driving automatics in manual gears

solarsvx · #1 12-11-2002, 09:09 AM

i have a verry bad habbit of manualy changing gears on my svx,, i like to drive around town in 2nd gear the car feel alot more peepy and i can use the full range of rpm without the tranny messing it up..

my question is does this hurt the tranny ?? maybe revving it high will cause more heat ?? or wear out the gears more or ?? cluches

also on the highways i drive in 3rd gear does 70 mph around 4,000 rpm wich u punch the gas the rpm and torque is right there..

i only do this whene i feel to drive more reponsive..

so maybe half the time im in regular drive gear and then the other half im manually driving,,

just wanted to hear some input from u guys..

#2 12-11-2002, 11:19 AM

Hmm I would be interested to hear what people have to say about this too.... only in the Tech forum.

Mike

CigarJohnny · #3 12-11-2002, 11:19 AM

I can't imagine it doing anything more than causing more heat than if it was allowed to upshift itself. Your gas mileage probably suffers a little but you probably don't care much about that

solarsvx · #4 12-11-2002, 12:05 PM

green good pointe,, => if u like move the thread to technical

oab_au · #5 12-11-2002, 04:22 PM

Quote:

Originally posted by solarsvx
i have a verry bad habbit of manualy changing gears on my svx,, i like to drive around town in 2nd gear the car feel alot more peepy and i can use the full range of rpm without the tranny messing it up..

my question is does this hurt the tranny ?? maybe revving it high will cause more heat ?? or wear out the gears more or ?? cluches

also on the highways i drive in 3rd gear does 70 mph around 4,000 rpm wich u punch the gas the rpm and torque is right there..

i only do this whene i feel to drive more reponsive..

so maybe half the time im in regular drive gear and then the other half im manually driving,,

just wanted to hear some input from u guys..

You would not do any harm by driving in the lower gears, in fact it can only help to keep the heat down. The 1st,2nd,3rd slots on the shifter are not just there, to tell you how many gears there are. They are there to be used.

As we all know this car is geared very high, driving around in D causes the torque converter to work hard to lower the ratio and reduce the load on the engine. This produces a lot of heat as the torque converter multiplies the torque.

It is much better to use a lower gear so that the converter does not have to work so hard. I allways use 3rd, unless I am going to run at high speed and if it is a bit of a twisty climb, I am in 2nd.

In third the gearbox does nothing, it is like a solid shaft, in one end, out the other. Nothing is running or wearing out, you can't do better than that.

Using the lower gears also places you up in the meaty part of the torque curve where the engine is most efficient.

Harvey.

svxistentialist · #6 12-11-2002, 04:32 PM

I reckon that downshifting manually and not matching engine speed to road and gear speed may well add stress and pressures to the tranny, and hasten failure.

That said, I am now driving mine in 3 all the time, and not slipping up to 4 until on a main road and over 60. It is bad for the box to be labouring in gear, top is a very high overdrive.

Also solar, I do find the tranny lazy. It prefers to hang on to higher gears, and accelerate using the torque available. I normally prefer to pre-empt the kickdown, and select the lower ratio if I am about to overtake. Hope I am not doing harm, but for safety sake, I want the car to be able to shift donkey when I say Shoo!

Arthur in England reckons the box "learns" your driving habits. So if you drive smooth and unhurried all week, and then put your foot down for some serious acceleration, the ECU decides you still want smooth, and holds the upper gears.

I tend to agree with him. You look for a bit of rapid push, not much happens, slow steady speed build-up. You get irked at this, floor the pedal, at which point all hell breaks loose, it snarls and drops two ratios, and the other motorists wonder, "what's up with him?, is it stolen?"

There seems to be no way of getting brisk acceleration from the tranny, unless you make it go flat out. I find this quite annoying, but do understand that normal progress for the SVX is quicker than most ordinary cars.

Joe

lee · #7 12-11-2002, 06:21 PM

Quote:

Originally posted by oab_au

...snip...In third the gearbox does nothing, it is like a solid shaft, in one end, out the other. Nothing is running or wearing out, you can't do better than that....snip...

