How do you money shift without the clutch?
06-12-2017, 11:45 AM
#1
How do you money shift without the clutch?
I was watching NASCAR yesterday and Dale Jr. blew his engine with a 3-2 money shift. Later in the race, Kevin Harvick did the same thing, though his somehow survived.
Forgetting that this is pretty rare so it was downright bizarre to have it happen twice in the same race, I couldn't help but wonder how it's even possible and, for that matter, how they manage to shift race cars so quickly without using the clutch.
I understand that it has something to do with having straight cut gears but I can't for the life of me figure out how this actually helps and how it works.
I know how to shift gears in a street car without using the clutch. So long as the revs match up, the gear lever will slide right into place. No problem.
When up shifting, I expect you can just lean on it and when the RPM comes down enough it'll go in. Race engines are so free-revving that I expect this happens really quickly so it makes sense to me.
When downshifting though... you need to go to neutral, bring the revs up, and then put it back into gear. If the revs aren't right, then it's not going into gear and you'll probably get some awful noises if you try to force it.
SO... this brings me to the money shift. If you were planning to up-shift but grab the lower gear and haven't brought the revs up, how does it even get into gear at all? How is that possible? What forces the revs up?
And how the hell do they downshift so fast without the clutch? Watching them do it, I can't imagine how they can possibly bring the revs up in the time between getting out of gear and getting back into the lower gear.
Can someone explain this in terms I might understand?
Forgetting that this is pretty rare so it was downright bizarre to have it happen twice in the same race, I couldn't help but wonder how it's even possible and, for that matter, how they manage to shift race cars so quickly without using the clutch.
I understand that it has something to do with having straight cut gears but I can't for the life of me figure out how this actually helps and how it works.
I know how to shift gears in a street car without using the clutch. So long as the revs match up, the gear lever will slide right into place. No problem.
When up shifting, I expect you can just lean on it and when the RPM comes down enough it'll go in. Race engines are so free-revving that I expect this happens really quickly so it makes sense to me.
When downshifting though... you need to go to neutral, bring the revs up, and then put it back into gear. If the revs aren't right, then it's not going into gear and you'll probably get some awful noises if you try to force it.
SO... this brings me to the money shift. If you were planning to up-shift but grab the lower gear and haven't brought the revs up, how does it even get into gear at all? How is that possible? What forces the revs up?
And how the hell do they downshift so fast without the clutch? Watching them do it, I can't imagine how they can possibly bring the revs up in the time between getting out of gear and getting back into the lower gear.
Can someone explain this in terms I might understand?
06-12-2017, 01:15 PM
#2
Rennlist Member
Their "syncros " are very strong and have enough bite to grab disparate RPMs pretty easily. (see pic) gear-like or puzzle piece "synchros" that are really not synchros. (see pic below for comparison of traditional syncro vs dog box "synchro" mechanism ) which is how they can shift , even up shift with no clutch. they dont wait for the RPM to fall, they just forcefully shift and it brings down the engine speed, with a force transferred to the rear wheels. (as a "clunk") most can downshift with no clutch as well. similar to what a cup car can do, but you need to rev match through neutral, otherwise you will get a huge force at the rears that can unstablize the car.
same kind of process and principles of driving a motorcycle and its gear box with out the sequential part being on the NASCAR.
same kind of process and principles of driving a motorcycle and its gear box with out the sequential part being on the NASCAR.
I was watching NASCAR yesterday and Dale Jr. blew his engine with a 3-2 money shift. Later in the race, Kevin Harvick did the same thing, though his somehow survived.
Forgetting that this is pretty rare so it was downright bizarre to have it happen twice in the same race, I couldn't help but wonder how it's even possible and, for that matter, how they manage to shift race cars so quickly without using the clutch.
I understand that it has something to do with having straight cut gears but I can't for the life of me figure out how this actually helps and how it works.
I know how to shift gears in a street car without using the clutch. So long as the revs match up, the gear lever will slide right into place. No problem.
When up shifting, I expect you can just lean on it and when the RPM comes down enough it'll go in. Race engines are so free-revving that I expect this happens really quickly so it makes sense to me.
When downshifting though... you need to go to neutral, bring the revs up, and then put it back into gear. If the revs aren't right, then it's not going into gear and you'll probably get some awful noises if you try to force it.
SO... this brings me to the money shift. If you were planning to up-shift but grab the lower gear and haven't brought the revs up, how does it even get into gear at all? How is that possible? What forces the revs up?
