Problem with clutch engaging when accelerating quickly

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Old Mar 2, 2011 | 09:41 AM
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Problem with clutch engaging when accelerating quickly

I have an 08 TL-S manual and I find that maybe half the time I try to accelerate quickly and go through the gears at a good rate, i.e. racing, the clutch seems to have trouble engaging. No, it's not the infamous 3rd gear problem, which I do have btw. But it does happen going into 3rd OR 4th.

My attempt at a description: since I'm going for speed, when I shift out of 2nd or out of 3rd, the RPM is in the 3k, possibly 4k. With full knowledge that I have put the shifter completely into the next gear, I lay on the gas (more than normal driving) and let out the clutch relatively quickly (even then, I try to make sure that I let out the clutch AS I give gas, I don't rev THEN let out the clutch). And what happens sometimes is once I've completely let out the clutch the RPMs still linger rather high and the clutch doesn't quite engage, it feels like it's half engaged (no grinding or anything), and then after a second or two it engages, or if I take my foot off the gas it engages. Thus, next to no immediate acceleration. Once it really is engaged, it's fine, I can really feel the car pull. I notice it isn't as bad with VSA off, though it still happens. It seems like the car's electronics are saying "Screw you for trying to drive me this fast! I'm gonna keep you from accelerating".

So, is it a tranny problem? Are the car electronics actually saying "Screw you"? Is there a certain technique I should be using when trying to accelerate quickly? Something else?

Again, I know about the 3rd gear problem everyone and myself has, but this really seems quite different.

Graci!
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Old Mar 2, 2011 | 09:45 AM
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gas and clutch at the same time!?!?!?
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Old Mar 2, 2011 | 09:50 AM
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Well I first learned stick on an '89 Accord and was taught in normal driving circumstances to apply a very small amount of gas when letting out the clutch, since then I've been on my own with bettering my driving skills, thus no one to tell me how to 'performance' drive and how it my differ from car to car.

That being said, I'm assuming from your response that I should let out the clutch entirely before even touching the gas?
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Old Mar 2, 2011 | 10:16 AM
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Originally Posted by SouthernBoy
Here's a collection of postings I did on another gearhead website. Hope it helps.

================================================== ============



Note: As it says, this is a collage of various postings I have made over the past one and a half years on the altimas.net website. So you are likely to see redundancy as well as a few other items of disarray. But enjoy and I hope you learn something.




PROPER MANUAL TRANSMISSION DRIVING TECHNIQUES

What follows is a collection of writings which I have posted at various times on this website in an effort to help answer some questions regarding the proper manner in which a manual transmission should be operated. While there are certainly many ways to drive a car with a manual transmission, there is really only one correct way. I was most fortunate to have learned these techniques while I was still in my teenage years. In so doing, I was able to avoid developing entrenched habits before they became really bad habits and difficult to correct. It is my hope that this helps you learn what I have learned and perfected over the years. If you do, you will reap the rewards, both financial and in the knowledge that you have mastered a technique that few do in their lifetimes. Have fun!

Under normal driving situations (not racing), when you start out from a standing start, you do so with the lowest possible RPMs, get the clutch out to full engagement as soon as you can while adding throttle. If you do this correctly, the transition will be smooth and seamless, and the wear on your clutch disk, pressure plate, release bearing, and flywheel will be minimized.

If properly designed (sufficient size and clamping pressure, etc.), and properly installed with no defects (correct torque, non-faulty equipment, alignment, etc.), then the next, and most important, factor to the life of the clutch assembly is the operator.

THERE IS ABSOLUTELY NO REASON WHY A CLUTCH CANNOT LAST THE LIFE OF THE ENGINE UNDER NORMAL DRIVING CONDITIONS.

When I speak of engine life here, I am referring to life before a serious teardown or part replacement such as a timing chain (200,000+ miles) or headwork. If you cannot get at least 100,000 miles out of a clutch, you are doing something terribly wrong. Obviously, racing and other extreme conditions such as towing constitute a whole different approach and, as such, do not come under this.


Don'ts:

Do not use any more engine speed (RPMs) than absolutely necessary to get the car rolling in first gear.
Do not hold the car on a hill with the clutch.

Do not wait for a traffic light to turn green with the transmission in gear and the clutch depressed.

Do not rest your foot on the clutch while driving.


Do not ride the clutch in any gear (obviously you will to a small degree in first to start off).

