High RPM clutch drag
-
- Master Standardshifter
- Posts: 11612
- Joined: Mon Mar 16, 2009 3:44 pm
- Cars: '08 Jeep Liberty
- Location: Greater Detroit Area
Re: High RPM clutch drag
When all else fails, blame it on the nut that holds the steering wheel.
'08 Jeep Liberty 6-Speed MT - "Last of the Mohicans"
-
- Master Standardshifter
- Posts: 11612
- Joined: Mon Mar 16, 2009 3:44 pm
- Cars: '08 Jeep Liberty
- Location: Greater Detroit Area
Re: High RPM clutch drag
When all else fails, blame it on the nut that holds the steering wheel.
'08 Jeep Liberty 6-Speed MT - "Last of the Mohicans"
-
- Master Standardshifter
- Posts: 11612
- Joined: Mon Mar 16, 2009 3:44 pm
- Cars: '08 Jeep Liberty
- Location: Greater Detroit Area
Re: High RPM clutch drag
High rpm crank-flexing makes the flywheel and clutch cover assembly rotate with a wobble. The wobble is accentuated the further away from the rear main bearing you go. This wobble leads to contact between the flywheel and/or pressure plate and the clutch disk and tries to drag it along at engine speed.
'08 Jeep Liberty 6-Speed MT - "Last of the Mohicans"
-
- Senior Standardshifter
- Posts: 370
- Joined: Thu Jun 28, 2012 1:18 pm
- Cars: VW Golf R
Re: High RPM clutch drag
This is what I think I meant when I said look the mounts. Stiffer engine/transmission mounts would help in this case, wouldn't it?Rope-Pusher wrote:High rpm crank-flexing makes the flywheel and clutch cover assembly rotate with a wobble. The wobble is accentuated the further away from the rear main bearing you go. This wobble leads to contact between the flywheel and/or pressure plate and the clutch disk and tries to drag it along at engine speed.
2012 VW Golf R
-
- Master Standardshifter
- Posts: 11612
- Joined: Mon Mar 16, 2009 3:44 pm
- Cars: '08 Jeep Liberty
- Location: Greater Detroit Area
Re: High RPM clutch drag
No, crankshaft bending isn't the same as the powertrain moving around underhood. It is due to the thrust of the pistons, through the connecting rods, flexing the crankshaft.daleadbull wrote:This is what I think I meant when I said look the mounts. Stiffer engine/transmission mounts would help in this case, wouldn't it?Rope-Pusher wrote:High rpm crank-flexing makes the flywheel and clutch cover assembly rotate with a wobble. The wobble is accentuated the further away from the rear main bearing you go. This wobble leads to contact between the flywheel and/or pressure plate and the clutch disk and tries to drag it along at engine speed.
'08 Jeep Liberty 6-Speed MT - "Last of the Mohicans"
-
- Senior Standardshifter
- Posts: 370
- Joined: Thu Jun 28, 2012 1:18 pm
- Cars: VW Golf R
Re: High RPM clutch drag
Is that really a concern in today's engines especially in a lower powered production car?Rope-Pusher wrote:No, crankshaft bending isn't the same as the powertrain moving around underhood. It is due to the thrust of the pistons, through the connecting rods, flexing the crankshaft.daleadbull wrote:This is what I think I meant when I said look the mounts. Stiffer engine/transmission mounts would help in this case, wouldn't it?Rope-Pusher wrote:High rpm crank-flexing makes the flywheel and clutch cover assembly rotate with a wobble. The wobble is accentuated the further away from the rear main bearing you go. This wobble leads to contact between the flywheel and/or pressure plate and the clutch disk and tries to drag it along at engine speed.
Last edited by daleadbull on Thu Jan 09, 2014 4:17 pm, edited 1 time in total.
2012 VW Golf R
- ClutchFork
- Master Standardshifter
- Posts: 1937
- Joined: Wed Mar 06, 2013 2:55 pm
- Cars: 2008 Fusion 2.3L manual
- Location: Detroit MI
Re: High RPM clutch drag
All else equal, a greater number of main bearings would reduce this. I recall the old inline six-bangers used to have 4 mains, but then some were upgraded to 7 mains. Of course those engines never ran that high of rpm for it to matter much. Also a forged steel crank (rings like a bell when thwacked with a wrench while sitting on carpet) would be better than a cast iron crank (makes a dull thunk when thwacked with a wrench).Rope-Pusher wrote:High rpm crank-flexing makes the flywheel and clutch cover assembly rotate with a wobble. The wobble is accentuated the further away from the rear main bearing you go. This wobble leads to contact between the flywheel and/or pressure plate and the clutch disk and tries to drag it along at engine speed.