And how the hell do they downshift so fast without the clutch? Watching them do it, I can't imagine how they can possibly bring the revs up in the time between getting out of gear and getting back into the lower gear.
Can someone explain this in terms I might understand?
Forgetting that this is pretty rare so it was downright bizarre to have it happen twice in the same race, I couldn't help but wonder how it's even possible and, for that matter, how they manage to shift race cars so quickly without using the clutch.
I understand that it has something to do with having straight cut gears but I can't for the life of me figure out how this actually helps and how it works.
I know how to shift gears in a street car without using the clutch. So long as the revs match up, the gear lever will slide right into place. No problem.
When up shifting, I expect you can just lean on it and when the RPM comes down enough it'll go in. Race engines are so free-revving that I expect this happens really quickly so it makes sense to me.
When downshifting though... you need to go to neutral, bring the revs up, and then put it back into gear. If the revs aren't right, then it's not going into gear and you'll probably get some awful noises if you try to force it.
SO... this brings me to the money shift. If you were planning to up-shift but grab the lower gear and haven't brought the revs up, how does it even get into gear at all? How is that possible? What forces the revs up?
And how the hell do they downshift so fast without the clutch? Watching them do it, I can't imagine how they can possibly bring the revs up in the time between getting out of gear and getting back into the lower gear.
Can someone explain this in terms I might understand?
Last edited by mark kibort; 06-12-2017 at 01:38 PM.
06-12-2017, 01:34 PM
#3
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The NASCAR transmission design allows for a larger rev mismatch, and doesn't require force to select the gear like a synchromesh does. You can just select the gear and one of three things happen:
1) you continue going forward
2) you get the quickest all neutral gear transmission fabrication for $0
3) you lubricate the track for your friends complaining of high tire wear and high speed machine your engine parts.
This following article and quote sums it up well:
Copied from -> http://automotivethinker.com/transmi...x-and-dog-box/
"The dogs on a dog engaged transmission are spaced wider apart than those on a synchromesh trans and allow for a small amount of rpm mismatch. This makes for a clunky and noisy shift, but who cares in a race. Clutchless shifts are accomplished by simply letting off the throttle for a split second, and once the load is off the transmission, the shifter is simply thrown into the next gear. No synchromesh box can match the speed of these shifts. Another benefit is that dog boxes require virtually no force to be put into gear since there is no synchro’s to operate."
Another related article:
http://automotivethinker.com/transmi...rs-vs-helical/
1) you continue going forward
2) you get the quickest all neutral gear transmission fabrication for $0
3) you lubricate the track for your friends complaining of high tire wear and high speed machine your engine parts.
This following article and quote sums it up well:
Copied from -> http://automotivethinker.com/transmi...x-and-dog-box/
"The dogs on a dog engaged transmission are spaced wider apart than those on a synchromesh trans and allow for a small amount of rpm mismatch. This makes for a clunky and noisy shift, but who cares in a race. Clutchless shifts are accomplished by simply letting off the throttle for a split second, and once the load is off the transmission, the shifter is simply thrown into the next gear. No synchromesh box can match the speed of these shifts. Another benefit is that dog boxes require virtually no force to be put into gear since there is no synchro’s to operate."
Another related article:
http://automotivethinker.com/transmi...rs-vs-helical/
06-12-2017, 01:47 PM
#4
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Just a bit more... this may help add to the overall knowledge pool in your head:
https://www.highpowermedia.com/blog/...ox-of-tomorrow
Re-reading your post, here are quick answers to your questions:
If you were planning to up-shift but grab the lower gear and haven't brought the revs up, how does it even get into gear at all? How is that possible? What forces the revs up?
>And how the hell do they downshift so fast without the clutch?
In the cars you drive, you feel the force of the synchros pushing back. In a stock car box, no force pushes back when you select. It just clicks in without the clutch if you give it a VERY slight pause.
>Watching them do it, I can't imagine how they can possibly bring the revs up in the time between getting out of gear and getting back into the lower gear.
That's because they don't have to... the rev matching window is much wider than you think in the NASCAR box based on design.
>Can someone explain this in terms I might understand?
Bubba has a special box-o-gears where he just push the gear he wants... yeup, it's a big ole sucker, makes a heck-of-a-noise also, but gosh darnit does it git-er-going. Bubba don't drove like that in all his cars, like on the street he changes those gears in his Vette like you-n-I, her sure does. Something about experience and blowen lots of gearboxes and engines if you do it wrong I hear. One crew guy I know said that anybody could do it once you showed how. I did hear about a fancy Porsche or European type machine that had something totally different and not related to this at all, but it did the same thing... darn thing so expensive and complicated... and they steal are jobs too... best stick to what yer know best, know what I mean?
https://www.highpowermedia.com/blog/...ox-of-tomorrow
Re-reading your post, here are quick answers to your questions:
If you were planning to up-shift but grab the lower gear and haven't brought the revs up, how does it even get into gear at all? How is that possible? What forces the revs up?
