Engine Braking - Not Recommended (if you arent rev matching)
05-29-2013, 11:07 AM
#26
One simple way to figure out the correct answer:
If you are in 2nd gear at 50mph, and let off the gas, are you engine braking? Yes.
Have you magically caused clutch wear? No.
Clutch wear is ONLY ONLY ONLY ONLY ONLY from when the clutch is transitioning between disengaged and engaged AND there is a speed difference between the flywheel and the pressure plate. No speed difference and there is NO clutch wear. Period. Did you know that you can even shift up or down without using the clutch at all? How would this cause clutch wear?
You can accomplish excessive clutch wear without engine braking at all. In fact, normal proper driving nearly all clutch wear will come from starting from stopped. Have you addressed that yet?
Such a misunderstood subject...
If you are in 2nd gear at 50mph, and let off the gas, are you engine braking? Yes.
Have you magically caused clutch wear? No.
Clutch wear is ONLY ONLY ONLY ONLY ONLY from when the clutch is transitioning between disengaged and engaged AND there is a speed difference between the flywheel and the pressure plate. No speed difference and there is NO clutch wear. Period. Did you know that you can even shift up or down without using the clutch at all? How would this cause clutch wear?
You can accomplish excessive clutch wear without engine braking at all. In fact, normal proper driving nearly all clutch wear will come from starting from stopped. Have you addressed that yet?
Such a misunderstood subject...
05-29-2013, 05:09 PM
#31
rev it up
I do not usually engine brake in daily driving. However, at the track if I am on the straight and about to go into a slow corner I will select the correct gear for that corner and use the engine to help me slow the car down together with stomping on the brake as I am usually going over 200 kmph.
The car does protest a bit with the revs hitting the rev limiter and the back end wobbles a bit. However, this allows me to brake deep into the corner and overtake faster cars that are slower around corners.
I have been going this for years and still on my original gear box with over 50 track days.
The car does protest a bit with the revs hitting the rev limiter and the back end wobbles a bit. However, this allows me to brake deep into the corner and overtake faster cars that are slower around corners.
I have been going this for years and still on my original gear box with over 50 track days.
05-30-2013, 01:31 AM
#32
Registered
I do not usually engine brake in daily driving. However, at the track if I am on the straight and about to go into a slow corner I will select the correct gear for that corner and use the engine to help me slow the car down together with stomping on the brake as I am usually going over 200 kmph.
The car does protest a bit with the revs hitting the rev limiter and the back end wobbles a bit. However, this allows me to brake deep into the corner and overtake faster cars that are slower around corners.
I have been going this for years and still on my original gear box with over 50 track days.
The car does protest a bit with the revs hitting the rev limiter and the back end wobbles a bit. However, this allows me to brake deep into the corner and overtake faster cars that are slower around corners.
I have been going this for years and still on my original gear box with over 50 track days.
05-30-2013, 09:27 AM
#34
Registered
05-30-2013, 05:11 PM
#35
Registered
By the way.....does the OMP feed (some) oil to the rotors during long engine breaking, beeing high rev/accelerator untouched/carb. airvalve almost closed.......or are the rotors finally running more or less "dry" ........???
Who knows.........?
The OMP does feed (some) oil when engine is running stationary/accelerator untouched/carb. airvalve almost closed, as far as I know......
Who knows.........?
The OMP does feed (some) oil when engine is running stationary/accelerator untouched/carb. airvalve almost closed, as far as I know......
05-30-2013, 09:49 PM
#36
Registered
By the way.....does the OMP feed (some) oil to the rotors during long engine breaking, beeing high rev/accelerator untouched/carb. airvalve almost closed.......or are the rotors finally running more or less "dry" ........???
Who knows.........?
The OMP does feed (some) oil when engine is running stationary/accelerator untouched/carb. airvalve almost closed, as far as I know......
Who knows.........?
The OMP does feed (some) oil when engine is running stationary/accelerator untouched/carb. airvalve almost closed, as far as I know......
09-26-2013, 11:16 PM
#38
Real Racing 3 fan
Thread Starter
I was engine and clutch braking at the same time. The braking effect was significant but it made me ruin my clutch. I'm driving better now. Thanks for the tips Forum!
09-27-2013, 09:10 AM
#39
Registered
10-12-2013, 01:40 PM
#40
kevin@rotaryresurrection
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I would disagree with several of your points.
Rotary engines have little to no rotating inertia and no useful beginning torque. As a consequence you pretty much have to slip the clutch more on this car than you might on say a pickup truck or a V8 mustang which are vehicles that you can basically drop the clutch and it will go fine without stalling. Add to that, that the rx8 is the heaviest chassis equipped with a rotary engine, so it is the most difficult to get going from a stop. SO because of the very nature of rotary engine cars and the rx8 specifically, you WILL always wear clutches out much sooner than in a "regular" car. You will also put more heat into the flywheel and pressure plate for the same reasons, so those parts usually come out looking worse with more heat marking and cracking than in a "regular" car.
