| Author | Message | ||
| Dave328GTB (Hardtop)
Junior Member Username: Hardtop Post Number: 228 Registered: 1-2002 |
I had to drive a 328 with a broken clutch cable about 40 miles using the method James described for stops. However, you can actually start the car in 2nd which reduces shifting. I recommend to everyone that learning to double clutch and shifting without a clutch is a good thing to learn if you have old cars. However, I would practice on something other than a Ferrari becuase you will grind some meat while learning. Dave | ||
| Richard Stephens (Dino2400)
Junior Member Username: Dino2400 Post Number: 143 Registered: 10-2001 |
Thanks for the no-clutch emergency driving tips. Hopefully I'll never have to find out whether I can master that technique or not! (but since I don't even own a car newer than 1978, more than likely I will have to try it someday, ha!) | ||
| Hans E. Hansen (4re_gt4)
Junior Member Username: 4re_gt4 Post Number: 141 Registered: 4-2002 |
Had a clutch break in a '77 Corvette. One of the springs in the center of the disc broke, and got jammed up. Couldn't disengage the clutch. This happened while I was travelling home with a sailboat in tow. (Yes, you can tow with a Corvette.) Panic. Didn't know what to do. Still had some road ahead, time to think. Let's see..... I should be able to shift, if careful about matching revs. What about stops? Don't know. Easy answer: DON'T STOP! Anyway, what I ended up doing was lagging back in traffic and observing the lights way ahead of me. With careful timing, I was able to drive right into the repair shop door w/o stopping. | ||
| James Selevan (Jselevan)
Junior Member Username: Jselevan Post Number: 107 Registered: 6-2002 |
Richard - I had to drive a Dino 246gt home without a clutch for a friend. He did not trust himself, and I had a great deal of experience on crash boxes. The technic is simple. When first beginning your journey, start the car in neutral and warm the engine. After warm (and therefore easy to start), turn off the engine, get into 1st gear, and start the car in 1st gear. It will role, and perhaps buck just a little, but you will easily achieve 1st gear speed of 5 mph without difficulty. Once rolling along in 1st, you can reduce throttle (NOT LET OFF) to remove load from the drive train. Then "punch" into neutral with a palmer thrust of the gear lever (like that medical term?). Match your revs and go into 3rd gear (not 2nd). If you need more speed, go next into 5th. This minimizes shifting. When you come to a stop light, punch into neutral and TURN THE CAR OFF. Get into first and do it again. Do not try to get into first at a stop light while the engine is running - unless you desire a new transmission. Most of the time you can lay way back distant from the light, rolling in neutral, and time your rev match and shift into 3rd to correspond with the light change, thereby avoiding the stop and engine shut down. Hope this helps. Jim S. | ||
| Richard Stephens (Dino2400)
Junior Member Username: Dino2400 Post Number: 142 Registered: 10-2001 |
I only double-clutch on worn boxes (right now I have one Fiat that I even double clutch on the way up to 2nd). The rest of the time I rev-match on downshifts just because it's fun and more stable should you downshift in a corner or at corner entry. I have been able to shift cars without the clutch before but I've found that it only goes in smoothly when the car has slowed way down to like 2-3000rpm which takes you out of the power band. I can't quite understand this since if engine speed and "layshaft" speed is matched, it should slide into gear regardless of the rpm. Can anyone explain? (btw, i always though that if my clutch cable breaks or something, I could get home without the clutch. But then I realized that I would have problems if I actually had to stop and start again. For those that have "driven a car home without clutch", how did you get going from a dead stop? Jam it in 1st and go for it? ha!) | ||
| Dave328GTB (Hardtop)
Junior Member Username: Hardtop Post Number: 226 Registered: 1-2002 |
Double clutching is most useful in downshifts and speed of the shift is not as important as upshifts in track situations. Double clutching is not done instead of heal toeing as some of you seem to imply. You just blip the throttle when lever is in neutral and clutch is engaged. You still brake and blip simultaneaously. This can be done very quickly though probably not as fast as just jamming it into gear. Since sponsers have not lined up at my door, I think I will do all I can to minimize wear. Dave | ||