>And how the hell do they downshift so fast without the clutch?
In the cars you drive, you feel the force of the synchros pushing back. In a stock car box, no force pushes back when you select. It just clicks in without the clutch if you give it a VERY slight pause.
>Watching them do it, I can't imagine how they can possibly bring the revs up in the time between getting out of gear and getting back into the lower gear.
That's because they don't have to... the rev matching window is much wider than you think in the NASCAR box based on design.
>Can someone explain this in terms I might understand?
Bubba has a special box-o-gears where he just push the gear he wants... yeup, it's a big ole sucker, makes a heck-of-a-noise also, but gosh darnit does it git-er-going. Bubba don't drove like that in all his cars, like on the street he changes those gears in his Vette like you-n-I, her sure does. Something about experience and blowen lots of gearboxes and engines if you do it wrong I hear. One crew guy I know said that anybody could do it once you showed how. I did hear about a fancy Porsche or European type machine that had something totally different and not related to this at all, but it did the same thing... darn thing so expensive and complicated... and they steal are jobs too... best stick to what yer know best, know what I mean?
06-12-2017, 02:49 PM
#5
>Can someone explain this in terms I might understand?
Bubba has a special box-o-gears where he just push the gear he wants... yeup, it's a big ole sucker, makes a heck-of-a-noise also, but gosh darnit does it git-er-going. Bubba don't drove like that in all his cars, like on the street he changes those gears in his Vette like you-n-I, her sure does. Something about experience and blowen lots of gearboxes and engines if you do it wrong I hear. One crew guy I know said that anybody could do it once you showed how. I did hear about a fancy Porsche or European type machine that had something totally different and not related to this at all, but it did the same thing... darn thing so expensive and complicated... and they steal are jobs too... best stick to what yer know best, know what I mean?
Bubba has a special box-o-gears where he just push the gear he wants... yeup, it's a big ole sucker, makes a heck-of-a-noise also, but gosh darnit does it git-er-going. Bubba don't drove like that in all his cars, like on the street he changes those gears in his Vette like you-n-I, her sure does. Something about experience and blowen lots of gearboxes and engines if you do it wrong I hear. One crew guy I know said that anybody could do it once you showed how. I did hear about a fancy Porsche or European type machine that had something totally different and not related to this at all, but it did the same thing... darn thing so expensive and complicated... and they steal are jobs too... best stick to what yer know best, know what I mean?
06-12-2017, 02:58 PM
#6
Ok... so if I understand this correctly then...
The engines rev up and down quicker than anything I've ever driven... and Porsche engines already change speed awfully quick compared to anything ELSE I've ever driven so race engines would probably feel like alien technology to me.
So to upshift, you just barely lift while slamming the gear lever into gear and that's enough to pull the RPM to where you need it.
To downshift... do you effectively make the shift without lifting so the brief instant when you're between gears the engine is revving up and the gear just catches it on the way up?
And for the money shift... even though you've lifted a little expecting the revs to come down, the engine is so free-spinning and those gears shaped to just grab and go that it spins it up before you've really had a chance to do anything about it? No synchros to resist the shift... so the lever DOES go and it just grabs on and chaos ensues?
Is it safe to assume that race engines have little to no flywheel to resist this?
The engines rev up and down quicker than anything I've ever driven... and Porsche engines already change speed awfully quick compared to anything ELSE I've ever driven so race engines would probably feel like alien technology to me.
So to upshift, you just barely lift while slamming the gear lever into gear and that's enough to pull the RPM to where you need it.
To downshift... do you effectively make the shift without lifting so the brief instant when you're between gears the engine is revving up and the gear just catches it on the way up?
And for the money shift... even though you've lifted a little expecting the revs to come down, the engine is so free-spinning and those gears shaped to just grab and go that it spins it up before you've really had a chance to do anything about it? No synchros to resist the shift... so the lever DOES go and it just grabs on and chaos ensues?
Is it safe to assume that race engines have little to no flywheel to resist this?
06-12-2017, 03:44 PM
#7
Originally Posted by Wild Weasel
Ok... so if I understand this correctly then...
