I routinely downshift my auto trans to maintain speed without braking in traffic and downhill. I can get into 2nd by shifting to 1 at speeds above 25MPH, but if I let the speed drop below 25, it downshifts to 1 with heavy engine braking, a hazard in traffic. For smoothness, I feel that the 2-1 shift should occur at 15 MPH.
Does anyone know if it's possible to lower this shift point (2-1 with lever in 1) without installing a reprogrammed ROM?
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I routinely downshift my auto trans to maintain speed without braking in traffic and downhill. I can get into 2nd by shifting to 1 at speeds above 25MPH, but if I let the speed drop below 25, it downshifts to 1 with heavy engine braking, a hazard in traffic. For smoothness, I feel that the 2-1 shift should occur at 15 MPH.
Does anyone know if it's possible to lower this shift point (2-1 with lever in 1) without installing a reprogrammed ROM?
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What mode do you have the gearbox in, because I believe the economy / sport modes change the speed at which the downshift occurs - I can't remember which way round it is, but in one mode, the downshift should be a 25 mph, in the other mode, I think it's 6 mph (quite a difference).
Ah well it must be different in your age of 850. I have a 98 S70 auto, and from memory of reading my handbook, and actual use, there is quite a marked difference between economy and sport mode, in the downshift to 1st when in L. Recently I had reason to experiment with this, when on holiday, one of the country lanes, had quite a long descent, that you couldn't really drive down quickly, so needed the 1st to keep the speed down.
It's the same gearbox, between your 850 and my S70, although I think there was the odd revision (possibly software only) from the early 850s (I did once read somebody's account of their early 850 and the gearbox would downshift, automatically, when off the throttle and descending a hill, for engine braking - but I've only ever read one account of this).
Do you have your handbook, and does it say anything about this? I'm pretty sure mine does. So the question, really is a slightly different implementation - or the possibility that your sport / economy mode switch isn't working? Can you confirm from the other characteristics, that sport / economy mode is definitely making a difference?
I hope that you don't take this the wrong way, but....I've always wondered why people are do intent upon saving a few hundred dollars in brakes at the expense of several thousand dollars worth of transmission.
Just as an aside, here in Las Vegas on certain downgrades, there are signs posted that prohibit downshifting, like on Cheyenne Eastbound from the Beltway through Summerlin.
All the signs I've seen are for commercial vehicles with "engine brakes" ("jake brakes") and are in or around towns and cities. We have one here in town that reads "engine braking prohibited" but I've seen them worded with "downshifting." Unmuffled engine brakes create that loud BRAPPP noise. Muffled ones really aren't very loud.
As far as long descents are concerned, I can definitely see the purpose of downshifting, but as far as downshifting while coming up to a traffic light, it just seems totally counter-productive.
I followed a car down a long mountain road, watching brake lights and smelling burning brake pads all the way, expecting them to lose it when the brake fluid boiled.. Fortunately, the slope ended before that.
Also, it's the engine that absorbs most of the braking energy, not the transmission itself. I suppose the torque converter converts some kinetic energy to heat as well, but it's not a wear item. The heat ends up in the radiator via the transmission cooler. Engine braking puts no more wear on the trans than does normal driving.
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I don't do that either. I use to to control speed on downgrades, and to maintain slow traffic crawl speeds without braking every 10 seconds. Now, with a manual trans, I'd downshift, if I thought the light might turn green soon, so I'd be in a good gear to accelerate again. Otherwise, when the speed got too low, I'd just shift to neutral.
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I'm glad that you agree with me. Downshifting for a red light which I think is what the OP alluded to is just ludicrous. Very true what you say about putting no more wear than normal driving. Every time that bands and clutches engage and disengage there is wear. If you were to downshift at every light, you would be creating twice the wear. Don't delude yourself that the wimpy little coil in the radiator is doing a whole hell of a lot, it's a marginal stopgap at best even when everything is new. I just gotta tell you something funny. Last Summer, one of the hottest Summers on record here In Las Vegas, I went into the dealer for an oil change. As I was waiting, I walked around the entire building to smoke a cigarette (Don't go there). At the far rear of the lot, I saw this guy with an electric "pusher" that he was using to push an XC wagon into the very rear next to a wall. I walked over because I was interested in this machine and when I asked what was wrong with the car that they were pushing he just said "transmission...these hot days really bring them in". When I asked how many of the cars in the lot were in for transmission repairs, he pointed to the last two rows. TWENTY-THREE of them, all under five years old. He then added, "Oh, we have fifteen more in the storage lot". No wonder that they now have Volvos go into neutral when you come to a stop. Too bad it doesn't do it when the A.C. is on. With the kind of driving that I do, I think that I'll have the trans flushed on a yearly basis. I can just imagine a transmission failure on a 123 degree day with clients in the car.
Fortunately, manual transmissions don't break as easily, and a sizable fraction of Volvo models (S40,V50,S60,V70 but not S80 or the XCs) are offered with one. One more reason why slusheeboxes[*] suck.
[*]- The exceptions to this rule seem to be the AW7x boxes offered on the old RWD Volvos. Those seem to be pretty bulletproof, and maybe even better than the 4+OD manual trannies offered on the same cars.
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