Stick shiftin since '77
theholycow wrote:Why in the world would you even want to be as smooth as an automatic? Might as well just drive an automatic...
- bk7794
- Master Standardshifter
- Posts: 1561
- Joined: Tue Jul 05, 2011 3:16 am
- Cars: 00 Civic (Stock)
- Location: Central CT
Re: High RPM clutch drag
Rope-Pusher wrote:When all else fails, blame it on the nut that holds the steering wheel.
This?
2004 Honda Accord 2.4 5 Speed
1989 Ford Taurus SHO 5 speed
1989 Ford Taurus SHO 5 speed
- theholycow
- Master Standardshifter
- Posts: 16021
- Joined: Tue Jun 24, 2008 1:36 pm
- Cars: '80 Buick LeSabre 4.1 5MT
- Location: Glocester, RI
- Contact:
Re: High RPM clutch drag
Not sure if question is serious, but Rope meant this:
1980 Buick LeSabre 4.1L 5MT
Put your car in your sig!
Learn to launch/FAQs/lugging/misused terms: meta-sig
Put your car in your sig!
Learn to launch/FAQs/lugging/misused terms: meta-sig
watkins wrote:Humans have rear-biased AWD. Cows have 4WD
-
- Master Standardshifter
- Posts: 11612
- Joined: Mon Mar 16, 2009 3:44 pm
- Cars: '08 Jeep Liberty
- Location: Greater Detroit Area
Re: High RPM clutch drag
You're likin' that decoder ring I sentcha.theholycow wrote:Not sure if question is serious, but Rope meant this:
'08 Jeep Liberty 6-Speed MT - "Last of the Mohicans"
- bk7794
- Master Standardshifter
- Posts: 1561
- Joined: Tue Jul 05, 2011 3:16 am
- Cars: 00 Civic (Stock)
- Location: Central CT
Re: High RPM clutch drag
Rope-Pusher wrote:You're likin' that decoder ring I sentcha.theholycow wrote:Not sure if question is serious, but Rope meant this:
So the other day I decided to take it up to around 5k in first gear. I then tried shifting it into second and it went in somewhat easily. One thing I hate about that is then I botch the shift going into second because I'm so dead set on trying to determine how the shifter feels lol.
2004 Honda Accord 2.4 5 Speed
1989 Ford Taurus SHO 5 speed
1989 Ford Taurus SHO 5 speed
-
- Senior Standardshifter
- Posts: 260
- Joined: Thu May 17, 2012 4:31 pm
- Cars: 2012 Chevy Sonic Turbo
- Location: GA
Re: High RPM clutch drag
lol @ all the noobs in this thread. bk's problem is actually very simple.
bk, your clutch isn't fully disengaging. Its like you're partially shifting without using the clutch. The problem is worst shifting to 2nd at high rpm in 1st because that has the biggest gap between gears of any shift in that car. Also, if you're trying to shift fast it'll make it worse as you're not rev-matching the shift. Waiting at the gate for 2nd and going in at the right time should revmatch it and have it shift smoothly. You're not having a problem with it in the other gears because in those gears you shift slow enough for it to just revmatch on its own with your normal timing.
Also, another thing. What you're referring to as "clutch engagement" isn't what you think it is. You're referring to it as a point. Its not a point, its an area in the clutch pedal's range of motion. And that area/range will increase as your clutch wears. If the clutch pedal has a range of motion of about 12", ideally you'd want it to grab and fully hookup over an area of an inch or two, and starting at least an inch or 2 off the floor to have some breathing room for clutch disengagement. If your clutch starts to grab "beneath the floor" like you've said, and doesn't fully hook up til high in pedal travel, you're wearing it pretty bad. If anything you've got a glazed clutch, if not one that's on its way out. For one thing the 'not fully disengaging' problem you're having isn't good for a clutch.
Time to go off-topic from your problem. 1st-2nd is a tricky shift for a lot of cars. The Sonic forums have a lot of people who complain about it. Supposedly, the Sonic has a notchy 2nd gear that doesn't like to engage with a high-rpm shift from 1st. Me....I've never had a problem with it. You just have to realize, that's the biggest gap between gears, and you have to give the synchro an extra split second to do its thing. So to me, shifting my Sonic to 2nd at high rpm is actually smoother than low-RPM. At low-rpm its more complicated, a combination of the big gap between gears and the right speed/timing required to get it right. High-RPM its just a fast shift with an extra split second waiting at the gate for 2nd gear.
bk, your clutch isn't fully disengaging. Its like you're partially shifting without using the clutch. The problem is worst shifting to 2nd at high rpm in 1st because that has the biggest gap between gears of any shift in that car. Also, if you're trying to shift fast it'll make it worse as you're not rev-matching the shift. Waiting at the gate for 2nd and going in at the right time should revmatch it and have it shift smoothly. You're not having a problem with it in the other gears because in those gears you shift slow enough for it to just revmatch on its own with your normal timing.