The engines rev up and down quicker than anything I've ever driven... and Porsche engines already change speed awfully quick compared to anything ELSE I've ever driven so race engines would probably feel like alien technology to me.
So to upshift, you just barely lift while slamming the gear lever into gear and that's enough to pull the RPM to where you need it.
To downshift... do you effectively make the shift without lifting so the brief instant when you're between gears the engine is revving up and the gear just catches it on the way up?
And for the money shift... even though you've lifted a little expecting the revs to come down, the engine is so free-spinning and those gears shaped to just grab and go that it spins it up before you've really had a chance to do anything about it? No synchros to resist the shift... so the lever DOES go and it just grabs on and chaos ensues?
Is it safe to assume that race engines have little to no flywheel to resist this?
The engines rev up and down quicker than anything I've ever driven... and Porsche engines already change speed awfully quick compared to anything ELSE I've ever driven so race engines would probably feel like alien technology to me.
So to upshift, you just barely lift while slamming the gear lever into gear and that's enough to pull the RPM to where you need it.
To downshift... do you effectively make the shift without lifting so the brief instant when you're between gears the engine is revving up and the gear just catches it on the way up?
And for the money shift... even though you've lifted a little expecting the revs to come down, the engine is so free-spinning and those gears shaped to just grab and go that it spins it up before you've really had a chance to do anything about it? No synchros to resist the shift... so the lever DOES go and it just grabs on and chaos ensues?
Is it safe to assume that race engines have little to no flywheel to resist this?
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06-12-2017, 03:49 PM
#8
I just didn't know how a racing transmission allowed it to happen without the clutch being put in.
If you tried to do it on a street car there's no way you'd get the lever into gear. It would be like downshifting most cars to 1st without double-clutching. The lever just won't go in there.
06-12-2017, 04:01 PM
#9
Originally Posted by Wild Weasel
Yeah... I know what a money shift is.
I just didn't know how a racing transmission allowed it to happen without the clutch being put in.
If you tried to do it on a street car there's no way you'd get the lever into gear. It would be like downshifting most cars to 1st without double-clutching. The lever just won't go in there.
I just didn't know how a racing transmission allowed it to happen without the clutch being put in.
If you tried to do it on a street car there's no way you'd get the lever into gear. It would be like downshifting most cars to 1st without double-clutching. The lever just won't go in there.
Edit: I understand now that I read what you're asking
06-12-2017, 04:55 PM
#10
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So the shaft says: "Yo! Where my Slot B at?"
In these boxes, this is so simple. Let's say you are shifting at close to max RPM, cause you're racing right? You want to go into 5th from 4th, but your confused, so you go into 3rd. Over rev and BOOM! Nothing, and I mean nothing prevents you from selecting the wrong gear. It's not like a synchro box where even if you force it you may have trouble getting it in (that's what she said!). You can select any gear, easily, at any speed, and at any RPM. The gearbox does not protect you from stupidity.
To summarize, select any gear, and the drive train absorbs it within reason. If the difference is too big, bad things happen in escalating severity in relation to the delta.
06-12-2017, 04:58 PM
#11
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To shift these such that you get a smooth ride while not driving at race speeds is an art form... but just shifting is not a problem for any monkey.
06-12-2017, 05:10 PM
#13
Nice!! That last graphic makes it all make sense. It just goes in and grabs and lets the whirly bits figure out the rest. If you're somewhat in the right ballpark things just carry on but if you're way off, something is getting jarred somewhere along the way and you just hope it's not hard enough to break.
06-12-2017, 09:48 PM
#14
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Nice!! That last graphic makes it all make sense. It just goes in and grabs and lets the whirly bits figure out the rest. If you're somewhat in the right ballpark things just carry on but if you're way off, something is getting jarred somewhere along the way and you just hope it's not hard enough to break.
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06-13-2017, 11:23 AM
#15
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Nice!! That last graphic makes it all make sense. It just goes in and grabs and lets the whirly bits figure out the rest. If you're somewhat in the right ballpark things just carry on but if you're way off, something is getting jarred somewhere along the way and you just hope it's not hard enough to break.
If you watch the NASCAR at the Glenn, you will most likely see wheel hop from a few guys going into the bus stop, or at other hard braking corners. Often this is why they spin. Just think that all this gets selected but when the RPM difference in too great, the wheels are under speed compared to the track, the wheels lockup, and the suspension design under braking allows them to skip on the pavement.
Here is a great example:
http://www.nascar.com/en_us/news-med...238018001.html