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  1. #1
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    Default Stopping in snow and tranny explosions (extremely long)

    I just wanted to reply AirMoore here wtihout hijacking the computersoc's thread NYS Thruway any further

    Quote Originally Posted by AirMoore
    First off I had a complete response typed out and it explain everything I said in detail and I an really *beep* pissed this website for some reason (even with message sent confirmation) it never appeared so this has mispellings problems etc etc: Here is the jist of it all:

    I believe you are misunderstanding me as most of your post has very little to do with what I was reffering to.

    (Again I am going to be short w/this it will seem very hostile (but its not meant to be) because I took about 10minutes to type a response and it didnt show up...so I punched a hole in the wall (that I now have to fix and i have something in my eye from it)
    :shock: Oh my Goodness! I'm sorry if my post provoked you so much, I hope it's nothing serious ops: :roll:
    Although if what you replied here is what you consider short, I can imagine why the website didn't like your original one :wink:

    Quote Originally Posted by AirMoore
    Ok, the failures in a drivetrain work like this: first the tires slip, if they have great traction, the clutch slips, if you've got a great performance tripple plate clutch the engine will stall, and if you've got a 500 hp engine and you are redlining it, then you can expect the gears to take damage.
    This has nothing to do with what I was refering to...I think you are just making this as a statement (rather then a response) to say that the tranny would be the last thing to go in a DTS, which is correct...but my post kind of already said that (I stated other DTS components would fail).
    I believe it's got a lot to do with what you were refering to, specifically the part where you are talking about transmission explosion. I was just trying to clarify what conditions would have to be fullfiled inorder for a tranny to explode. I would also like to add that for a tranny to explode you would really need a tremendous amount of force, such as en engine producing a 1000 or more hp, a set of huge slich tires and a drag racing style cluch.
    And yes, if by "other DTS componet failure" you mean tires or clutch slipping (which are the first parts to "fail"), you are proving my point

    Quote Originally Posted by AirMoore
    What you are saying is like: (maybe you've seen it before) a car is driving up a steep slippery road covered in snow and suddenly starts slipping and sliding downhill faster and faster even though the wheels are spinning forward and driver is reving the engine. According to you, anyone near by should be ducking for cover in expectation so see flywheel and gears flying through the air. Thats why the clutch is designed as two flat discs sliding against each other and not gears that positivelly lock up <- it must be able to slip, so the parts wouldn't brake. The energy has to go somewhere and in such case it would turn into heat between plates in the clutch.
    This analogy has nothing to do with what I was talking about. I believe you misunderstood me (what you described also doesnt shock the DTS is is constant pressure...a shock will do more damage)... (I dnk what you are trying to refer this to) because nothing you quoted refers to any of this...nor none of my post. (Again maybe you misread/misunderstood it.)
    Again I don't think I misunderstood you, maybe I wasn't precise enough in my analogy, and I apologize for that. I wanted to describe the situation where the car is being driven up the hill on a snowed in road and it starts to slide downhills. First the driver is, naturally, try to brake, the car keeps sliding so he let's go of the brake (at that point wheels start rolling backwards) and then he releases the clutch and applies the throttle (at which point the wheels quickly start sppining forward). I didn't stress this before becouse I didn't know what is the exact reason why you thought the gearbox would fail (and that makes this less than precise analogy anyway, as in this case wheels going in one direction at 60 mph and then moving in the other 10 - 20, while in analogy it's the other way around). What seems to be bothering you here, as much as I can understand, is wheels turning in one direction and then suddenly in the opposite direction. The friction between tire and snow deppends on the tires of course (size, thread pattern, compound, all season or winter....) as well as the surface, but assuming that you've already started losing control, means that the friction coefficient is low. And as you say the constant pressure is not the problem, but the shock is, I drew the conclusion as stated above. If that is so, you could expect the gearbox to explode/fail in the situation like when you have car jacked up, wheels spinning freely, start the engine and spinn the wheels to a velocity equivalent of 60 mph then shift in reverse and heve them spinning in the opposite direction instantly. And what is another thing that, I'm sure, is making you judge this methode like you did is what I said about releasing the clutch in my first post and agiain I appologize if it gave anyone wrong ideas. What I assumed that person driving a car equiped with a manual knows how to operate the clutch and wouldn't take the word "dump" literally. I wanted to say clutch needs to be released fast and not just "dumped" like if you move your foot of a fully depressed pedal to the left and let it "pop" back into position or something similar. On a manual car amount of stress applied to the drivetrain is proportional to drivers skill in operating it (particularly the cluch) and if he/she has basic knowledge and a little practise they shoud be able to do this without cousing any significant stress on th drivetrain. Clutch is expendable part of the car that wears out just like the brake pads (which are made of a very similar material) and is meant to be controllably slipped by drivers, I'm sure that anyone who knows how to drive a manual is aware of that, at least subconsciously, becouse they have to do it every day. And iven if a driver dumped the clutch violently, chances that the gearbox fails are relatively low, and it would take many of such stunts to destroy it.

