Nissan Cube Life - Nissan Cube Car Forums banner
1 - 20 of 22 Posts

·
Registered
Joined
·
303 Posts
Discussion Starter · #1 ·
Well, this might be a silly concern, or not.

The other day I was going downhill, not a very steep slope by the way. I let my foot "off" the gas, and then I heard the engine revving, I looked down and saw the RPM go up to 3,000. It sounded as if I was accelerating, but I clearly wasn't. Have any of you experienced this, or is this basically "normal"? I have the CVT engine by the way. I'd appreciate any feedback, thanks.
 

·
Registered
Joined
·
839 Posts
It may be possible that the grade was just enough for your tranny to seek a lower ratio, but then again I don't have any knowledge of how the CVT works. Never even driven one. But reving to 3k isn't dertimental anyway. - Dan
 

·
Moderator
Joined
·
2,084 Posts
Like above 3K is of no big issue, most vehicles are considering a shift at that RPM but can go much higher in the band.

I have not experienced this in my CVT but I also cant say I was trying the jake brake thing in it either!

If the system figured this into the equation maybe the engine was correcting itself? Jake brake (compression from engine to reduce speed) can be harmful to the engine and this the result you received. The vehicle may have been smarter than the operator on this one, but in manual trans the operator would rein king!
 

·
Registered
Joined
·
24 Posts
This is a programed function. It is automatic engine braking that is programmed into most CVT transmissions. Don't ask me why they do this. i know if you want there is a way to reprogram that part out of your PCM but it cost an arm and a leg.
 

·
Registered
Joined
·
839 Posts
Downshifting to a lower gear using engine compression to slow you down is completely harmless, unless you over rev the engine. This practice has been used by many many drivers on hundreds of thousands of cars, trucks, and motorcycles since the beginning. As long as you select the proper gear to down shift to you shouldn't have an issue. This is a more common practice for those with manual tranny's since an automatic does this by itself to some degree. I've always down shifted using engine compression to slow me down. Big Rigs use Jake Brakes which is a more sophisticated setup but works on the same principal. The only reason Jake Brakes are used in Big Rigs instead of just down shifting like in a car, is because simple engine braking on a car is very effective. But on a Big Rig simple compression braking isn't enough to effectively slow down an 80,000 lb vehicle. - Dan
 

·
Moderator
Joined
·
2,084 Posts
For a manual trans setup and using compression to stop the vehicle I say this, brakes are way cheaper than clutches!

I used to down shift to aid in braking, do not not do this any longer
 

·
Registered
Joined
·
839 Posts
ChristineK said:
For a manual trans setup and using compression to stop the vehicle I say this, brakes are way cheaper than clutches!

I used to down shift to aid in braking, do not not do this any longer
True, brakes are cheaper than clutches. But if you know what your doing you should never have to replace your clutch. Like I said. I have ALWAYS used engine braking. I put over 250k on our Festiva and never replaced the clutch, and brakes just once. I put 74K on my Focus, again, never replaced the clutch nor the brakes. - Dan
 

·
Registered
Joined
·
839 Posts
none said:
Don't say that to performance car enthusiasts.
Why, I've been racing for over 40 years, and although I've replaced many clutches over the years I've never had to replace one due to using compression braking on a daily driver.

I would think the performance enthusiast would be the first to agree. We are the folks who most often mis-use a clutch. We do things like speed shift, power shift, clutchless shifting, etc., not exactly how the clutch is designed to be used.

What I'm talking about is the daily grocery getter. If your using the clutch properly, upshifting, down shifting, (yes even compression braking) your clutch could last virtually forever.

I've replaced many clutches in my hot rods and performance cars. But never in any of my daily drivers. - Dan
 

·
Registered
Joined
·
117 Posts
Square1 said:
I would think the performance enthusiast would be the first to agree. We are the folks who most often mis-use a clutch. We do things like speed shift, power shift, clutchless shifting, etc., not exactly how the clutch is designed to be used.
I am in total agreement!

This is one of the reasons I seek out manual transmissions for most of my cars. Engine breaking saves a lot of wear a tear on the breaks and can have no bad effect on the clutch if done correctly.

This is also one of the reasons I really love my Cube's CVT. That revving you hear when you go downhill is called hill decent breaking assist. The engine breaking gets stronger once the cube is fully broken around 4000 miles. I, personally, notice it a lot more in my cube since I have no rear muffler. It really sounds just like a jake break!

On long hills my cube will rev as high as 3500RPM without touching the overdrive off button. If I press overdrive off then it revs above 4000. Shifting into low will keep the revs above 4500RPM even when driving very slowly. Low should only be used in very steep areas at residential speeds (25MPH)

This helps me maintain a steady rate of speed on long downhill areas without touching my brake pedal at all (meaning no wear and tear on my brakes)!! :D
 

·
Registered
Joined
·
303 Posts
Discussion Starter · #13 ·
Well as for the "overdrive button", I dont think I did anything. I havn't even checked the manual to see where its at... :-[ As I was going down the slope, I just let go of the gas, and that was it. Didn't press anything else. I might go down that slope againg and see what the cube does, and if it continues, I guess I'll just ask the service dept. to check it out and see what they say. Hopefully it's nothing like some of you have said. Thanks for your feedback!
 

