Transmission: Myth's Or Rumors!

[jcrome04]

Hey guys! I was just thinking about a couple of things me and my buddies have spoken about a little bit, but just aren't 100% sure of the answers. So I'm hoping that maybe a few questions I have can get answered here, and if anyone else has any, feel free to ask!!!

CONFLICTION #1: So me and my buddy we talking the other day about putting on the parking brake. When I park, I usually (don't know why) put the car into Neutral, set the parking brake, then put it into Park. He was asking me why I did this, and I told him how I hate it when you're parked at an angle, go to shift into Drive, and there is that loud "THUNK" of the tranny shifting into Drive with the weight of the vehicle on it. So I figure why not put the weight of the vehicle onto the brakes, instead of the tranny. But is that kind of weight ok to just sit on the rear brakes?? I really hate that "THUNK", but just am concerned as to if I am causing an excess amount of stress to the rear braking system.

CONFLICTION #2: Another thing I have always wondered, but never have received a 100% straightforward answer to is shifting the automatic transmission through the gears like a manual. Now, I DO NOT, let me repeat DO NOT drive like this, but am just curious about getting a good answer. I have never driven like this either. All the common sense I've had ever since my first vehicle tells me NOT to do this. But I have heard of one guy saying he drives his LS like that on a daily basis and has never had a problem. (Don't know any more details as to HOW, or HOW LONG it was driven like that) And another local kid said he drove his Dodge Neon like this all the time.

CONFLICTION #3: I don't do this, but my buddy does in his 01 Nissan Maxima GLE. He burns out ALL the time and smokes the tires up to (and sometimes into) the redline. A couple of times after doing this the transmission has been sluggish and even seemed like it was slipping a bit. He gets nervous, and shuts his car off. Waits for a little while. Starts it up again, and everything is 100% like it never happened. Is this due to the transmission over-heating or something?? This also just does NOT seem like a good thing to be doing to a poor little automatic transmission, OR is it an OK thing to do every now and again??

Thanks a lot to everyone in advance! And I hope we can get some rock solid answers on these "transmission" topics. As I said before if anyone else has any questions about transmissions as well, feel free to ask here!!!

[eatingupblacktop]

You got some side bets going?

Last one first - going above the redline indicates someone who doesn't like limitations placed on them - an antisocial attitude who's decided to abuse his car instead of his neighbour (probably speeds regularly as well)

Nothing wrong with manually shifting a slushbox - might wear out the shifter though.

The parking brake is designed to hold the entire weight of the car on a grade (don't know exactly what grade). Putting the tranny in neutral first is very wise because it takes the stress off the teeth of the parking gear which mechanically locks the output shaft and the drive wheels.

[jcrome04]

Hahaha no side bets here! I wish there was lol.

You're dead on man. He speeds EVERYWHERE!

I always thought it was really bad on the tranny to manually shift it! I KNOW neutral dropping it is a bad bad thing to do.

Awesome to know about the parking brake though. And that I'm not just being a dork!

[SRK]

Back in the days of mechanical controls up-shifting an automatic (domestic and some European) under full throttle was a VERY bad thing to do. Now that most transmissions are electronically controlled, it MAY be OK. But if the lever moves a spool valve, I wouldn't do it as a routine thing. Your buddies trans was overheating, and he'll reap the rewards of that abuse with a new trans - which will teach him an expensive lesson.

Downshifting every now and then for added engine braking is fine, but it's worth remembering that brakes are a lot cheaper than transmissions. If you like shifting, get a car with a manual.

The clunk you feel is the parking brake pawl disengaging. It won't hurt anything, as they are designed to suffer much abuse. Remember though that Lexus had a huge recall on the '04 LS transmissions because in a few instances the pawl stripped teeth off of the parking gear and caused some internal shifting problems.

And as Blacktop says, the parking brake is designed to hold the car, usually up to a 30% grade, and is quite capable of doing so. In fact using the brake keeps the cables moving freely.

Your buddy is unable to over-rev the engine as all modern ECM's have engine speed limiters built in - some will drop cylinders, others will shut the engine down for a moment, but the bottom line is the computer prevents rpm's from exceeding safe levels.

