I do believe Ron Zitza still does the double clutch thing. And yes I grew up driving old farm trucks with no synchro's.

Peter

 

I'll ask him! He and I have taught school together for eight or ten years and we use some of his videos. Have not seen that on his videos. And we haven't talked about that in class (or out). But I'll ask!

Double declutching does take time. A LOT of time, especially when there are more pressing things, like slowing down FAST.

 

We do know Ron is FAST. Randy who has Ron maintain his car and sometime co-drive in Enduro's was the one who told me. Might be something with the 915 box.

Peter

 

How does this magic happen if you don't double clutch? The synchros start doing their job AFTER the clutch is depressed and have finished their job BEFORE the clutch is let out.

How can what the engine is doing while the clutch is depressed have anything to do with what is going on in the transmission during the shift?

Come on Mark, think here a little bit.....

 

What's the over/under on how many pages
It takes till someone gets banned?

 

its funny... I quote an expert in transmissions on this sub-topic, (based on someone using an analogy for the brake problem) and he says, Kaib is absolutely wrong. However, i look at what has been said and now am questioning him as well. I get the point of the synchros doing most of the work, because the engine is out of the equation..... but do i go blast him and tell him he is an idiot???? he might even have an answer , so i ask, not insult.

anyway, see my responses below.

i know the first thing that goes is the dogring, but if that doesnt work, i thought you get gear to gear wear, chipping, etc. thats it, im pulling the cover of the transmission in the garage and start spinning things.

again..... classless

you are missing the point of real performance driving if you think that. did you know i was able to run a 1:45 at laguna with out even using brakes?? this is faster than VR has ever driven there. . I did it by big downshifts , and used compression braking as my decel force as well as inducing a huge push to slow the car near the end by sacrificing the front tires. i have video of it, if you want to see. (complete brake failure, due to front brake line exploding)
no off track, like VR. just had to start the slow down process earlier, and use the gears! (and not panic..... like VR)
plus, its like having ABS in the rear (if you dont have it), it adds to the rear brake bias by the negative force it provides, and keeps the rears from locking up. )


again..... never adding value, and not really aware what is going on or what is being said!

stick around!

If you have spent time on clutches as i have, and seen a dragging clutch. when the clutch is pushed in , you might still have a slight engagement due to the discs barely touching each other. not enough to effect a shift, but enough to spin up the driveline. this could be part of it. as soon as you push in the clutch, say not all the way to the floor, you disengage the engine from tranny, and blip the gas. the driveline is spun up too due to some friction still in the clutch pack., which lessens the load on the synchros which dont have to do as much work to spin up the driveline..... this all happens as you go through neutral.
again, try and downshift into 1st from 2nd 40mph, with the engine off, and see how that works for you. should be no problem , right..... it will be based on what im talking about. then try and do the same 40mph downshift in to 1st by reveing the engine to 5k and then shift.......... you will see what im talking about.
all double clutching does is spin up the driveline with authority to engine speed, as you release the clutch while in neutral. and then again after you have finished the gear selection.

again.... its a discussion.... have some class and add some value or not post. its that simple.

 

of course i always provide educational videos here: not to disappoint...

double clutching, not only a car but the car in question here.

enjoy. yes, some still double clutch thinking they will help transmission issues. usually, with modern transmissions and the things i talk about , its not needed.

Senna has nothing on this guy! Heck, he is working twice as hard!

 

Mark, you are hopeless.

The gears are always meshed......so there is no grinding between the gears when shifting.

Your are all wet on the synchro deal.....a dragging clutch is a problem to be fixed.

I am really done now. You do need professional help.

 

Peter, I honestly think you should include this quote in your sig line!

 

If you try to simply depress the clutch, and slide the lever into 1st going 40mph, your car is going to give you a big old hellllll no. If you depress the clutch, blip the throttle, and try to slide it into first, same result. Depending how fresh your gearbox is, you may get it to slide in, but your synchros are going to be Really unhappy. I'd wager with an older car with tired synchros you either cant force it into gear, or get a nice loud dog gear Grunch if you do.

If you let the clutch out in neutral first, give it a health rev, it will go in without protest (if your rev is correct, yadda yadda.)

 

If you are just joing the discussion, and an effort to get the discussion back on topic, I started this discussion to find a problem that I have at one particular braking zone at one particular track. It started with the 10mph gained by a 15% HP increase getting my car to 130mph down the main straight of laguna. with no other issues anywhere on the track, and no soft pedal ever, I have fade in the last 2 seconds of a 4 second braking zone from 130mph to 50-60mph..... Ive also done a cool down lap before i hit the straight and braking zone, with no change in outcome. Its a serious fade, that allows me to use tremendous foot pressure on the pedal, with no ability to slow the car down as it should, (to the limit of the tire). once there is even a momentary release, braking force is restored. ( but this isnt an option to get expected braking performance).

