if I had a clutch but I am sure that there is a lot of folks who wished they had a standard in their 940. (for all you folks across the pond, lots of US Dollars waiting to be exchanged for 940 standard transmissions)

I will keep an eye on the gas mileage just to see how much worse the non-lockup is over the lockup.

Not sure I understand exactly all the differences between the non-lockup and the lockup but the way it was explained to me was that if I were going down a steep hill with the cruse control set the non-lockup would not maintain the cruse setting but would gain in speed. Personally I think the real answer has a lot to do with which way the wind blows.

Haven't had the car long enough to get the feel of all this, perhaps a longer trip is in order soon if the price of gas drops a bit more.

Thanks to all that replied

The 850 and the following S/V70s always had lock up from the very beginning of the production. The shifting strategies changed over time but the concept remained the same.

Joerg, driving a V70 D5 11/2005