All of your numbers seem artificially inflated...or perhaps you pay the highest retail and labor prices that you get quoted without shopping around. You can get a set of brake pads for all 4 wheels for 70 bucks any day of the week, and labor should be about an hour at an indy shop for $50 or so.
You can get a decent stock clutch kit for about $150-200, and the labor should be 2.5-3 hours for a good mechanic. I've done the job in well under 3 hours, and I don't have a lift.
Flywheel resurfacing should cost no more than $50. I usually get charged $30-35 by the local shop that I use.
The way I see it, you'll quite possibly go through engines in this car as often as you go through clutches, so it really should be a moot point; you replace the clutch when you replace the engine. With that aside, a clutch job is not that huge a deal, and might run you 5 or 600 bucks total if you're paying for the labor to get it done. IF you can't afford to put 500 bucks into a car every 65k miles, then you might need to reevaluate your priorities and choices in life, because you're doing something wrong.
Rotary engines have little to no rotating inertia and no useful beginning torque. As a consequence you pretty much have to slip the clutch more on this car than you might on say a pickup truck or a V8 mustang which are vehicles that you can basically drop the clutch and it will go fine without stalling. Add to that, that the rx8 is the heaviest chassis equipped with a rotary engine, so it is the most difficult to get going from a stop. SO because of the very nature of rotary engine cars and the rx8 specifically, you WILL always wear clutches out much sooner than in a "regular" car. You will also put more heat into the flywheel and pressure plate for the same reasons, so those parts usually come out looking worse with more heat marking and cracking than in a "regular" car.
All of your numbers seem artificially inflated...or perhaps you pay the highest retail and labor prices that you get quoted without shopping around. You can get a set of brake pads for all 4 wheels for 70 bucks any day of the week, and labor should be about an hour at an indy shop for $50 or so.
You can get a decent stock clutch kit for about $150-200, and the labor should be 2.5-3 hours for a good mechanic. I've done the job in well under 3 hours, and I don't have a lift.
Flywheel resurfacing should cost no more than $50. I usually get charged $30-35 by the local shop that I use.
The way I see it, you'll quite possibly go through engines in this car as often as you go through clutches, so it really should be a moot point; you replace the clutch when you replace the engine. With that aside, a clutch job is not that huge a deal, and might run you 5 or 600 bucks total if you're paying for the labor to get it done. IF you can't afford to put 500 bucks into a car every 65k miles, then you might need to reevaluate your priorities and choices in life, because you're doing something wrong.
10-13-2013, 10:47 AM
#41
Driving my unreliable rx8
I replaced my clutch at 138K miles only becuase I had the engine out. S1 Transmission
I don't heal toe, I left foot brake and use my right foot to rev match. No clutch at all for shifting. My most common downshift is from 6th to 3rd then I drop it to second and neutral until I'm at a full stop. If I am still rolling I'll rev match then drop it in gear and go.
I normally Use the clutch for starting from a stop and upshifting.
When Stoped I don't touch the clutch pedal until I am ready to move. So I don't wear the throwout bearing(it only has a teaspoon of grease or so in it. When I press the clutch I push it to the floor.
When starting from a dead stop I feather the clutch out smoothly but quickly until I am moving. It takes less then 2 seconds. Then My foot is removed from the clutch pedal completely.
When moving If I want to be smooth. I use the gas pedal to remove the engine load and slide the transmission to neutral. Then I rev match. Once revs are right I press the clutch pedal to the floor put it in gear and immediately release the clutch.
I've never had a clutch failure with 300 K miles on my 87 Nissan pathfinder, I had about 750 K Miles on my 80,000 Pound truck at work and still had the origional clutch. On top of many other vehicles I have driven.
My 8 has had the clutch abused, No track time, but a lot of stupid driving.
6-9KRPM clutch drops,
Sliping the clutch two or three times while in the same gear to keep rpms high and power maxed.
I almost reused the clutch when I rebuilt the engine it looked so good.
I don't heal toe, I left foot brake and use my right foot to rev match. No clutch at all for shifting. My most common downshift is from 6th to 3rd then I drop it to second and neutral until I'm at a full stop. If I am still rolling I'll rev match then drop it in gear and go.
I normally Use the clutch for starting from a stop and upshifting.
When Stoped I don't touch the clutch pedal until I am ready to move. So I don't wear the throwout bearing(it only has a teaspoon of grease or so in it. When I press the clutch I push it to the floor.
When starting from a dead stop I feather the clutch out smoothly but quickly until I am moving. It takes less then 2 seconds. Then My foot is removed from the clutch pedal completely.
When moving If I want to be smooth. I use the gas pedal to remove the engine load and slide the transmission to neutral. Then I rev match. Once revs are right I press the clutch pedal to the floor put it in gear and immediately release the clutch.
