I used to downshift a lot when slowing down to decrease the wear on my brakes, but heard that it creates high compression and can be harmful to the engine, is this true?
If so, would rev matching before disengaging the clutch be better so that it's not winding the engine up and then down again while slowing down? Any comments? I hope this is all clear.

 

Brake pads are alot cheaper to replace than engines..................

 

downshifting isn't bad so-to-speak, but brake pads are alot cheaper to replace

 

It's bad for the engine only if you don't match the rpms. If you match your RPM it will not do anything bad.

 

What about downshifting in an auto to slow down? does that put alot of strain in the tran? heat up the fluid too much? just plain bad overall?

 

wait, nevermind. there are other threads that have heated debated about the whole auto shifting thing. mea culpas, y'all.

 

Is it actually bad for the engine or just bad for the clutch? I rev match as is, but I'm curious.

 

it's not bad for the engine unless you run it up near redline. when you get there, there's a lot more stress on the bearings that's not usually there. The engine is in high vacuum mode and there's very little fuel going through, so the pistons are essentially pulling backwards from what they would be under throttle conditions.
Of course, the engine is designed to take this, but it's still a matter of wearing parts that usually don't see those forces.

 

There's less of a load on the bearings at redline than there is at 1500rpm assuming the same throttle position. Downshifting at redline doesn't cause excessive engine wear if the engine is well lubricated and at operating temperature. Especially if that oil is synthetic.

Remember, the vast majority of engine wear occurs at startup. The amount of wear on a engine at operating temperature is negible and inconsequential.

 

speaking about downshifting and wear on transimisions. I just picked up 03 SE with 85K miles on it? What if anything should I do in terms of AT maintenance?

 

if the fluid isn't bright cherry red, go have the tranny flushed.

 

I've gone through 2 sets of brakes, and still on the same clutch, and I engine brake down to 3rd gear. Those brakes costs as much as a clutch, so the cost issue between the 2 can't be easily argued.

As for wearing the engine... I dunno. I also haven't heard of many people replacing engines due to engine braking.

Jae

 

Well, not matching your RPM causes a sudden stress to every moving part in your car, so it's bad for every drive-train component including the clutch and the engine.

 

honsetly, who doesn't rev-match, or at least come close to matching?
Jae

 

Well yeah, but sometimes if I'm close, like just slowing down from 3rd to second coming to a stoplight or something, i'll just put it in second, and slowly let out the clutch, the rpms will slowly rise, the clutch will engage, and as i get closer to the stoplight I then start using my brakes. I think this is pretty common.

 

I usually never downshift when coming to a stop. No need to put wear on the clutch or synchros. I just let the engine brake from whatever gear I am, then when the RPMs go down low enough (about 1500) I clutch in and use the brakes.

 

The only time I use engine braking is when I go down a very long hill where you would have to hold your brakes pressed all the time otherwise.

 

I used to never rev match, now it's second nature.

Brake pads are alot cheaper and EASIER to replace than a clutch.

 

I always thought engine braking was more of a detriment to the transmission system than the engine? I usually only engine brake coming off the highway, where I go from 5th --> 3rd and am still below 4k RPM.

 

two words:

"heel-toe"

FTW

 

I don't see why you would engine brake because honestly it hardly slows you down unless it's a long downhill. BTW I can rev match perfect but I don't see the point in engine braking when coming off the freeway or for red lights.

 

I should clarify - I don't downshift to slow down...if you're downshifting to slow down dramatically, you're probably not utilizing a revmatch correctly.
In response to "who doesn't revmatch at least close?"
Well, my whole family doesn't revmatch, and just let's the clutch take up the slack...it makes me cringe.

 

You must be running a cheap POS clutch if it cost as much as your brake pads. Changing brake pads = 20 - 30 minute job. Changing clutch = ~ 8 - 10 hours. I'll take the brake pads.

 

I did a clutch job on a 95 maxima recently. It took me about 3 hours to do. If you have air tools, changing the brake pads takes about 10-15min.

 

Not if you take your time and clean and relube the pins, lube the retainers, and apply anti-squeal lube and allow it to set up.

 

Right, I'm saying a pad slap would only take 10-15 min.

 

I see your point from a money aspect only if you are replacing your own parts. If you were to have a shop replace your clutch or brakes, the clucth R&R would cost much more in labor than a brake job.

 

shops usually charge $500 min for a clutch job. you can DIY for $150.

 

They wanted $425 to do the clutch in my 95 Kingcab. I did it in my garage for just over $200. That included the clutch kit.