| Terry Springer (Tspringer)
Member Username: Tspringer Post Number: 261 Registered: 4-2002 |
Seems some guys are thinking that double clutching will gain you a smoother shift or some other advantage from a performance standpoint. I dont think this is the case. On the track in a modern car, if your using heel and toe and dont mind being a tad forceful on the transmission to shift it very quickly I believe you can obtain as smooth and fast a shift as is possible. Where double clutching is going to help you is in transmission life. That smooth but fast normal shift is taxing the syncros to the max. They will wear out faster. The skilled double clutcher will shift just as fast and smooth (not not more so) and will be putting very little if any wear on the syncros. Thus I justify the effort as being easy on the equipment... though a more honest response is that its just a long standing habit. | ||
| Peter (Bubba)
Junior Member Username: Bubba Post Number: 196 Registered: 5-2002 |
Hans, although I am an idiot mechanically, I can second what you are saying. On my way home after collecting the Mondial (before it died a mile off home due to possible alternator failure), I tried double clutching a few times during the drive. The pause in neutral between gears did seem to make the gear change very smooth and easy, much smoother than straight shifts. | ||
| Hans E. Hansen (4re_gt4)
Junior Member Username: 4re_gt4 Post Number: 138 Registered: 4-2002 |
As a bit of a follow-up, I've been thinking some about the link posted by Wayne. Upon reflecting on previous experience, and a little recent experimentation, I've come to realive that the F-car transaxle has either an exceptionally massive countershaft (and associated meshed gears), or it's mounted in some good bearings. It takes a while to 'spin down' on its own. Try this: Shift from, say, 2nd to 3rd (the actual gear selection is largely irrelevant, just do any upshift). Do it quickly. Notice a bit of a lag, a resistance in the feel of the shifter? Some of that Ferrari notchy-ness? Now, do it again. But this time, pause noticeably in neutral. Complete the shift. It should 'slide in' a little easier. Do it again, pausing more. Will probably slide in easier. In my car, a substantial pause (say around 1 full second, maybe more) gives the smoothest, easiest engagement. Slicker than greased snot, no shifter effort. Just goes immediately into gear. This indicates that the syncros are doing little or no work. You've matched gear speeds yourself, not the syncros. The lesson: With a substantial pause on the upshift, the gear (syncro) speeds match because of the decelerating countershaft ends up matching the next selected gear. If you haven't taken a tranny apart, it might be hard to visualize exactly what I am talking about. The countershaft must be massive, else it would spin down faster, making for a quicker 'no-effort' shift. As this applies to downshifts, the previously mentioned link mentions that under hard vehicle braking, the car may be slowing down at a similar rate as the disconnected countershaft, eliminating the need for a double clutch. This is more likely in the case of a massive, or free-spinning, counershaft. Food for thought. As for me, rightly or wrongly, I'm convinced that double clutching saves a bit of tranny wear. I always do it. I bought the F-car partly because it is fun to shift, and I probably do it way too often. Just my way of enjoying the car. If a double clutch can extend the life of my otherwise overtaxed gearbox, I guess I'll continue doing it. | ||
| Kevin Marcus (Rumordude)
New member Username: Rumordude Post Number: 48 Registered: 9-2001 |
I've been unfortunate enough to experience the rear wheel lockup which actually was kind enough to toss me into a spin around 70 mph (my foot actually missed the blip!) however, I dont see how any of this has anything to do with double clutching -- again my belief is that just doing a normal heel-toe with an attempt as rev matching is all you need... | ||
| Verell Boaen (Verell)
Member Username: Verell Post Number: 299 Registered: 5-2001 |
I double clutch every std. tranny vehicle I'm in. My 1st sports car was a 10 year old Jag XK-150 with the old moss crashbox. You either double clutched, or you didn't downshift from 2nd to 1st while moving. I've tried rev matching & clutchless shifts a few times. I agree w/the school that rev. matching wears the synchros more than double clutching. In a performance situation, I'm not sure which is fastest. I suspect clutchless once you've got it perfect. I usually do clutchless up & down shifts on my Yamaha Radian. Just feels natural on a bike. Guess I started doing it by accident or ignorance on a bike back in college on my Ducati 250. I don't remember anyone teaching me or telling me. | ||