I've never had a clutch failure with 300 K miles on my 87 Nissan pathfinder, I had about 750 K Miles on my 80,000 Pound truck at work and still had the origional clutch. On top of many other vehicles I have driven.
My 8 has had the clutch abused, No track time, but a lot of stupid driving.
6-9KRPM clutch drops,
Sliping the clutch two or three times while in the same gear to keep rpms high and power maxed.
I almost reused the clutch when I rebuilt the engine it looked so good.
10-14-2013, 02:27 AM
#44
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I'm still new to manual driving, I tend to have issues when I upshift. Sometimes, depending on speed and gear, I need to let go of the clutch pedal quickly to prevent the car from shaking from a the rpm dropping too much while other times, it is the opposite...
I think that I'm getting better, but I am sure that I shortened the life of the clutch a lot. nowadays, it barely grabs when I am starting from a standstill. I gotta get the rpm to 1.5k-2k and slowly let the clutch pedal go. If I just let the clutch go slowly without adding gas, it barely grips or makes the car go forward. I hope it will last at least until spring, when I planned to get a new one.
Sorry if I'm off topic, I thought it would be better than making a new thread:
Mod edit:
Creating a new thread is better than derailing the topic.
Finding a prior thread discussing it is better than creating a new thread, unless the only threads you find are very old and/or loaded with mis-information.
-RIWWP
I think that I'm getting better, but I am sure that I shortened the life of the clutch a lot. nowadays, it barely grabs when I am starting from a standstill. I gotta get the rpm to 1.5k-2k and slowly let the clutch pedal go. If I just let the clutch go slowly without adding gas, it barely grips or makes the car go forward. I hope it will last at least until spring, when I planned to get a new one.
Sorry if I'm off topic, I thought it would be better than making a new thread:
Mod edit:
Creating a new thread is better than derailing the topic.
Finding a prior thread discussing it is better than creating a new thread, unless the only threads you find are very old and/or loaded with mis-information.
-RIWWP
Last edited by RIWWP; 10-14-2013 at 06:16 AM.
10-25-2013, 08:50 AM
#49
Registered
I replaced my clutch at 138K miles only becuase I had the engine out. S1 Transmission
I don't heal toe, I left foot brake and use my right foot to rev match. No clutch at all for shifting. My most common downshift is from 6th to 3rd then I drop it to second and neutral until I'm at a full stop. If I am still rolling I'll rev match then drop it in gear and go.
I normally Use the clutch for starting from a stop and upshifting.
When Stoped I don't touch the clutch pedal until I am ready to move. So I don't wear the throwout bearing(it only has a teaspoon of grease or so in it. When I press the clutch I push it to the floor.
When starting from a dead stop I feather the clutch out smoothly but quickly until I am moving. It takes less then 2 seconds. Then My foot is removed from the clutch pedal completely.
When moving If I want to be smooth. I use the gas pedal to remove the engine load and slide the transmission to neutral. Then I rev match. Once revs are right I press the clutch pedal to the floor put it in gear and immediately release the clutch.
I've never had a clutch failure with 300 K miles on my 87 Nissan pathfinder, I had about 750 K Miles on my 80,000 Pound truck at work and still had the origional clutch. On top of many other vehicles I have driven.
My 8 has had the clutch abused, No track time, but a lot of stupid driving.
6-9KRPM clutch drops,
Sliping the clutch two or three times while in the same gear to keep rpms high and power maxed.
I almost reused the clutch when I rebuilt the engine it looked so good.
I don't heal toe, I left foot brake and use my right foot to rev match. No clutch at all for shifting. My most common downshift is from 6th to 3rd then I drop it to second and neutral until I'm at a full stop. If I am still rolling I'll rev match then drop it in gear and go.
I normally Use the clutch for starting from a stop and upshifting.
When Stoped I don't touch the clutch pedal until I am ready to move. So I don't wear the throwout bearing(it only has a teaspoon of grease or so in it. When I press the clutch I push it to the floor.
When starting from a dead stop I feather the clutch out smoothly but quickly until I am moving. It takes less then 2 seconds. Then My foot is removed from the clutch pedal completely.
When moving If I want to be smooth. I use the gas pedal to remove the engine load and slide the transmission to neutral. Then I rev match. Once revs are right I press the clutch pedal to the floor put it in gear and immediately release the clutch.
I've never had a clutch failure with 300 K miles on my 87 Nissan pathfinder, I had about 750 K Miles on my 80,000 Pound truck at work and still had the origional clutch. On top of many other vehicles I have driven.
My 8 has had the clutch abused, No track time, but a lot of stupid driving.
6-9KRPM clutch drops,
Sliping the clutch two or three times while in the same gear to keep rpms high and power maxed.
I almost reused the clutch when I rebuilt the engine it looked so good.