Also, another thing. What you're referring to as "clutch engagement" isn't what you think it is. You're referring to it as a point. Its not a point, its an area in the clutch pedal's range of motion. And that area/range will increase as your clutch wears. If the clutch pedal has a range of motion of about 12", ideally you'd want it to grab and fully hookup over an area of an inch or two, and starting at least an inch or 2 off the floor to have some breathing room for clutch disengagement. If your clutch starts to grab "beneath the floor" like you've said, and doesn't fully hook up til high in pedal travel, you're wearing it pretty bad. If anything you've got a glazed clutch, if not one that's on its way out. For one thing the 'not fully disengaging' problem you're having isn't good for a clutch.
Time to go off-topic from your problem. 1st-2nd is a tricky shift for a lot of cars. The Sonic forums have a lot of people who complain about it. Supposedly, the Sonic has a notchy 2nd gear that doesn't like to engage with a high-rpm shift from 1st. Me....I've never had a problem with it. You just have to realize, that's the biggest gap between gears, and you have to give the synchro an extra split second to do its thing. So to me, shifting my Sonic to 2nd at high rpm is actually smoother than low-RPM. At low-rpm its more complicated, a combination of the big gap between gears and the right speed/timing required to get it right. High-RPM its just a fast shift with an extra split second waiting at the gate for 2nd gear.
Re: High RPM clutch drag
A "notchy" shift from 1st gear to 2nd gear simply means that the sychronizer isn't up to the job of, well, synchronizing shaft speeds. Why that happens isn't always easily apparent. In some cases, cold temps magnify the issue, mostly because of the viscosity of the gear lube in the box. In other cases, it could be a case of a worn synchro itself. And in other cases, the synchro may be in good condition, but it's just not designed robust enough to effectively do its job properly under all circumstances. Either way, no driver should be forced to compensate by purposely shifting at a specific RPM to avoid a notchy shift. Sure, that may be an easy way to minimize the issue, but a better option is to correct the issue in the first place so you have the freedom and ability to shift at any RPM without getting a notchy shift in the first place.SonicHKS wrote:
Time to go off-topic from your problem. 1st-2nd is a tricky shift for a lot of cars. The Sonic forums have a lot of people who complain about it. Supposedly, the Sonic has a notchy 2nd gear that doesn't like to engage with a high-rpm shift from 1st. Me....I've never had a problem with it. You just have to realize, that's the biggest gap between gears, and you have to give the synchro an extra split second to do its thing. So to me, shifting my Sonic to 2nd at high rpm is actually smoother than low-RPM. At low-rpm its more complicated, a combination of the big gap between gears and the right speed/timing required to get it right. High-RPM its just a fast shift with an extra split second waiting at the gate for 2nd gear.
One thing that can help a great deal (and sometimes completely eliminate notchy shifts) is a simple swap of the gear lube. For example, Redline makes some great products that have been known to completely eliminate notchy shifts. You should try them yourself and maybe then you won't have to run your engine to high RPM in 1st gear all the time to get a smooth shift into 2nd. And you won't have to delay your shift either. I don't want the gearbox telling me how to drive the car; I want to tell the gearbox how I'm going to drive the car. That's the whole point in driving a manual transmission car in the first place.
- bk7794
- Master Standardshifter
- Posts: 1561
- Joined: Tue Jul 05, 2011 3:16 am
- Cars: 00 Civic (Stock)
- Location: Central CT
Re: High RPM clutch drag
I've got a funny issue. The only thing I can guess is that it has something to do with the pitch of the car. When I first start my car in the morning. I go up a slight grade and both the 91 and 00 shift fine into 2nd. Then I come to the end of my street, when I turn right I go downhill, both of the cars definitely do feel notchy only when I go down that hill in the cold weather. Must be the oil sloshing to one side of the transmission. Kind of a funny issue.
http://en.wikipedia.org/wiki/Shift_blocking
I wondered what your opinion was. This is actually brand new to me.
