GOBOGIE

I'm what you would call a hugh sports car fan especially Porsche's (Have '86 944) but a novice mechanic. I've been told different answers over the years about whether or not down shifting is bad for the transmission. Does anybody know the correct (not an opinion) answer? I like doing it because it gives you greater control when slowing down from high speeds when approaching corners.

Cory

Skip

Not sure I want to be the first to touch this one

Downshifting is bad for the running gear... all of it! When street driving a Porsche manual transmission I would not recommend it. If you're practicing for the next event, then by all means, heal-toe yourself to death.

Why??? Very simply economics. Think of all the things that get stressed when using the engine/transmission to slow the car... now repair or replace all of them. Now, look up what a good set of brake pads and rotors cost

This style doesn't work for most folks with "sports" cars.... because it just ain't cool enuf

YMMV!

Skip

JackOlsen

There's also a difference between downshifting to "engine brake" with the drivetrain and downshifting in order to be in the correct gear when you come out of a turn. Using the engine as a brake is not smart. Transitioning smoothly through turns (matching engine revs to reduce stress on the drivetrain) is smart, although I'd say it's largely unnecessary on public roads.

Thaddeus

I am of the opinion you shouldn't use your engine as a brake. Hard on clutch, tranny, etc., and that's what brakes are for. ALSO, if you are using the engine to brake, you run the risk of inducing a rear-end slide/ oversteer if you pop it down in a curve.



Thaddeus

Adam Richman

I am not an expert on this but would agree in principle that brake pads are much cheaper than a tranny. Also remember that you can greatly reduce syncro wear by double clutching to downgear. Here is a very good article - Double Clutching

jim968

Well, I guess I'll kinda swim upstream on this 'un, being the natural contrarian that I am.... but remember in reading this, that I'm not advocating high-revving, ******-the-stick downshifting here.

Coming to a simple stop on a flat road, I'm sure downshifting doesn't make sense. But I live in the mountains. I'll always downshift for a long downgrade, or a short one if I expect to have to stop at the bottom.

Two simple mechanical thoughts: One, your brakes are wearing the whole time they're applied, and they're heating up. The clutch goes thru one brief wear cycle as the RPM's match, but once it's engaged in the lower gear, there's _no_ wear on it.

Wear on the gears themselves is a _total_ non-starter, since when your're backdriving the gear train, the wear is on the other side of the teeth from when you're under power.

Yep, there's wear on bearings, synchros and engine, but it's minimal; Driving like this for almost 40 years, I've had to replace one... count 'em, _one_ clutch, and that was in a 4x4 truck that was used for serious hauling & off-roading. I've never replaced more than a shaft seal on a tranny, and that only once, in the same situation. The original engine, clutch, & tranny were still in my old '83 GTI at 'way over 165K mile, after I'd flogged the crap out of it for the first 90K.

I'm _not_ gonna argue with anybody over this issue; it's a matter of preference as much as anything; but I like to be in the gear that gives me the most immediate control of the car, either for slowing or getting moving. Heck, I even downshift automatics on the rare occasions when I drive one.

It's also a part of the pleasure of driving a stick.... if you're not going to downshift, you miss half of it. Hang the cost!
Jim, swimming upstream here...

PSUice944

Jim, I've gotta agree with you! You really are missing "half the fun" if you never downshift. Granted, I don't do it too much (read unnecessairily), but we drive sports cars right, drive like it and expect to pay for however much you play

Just my $.02 I love to shift!

keith

what about the added strain on the bottom end of the engine???

Skip

Good to see some others on this topic... I'll append my remarks...

I do downshift, heal-toe, and anything_else_that's_fun whilst street-driving. But, I love ripping the car apart too... don't mind it one bit (wife prolly don't like it as much )

Jack (911 guy on our list.. hehe) brought up a good point... the difference between engine braking and running the smooth transition. I'll offer this useless opinion... Using the "correct gear" can be a tranny saver. I've ridden with folks that understand the "using the brakes to slow down" principle... but, when it comes to choosing a gear to restart the acceleration phase, I usually end up in the windshield

Again, YMMV!

Skip

Tabor

I just though I would chime in and say:

1. how do you drive a stick without downshifting? Does that mean once I am in 5th on the freeway I'm stuck there?

2. I down shift to the correct gear before entering corners.

3. Brakes are cheeper than engine/tranny/clutch. However, engine breaking does not wear the clutch/tranny any more than any other kind of driving. However, the pistons end up going up and down more, and they will only go up and down so many times before a rebuil. So, I don't engine brake, unless I am on a long shallow grade and want to maintain a constant speed.