In the final analysis, it's best to let the trans do it's thing, in it's own way. Put it in D and drive it.

[John A.S.]

Back in the days of mechanical controls up-shifting an automatic (domestic and some European) under full throttle was a VERY bad thing to do. Now that most transmissions are electronically controlled, it MAY be OK. But if the lever moves a spool valve, I wouldn't do it as a routine thing. Your buddies trans was overheating, and he'll reap the rewards of that abuse with a new trans - which will teach him an expensive lesson.

Downshifting every now and then for added engine braking is fine, but it's worth remembering that brakes are a lot cheaper than transmissions. If you like shifting, get a car with a manual.

The clunk you feel is the parking brake pawl disengaging. It won't hurt anything, as they are designed to suffer much abuse. Remember though that Lexus had a huge recall on the '04 LS transmissions because in a few instances the pawl stripped teeth off of the parking gear and caused some internal shifting problems.

And as Blacktop says, the parking brake is designed to hold the car, usually up to a 30% grade, and is quite capable of doing so. In fact using the brake keeps the cables moving freely.

Your buddy is unable to over-rev the engine as all modern ECM's have engine speed limiters built in - some will drop cylinders, others will shut the engine down for a moment, but the bottom line is the computer prevents rpm's from exceeding safe levels.

In the final analysis, it's best to let the trans do it's thing, in it's own way. Put it in D and drive it.

Amen to that!

[oldskewel]

...

Your buddy is unable to over-rev the engine as all modern ECM's have engine speed limiters built in - some will drop cylinders, others will shut the engine down for a moment, but the bottom line is the computer prevents rpm's from exceeding safe levels.

...

On a few occasions (like 3 or 4, mostly as a test), I have floored my 91 LS400 from a complete stop (in Drive). When I do this, I keep an eye on the tach, and each time I've done it I notice that the revs go past redline. As soon as they go past (maybe 200 RPM past), I instinctively let my foot off the gas, which causes the AT to shift up. I can certainly live with this behavior, but wonder if it indicates a problem with the AT or the rev limiter. Any ideas?

Oldskewel

91 LS400

85 911 Cabriolet (5-speed, rev limiter works great)

[jcrome04]

Mine goes into the redline a little bit too sometimes but that's when I'm 100% into the throttle and I'm in PWR mode. and it shifts immediately after.

[SRK]

The rev limiter is usually set for several hundred rpm above the "redline" on the tach. The redline is not some instant engine destruct point, but more a conservative limit that the factory would like observed, mostly for warranty periods. The Ford 5.0 HO engine is redlined at 5800, but the limiter doesn't hit until 6200 for example. I'm sure the Lexus V-8 can do 7k without damage.

[jcrome04]

I'd love to boost the 1UZ around town at 7k RPM! :D :D

[SW03ES]

I am ECSTATIC to hear you use your parking brake! Most drivers in the US don't on automatic transmission cars which is extremely dangerous. The teeth on the parking prawl aren't designed to hold the whole weight of the car, although everybody thinks they are.

What you do is very smart, I set the parking brake before releasing the service brake which accomplishes much the same thing.

Your parking brake is actually not the rear brakes. On cars with rear disc brakes there are usually seperate parking brake drums (or drum).

[jcrome04]

Now that you mention it Steve someone told me once they did a rear brake job on an LS them self, and they didn't understand why there was a set of shoes in there as well. Turns out it was the Parking brake's brakes!!

I try to tell everyone I know to do it too, but for some reason they WON'T!!! Even though I tell them all this information, they still insist on "grinding their teeth"!!! :D :D

[eatingupblacktop]

I try to tell everyone I know to do it too, but for some reason they WON'T!!! Even though I tell them all this information, they still insist on "grinding their teeth"!!! :D :D

The reason I think a lot of people don't use their park brake (besides being lazy or having bad habits) is because they've probably had a cable either brake or seize in the past from not having it regularly serviced. All you need to do is make sure the cable's greased and adjusted, shoes cleaned and checked regularly, and use it often. Easy peasy lemon squeasy.