·
Registered
Joined
·
119 Posts
My Cube has the CVT and just the other day, like you, I went down a fairly steep hill. It was steep enough that without pressing on the gas I reached a speed of 50mph very quickly and sure enough my engine rpm’s were just about 3,000. Initially I though it was high but then remembering the engine red lines above 6,000 rpm’s I thought no big deal.
 

·
Registered
Joined
·
839 Posts
AGCube said:
My Cube has the CVT and just the other day, like you, I went down a fairly steep hill. It was steep enough that without pressing on the gas I reached a speed of 50mph very quickly and sure enough my engine rpm’s were just about 3,000. Initially I though it was high but then remembering the engine red lines above 6,000 rpm’s I thought no big deal.
Sounds like your tranny is working as it should. You're right, 3k is way under over reving so you should be just fine. Most ATX tranny's allowed to control itself won't allow over reving anyway, unlike a manual where the nut behind the wheel has all the control...LOL - Dan
 

·
Registered
Joined
·
671 Posts
Square1 said:
Downshifting to a lower gear using engine compression to slow you down is completely harmless, unless you over rev the engine. This practice has been used by many many drivers on hundreds of thousands of cars, trucks, and motorcycles since the beginning. As long as you select the proper gear to down shift to you shouldn't have an issue. This is a more common practice for those with manual tranny's since an automatic does this by itself to some degree. I've always down shifted using engine compression to slow me down. Big Rigs use Jake Brakes which is a more sophisticated setup but works on the same principal. The only reason Jake Brakes are used in Big Rigs instead of just down shifting like in a car, is because simple engine braking on a car is very effective. But on a Big Rig simple compression braking isn't enough to effectively slow down an 80,000 lb vehicle. - Dan
FWIW -- The only downside to engine breaking is engine wear and tear. It's much cheaper to replace friction brake pads than to have engine work performed. However, the other side of that coin is "excessive" friction braking will result in over heating which reduces breaking effectiveness, and can also warp the rotors. Bottom line is, from my perspective, it's more cost effective to replace brake pads and rotors than to rebuild the engine :)! So, I emphasize my brakes, with engine breaking as a backup. YMMV!
 

·
Registered
Joined
·
839 Posts
Engine Braking DOES NOT CAUSE PREMATURE ENGINE WEAR.....PERIOD.

Unles the driver is an IDIOT and selects too low a gear and causes excessively high engine RPM.

Car engines do engine braking even without the help of the driver, especially on automatics. Those of you who drive cars with ATX, do you notice that as your slowing to a stop the tranny shifts itself into a lower gear, it does that to assist slowing down using ENGINE BRAKING.

I've been building engines over 40 years and have never seen an engine prematurely wear out because the driver uses engine braking. I have seen engines damaged (usually caused by floating valves) because some idiot went from 4th gear to 2nd gear when down shifting using too low a gear for engine braking causing an over rev condition. But if you use the proper gear when using engine braking it will not cause any harm.

OK, say your driving down the freeway at 70 MPH and the traffic starts to slow down, you take your foot off the throttle and let the car slow down on it's own. What do you think is taking place here.......ENGINE BRAKING. - Dan
 

·
Registered
Joined
·
671 Posts
To be sure, there's plenty of wear and tear on an engine normally, engine braking is just an additional factor. My personal preference is to steer that aspect of wear to the braking system and away from the drive train (braking for lights and stop signs etc, not minor variations in traffic speed which don't even require a gear change). Clearly, to each their own -- that's why I added "YMMV" to the end of my above comment :)!

PS. At one time I fully exercised engine braking (one gear differential, not two or more), but I've long since shelved it in favor of the brakes -- I find the economic argument compelling :).

PPS. By the way, I'm still on my original clutch with my 1990 Eclipse and it shows no sign of issues, so it's very encouraging to read your remarks about the life of a clutch on a daily driver. I'll be only too happy if I never need to replace it :)!
 

·
Registered
Joined
·
315 Posts
I totally agree with Square1 on this one. Engine braking -when used properly- does NOT cause damage to your car. The CVT engine break automatically. You have nothing to worry about. The only downside to the auto tranny is that you have no control over when the engine braking occurs. If they SL trim would have come in a manual tranny, I would have a manual as well, party because of the fact that you have more control over the engine braking. This being said, as someone said earlier, the computer behind the auto tranny is set to not allow over revving anyways.
 
1 - 20 of 22 Posts
Top