Harvey,

First, I will admit to not knowing much about automatic transmissions specifically, or maybe even Subaru's in general. I realize your comments (and others) were dealing with certain speed/gear ranges. This latter part makes me wonder if I should post this at all, but I honestly want to make sure I understand.

Second, I agree to specify that as long as the speed is below that required to achieve TC lock-up, a lower gear would require less torque multiplication by the TC and therefore less heat should be generated.

However, I don't think the transmission will allow TC lock-up unless in 4th gear (somebody help here - I know mine won't - but maybe I have a problem in my unit). It seems to me a 3rd gear run would not result in 'a solid shaft system', and that could only occur in 4th with lock-up ~50mph or 80kph.

My driving conditions are very flat (and boring) roads, and so for steady cruising, at say 65kph (~40mph), my TC does not have to add a lot of multiplication. That may be adding to my confusion.

So, my question(s):

Is this a US model vice the rest of the world thing, or, what am I missing about how the unit works in 3rd vice 4th?

Trevor · #8 12-11-2002, 08:46 PM

Lee,

I am sure Harvey was talking about the transmission as a gear box when refering to straight through drive and was not bringing the the fluid bits into the equation.

My thoughts are that if Subaru had labelled " D " " O/D " and " 3 " " D " the tranny problems could have been much reduced if not elliminated. But no doubt once again the sales team won the day against the engineers on the grounds of being able to shout about four speeds or whatever.

lee · #9 12-11-2002, 09:16 PM

OK, that makes sense. thanks

svxistentialist · #10 12-12-2002, 04:35 AM

Lee

I am of the opinion that lock-up with this box applies to 3 and D[4], but not the other ranges.

Somebody correct me if I am wrong, but I believe that to be the case, and will check the manuals for proof when I am home.

Lock-up gives the equivalent of direct drive that you would have using pinions. So at steady speed, no multiplying at the torque convertor. This in turn implies less heat converted, less energy wasted, and translates as better fuel economy than would be the case with the torque convertor linked in all the time.

What you would save should depend on your driving style, how much stop-start traffic you drive and how hilly your roads may be. At a guess though, I suspect the lockup clutch will save about 2 mpg for normal driving, and possibly 4mpg+ on longer runs.

Joe

PS I agree with Harvey and Trevor, the Antipodean Duo, about driving in 3 most of the time. I treat 4 as an overdrive.

svx_commuter · #11 12-12-2002, 05:32 AM

Please remember that the "down under" trannys are different. So I really do not know if they operate the same or not.

As far as the USA trannys go, it's like this. The least amount of tranny heat is generated when the tranny locks up. This occurs around 45 mph with a light throttle and a level road. The selector must be in D. Lock-up does not occur in 1, 2 or 3 regardless of what the SM says.

The tranny has 4 forward gear ratios and the lock-up. If this was a Crysler product, the lock-up would make the tranny a 5 speed

I think there is no harm in running around in 1, 2, or 3 rd gear. Other than increased fun which tends to lead one to do it more and maybe wearing out the engine and tranny a little sooner.

I will however suggest that accelerating while turning may be harmful. In the US tranny the transfer clutchs will have to slip to allow for the difference in speed from the fornt to rear wheels. I think this can generate excessive heat if it is keep up for a long time.

I also think that driving hard with a broken tranfer valve will cause extra heat.

lee · #12 12-12-2002, 12:03 PM

svx_commuter,

So then it looks like it IS a North America vice Rest of World model issue.

Havey, et al, can get lock-up in third - then I can clearly see why they recommend driving in third.

For the NA models it would seem best to accelerate to 50mph, get lock-up, then slow to just above 45 (doesn't lock-up drop out at ~44?) to get lowest induced temperature.

Of course this doesn't apply to stop and go traffic, that would have too many variables for me to figure out.

svxistentialist · #13 12-12-2002, 04:22 PM

Quote:

Originally posted by svx_commuter
Please remember that the "down under" trannys are different. So I really do not know if they operate the same or not.

As far as the USA trannys go, it's like this. The least amount of tranny heat is generated when the tranny locks up. This occurs around 45 mph with a light throttle and a level road. The selector must be in D. Lock-up does not occur in 1, 2 or 3 regardless of what the SM says.

Looked up the information on this. The US manual [Sado-Masochist one, as per Commuter

] states "Non-Lock-Up operation during 1st Speed, N, R and P position."