| Steven J. Solomon (Solly)
Member Username: Solly Post Number: 379 Registered: 6-2001 |
Ditto on Lawrence's post. Especially important in road racing if you screwed up and are already in a turn and now need to downshift. If you put any drag on the rear wheels while the car is not pointed straight ahead by forgetting to blip, you are almost guaranteed to go into a spin. | ||
| Lawrence Coppari (Lawrence)
Junior Member Username: Lawrence Post Number: 231 Registered: 4-2002 |
Besides making it easier to get the tranny in the lower gear, matching engine and drive train speeds makes for less braking action of the rear wheels. If you don't match and threshold break with a closely balanced brake bias, you risk having the rear wheels lock up because the engine must pick up speed which essentially is applying more brake torque to rear wheels. Then your friction coefficient goes from static to dynamic (less) and the rear can come around on you. | ||
| Nika (Racernika)
Member Username: Racernika Post Number: 676 Registered: 12-2001 |
I not only double clutch - I certainly match the revs with a good blip when downshifting. (This is where heel/toe comes in)Everyone who has every owned a 308 know that until that baby is warmed up - don't even try to get 2nd gear - I must go first to third for the first littlw while only then is my baby SLEAKER THAN A GREASED CHEETAH!! Just try to do this with HEELS on, guys!!! Just try!!!!!  | ||
| Najib Amanullah (Najib)
Junior Member Username: Najib Post Number: 181 Registered: 4-2001 |
It actually works. I was skeptical at first but today I tried to shift on my Isuzu Trooper without any clutch - after reading the postings on this topic. From second to neutral and up to third.... first a little bit of accelerator (blip) to increase revs and then up to third without using the clutch. I was expecting to hear a CRUNCH but there was none. Just a very smooth shift. Now I BELIEVE. I still do not have the guts to try it with the Ferrari though. | ||
| Kevin Marcus (Rumordude)
New member Username: Rumordude Post Number: 47 Registered: 9-2001 |
IMHO, for road racing (assuming you have a manual tranny and a car with synchros) heel-toe or rev-matching is absolutely the way to go, but it will take a little bit of practice, esp. as you move from car to car. | ||
| Steven J. Solomon (Solly)
Member Username: Solly Post Number: 377 Registered: 6-2001 |
1) Correct double-clutching is done as Pino mentioned, except that once you shift to neutral and let the clutch out you immediately blip the throttle to fairly high rpm. You then clutch in again and shift to the lower gear you were planning on. If you do this correctly and quickly (it takes a lot of practice to get smooth), you will catch the right rpm for the lower gear you are trying to get into as the rpm's fall back down from the height of your blip in neutral. Some practice will show you how high you need to blip the rpm's for any given gear, at any given speed. In general, higher is better, without exceeding redline-gives more time to make the shift. Skip Barber teaches the double clutch as an auditory exercise where you don't even need to look at the tach. They call it "YUUNGH-UH". Basically you nail the accelerator once you are in neutral, and listen for that sound,then you know you have blipped the throttle enough. 2) For road-racing, the fewer gear changes you can make, the better. Each is a chance to screw up with a missed shift. So if speed is the primary concern, and you have a synchronized gearbox, you are better off with just rev-matching (1 shift, blip with clutch depressed) than with double-clutching, which takes 2 separate shifts for each gear change. | ||
| Rikky Alessi (Ralessi)
New member Username: Ralessi Post Number: 11 Registered: 5-2002 |
can anyone answer the question about what is best for road racing? double clutching or rev matching without double clutching or...? thanks | ||
| Andrew Menasce (Amenasce)
Junior Member Username: Amenasce Post Number: 205 Registered: 10-2001 |
What about matching the revs ? Once its in neutral , i revv it a bit , then clutch in , and shift to lower gear , clutch out..No ? | ||
| Mitchell Minh Le (Yelcab1)
Member Username: Yelcab1 Post Number: 343 Registered: 11-2001 |