Do not down shift by just removing your foot from the gas, moving the shifter into a lower gear, then releasing the clutch slowly.


Do's

Start off smoothly and with low engine speed, and shift in such a manner that if you had a passenger on board, they would not even notice the shifts.

Hold the car on hills with the brakes.. that's what brakes are for. NEVER hold a car on a hill with the clutch. The amount of heat generated by doing this is incredible.

While waiting for a light to change or while sitting in heavy traffic, put the transmission in neutral and get your foot completely off of the clutch petal. Leaving it in gear for extended periods heats up and shortens the life of the release bearing. The normal condition of a clutch is fully engaged so it stands to reason that's where it should be most of the time.

Resting your foot on the clutch petal while driving engages the release bearing.. see above.

Avoid riding the clutch as much as is humanly possible. You will extend its life significantly.

If you do not know how to properly downshift, DON’T. Use the brakes (should do this anyway), and avoid downshifting any more than necessary. Improper downshifting is analogous to riding the clutch because that is what you are actually doing. Learn how to properly downshift first and save yourself the frustration of premature clutch failure.

Clutches are wear items, heavily affected by heat caused by friction. In a front wheel drive car, they are costly to replace, so unless you like shelling out a lot of money periodically for the replacement of these components, learn the correct way. Learn it until it becomes second nature like breathing.



I spent some time teaching a lady with whom I worked 10 years ago these techniques when she purchased a new '92 Honda Accord LX. When I last spoke with her, she had well over 140,000 miles on the original clutch with no signs of slippage. So I'm not jerking anyone's chain here. Learn to operate a manual transmission correctly and you will reap the rewards by saving a lot of money. Plus you will be one of the few who know how to do this right.

I don't mean to set myself up here as some kind of guru because I am not. But I have been driving vehicles with manual transmissions for over 40 years. I have spent the time to perfect the process into an art form because when done correctly, that’s what it is. When I sold my '88 Mustang LX 302CID, it was 6 years old and had 77,000 miles on it. When the buyer drove it, he asked me when I replaced the clutch because to him, it felt very positive. I told him that I had never replaced it and that it was the original unit. I added that it wouldn't make any sense to replace a clutch after only 77,000 miles since that is not very much wear. He had a little bit of a hard time believing this, but he did buy the car. Three months later, he called me up to let me know how much he liked the car and to tell me had had not wrapped it around a tree. He again asked about the clutch and I again told him that it was the original clutch.

I used to own a 1966 Chevelle SS396/360HP. I was the original owner of the car. For a period of about 2 years, I was street racing the car frequently on the weekends. At 83,000 miles when I sold it, it would still break traction in all four gears and the clutch had no slippage. It was tight and strong. Now granted, American cars have traditionally had stronger clutches than Japanese cars. This is changing because the Japanese are putting larger and stronger (torque) engines in their cars.



Downshifting

Ah yes, downshifting. If I had to name just one facet of manual transmission errors-of-operation, this would probably be it.

To understand how to operate a manual transmission, you have to know how the clutch assembly and transmission work, and I am going to take the assumption that most do on this forum. I will only clarify synchronizers. They serve to match the speed of the gears in the transmission as the shifter is moved to a given gear. Now for downshifting.

Let's say you are in fourth gear and you are approaching a stop sign, so you decide to downshift from fourth gear into third. What most people do is just remove their foot from the throttle, depress the clutch while moving the shifter from fourth to third, then start releasing the clutch slowly until they achieve full engagement. If you do this, what you are actually doing is riding the clutch in third gear. After all, the engine has returned to idle (or close to it), you get into third, then just ease the clutch out which pulls the engine from idle up to the RPM's at which it will operate at whatever speed you are traveling in third gear. Here is the correct way to do this in steps that I will break down in a moment.

Raise your foot off of the throttle.

Depress the clutch.

Start the shifter up into third.

As you pass through the neutral gate, let the clutch out a bit (doesn't have to be all the way) while at the same time blipping the throttle to increase engine speed BEYOND that which it will operate in the chosen lower gear.

Depress the clutch again.

Engage the chosen lower gear.

Let the clutch out while adding throttle.

As the engine RPM's decrease they will be met by the engaging clutch and opening throttle.

This should be a simple, smooth, fluid motion and you will know you've done it right if there is no jerking as the clutch comes out in the last step. Now for some details.