Have you heard of something called shift blocking?Shadow wrote:A "notchy" shift from 1st gear to 2nd gear simply means that the sychronizer isn't up to the job of, well, synchronizing shaft speeds. Why that happens isn't always easily apparent. In some cases, cold temps magnify the issue, mostly because of the viscosity of the gear lube in the box. In other cases, it could be a case of a worn synchro itself. And in other cases, the synchro may be in good condition, but it's just not designed robust enough to effectively do its job properly under all circumstances. Either way, no driver should be forced to compensate by purposely shifting at a specific RPM to avoid a notchy shift. Sure, that may be an easy way to minimize the issue, but a better option is to correct the issue in the first place so you have the freedom and ability to shift at any RPM without getting a notchy shift in the first place.SonicHKS wrote:
Time to go off-topic from your problem. 1st-2nd is a tricky shift for a lot of cars. The Sonic forums have a lot of people who complain about it. Supposedly, the Sonic has a notchy 2nd gear that doesn't like to engage with a high-rpm shift from 1st. Me....I've never had a problem with it. You just have to realize, that's the biggest gap between gears, and you have to give the synchro an extra split second to do its thing. So to me, shifting my Sonic to 2nd at high rpm is actually smoother than low-RPM. At low-rpm its more complicated, a combination of the big gap between gears and the right speed/timing required to get it right. High-RPM its just a fast shift with an extra split second waiting at the gate for 2nd gear.
One thing that can help a great deal (and sometimes completely eliminate notchy shifts) is a simple swap of the gear lube. For example, Redline makes some great products that have been known to completely eliminate notchy shifts. You should try them yourself and maybe then you won't have to run your engine to high RPM in 1st gear all the time to get a smooth shift into 2nd. And you won't have to delay your shift either. I don't want the gearbox telling me how to drive the car; I want to tell the gearbox how I'm going to drive the car. That's the whole point in driving a manual transmission car in the first place.
http://en.wikipedia.org/wiki/Shift_blocking
I wondered what your opinion was. This is actually brand new to me.
Keep in mind the high engagement is on a cable clutch. One adjustment and you can move the engagement point down. Then again you get lousy pedal feel. But when you're trying to get as much life out of the clutch as possible, who cares. I'm wondering about the clutch in my 00. With it being a used car I have no idea on how the car was treated, the clutch and all that. I must admit I'm sure the transmission wasn't treated all too well with Reverse having some problems engaging. It all works now and I just like having the peace of mind knowing I can get into 2nd if I am in a hurry.SonicHKS wrote:lol @ all the noobs in this thread. bk's problem is actually very simple.
bk, your clutch isn't fully disengaging. Its like you're partially shifting without using the clutch. The problem is worst shifting to 2nd at high rpm in 1st because that has the biggest gap between gears of any shift in that car. Also, if you're trying to shift fast it'll make it worse as you're not rev-matching the shift. Waiting at the gate for 2nd and going in at the right time should revmatch it and have it shift smoothly. You're not having a problem with it in the other gears because in those gears you shift slow enough for it to just revmatch on its own with your normal timing.
Also, another thing. What you're referring to as "clutch engagement" isn't what you think it is. You're referring to it as a point. Its not a point, its an area in the clutch pedal's range of motion. And that area/range will increase as your clutch wears. If the clutch pedal has a range of motion of about 12", ideally you'd want it to grab and fully hookup over an area of an inch or two, and starting at least an inch or 2 off the floor to have some breathing room for clutch disengagement. If your clutch starts to grab "beneath the floor" like you've said, and doesn't fully hook up til high in pedal travel, you're wearing it pretty bad. If anything you've got a glazed clutch, if not one that's on its way out. For one thing the 'not fully disengaging' problem you're having isn't good for a clutch.
Time to go off-topic from your problem. 1st-2nd is a tricky shift for a lot of cars. The Sonic forums have a lot of people who complain about it. Supposedly, the Sonic has a notchy 2nd gear that doesn't like to engage with a high-rpm shift from 1st. Me....I've never had a problem with it. You just have to realize, that's the biggest gap between gears, and you have to give the synchro an extra split second to do its thing. So to me, shifting my Sonic to 2nd at high rpm is actually smoother than low-RPM. At low-rpm its more complicated, a combination of the big gap between gears and the right speed/timing required to get it right. High-RPM its just a fast shift with an extra split second waiting at the gate for 2nd gear.
2004 Honda Accord 2.4 5 Speed
1989 Ford Taurus SHO 5 speed
1989 Ford Taurus SHO 5 speed
-
- Master Standardshifter
- Posts: 4029
- Joined: Tue Apr 26, 2011 9:04 pm
- Cars: 17 Mazda6 To, 18 Mazda3 i
- Location: Shakopee, MN
Re: High RPM clutch drag
If I were forced to shift that way I'd have to break something. As Clarkson would say, "I'm the driver, I know what gear I want, not you. You silly thing, you."
I skip shift all the time, but that's by choice not some farsical automotive engineering "feature".
I skip shift all the time, but that's by choice not some farsical automotive engineering "feature".