Transmission types |
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Manual |
Automatic / Semi-automatic |
Bicycle gearing |
Any race driver worth a darn shifts without the clutch. Once the car is rolling the clutch is unnecessary. Most street cars can be shifted without the clutch once you know how. It's a skill anyone can learn with enough practice. Done correctly, it does no damage to the transmission.
A sequential manual transmission is a type of manual transmission used mostly for motorcycles and racing cars.[1] It produces faster shift times than traditional synchronized manual transmissions and restricts the driver to selecting either the next or previous gear.
Design[edit]
Gear shift lever on a motorcycle (above the toe of the rider's boot)
A sequential manual transmission allows the driver to select either the next gear (e.g. shifting from second gear to first gear) or the previous gear (e.g. shifting from second gear to third gear). This restriction avoids accidentally selecting the wrong gear, however it also prevents the driver from deliberately 'skipping' gears.[2] The use of dog-clutches (rather than synchromesh) results in faster shift speeds than a manual transmission.[3]
On a sequential manual transmission, the shift lever operates a ratchet mechanism that converts the fore and aft motion of the shift lever into rotation of a selector drum (sometimes called a barrel) which has three or four tracks machined around its circumference.[4] Selector forks are guided by the tracks, either directly or via selector rods. The tracks deviate around the circumference and as the drum rotates, the selector forks are moved to select the required gear.[5]
A sequential manual transmission is not to be confused with a 'sequential' shifting function sometimes fitted to hydraulic automatic transmission, marketed with terms such as 'Tiptronic' or 'SportShift'. This function allows the driver to select the previous or next gear through use of buttons or a lever (usually near the gear shifter or steering wheel), however the mechanicals of the transmission remain unrelated to a sequential manual transmission.
Usage[edit]
Most modern motorcycles use a sequential manual transmission. Controlling the gear shifter with the rider's foot allows their hands to remain on the handlebars.[6] However, most motor scooters do not use a sequential manual transmission, instead using either a hydraulic automatic transmission or a continuously variable transmission.
Some specialised racing cars also use a sequential manual transmission, beginning with Formula One cars in the 1990s. Due to the high rate of wear and abrupt shifting action, sequential manual transmissions are rarely used in road cars.
See also[edit]
References[edit]
- ^Cameron, Kevin (1998). Sportbike Performance Handbook. Motorbooks. p. 82. ISBN9780760302293.
Motorcycle transmissions and the latest auto-racing gearboxes are of the sequential type
- ^'Gearbox technologies'. www.drivingfast.net. 27 October 2016. Retrieved 2 January 2020.
- ^'How Sequential Gearboxes Work'. www.howstuffworks.com. 4 April 2003. Retrieved 2 January 2020.
- ^'How Sequential Gearboxes Work'. www.howstuffworks.com. 4 April 2003. Retrieved 2 January 2020.
- ^'BMW M3 SMG - Short Take Road Test - Auto Reviews'. Car and Driver. Archived from the original on 2009-04-08. Retrieved 2011-08-29.
- ^Cameron, Kevin (2009), Top Dead Center 2, Motorbooks, p. 58, ISBN9780760336083
Retrieved from 'https://en.wikipedia.org/w/index.php?title=Sequential_manual_transmission&oldid=934009680'
Sun Mar 4, 2012, 05:31 PM
5 speeds have been common in street cars for decades now, and in modern cars 6 speeds isn't uncommon, while some have as many as 8 forward gears. Anyone know why NASCAR is limited to 4? |
26 replies, 81720 views
Always highlight: 10 newest replies | Replies posted after I mark a forum
26 replies | Time | Post |
Why do they still only have 4 speed transmissions in NASCAR? (Original post) | Mar 2012 | OP |
Mar 2012 | #1 | |
Mar 2012 | #2 | |
Mar 2012 | #3 | |
Mar 2012 | #4 | |
Mar 2012 | #5 | |
Mar 2012 | #6 | |
Mar 2012 | #7 | |
Apr 2012 | #8 | |
Apr 2012 | #10 | |
Apr 2012 | #13 | |
Apr 2012 | #16 | |
Jan 2013 | #21 | |
Jan 2013 | #24 | |
Apr 2012 | #9 | |
Apr 2012 | #11 | |
Apr 2012 | #12 | |
Apr 2012 | #15 | |
Apr 2012 | #14 | |
May 2012 | #19 | |
Apr 2012 | #18 | |
Apr 2012 | #17 | |
Jun 2015 | #25 | |
Jun 2012 | #20 | |
Jan 2013 | #22 | |
Jan 2013 | #23 | |
Aug 2015 | #26 |
Response to Electric Monk (Original post)