As you move into the neutral gate with your foot off of the throttle, the engine RPM's will be returning to idle. This is the point at which you want to blip the throttle a bit while at the same time engaging the clutch some. You want to get the engine turning faster than it will when you are in the lower gear you have chosen. The reason is that you want to spin the gears up to a speed that equals that at which they will be operating when you finally release the clutch in your downshift. If you do this right, there is no clutch slippage because the engine and the gears in the transmission will be spinning at the same or nearly the same RPM's. No slippage means you will get into gear with full engagement of the clutch sooner and with virtually no wear. To best understand this, you really need to know how a clutch assembly and transmission work together to deliver power from the engine to the drive wheels.

This takes a lot of practice, but if you get it down, you will be heads and shoulders above just about anyone else who drives a car with a manual transmission. You will begin to notice the mistakes other are making when they drive. Learn from their mistakes and it will both save you money and make you a far better driver.

So it's in with the clutch, start the shifter into the chosen lower gear, while passing through the neutral gate, blip the throttle and at the same time engage the clutch a bit to spin up the gears, then back in with the clutch as you get into the chosen gear, then finally release the clutch in one smooth operation.

Here's another little tip. Say you are waiting at a light for the green and your transmission is in neutral like it should be with your foot completely off of the clutch petal. When the light turns green, instead of just depressing the clutch and pushing the shifter up into first, pull the shifter partially into a higher gear first, such as second or third. The gears in those selections are not spinning as fast as the gears in first. By starting the shifter into a higher gear before you go to into first gear, you will cause less wear on the synchronizers and they will last far longer because they do not have to stop gears which are spinning at a higher speed. For cars which do not have synchronized reverse, definitely do this and you will not experience the grinding affect when shifting into reverse.

Say you are driving normally, shifting up through the gears to the one in which you wish to be for cruising. As you disengage the clutch and move the shifter to the next higher gear, you might notice a slight resistance just before you finish the shift. What you feel is the synchronizer for that gear forcing the drive gear(s) from the input shaft and the gears selected to "mesh". That is to say, their speeds are forced to equalize so that as they engage, there is no grinding and no damage to the gear teeth. That said, we can move to double clutching.

Double clutching was a technique that came about when earlier manual transmissions did not have synchronizers. If you did not double clutch, you would experience some serious gear grinding when shifting.

If you did not have synchronizers in your transmission, you would have had two choices when shifting gears: (1) put up with some really serious grinding and damage/breakage to gear teeth, or (2) manually match the speed of the gears in each selected shift so that you would eliminate the problems just mentioned in #1.

Suppose you are traveling in second gear, the engine is turning at 2500 RPM, and you are getting ready to shift to third. At the road speed you are going, let's say that once in third, your engine would be turning at 1800 RPM. When you remove your foot from the gas, the engine is going to loose RPMs quickly and by the time you get into third, the engine might only be turning 1200 RPM. Without synchronizers, you would need to raise the engine back up to 1800 RPM in order for the gears to mesh. By blipping the throttle and at the same time letting the clutch out some when you are passing through the neutral gate, you will both increase engine RPM and increase gear speed. As the engine RPMs fall back off, they will reach a point at which you will be able to complete the shift.

Since for years, manual transmissions have been fully synchronized, there is no need whatsoever to double clutch when upshifting and I definitely recommend against this practice.

Now downshifting is much like this, only in reverse. In other words, you are going from a higher gear to a lower gear so if your engine was turning at 2500 RPM and you wanted to shift to second, You would want to blip the throttle enough to raise engine speed to perhaps around 3200 - 3500 RPM.

When you are upshifting, the RPMs fall off and most people find it pretty easy to adjust to this and to add throttle at the right time so that when the clutch comes back out, they have the proper RPM's for the gear selection/road speed.

However, most people downshift by (1) removing their foot from the throttle, (2) moving the shifter into the next lower (or chosen) gear, then (3) slowly releasing the clutch while adding little or no throttle. This is NOT the proper manner in which to downshift. What you are doing in effect, is riding the clutch in reverse. In other words, you probably wouldn't dare attempt to start your car off in third gear because you would have to add a lot of throttle and really slip the clutch to get the car moving. When you downshift like the example I just gave, you are doing something similar to starting off in a higher gear, though it does take more energy to get a car moving from a dead start. Now if you double clutch during the downshift, you are spinning up the gears and the transition to the next gear will be quite smooth.