This of course implies that there is lockup for the other positions, 2 range, 3 range and D.

However, the ATSG gives more information than the Service Manual, and in so doing validates Commuters comment that it will only happen in D, at least in the US and UK models.

Their chart shows that lockup can happen in 2, 3 and D. However, tellingly, as we are dealing with a 2-mode box, i.e. Normal and Power modes, lockup only occurs in 2 or 3 in Power mode. In D range it can be in Power mode or Normal mode for two different reasons. In Normal mode[D range] lockup stated purpose is "Lower fuel consumption". In D Power mode, stated purpose is "Higher performance"

For the 2 or 3 range, lockup stated purpose is "Higher performance" As lockup will not operate due to certain conditions such as oil temp lower than 40degC, during gear shifts, when throttle fully closed or during rapid acceleration, effectively this means that in US or UK cars, lockup will never activate in the 2 or 3 range. This is because the Power mode is only caused to activate electronically during rapid acceleration.

My car being JDM spec has a switch on the console that will permanently switch in the Power mode. If this switch is on, then the tranny will lockup in 2, 3 or D.

So we were both right in a way Commuter, and both partially wrong also.

Joe

oab_au · #14 12-12-2002, 05:42 PM

Quote:

Originally posted by lee
svx_commuter,

So then it looks like it IS a North America vice Rest of World model issue.

Havey, et al, can get lock-up in third - then I can clearly see why they recommend driving in third.

For the NA models it would seem best to accelerate to 50mph, get lock-up, then slow to just above 45 (doesn't lock-up drop out at ~44?) to get lowest induced temperature.

Of course this doesn't apply to stop and go traffic, that would have too many variables for me to figure out.

No Lee I wasn't including the torque converter in the solid drive thing.
If you are going to use the lower gears, then you are not too interested in converter lock up. It's the "GO" feature that you are looking for.

If you are driving in D and you give it some throttle to accelerate, the converter will un lock and will start multiplying torque, to load the high clutch and epicyclic gear set. These are the bits that carry the most load and suffer from low lube and high heat.

So the way I see it, is to not load them up more than you have to. Third gear removes all the load from these items as the whole gear sets are locked together as a unit. Sure you don't have lock up but if it's economy your after, then it's D and a light throttle at a higher speed when the load is less.

I don't think that there is any difference in the two types of gearbox other than the AWD section.

Harvey.

svx_commuter · #15 12-13-2002, 05:24 AM

This is all very interesting. Thanks Joe for the info and I would like to know a little more.....

Quote:

Originally posted by svxistentialist

However, the ATSG gives more information........

Their chart shows that lockup can happen in 2, 3 and D. However, tellingly, as we are dealing with a 2-mode box, i.e. Normal and Power modes, lockup only occurs in 2 or 3 in Power mode. In D range it can be in Power mode or Normal mode for two different reasons. In Normal mode[D range] lockup stated purpose is "Lower fuel consumption". In D Power mode, stated purpose is "Higher performance"

For the 2 or 3 range, lockup stated purpose is "Higher performance" As lockup will not operate due to certain conditions such as oil temp lower than 40degC, during gear shifts, when throttle fully closed or during rapid acceleration, effectively this means that in US or UK cars, lockup will never activate in the 2 or 3 range. This is because the Power mode is only caused to activate electronically during rapid acceleration.

My car being JDM spec has a switch on the console that will permanently switch in the Power mode. If this switch is on, then the tranny will lockup in 2, 3 or D.

So we were both right in a way Commuter, and both partially wrong also.

Joe

So what does ATSG stand for?

I know my car will not lock-up other than in D at normal throttle levels. However, my 97 OBS locks-up in 2 and 3 as well as D at normal throttle levels. The first time I saw this I was impressed. Stomping on the throttle will bring it out of lock-up and then the TC does the job.

So now you have me wondering and I want to get this right. Your JDM car will lock-up the TC when you are accelerating? If this is true it will take a heck of alot of heat off the tranny as compared to one that does not lock-up. It would be similar to having an automatic clutch where the TC lock-up is acting like the clutch. Fuel economy would be better and thsi would be very fantastic auto tranny.

John
(User of the SM)