    Quote Originally Posted by AirMoore
    (The part you quoted for that was a part that I refered to from a post you made a where #2 exclaimed things about drivers school cars)
    You stated you talked to drivers school instrcutors and they have the stop tranny in them even after much abuse....but as I said the tranny doesnt get much if any abuse from the things you exclaimed...other parts of the car do Examples:

    You said: People shift w/o clutch: This would have an impact on the tranny but not a big one...the dogteeth would wear down..so of course the cars can kleep their stock tranny as the dogteeth are there...if they werent (pre dogteeth) the tranny would have had some major problems...but now to create the mesh the dogteeth save a lot of problems...thats why you wear the grrrrrinndddd when people shift improperly its the dogteeth saving car parts. (so again the tranny is essentially saved...other parts take the beating henceforth stock tranny still ok)

    You said: Release the clutch early and miss the gear...this does very little to the DTS and nearly nothing to the tranny..but as I said the engine would get worn down...because the RPMS skyrocket and the engine parts 'stretch and wear' easy under conditions of no loads and high RPMS...they are meant to have a pressure/load upon them. (So again the engine would take the hit...not the tranny so the stock tranny would still be ok)

    I took noticed with the whole 80mph downshift into first gear. As this would hurt the tranny....slamming a car down into 1st gear at 80mph would create a problem for the whole DTS. Granted the tranny would eb the last thing to go because again the rest of the DTS is made to fail and bleed off shock and energy before you get into the 'big spenders' like the tranny. So would the tranny blow up like the Imperial Death Star?...No...would the DTS have major failures (probably) would the tranny explode...probably not....again alot of the rest of the DTS is made to save it....but would it probably hurt the tranny somewhat? yes it would sure not be beneficial.
    Ok, I mentioned the driving school to stress how much combined abuse is transmission able to withstand and that is real: at least a dozen students goes "through" each car, averaging 30 hours, and overall such incidents happen 3 - 4 times an hour (on average again) and include all of the above and many more like releasing the clutch to early, before teath gave completely engaged, and yes it happens often that a student shifts in a first gear by mistake while driving at various speeds including high speeds like 60 - 80 mph. It may not happen every day but it certainly does.
    Now about engine wear, I don't believe that you are damaging the engine significantly as you are trying to clame. Engine is certainly built strong enough to take abuse of stalling as well as skyrocketing the rpm's and in fact all driving students here are tought to brake car with the engine instead with breakes whenever posible by downshifting. Of course it's not recomended to shift in first gear while doing 80 or so (not trying to say that it's not bad for the engine to do thi but I still believe clutch and tranny would take more stress from this than the engine) , but I can say that I haven't heard of engine failure becouse of it, and cars in driving schools here literally take that kind of abuse dozens of times every year.

    Quote Originally Posted by AirMoore
    Granted the tranny would eb the last thing to go because again the rest of the DTS is made to fail and bleed off shock and energy before you get into the 'big spenders' like the tranny. So would the tranny blow up like the Imperial Death Star?...No...would the DTS have major failures (probably) would the tranny explode...probably not....again alot of the rest of the DTS is made to save it....but would it probably hurt the tranny somewhat? yes it would sure not be beneficial.
    And again thanks for proving my point , thats pretty much what I said in the first place: tranny wouldn't explode or fail instantly, and the tires and the clutch would be first to "fail" and bleed off energy. As for major failures, unless you are stuck with a very poor tranny or one just about to fail, you would need to pull this stopping procedure hundreds or thousands (if you are using the clutch properly and slip it manually to reduce the shock) of times before the tranny would fail.
    And please read my post thoroughly, I never said this was actually beneficiall for the tranny. :idea:

    Quote Originally Posted by AirMoore
    I never refered to it causing stress in what you quoted...I refered to the extra stress previously and assume thats what you are commenting on...and in that case you would be correct. I understand you really only do this after you have a loss of control....but it still shouldnt be done...the proper use of downshifting and braking should help you (re)gain some traction as you first countermeasures...

    If all is lost there is a better way to do what you do. (It is more effective and safer for the experienced driver and the car.)