Junkyard asked a question about the concept of “passing through the neutral gate”. You don’t stop or stay in neutral. You are just passing through, so to speak. In your second question, you said I had mentioned to put the car in neutral when downshifting. Not exactly. Try this with the engine off.

Put the car in fourth. Depress the clutch and shift to third and let the clutch out. Now do the same thing, only this time as you pass through the neutral gate, let the clutch out some or a good deal and blip the throttle, then clutch back in, get into third, clutch comes out for the final time. That is the movement you want.

Incidentally, blipping the throttle is just a little stab at the petal, enough to raise RPMs to the desired level. You do not want to be on the throttle long because you will be in the process of shifting. Yes, this does take a lot of practice and may not come easily for many, but it is the best way, in fact the only proper way, to downshift because it very significantly reduces clutch and synchronizer wear (especially clutch), and once you get the hang of it, you will be able to do it quite fast.

The bottom line to all of this folks is to match engine speed to wheel speed in a given gear, and to do it in such a manner as to eliminate undue trauma to your drive train. I do this all of the time and have been downshifting like this since my late teens. I actually learned it from a magazine article (as I can best recall). If you know how a manual transmission and clutch assembly operate, all of the components and how they perform together, you will understand the beauty of the process.

Oh the grinding noise Junkyard hears when he starts letting up the clutch too quickly is most likely due to not having fully engaged the gear teeth and they separate (pop out of gear). That or he actually begins engaging the gear teeth before the clutch is fully depress so there is still some flywheel/disk/pressure plate contact.


One of the things I noticed right off the bat on my SE was that the clutch began to engage much too close to the floor for me (a contributor to the problem Junkyard has had). It was starting to engage about 1 inch from the floor, so I adjusted it out to 2 inches and it is fine. If you do this, just make sure you have the required toeplay, otherwise you will prematurely wear out your release bearing.

The purpose of letting the clutch out some as you pass through the neutral gate is to spin the gears up in preparation for the speed at which they must be at for the lower gear selection. This will allow you to get into that gear very easily. When you depress the clutch, you disengage the crankshaft from the transmission. The gears in the transmission will begin to slow down. By letting out the clutch some (or completely) in the neutral gate, you once again, MOMENTARILY, engage the full drive train and get the gears spinning. Only this time since you have blipped the throttle, they'll be spinning faster. As they slow down from the higher speed, your clutch will be coming out for the final time with the transmission in gear and the mesh will be smooth.

Try it both ways. Do it first the way you do it and notice that you have to add a little bit of force to get the shifter into gear. That's because the synchronizers are doing their job of gear speed meshing. Now try it the way I outlined and if you do it right, you will have virtually no resistance as you slip the shifter into your chosen gear.

Instead of going right into first as the light starts to go green, try starting the shifter into second gear.. don't have to go all the way into gear, though it won't hurt. This slows the gears down just as though you had gone on into first, but it's much easier on the synchronizers. And you won't get the "crunch" you mentioned when you have to move quickly.


To prevent rollback; practice, practice, practice, practice.

One way to do this is to find a nice little hill someplace where you won't be a bother to anyone. Take along some masking tape and mark off two sections with the tape a foot apart. Your goal is to keep the car from coasting back more than 1 foot.. of course you do not use the clutch to hold the car.. use the brakes. As you learn to do this, find another hill a little steeper. And so on, and so on.
this is our "shifting guru"
PM him for more info
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Old Mar 2, 2011 | 01:48 PM
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Search for "slave cylinder check valve" or similar. When you remove it (like I did) your car will shift like a normal manual transmission car.

Completely changed the feel for me.

There is a thread in the garage that explains it all

Last edited by Bucks13; Mar 2, 2011 at 01:58 PM.
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Old Mar 2, 2011 | 02:33 PM
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Do as Bucks13 says and you will love your car. I had the same problem, when i would shift it really fast and be back on the gas as soon as let go of the clutch, it had a hard time actually grabbing. Since I removed the clutch delay valve, i can slam into second and spin tires till about 120kmph . If you continue driving your car the way you are, it being set up the way it is, meaning stock, you will burn out your clutch in no time. The mod is quite simple, to remove the slave will take you about 10min. All you need is a 12mm to remove the mounting bolts, and a 10mm to remove the feed line. Once you reassemble everything you'll need an 8mm to purge the air from the system. Now when you let go of the clutch there will be no delay.
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Old Mar 2, 2011 | 02:41 PM
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Originally Posted by MJRHector
I have an 08 TL-S manual and I find that maybe half the time I try to accelerate quickly and go through the gears at a good rate, i.e. racing, the clutch seems to have trouble engaging. No, it's not the infamous 3rd gear problem, which I do have btw. But it does happen going into 3rd OR 4th.