Sun Mar 4, 2012, 06:27 PM
1. They don't need overdrive.
Response to Electric Monk (Original post)
Mon Mar 5, 2012, 12:28 AM
2. Don't need no more...... - and a cost issue
The 4-speeds in current use are evolutinary copies of the Ford 'top loader' (Jerico) and the Borg-Warner T-10 (Tex 'T-101' One of the major differences is that these transmissions are available in a wide variety of ratio combinations - low gears range from ~3.5/1 to ~1.8/1. Rear gear ratios are easily changeable as well - when DW mentions a 'gear', he is talking about a removable carrier assembly, which holds the ring & pinion and the differential - 2 guys can change one in about 20 min. Available gears range from ~2.6/1 to ~7/1. with these options available, it's pretty easy to get a gear combination that works for the particular track. Cost is not a small issue - Quaife just introduced a new hi-torque racing transmission, to compete in the same market as the Jerico. Jerico =$3500, Quaife = $14K Jerico has a 5 spd sequential for Grand Am & SCCA, goes for ~$7500. How many transmissions does a Cup team have in stock, per car/driver? I'd bet a dozen... |
Response to Electric Monk (Original post)
Mon Mar 5, 2012, 10:24 AM
3. They don't need a 'cruise' gear
Which is what most 5th and 6th gears are. Most cars with an overdrive high gear will go faster in their direct drive (1/1) gear than in overdrive. How is this possible? There is not enough power available in o/d! |
Response to Mopar151 (Reply #3)
Mon Mar 5, 2012, 04:23 PM
4. F1 cars don't need a 'cruise' gear either, but they have 7 speed transmissions
Response to Electric Monk (Reply #4)
Mon Mar 5, 2012, 05:56 PM
5. True - but!
Nascar Cup, and their other divisions are a production based racing series. -The transmissions currently used are updated versions of production transmissions. F1 engines turn 15000 rpm plus, and do not have a particularly wide powerband - thus the need for more speeds, with closer ratios, and the paddle shifters, cuz' ya gotta shift so much to kep the little missle up in it's powerband. The big beast of a sedan has similar horsepower, but turns 1/2 the RPM, with a broader powerband. The other thing is - 7 speed, paddle shifters would increase costs considerably (especially with the necessary sophisticated engine control software), and would not improve the show. |
Response to Mopar151 (Reply #5)
Mon Mar 5, 2012, 06:53 PM
6. Back to my original point. The street versions sell with 5 or 6 speed trannies, not 4.
Response to Electric Monk (Reply #6)
Mon Mar 5, 2012, 07:01 PM
7. Your point was addressed in response #2.
If NASCAR needed 7 speeds to win, they would have 7 speeds. For the ovals, the get out of the pits and get into top gear and stay there. The road courses don't need 7 gears to negotiate with the wide powerband and prodigious amounts of torque available from the pushrod V8s. |
Response to Electric Monk (Reply #6)
Mon Apr 9, 2012, 01:18 PM
8. When all your racing is done in circles, at comparatively steady speeds....
you don't need the extra gears. And the only relationship NASCAR cars have to their street brethren, is name and approximate sheetmetal profile. |
Response to PavePusher (Reply #8)
Mon Apr 9, 2012, 02:59 PM
10. Nascar has road races at most of it's professional levels
And none of it's venues is a circle. I know of a couple that are close - do you know which ones they are? |
Response to Mopar151 (Reply #10)
Mon Apr 9, 2012, 06:38 PM
13. Sorry, I forgot to make the tone more clear that I was indulging in mild ribbing.
The road races are the best part of NASCAR, I wish they had a lot more of them. |
Response to PavePusher (Reply #13)
