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-   -   Is it bad to downshift? (http://www.peachparts.com/shopforum/diesel-discussion/81608-bad-downshift.html)

JenTay 12-10-2003 01:20 PM

Is it bad to downshift?
 
guys,
i wanted to ask if downshifting is bad for the car. whenever i do it, there just seems to be a lot of engine noise in a bad way.
it just seems like gas cars take it in stride and mine hates it.

i'm on lunch break and it is more fun that getting rained on outside. besides, my finger just got bit by a kid who didn't want me cleaning his teeth. ugh.

jt

Rick Miley 12-10-2003 01:33 PM

Is this an automatic or manual transmission?

In any case, using the engine to slow the car down is not adviseable. The brakes are specifically designed for that, and brake parts are a lot cheaper to replace than engine, clutch, or transmission parts.

If you're talking about using a lower gear to hold the speed down while you're descending a mountain, that's not so bad as long as you don't overrev the engine. The dots on the speedometer indicate the maximum safe speed for each gear.

janko 12-10-2003 01:37 PM

you be double clutching? if manual.

JimSmith 12-10-2003 01:38 PM

jt,

Downshifting is good for control when you do it right and should not adversely affect the rest of the car in any way. If you are coming to a stop, it is likely easier on the clutch to use the brakes though, and since you have no use for the extra power available at the higher rpm after you downshift when you are coming to a stop, it makes more sense to use the brakes.

You will likely get a number of responses to this question, but engine noise, unless there is a loud and not healthy sounding metallic clanking, is not unusual. Most of the normal noise is really exhaust system noise in most cases, and it gets very loud veryt quickly as the engine speed increases. Not much you can do about it, so most of us just accept the noise and drive on.

My daughter drives our 1982 240D very hard, at high rpm (she virtually redlines before shifting in every gear), and the car runs extremely well. It has 311,000 miles now, and she drove it back and forth across the country last summer. It starts in 20*F weather without any hesitation or plug in water heater help, etc. So, downshift when you need the extra power or control, and take care not to slip the clutch or use the clutch as a brake - they cost a lot more to repair/replace than brake pads - and the car will probably be rejuvenated.

Good luck, and next time a kid bites your finger give him a squirt of Tabasco sauce or something. They are like puppies and need to be taught to connect bad behaviour with bad experiences.

Jim

rickg 12-10-2003 02:09 PM

I was told years ago that excessive downshifting to slow a vehicle is hard on the differential. I guess it puts a reverse load on the pinion bearings and/or gears, or something like that. But I've never had that confirmed from another source.

jobah 12-10-2003 02:37 PM

I am quite certain that it does very little harm to a vehicle. Earlier, I used to downshift quite a bit. I still got 250 kmi from the clutch and I have now owned the car for over 300kmi. I do not have any noticeable damage from downshifting. I figure that as I am at over 370kmi with about 310kmi of it driven by me, if my driving style was poor or if I did things which were damaging to the car, the problems would have shown by now -- especially on a 60x which the board seems not to like as compared to a 61x (I do not share this feeling).

janko 12-10-2003 02:40 PM

this be a 240d. may be the downshifting is contemplated for keeping up with traffic.

Wes Bender 12-10-2003 03:14 PM

I don't think down-shifting our diesels is a good idea. Holding the speed on a downgrade is a different matter, though.

Back in the '50s and '60s everyone racing sports cars downshifted. If you didn't, the brakes wouldn't last the race. More modern brake materials have changed all that. Most racers now only downshift to the gear they need exiting the corner rather than using the engine to slow the car. Brake pads and linings are definitely cheaper than rebuilding engines or transmissions.

Just my $.02,

Wes

jas2wa 12-10-2003 03:23 PM

:confused:

Isn't he talking about hitting the kickdown switch, i.e. downshifting for better acceleration? This is how I read the first post-

Rick Miley 12-10-2003 03:26 PM

She hasn't answered my question - auto or manual. So everyone is guessing. :rolleyes: Jen, we're sitting around with nothing to do but answer your questions. C'mon, you have to keep up with us!

jas2wa 12-10-2003 03:36 PM

Ooops! She!

Sorry, Jen.

:o

You must clarify transmission- rickmiley's right- we all are sitting around with nothing better to do, trying to answer your question...

:D

JAS

moleskin 12-10-2003 03:37 PM

Being in the appropriate gear for your speed and road conditions is the way to think.
Unless you are racing or driving hard for a reason this normally means using the highest gear possible with out labouring the engine. Maximum torque is normally at low revs on older diesels.
However as previously stated by others, changing down a gear for long hill descents will allow the engine to do some of the braking.
Proper use of the clutch and gearbox will not cause unusual wear. After all this is what they are designed to do.
If on the other hand it's an auto box just let the box do the work, but downshifting with the lever is still useful for descents.

JenTay 12-10-2003 03:41 PM

sorry guys. this is not my day.

the car is a manual. don't you just love a girl who insists on a manual car?

jen

ps. not my day= got bit again. different kid. dang

the pics from the party came out. ugh. like i said , not my day

Rick Miley 12-10-2003 03:45 PM

Quote:

Originally posted by JenTay
not my day= got bit again. different kid. dang
Must have smelled the blood from the first bite.

DieselAddict 12-10-2003 07:57 PM

I'm a strong believer in downshifting and the key to avoiding stress on the transmission, whether auto or manual, is to match the engine speed of the next gear before completing the downshift. If you just release the clutch or pull the shift lever back with an auto tranny without pressing the throttle appropriately, then yes, that puts stress on your driveline. Otherwise it's just like upshifting, provided you don't overrev the engine.

Downshifting is very useful on long downgrades to avoid overheating your brakes and possibly killing yourself. Also while driving on snow or ice it's safer than applying the brakes if you do it smoothly and not downshift too low.


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