My attempt at a description: since I'm going for speed, when I shift out of 2nd or out of 3rd, the RPM is in the 3k, possibly 4k. With full knowledge that I have put the shifter completely into the next gear, I lay on the gas (more than normal driving) and let out the clutch relatively quickly (even then, I try to make sure that I let out the clutch AS I give gas, I don't rev THEN let out the clutch). And what happens sometimes is once I've completely let out the clutch the RPMs still linger rather high and the clutch doesn't quite engage, it feels like it's half engaged (no grinding or anything), and then after a second or two it engages, or if I take my foot off the gas it engages. Thus, next to no immediate acceleration. Once it really is engaged, it's fine, I can really feel the car pull. I notice it isn't as bad with VSA off, though it still happens. It seems like the car's electronics are saying "Screw you for trying to drive me this fast! I'm gonna keep you from accelerating".

So, is it a tranny problem? Are the car electronics actually saying "Screw you"? Is there a certain technique I should be using when trying to accelerate quickly? Something else?

Again, I know about the 3rd gear problem everyone and myself has, but this really seems quite different.

Graci!
The clutch and the transmission have nothing to do with one another. They are completely separate components of the drive train so if we're talking clutch, there shouldn't be any grinding.

You gave a good description of clutch slip and it is most likely symptomatic of the following: a failing clutch delay valve, also know as a check valve, or a slipping clutch which means your clutch is approaching the end of its life. Since your car is an '08, one would hope that it isn't a dying clutch. So let's try something that will isolate your problem a bit more perhaps.

Find a hill (road or parking lot) where there is no traffic and you can do this safely. Get going enough to where you are in third gear with the engine turning around 2500-3000 RPM. Once on the hill, go full throttle. Does engine speed suddenly race up or does it increase proportionately to the increase in road speed. In other words, when you do this does the tach suddenly register a quick rise in RPM's? If so, your clutch is slipping. If not, that is good.

Now try this again in fourth gear (may have to use a different hill), or second gear with a steeper hill and see what results.

I'm guessing your check valve is failing from what you have told us but a few things you said do indicate a dying clutch. Does your clutch pedal feel sluggish during its release when you drive like you mentioned? When driving normally, do you notice anything like this or is everything what you would consider, normal? How many miles are on the car and are you the original owner? Do you use proper techniques while operating a manual transmission? With normal use under normal conditions, you should expect well over 100,000 miles our of your clutch with 200,000+ miles more like it.

Last edited by SouthernBoy; Mar 2, 2011 at 02:52 PM.
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Old Mar 2, 2011 | 02:49 PM
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Originally Posted by justnspace
this is our "shifting guru"
PM him for more info
No, I'm no guru.

Man, I wrote that piece when I was on an Altima enthusiast website years ago. Probably needs some updating, eh?
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Old Mar 2, 2011 | 03:03 PM
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As a followup to the hill test, if you can't find a hill to use for what I suggested, then a stretch of level road or a long section of a parking lot will also work. The only thing is you'll have to use your brakes to hold the car against the straining engine. So take it up to 2500-3000 RPM in third gear then as you floor it, apply the brakes enough to keep the car from accelerating. Does the engine speed suddenly increase or is it held in check?

You don't want to do this too much because you can overheat your brakes so be careful.
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Old Mar 2, 2011 | 04:30 PM
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That is the best write up I have ever seen on how to properly operate a manual transmission. It should be standard reading for anyone new to the joys of this tranny!! Great Advice!!
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Old Mar 2, 2011 | 04:55 PM
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Thanks for the help everyone.

@Bucks13: I'll check into that
I'm guessing your check valve is failing from what you have told us but a few things you said do indicate a dying clutch. Does your clutch pedal feel sluggish during its release when you drive like you mentioned? When driving normally, do you notice anything like this or is everything what you would consider, normal? How many miles are on the car and are you the original owner? Do you use proper techniques while operating a manual transmission? With normal use under normal conditions, you should expect well over 100,000 miles our of your clutch with 200,000+ miles more like it.