    NOTE Niether what you said (nor what I am about to say) should ever be attempted by anyone(disclaimer)...especially someone who is not an experienced driver (this means an experienced driver as in having highly developed skills in the area of accident avoidal and evasive manueavuring...not just having been a driver for a long time).

    WHAT you can do is the following... Instead of shocking you DTS by dropping the clutch into reverse...(I have a friend who swears when all is lost that what you do is the most effective way to stop...and he is pretty good at it so I have seen it done)...............
    ...........
    ...........
    So now you say you are familiar with this and you've already seen it done by your friend?? And he is good at it, meaning he's got a lot of practise?? I take the transmission didn't explode or fail every time he tried it :wink: Or even after many attempts :? Doesn't that defeat your own point? I'm aware you admitted of exagerating in your last post, but I dont know how much. Did you, by exageration, mean that tranny would explode but the bellhousing/transmission shield prevented gears from flying through the cockpit windows/hood, or that meybe you would have just squirmed in your seat expecting an explosion but nothing happened? :? :?

    Anyway if you think you have a better method you should have just said so insted of attacking mine, especially if you've already seen that mine works, and we could heve been discussing the differences, but I'll leave that for later, this post is getting awfully long already. :roll:

    Quote Originally Posted by AirMoore
    Anycase I think 'Nothegger' that we are just misunderstanding each other here...I think we both have extensive knowledge into the matter and are pretty much talking about two different things, but the same thing all in all. I say tomato you say tamato...but we are still talking about that little red thing in the garden....Here you are talking about the tranny obviously not going to blow and the DTS is very solid and can handle its fair sahre of abuse...Well I am saying it can handle its fair share of abuse...but remember in the end one part or another of the DTS (or car in general will end up costing you money even if it isnt the tranny persay).
    I can say I agree with you here, my points were (as can be seen from my previous posts in the other thread) is that it would take A LOT of such abuse to significantly reduce the lifespan of your tranny AND as your friend says this is something to do when "all is lost", and it's pretty unbelievable that you would loose control of your car and stop this way hunderds of times, how much would take to damage the drivetrain would. And even if that is exactly what happened, I thing a price of a new tranny is negligable compared what you'd be paying if you crashed your car a hundred times :wink: :wink:

    In the end I just want to apologize for such a long post(s), I didn't mean to write any more than my original post but as others was getting in depth and technical, I had to try to clear things up a little. Hope noone is offended, we are all on the same side here :wink:

  2. #2

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    I have a question..why do you teach the students to downshift without using the brakes? I can understand downhills etc. but at every red light you are putting costly wear on the clutch. It is easier and not to mention cheaper to put the car in neutral close to light and use the brakes. I got 175,000 miles on my car with the original clutch and it may still be going (sold it). Plus my brakes lasted long as well. Down grades I agree downshifting is the best way so you don't overheat brakes. my two cents...

    Ryan

  3. #3
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    Quote Originally Posted by Ryanistheroad
    I have a question..why do you teach the students to downshift without using the brakes? I can understand downhills etc. but at every red light you are putting costly wear on the clutch. It is easier and not to mention cheaper to put the car in neutral close to light and use the brakes. I got 175,000 miles on my car with the original clutch and it may still be going (sold it). Plus my brakes lasted long as well. Down grades I agree downshifting is the best way so you don't overheat brakes. my two cents...

    Ryan
    thats a good question. im with you, when ever i drive a stick, ill always put it in neutral, unless i know the lights going to change soon.

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    The big issue with putting the car in neutral while it is in motion is you now have no power. So if something changes and you need to MOVE you have to rev the motor up to the speed to match a gear that you need to engage. Of course, you could have a Honda and then all you need to do is push in the clutch and snick the gear lever into the gear...

    I am always in neutral when coming up to a light. When the light goes yellow on the other end, I normally wait 1/2 sec, clutch in, 1st gear, and just as it goes green I slip the clutch, foot off brake, foot on gas. No stinking handbrake on hills stuff

    On an [old style] Saab 900 Turbo you have to be careful accelerating on snow because if you get a lot of wheelspin and the tires suddenly grab on asphalt you can crack the gearcase

  5. #5
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    Quote Originally Posted by Ryanistheroad
    I have a question..why do you teach the students to downshift without using the brakes? I can understand downhills etc. but at every red light you are putting costly wear on the clutch. It is easier and not to mention cheaper to put the car in neutral close to light and use the brakes. I got 175,000 miles on my car with the original clutch and it may still be going (sold it). Plus my brakes lasted long as well. Down grades I agree downshifting is the best way so you don't overheat brakes. my two cents...