double clutch every single car I ever had, with or without synchros. It just feels right. | ||
| Dave328GTB (Hardtop)
Junior Member Username: Hardtop Post Number: 221 Registered: 1-2002 |
I learned to double clutch driving 18 wheelers (no syncros) If you can double clutch correctly, you can also drive with no clutch, however this is easier in a truck with many closely spaced gears than in a car. If your car is grinding or crunching, you either have worn syncros or you shift lousy. If the problem is syncros, then double clutching will eliminate the grind/crunch. Otherwise, get lessons. Blipping the throttle helps the clutch by matching pressure plate and disc speeds, but does not affect the gearbox and won't help with worn syncros. Some 5 speed Ferraris, even when new, seem to like double clutch downshifts from 3-2 at high RPM's. Crunching or grinding wears syncros. Anything that stops it extends their life. Dave | ||
| Steve (Steve)
Junior Member Username: Steve Post Number: 202 Registered: 2-2001 |
Boy this discussion brings me back. In the late 60's I use to help my father-in -law who was in construction. We had this old Diamond Reo 10 wheeler dump truck with a crash box 2 sp transmission. You talk about double clutching , wow. I used to have a sore arm after a day with BIG RED (the REO)and moving dirt. I still remember the technique and use it when the 308 is cold and I need to hit 2nd gear. Brings back the old days . | ||
| L. Wayne Ausbrooks (Lwausbrooks)
Junior Member Username: Lwausbrooks Post Number: 237 Registered: 8-2002 |
LOL! :-o | ||
| Hans E. Hansen (4re_gt4)
Junior Member Username: 4re_gt4 Post Number: 130 Registered: 4-2002 |
Rehan: It's sort of like rubbing your tummy and patting your head. About as difficult, and accomplishes the same thing. <g> (The previous post explains it better.) | ||
| Joseph Caretti (Pino)
Junior Member Username: Pino Post Number: 72 Registered: 4-2002 |
clutch in, shift from gear to neutral clutch out, clutch in, shift to next gear clutch out | ||
| Rehan (F3606m)
New member Username: F3606m Post Number: 33 Registered: 4-2002 |
Hate to sound naive but what is double clutching? | ||
| Hans E. Hansen (4re_gt4)
Junior Member Username: 4re_gt4 Post Number: 124 Registered: 4-2002 |
Hugh: Heel-n-toeing won't "save" the gearbox. When you 'blip' during the heel-n-toe, the tranny is already in gear. What you are doing with the throttle at that point is largely irrelevant, gearbox-wise. (Of course, if you are *really* sloppy, you could shock load the gearbox with a rapid clutch release ) Terry: I agree. It became a habit with me after learning to do it with a worn out 'box, and seems to be a habit that I can't break. When I pull off a really good one, the 308 box slides in rapidly and smoothly, w/o the typical 'notchy' feel that these boxes are known for. I do it so quickly these days that my passengers aren't aware of the extra foot action involved. | ||
| Rikky Alessi (Ralessi)
New member Username: Ralessi Post Number: 10 Registered: 5-2002 |
Here is a question I have after reading the emails in the link, here are the cuts from the page -- Push in clutch and brake together - Layshaft equals Third gear speed, coasts down a bit Select Second near end of braking - The car has slowed, layshaft coasts while you are still braking, gears are slowing, no need to hang about in Neutral. No GRAUNCH, the speeds are close and the synchros work. Off brakes and on throttle - Here is where you do the rev matching so that there is no big jerk when you let out the clutch. Let out clutch- It is still well before the (late) apex. Add power - Well, this what you came here for. Go! Mind the attitude and unwind the wheel. ---- This works very well with a streetable car having a normal flywheel and synchros in an autocross situation. The reason it will not work as well in road racing is that the braking time is longer. A light flywheel that allows the engine to rev down faster is not going to help either. Alright, if it is not the best in a road racing situation, then what procedure would be the best? I am probably just not reading it right, but I went over it twice and could not find the answer. | ||
| Terry Springer (Tspringer)
Member Username: Tspringer Post Number: 257 Registered: 4-2002 |