@SouthernBoy: I'm currently in college in Pittsburgh, so hills are a way of life. I know for sure there is no jump in the tach in 2nd and 3rd, never been in 4rth on these hills. What exactly to you mean by the clutch feeling sluggish? And when I drive it normally, the car responds completely normal. I got the car second hand almost three months ago, with 90k (I know, high. I drive way less than the previous though). Everything about the car has worked and felt fine with the only known issue being that infamous 3rd gear problem, and what this thread concerns.
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Old Mar 2, 2011 | 04:56 PM
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^Didn't mean to include the quote in that one
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Old Mar 2, 2011 | 06:41 PM
  #13  
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Originally Posted by CrownTypeS
That is the best write up I have ever seen on how to properly operate a manual transmission. It should be standard reading for anyone new to the joys of this tranny!! Great Advice!!
Thank you. I really do need to update it, however.
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Old Mar 2, 2011 | 06:48 PM
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Originally Posted by MJRHector
Thanks for the help everyone.

@Bucks13: I'll check into that
I'm guessing your check valve is failing from what you have told us but a few things you said do indicate a dying clutch. Does your clutch pedal feel sluggish during its release when you drive like you mentioned? When driving normally, do you notice anything like this or is everything what you would consider, normal? How many miles are on the car and are you the original owner? Do you use proper techniques while operating a manual transmission? With normal use under normal conditions, you should expect well over 100,000 miles our of your clutch with 200,000+ miles more like it.

@SouthernBoy: I'm currently in college in Pittsburgh, so hills are a way of life. I know for sure there is no jump in the tach in 2nd and 3rd, never been in 4rth on these hills. What exactly to you mean by the clutch feeling sluggish? And when I drive it normally, the car responds completely normal. I got the car second hand almost three months ago, with 90k (I know, high. I drive way less than the previous though). Everything about the car has worked and felt fine with the only known issue being that infamous 3rd gear problem, and what this thread concerns.
Not the clutch, the clutch pedal. If the check valve is failing the clutch pedal will act differently. Sometimes it will be slow to release (on its own), sometimes it might stick, and sometimes it may need to be pumped before full engagement takes place.

Based upon what you have written initially coupled with this post, it appears to be either the check valve or the slave cylinder. Could be something as needing to change the hydraulic fluid. Since you stated the clutch performs normally and exhibits no slippage during normal operation, then I doubt the clutch is going bad. However, one thing that is a designed characteristic with our clutches is that they have a self-adjusting pressure plate and the thing works right up to the point where it fails.
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Old Mar 2, 2011 | 08:51 PM
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My 06-6MT acted the exact same way before I removed the check valve. I had less than 20K miles so I wouldn't think it's faulty. My take is that it is doing as intended, "saving" us from banging the gears.
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Old Mar 2, 2011 | 09:38 PM
  #16  
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Thanks to all! Spring break is next week and I've got some car projects to do...
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Old Mar 3, 2011 | 07:36 AM
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Gentlemen;

In going over the writeup I wrote which justnspace posted in #4 above, I definitely see where I need to do some updates. When I wrote that, most of my audience members on that website were young and newbies and were asking some very basic questions. I tried to keep my explanations as easy for them to understand as possible so that the ideas would convey with more meaning. I purposely avoided the term "double clutch(ing)" in the earlier part of the text because I wasn't sure they'd know what that meant and I wanted to give them some explanations that weren't confusing.

Also, I spoke of shifting gears since that is what most of them knew and understood. If I had introduced what is actually taking place in their transmissions, that would have only caused more confusion and would have caused the discussion to go off on some tangent. With this in mind, many of you may already know this but just in case, here is a little more information you might like to know.