Tue Apr 10, 2012, 07:50 AM
16. There is a big secondary market for stock cars in road racing.
Several series for tubeframe, composite body cars (aka pro stocks, super late models) like GT America, also often appear in SCCA GT1 and Super Production. There are a couple series, allied with vintage clubs, that run older Cup cars - some in original livery. And there are enough cars to often make them a standalone race. And quite a few time trial, 'track day', 'open road', hillclimb, etc cars based on stock car stuff, like the Troyer modified in the 'I built the engine' post here. |
Response to Mopar151 (Reply #5)
Mon Jan 7, 2013, 08:07 PM
21. No
Nascar transmission bare to resemblance to any current transmission. They have a striking resemblance to cars of the 60's trannies though. |
Response to crazyrayray (Reply #21)
Tue Jan 8, 2013, 07:54 PM
24. They are as 'stock' as any part of the rest of the car, other than the hood and roof skin.
With rare exception, any current production transmission would fail spectacularly the instant the clutch was dropped at full power in a NASCAR Cup car. |
Response to Electric Monk (Original post)
Mon Apr 9, 2012, 01:34 PM
9. Come on now, they only just this year admitted that fuel injection exists...
...it's not the lowest common denominator of motorsport without reason you know.... |
Response to truebrit71 (Reply #9)
Mon Apr 9, 2012, 03:08 PM
11. Fuel injection is not unknown to NASCAR
Witness this picture of NASCAR Hall of Fame Richie Evans' Lowest common denominator? Can't be the lowest, without Lucas electrics and SU carbs........ |
Response to Mopar151 (Reply #11)
Mon Apr 9, 2012, 04:19 PM
12. Aah yes...Lucas Electronics....
...bringing a new meaning to the phrase 'completely f*cking useless'.... |
Response to truebrit71 (Reply #12)
Mon Apr 9, 2012, 06:44 PM
15. Dude, I feel your pain.
My buddy's Shitfire runs pretty good with a couple Italian carburetors and a spark box made in Texas. The Japanese ND alternator works nice, too. |
Response to Mopar151 (Reply #11)
Mon Apr 9, 2012, 06:41 PM
14. Lucas electrics....
Frequently re-labeled 'Lucas, Prince of Darkness'.... Introduced to them on old Land Rovers while stationed in Britian. Good times.... |
Response to PavePusher (Reply #14)
Sun May 27, 2012, 11:06 AM
19. The 3 position Lucas Switch;
Dim Flicker Off. Why do the British drink warm beer? Because the refrigerators are made by Lucas. |
Response to Mopar151 (Reply #11)
Wed Apr 25, 2012, 10:28 PM
18. Sprint cars and some modifieds have run mechanical FI for years.
Just this year, NASCAR Sprint cup made the change from carbs to EFI. |
Response to Electric Monk (Original post)
Wed Apr 25, 2012, 10:23 PM
17. Nascar V8s have a fairly broad torque range
so they work fine with 4 speeds. Formula1, Indy cars, and Sports prototypes make all their power in the upper RPMs, with a narrow torque band... they need the extra gears to keep RPMs up in the slow corners. |
Response to HooptieWagon (Reply #17)
Thu Jun 11, 2015, 02:06 PM
25. LMP1
You are forgetting they use 6speed transmissions on LMP cars and the past decade have been dominated by diesels with power coming from as low as 2500 rpm with a peak of round 6000-7000 rpm but to + to his answer ? NASCAR doesn't need more gears on ovals but they prove useful on the road courses which brings us to another ? SHOULD NASCAR RUN MORE ROAD COURSES ? personally I think they should but which races to cut from the season ? They have so many great tracks and they've already cut several great tracks from the schedule to accommodate new tracks I'd rather they expanded the number of races in the schedule |
Response to Electric Monk (Original post)
Fri Jun 15, 2012, 01:44 PM
20. $$'s spent wouldn't improve the product
Of which there is less dollars available to NASCAR. A teams funding from a major sponsor being more on par with a F1 co-sponsor. The Nascar driver is also manually throwing the gear shift while in F1 the mechanism is powered. Making the shift take slightly longer and as drag racers discovered. There is a point of diminishing returns when each shift is a few hundred milliseconds of no power. |
Response to One_Life_To_Give (Reply #20)
Mon Jan 7, 2013, 08:11 PM
22. NO
If money wouldn't improve the market explain how the companies continually upgrade their products almost annually. |
Response to crazyrayray (Reply #22)
Tue Jan 8, 2013, 07:36 PM
23. What are you trying to say?
How will adding more gears to the transmission improve the competion in NASCAR racing? please be specific...... |
Response to Electric Monk (Original post)
Tue Aug 11, 2015, 04:28 AM
26. Because that's the way they've always done it
My preference for One Huge Change would be to put a speed-measuring device that doesn't require the engine be running into the cars - they measure pit road speed with their tachometers, which can't work if you're out of fuel. |
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