Double clutching in a sycromesh gearbox is indeed not necessary as you can get just as smooth a shift with a proper heel and toe technique. However, double clutching DOES help save the syncros and prolong the life of your gearbox. I believe Wayne has done an excellent job of explaining why this is. I drove a '63 Jag E-type roadster through college and it had the old Moss crashbox. You either double clutched or you didnt downshift (or you trashed the gears). This experience plus lots of other old cars has left me double clutching everything I drive that has a clutch... from the 308 to my Isuzu trooper. I think its possible to actually get a faster shift when double clutching once you are very comfortable with it in a given car. The 308 certainly seems to shift down faster and smoother this way plus I am confident the gearbox will last much longer. | ||
| Robert Jude Klein (Rjklein4470)
Junior Member Username: Rjklein4470 Post Number: 154 Registered: 3-2002 |
The manual says that it double clutch. | ||
| Hubert Otlik (Hugh)
Junior Member Username: Hugh Post Number: 184 Registered: 1-2002 |
Hans: Double clutching using a "working" synchromesh gearbox in a production vehicle is unneccessary; the synchro's are there to smooth out and to line up gears on downshifts, however, if your synchros are begining to go out; double clutching can save you for a little while longer. Personally, I never double clutch, never. I do however, heel and toe downshift on every downshift, and that really saves the gearbox. So, double clutching = not neccessary; heel and toe= neccessary. BTW- what the F1 tranny does on downshifts is "rev-match", not double clutching; it doesn't need to as the synchros take care of that. | ||
| Hans E. Hansen (4re_gt4)
Junior Member Username: 4re_gt4 Post Number: 123 Registered: 4-2002 |
Robert: Does the 360 actually double clutch, or just blip (match) the revs? If it indeed does a double clutch, that would be a point in favor of the technique. | ||
| Robert Jude Klein (Rjklein4470)
Junior Member Username: Rjklein4470 Post Number: 152 Registered: 3-2002 |
Ok I have a question pertaining to this topic. I have a 360 F-1, and in the sport mode it will double clutch. I have noticed that when below about 4k the computer shifts very slow but will still blip the revs, but above 4k it is very fast. Will down shifting at the lower RPM's in the sport mode add ware to the clutch or syncros | ||
| Dr Tommy Cosgrove (Vwalfa4re)
Member Username: Vwalfa4re Post Number: 257 Registered: 5-2001 |
Me too in my Alfa Spider. Have to. I do in the 308 mostly on the track. | ||
| Andrew Menasce (Amenasce)
Junior Member Username: Amenasce Post Number: 201 Registered: 10-2001 |
i double clutch but with my alfa spider ...Only fast way to get from 4th to 3rd and from 3rd to 2nd.. | ||
| Hans E. Hansen (4re_gt4)
Junior Member Username: 4re_gt4 Post Number: 122 Registered: 4-2002 |
Wayne: Previous post was before I saw your link. Where do you find this stuff? Pretty much as I suspected. The part that hadn't occured to me is the idea that while under heavy braking, the car (and gears) may be slowing at a similar rate as the 'layshaft' (as he put it - when I was overhauling trannies, we called it a 'countershaft'). This would, theoretically, make double-clutching irrelevant. Thanks much! My other half just informed me that it is past my bedtime. Nighty-night. | ||
| L. Wayne Ausbrooks (Lwausbrooks)
Junior Member Username: Lwausbrooks Post Number: 222 Registered: 8-2002 |
Hans, did you check that link? It's pretty technical, so here is the part that pretty much covers your question. I think Frere is not very concerned with wear and tear because it sounds like it will definitely save wear on the synchros: Does double-clutching do any good if you have a synchromesh box? Yes, it makes the synchros work less hard than they were designed to, so they will last longer. The synchros will make up for any errors. Can you rev-match the layshaft without double-clutching? Yes. Don't use the clutch at all: Ease the throttle Takes the load out of the system Select Neutral Layshaft equals engine speed Blip throttle Engine and layshaft speed up to Second gear speed Select Second No GRAUNCH if you have the speeds right This works exactly the same in a synchromesh box as a crash box. Since the layshaft is always connected to the engine, synchros will NOT help you. In fact, I think errors in this method can wreak your synchros. Normally, synchros only have to deal with the rotating mass of the layshaft. Now you are asking them to deal with your whole engine. They ain't gonna like it. You have to be perfect. This is what Rick Mears and many other disgustingly able drivers do. I couldn't do it on a bet. Can you rev-match the layshaft to the transmission gears by throttle - blipping with regular single clutching? No. The layshaft is not connected to the engine while the clutch is in. Those that recommend throttle-blipping rev-matching are right that it gives a smooth transition when they let the clutch out, but it does absolutely nothing to match the layshaft and does not save your synchros any work at all. | ||