    Ryan
    I'm not instructor myself, but I know few people who are. Without getting too technical, I think it's better to downshift because:

    1) Brakes wear a lot faster than the clutch. Material is basicly the same, however the cluch is engaged 99+% of the time, and if it's opereated properly very little slip occurs when you actually use it -> very little wear.
    On the other hand brakes 'slip' (brake pad slides agaist rotor) every time you brake, and they continue to wear until the car stops, or driver releases the pedal. Not to mention brakes are operated more often, and the pressure applied to the brake pads is much greater then the pressure in the clutch (the clutch plates have much larger surface, and driver is gently releasing the pedal, while he often stomps on the brakes hard and couses a lot more wear, especially if the car is equiped with power brakes)
    So basicaly, you can reduce wear of your brakes without noticably increasing wear of other components.

    2) It's bad idea to put the car into neutral while driving or the car is moving, not just because you might need to move quickly but also it is known that the car which is putting power to the wheels has better traction and more control than the one that is just rolling down the road

  6. #6
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    there was a kid at school that thought his 8?' crx was the ****. I think he had it boosted to a whopping 2 psi with a fiber hood and body kit (primer of course, must reduce weight). Anyways, he thought it was real fast ****, and he was wraping it out, and went from 3rd gear topped out to second and blew a piston through the block. I dont know if that was true, but my friend told me and his car was gone for a while and they were friends. After thinking about driving my car, I slip the clutch depending on how much power I need, but I am 80% nice and easy on it, and it always has its tuneups on time and done right (25+ years exp father). Anyways, I rarely use the brakes, except to stop really quick in combo with downshifting, and to hold the car at a stop. so my brakes 1 year after I changed them show about 80-85% life left. Thats pretty good in my book, and I did some buck+ speeds to 45/0mph before.


    P.S. My father told me to downshift because the manual transmission is MUCH stronger than an auto and the brakes, it wears the reverse side of the clutch, so realistically it wont wear out faster if you downshift ontop of normal shifting, it will wear out normally with the rest of the car.

  7. #7

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    As far as wearing out brakes out.... they are cheap compared with wearing out a clutch from unnessary downshifting especially coming to a redlight.. Lot of people go from 5 gear to 1 which day in and day does put lots of wear on the clutch.. especially in city driving. Plus you have to hold in the clutch. You can just go to neutral and apply brakes gently. When the light does turn green throw it into first or choose the right gear if the light changes while still moving..i.e. 3 gear etc.. depends on speed.

    I do agree to downshift for more power to pass and coming downhills where brakes can easily overheat.

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    Quote Originally Posted by Ryanistheroad
    As far as wearing out brakes out.... they are cheap compared with wearing out a clutch from unnessary downshifting especially coming to a redlight.. Lot of people go from 5 gear to 1 which day in and day does put lots of wear on the clutch.. especially in city driving. Plus you have to hold in the clutch. You can just go to neutral and apply brakes gently. When the light does turn green throw it into first or choose the right gear if the light changes while still moving..i.e. 3 gear etc.. depends on speed.

    I do agree to downshift for more power to pass and coming downhills where brakes can easily overheat.
    Cheap? What car are you driving? For Chevrolet impala decent brake pad set is about 50 - 70$ + a set of cheap rotors 220$. Clutch disk is 75$.
    Ford Explorer: cheap pad set is 40$, rotors 440$, clutch disk 100$ etc....

    As I said brakes wear out MUCH faster, and if the clutch is properly operated increase in wear is NEGLIGIBLE. You'll certainly run 4-5 rotors and 10 - 15 brake pad sets before needing clutch replacement.

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    Clutch is cheap when you got an old Saab, to change the clutch takes about 45 minutes if you have experience and the spacer tool Transmission underneath the engine, clutch right behind the radiator.

  10. #10
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    Firstly, if you are doing your downshifting correctly, then there is virtually no wear on the clutch. Reason? You're rev-matching to the next gear. Not everyone does this.. but for example, if you are in 3rd gear at 6000rpms, you wait till it drops to 3000rpms, shift into 2nd, and while the clutch is still in, blip the throttle to about 5-6000rpms and engage. If done correctly, virtually no clutch wear occurs.

    Clutch wear REALLY occurs when you use it to rev-match... so the clutch has to slip to rev the tire speed to the engine speed (or else other things break...).

    So if you want to balance out brake and clutch wear, then heel toe brake. It is the ONLY way to do it if you drive fast anyway like on Auto-X or track.

 

 

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