D versus 3 ( now that i have a tranny cooler)

[n00b on demand]

So ive been using 3 while driving in the city because i wanted to keep the temps down and go easy on the tranny. I now i have a tranny cooler so im wondering if i should keep it in 3 while in the city or just drive in D like normal. Mind you there are times i am driving 40 MPH and the car enters 4th gear then i have to suddenly brake and it downshifts again. I know downshifting is what causes the damage. Let me know what you guys think.

What are the advantages of leaving it in 3? I've always driven in "D".

[n00b on demand]

advantages are that its easier going on the tranny when you drive in the city. Helps keep the temps down as well. It wastes gas and i would imagine the engine wears a little more. I really only did this to keep the tranny temps down but since i have a big cooler i dont know if i should even bother anymore.

How does it do this? I am skeptical of your claims without any real evidence.....

Anyone with a tranny temp gauge check this out?

[Earthworm]

Originally posted by BoondockSVX
How does it do this? I am skeptical of your claims without any real evidence.....

Anyone with a tranny temp gauge check this out?

In 3 the torque converter slips less and the tranny turns faster pumping more oil through it cooling it better.

Less slip = less heat.

Can anyone else confirm this? I thought it was the same thing as D without 4th gear..........

[BordeauxComet]

I'm pretty sure Earthworm's right about that. There was a long thread about 3 vs D, I'll see if I can find it...

Soobiesvx93, I think now that you got the cooler, you don't need to worry as much about the tranny heat. So you could go back to driving in D, unless of course, you prefer the feel of driving in 3 like some people do.

-Nathan (who also drives in 3)

[Earthworm]

Originally posted by BoondockSVX
Can anyone else confirm this? I thought it was the same thing as D without 4th gear..........

Yes that's correct. Preventing 4th gear at lower RPM's helps keep tranny temps down.

I tried running in 3rd this summer up twisty gradient mountain roads. I have a tranny gauge that reads from the tranny. Having read previous threads claiming lower temps. while running in 3rd I eagerly tried it. My temp actually increased a minimum of 10 deg. while running in 3rd. It dropped what it had gained when running in D, but it took several miles to cool down. I tried this "test" many more times, all to no avail. Running in 3rd may work for other SVXes, but it did'nt work for mine. Just my two sense.

[BordeauxComet]

Here's the thread about 3 vs D

[n00b on demand]

"I drive the car in 3rd unless I am cruising at over 60MPH/2000rpm.

Why? I want the auto to last as long as possible.

This car was designed to be a high speed tourer, to run at sustained speeds of over 100MPH. To this end it runs an overall top gear ratio of 2.44:1, or 30MPH per 1000rpm.

Driving in 4th gear around town, has the engine turning less than 2000rpm. The engine has not even started to climb the torque curve, it's output is so low, that the torque converter has to work over time, to increase the torque to accelerate the car. If it had a 4speed manual box, no one would drive it at 2000 rpm in 4th gear, so why do it just because it has an auto?

Some say, "the box will use the right gear for the situation" and so it will, as long as you are using the car for the designed use, as a high speed tourer. If you use it as a shopping trolley or a 10 minute commuter then you will have to change your ways to compensate for misuse.

Driving in 3rd drops the overall gearing to 3.545:1, or 20MPH/1000rpm, so 2000rpm comes up at 40MPH, by the time you are doing 60 the engine is at 3000rpm and well into the torque peak, provided by the Inertia Inlet system. This provides ample torque to accelerate the car without too much torque converter action. It also keeps the alternator charge high.

The last and most important point is that in 3rd gear, the gears in the box are all locked together, as a solid unit, no gears are running against any other gear, gear box load and wear is totally removed.

The way I see it is, two problems arise in this gearbox, heat and low line pressure. Driving in 3rd helps to avoid both problems, the torque converter does not have to work as hard to provide the necessary torque and the oil pump runs faster to maintain enough pressure to keep bands and clutches from slipping.

This last point is why most autos self destroy. Trying to tramsmit the high torque loads, with the low line pressure caused by low speed driving in 4th gear. The line pressure is controlled by the throttle sensor, the more it is open the higher the pressure, the safer the gear box.

If you don't want to use the car for what it was designed for, compromise use 3rd, or get different car. Apart from the early facings problem, there is nothing wrong with this auto box, it is just abused in it's use."

That was some of the best info i have read.