| Hans E. Hansen (4re_gt4)
Junior Member Username: 4re_gt4 Post Number: 121 Registered: 4-2002 |
Wayne: Very interesting. That's why I started the thread. Frere is certainly worth listening to. FWIW - I've been to a few driving schools, and they seem mixed on the subject. After conflicting info, I was *hoping* for some kind of definitive answer, but I doubt one will be forthcoming. My ultimate goal is to find out what is the best way to treat my expensive syncros! Geez, I'd better get to sleep. | ||
| L. Wayne Ausbrooks (Lwausbrooks)
Junior Member Username: Lwausbrooks Post Number: 221 Registered: 8-2002 |
Hans, check this out: http://www.g-speed.com/pbh/double-clutch.html | ||
| L. Wayne Ausbrooks (Lwausbrooks)
Junior Member Username: Lwausbrooks Post Number: 219 Registered: 8-2002 |
My PC at home is located in my personal little automotive library. The walls are lined with bookshelves full of books covering just about every automotive topic and from time to time I will pull something off the shelf to help answer questions that arise on F-chat. This thing about double de-clutching got me to wondering so I scanned the shelves and found "Sports Car and Competition Driving" by racing legend Paul Frere. Frere has an entire section on changing gear and says (I'm paraprasing because he actually takes a page and a half to say this) that in older cars and many racing cars without synchros, "double de-clutching" is still a must but with modern sychroed road cars, it is usually done only to allow time to blip the throttle in between clutching in order to match revs. For whatever that's worth. | ||
| Hans E. Hansen (4re_gt4)
Junior Member Username: 4re_gt4 Post Number: 120 Registered: 4-2002 |
Wayne: There are two issues here. 1) Matching gear-to-gear speed. 2) Matching engine-to-gear speed. The syncros will do #1, but double clutching will make the speed match closer, *hopefully* reducing the wear-and-tear on the syncros. Blipping the throttle, with or w/o double clutching, reduces clutch wear - as well as minimizing scary engine braking effects when turning into a corner! | ||
| L. Wayne Ausbrooks (Lwausbrooks)
Junior Member Username: Lwausbrooks Post Number: 218 Registered: 8-2002 |
James, I don't understand. I always blip the throttle to match revs before letting the clutch out. It leads to very smooth downshifts that wouldn't break your heart. I don't understand the reasoning behind double clutching (actually, "double de-clutching") on a car with synchros. | ||
| James Selevan (Jselevan)
Junior Member Username: Jselevan Post Number: 98 Registered: 6-2002 |
I learned to drive in a Austin Healy bug-eye crash box (should I admit that it was new?). No synchromesh. Drove it for 10 years. Proper double clutching will reduce wear on clutch AND synchronizers. By matching gearbox speed and engine speed one removes the drag on the synchros. On the rare occasion that you do not have a clutch (e.g., broken clutch cable), the only way to proceed is proper double clutching. When down shifting, it breaks my heart to watch someone simply shift to a lower gear and let the clutch up. It's like finger nails on the black board. However, if wear and tear and cost is the issue, don't down shift. Use the brakes. They're good enough and a lot less expensive to change that a clutch or synchronizers. Jim S. | ||
| Hans E. Hansen (4re_gt4)
Junior Member Username: 4re_gt4 Post Number: 116 Registered: 4-2002 |
Interesting. Did they explain why it would wear out the syncros? | ||
| Arnaldo Torres (Caribe)
Member Username: Caribe Post Number: 408 Registered: 2-2001 |
I use to double clutch my TR until I was told it wears out the synchros faster. Replacing a clutch is a lot cheaper and easier to do than replacing the synchros. | ||
| Hans E. Hansen (4re_gt4)
Junior Member Username: 4re_gt4 Post Number: 114 Registered: 4-2002 |
As a youth, I had a Corvette with worn syncros. I had to learn to double clutch the downshifts, as it was the only way to get it into a lower gear. I still do it. In the Ferrari, I wonder what it does to the linkage, but I digress. How many of you do this, and do you have any credible evidence as to positive/negative wear characteristics on the clutch/gearbox? |