Our manual transmissions are called "constant mesh". What this means is the gears in the transmission are always in contact or in "mesh" constantly, hence the term. When you "shift gears" you are not actually shifting, or moving, any gears at all. You can't because they are in fixed positions on their shafts. What you are actually doing is forcing a collar to move into contact with a given gear set's hub. There are what's known as dog teeth on the collar's sides which mate with slots in gear hubs. As these collars are moved between gear sets, the differently sized gears become "activated" or engaged, and transmit rotational forces from the engine to the transmission output shaft. This is how we "shift" gears in our transmissions.
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Old Mar 3, 2011 | 09:44 AM
  #18  
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From: Indy
Originally Posted by KN_TL
My 06-6MT acted the exact same way before I removed the check valve. I had less than 20K miles so I wouldn't think it's faulty. My take is that it is doing as intended, "saving" us from banging the gears.
I completely agree, especially with the "saving" comment being in quotes. Just my opinion, but the TL is marketed to an "older" group, so they wanted to do what they could to make the driving experience as smooth as possible. The restriction valve does smooth out poor shifting, but it also makes aggressive shifting more difficult and less responsive.
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Old Mar 3, 2011 | 10:41 AM
  #19  
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Originally Posted by Bucks13
I completely agree, especially with the "saving" comment being in quotes. Just my opinion, but the TL is marketed to an "older" group, so they wanted to do what they could to make the driving experience as smooth as possible. The restriction valve does smooth out poor shifting, but it also makes aggressive shifting more difficult and less responsive.
The reason that there is a check (or delay) valve is the same reason that our manual TL's have a dual mass flywheel. Our friction disk is a solid hub piece. It does not make use of torque dissipation springs you commonly see arrayed around the spined hub on most friction disks. Those springs absorb shock to the drive train from the flywheel and pressure plate and also minimize chatter or shuttering. Since our friction disks don't have these springs, they designed in a delay (check) valve to control rapid engagement. This works in tandem with the dual mass flywheel to smooth out and protect the drive train.
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Old Mar 3, 2011 | 11:16 AM
  #20  
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From: Indy
Originally Posted by SouthernBoy
The reason that there is a check (or delay) valve is the same reason that our manual TL's have a dual mass flywheel. Our friction disk is a solid hub piece. It does not make use of torque dissipation springs you commonly see arrayed around the spined hub on most friction disks. Those springs absorb shock to the drive train from the flywheel and pressure plate and also minimize chatter or shuttering. Since our friction disks don't have these springs, they designed in a delay (check) valve to control rapid engagement. This works in tandem with the dual mass flywheel to smooth out and protect the drive train.
Well, you learn something new every day. Thanks.

So could the removal of my delay valve be the cause of the slight shutter I experience if I downshift without rev-matching (which isn't often)?
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Old Mar 3, 2011 | 11:44 AM
  #21  
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^only one way to find out.

I removed mine as well.
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Old Mar 3, 2011 | 11:48 AM
  #22  
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Originally Posted by Bucks13
Well, you learn something new every day. Thanks.

So could the removal of my delay valve be the cause of the slight shutter I experience if I downshift without rev-matching (which isn't often)?
If you let the clutch out quickly after getting into a lower gear then I suppose it could cause this. But I would think more than likely, no.
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Old Mar 3, 2011 | 11:03 PM
  #23  
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Chances are that you know how to drive stick properly. If i were you Id take an hour of your time and remove the stupid check valve. Youll be able to bang gears like all the other Honda speed racers. At the same time you'll save your clutch from premature failure because you will save it from slippage. Although this added torque on your drive components may cause premature wear on things like your engine mounts and drive shafts, and if your really unlucky, you may break your tranny. But mine is holding up, i just drive it reasonably.
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Old Mar 4, 2011 | 07:05 AM
  #24  
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Originally Posted by speedytypes
Chances are that you know how to drive stick properly. If i were you Id take an hour of your time and remove the stupid check valve. Youll be able to bang gears like all the other Honda speed racers. At the same time you'll save your clutch from premature failure because you will save it from slippage. Although this added torque on your drive components may cause premature wear on things like your engine mounts and drive shafts, and if your really unlucky, you may break your tranny. But mine is holding up, i just drive it reasonably.
If someone is of a mind to run their car hard or race it, absolutely... remove this check valve. What you wrote is right. But if the car is not going to be seeing that kind of service and the check valve is working as designed, I wouldn't touch it.
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Old Mar 4, 2011 | 08:29 AM
  #25  
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I KNOW you all know what you're talking about.
But from a layman's perspective I will say this.
Have driven manual transmission since 16 years old...and mostly Honda. Until I removed the checkvalve, I felt like it was my first time driving stick in my TL EVERY time I had to drop back to 1st and 2nd gear. It was annoying to the point of making me question my skill and making me feel like I wanted to sell the car.

Removed checkvalve and it felt "normal" again. And I loved driving the car again.

J.

That said, in my older years now, I try not to BANG thru the gears as much anymore. I take more time to be smooth between shifts, even if that means losing some ground in acceleration.
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