Im going to add cooling. (currently, just deflective air plates and routing.) I dont think that will work based on my tests, but am trying anyway. it doesnt seem that there would enough air flow to take the amount of heat out of the rotor and pad in such a short time to help, even if it was flowing better in the 2 seconds prior to the fade problem (fade only occurs in the last 2 out of 4 threshold braking time). I do like the "heat bucket" analogy that was brought up in the discussion. maybe it will do the trick. none the less, i am going to try it.

Rear Bias increase has been brought up, and will double rear brake forces, but again, dont think there is enough force to slow the car to point where this would eliminate the problem. if you think about it, i have 2 seconds out of 4 where the KE (heat) is just to high for the pads and rotor to deal with. I dont think bias can take that much distance out of the decel, to make an impact. but will try as well. also, many here are 911 guys with a rear weight balance, that allows for a lot more rear bias. its all about weight transfer. if you get an 80% weight transfer on a 3000lb car, one with 56/44% weight front to rear, vs a 911 with 40/60% front to rear, this is a huge reduction (comparatively) of force being able to be put on the front braking system. (all other things being equal)

Someone suggested lightening the car, but that is fundamentally not a way to achieve any heat or energy relief on the braking system, due to the equation we have been through in this discussion. Its already been agreed that 10% weight reduction to a 3000lb car would increase speed in cornering exit as well as down the main straight, AND if that increase was 5.3% greater than prior speed, the SAME KE would exist. (in other words, there would be no gain in braking heat dissipation)
-- as a side note, the simulators point to a 4% increase in speed is possible for a 7% decrease in mass. aero is included in this simulator. By the way, the laguna seca front straight has a downhill portion at the end that would probably counteract any aero decel forces. Other forces not considered, are engine compression forces and rolling friction on decel. you disagree... show your work as Mike did.
also, in an other discussion, someone posted how a 20degree temp change on a track day, gave him 6mph greater top end speeds, (5-10hp diff net due to air density, generally) BUT, when i say that 200lbs lighter (which is like a 20hp diff). and i figure 5mph increase in speed at lagunas main straight, i get blasted by the same people as being far fetched. this group is quite funny!

So, I have tried to discuss the topic, but the ignorant or arrogant (or impatient causing an inability to be able to read entire paragraphs before forming retorts) , proved to be too much for the discussion, because god help us if someone does have a unique situation, or a different way of looking at a variation of a popular problem.

In the end, i have some good information by those that did take the high road. I have a test plan the next time out and will report with the data of rotor temps, in the hot pits, after cool laps, after hot laps, and see we can see what can solve the issue.
in the end..... i might just do all of the things suggested , but try a pad that has the temp rating needed for the fade in this narrow section of track. XP20s by carbotech have been suggested. otherwise, the larger rotors are next... to give 15% more leverage, 15% more mass, 15% more surface area to allow 15% less pedal pressure for the same braking force. its the easy solution, but this discussion is good to find the easiest way to correct the issue and nail down the problem causes.


BY THE WAY I had thoughts: Related to discussion about rear brake bias:

3000lb car 56/44% front to rear vs 40/60% 911 braking comparison.

50/50 during a 2g slow down, there is near an 80% weight transfer.
1500 F to 1500 R goes to 2400lbs front 600lbs rear

Front engined 928: 56/44% (1680/1320lbs) under braking goes to 2580 front to 420lbs rear

911: 40/60%( 1200/1800lbs) under braking goes to 2100lbs front, 900lbs rear.

Check my work here, as I dont have the equations handy to calculate, but it seems like if this is true, the front engined car has 23% more weight up front and the 911 has 114% more weight in the rear under decel. (over 2 times the weight!) or another way of looking at it, is the 911 has 19% less weight up front, and the front engine'd car has 54% less weight in the rear. If this is correct, its no wonder you want a lot less bias in the rear on a front engined car (for the same at limit braking force) and its no wonder that the rear engine'd car is MUCH easier on brakes up front, given the same braking system size and capabilities.

 

again.... value??

well, thats the issue. ive done it a 1000 times. not reving the engine before a 1st gear shift at 40mph, (which has a redline of 55mph by the way) , so ive done it at a faster speed, (i was using 911 speeds for ya), gives you a grind, beyond comprehension. But, bliping the throttle, gives a smooth shift. why??
my last video shows a mistake i made during the race into turn 11, i forgot to blip, and it made a grind as it went in. with the blip, no issues at all goes right in...... why???

ive also driven a car with shot synchros. (i have this video too.) if you get the revs right, it shifts well, get it wrong and those synchros scream at you
Im have to look, but i think you might be right. so all that grinding is the poor synchros. you see..... you just added some value..... i think many still think if the synchros are gone, you get gear grinding, but you have added some knowledge here. i probably should know this, but never spent the time to think about it. what if you dont have sychros like the old cars?

 

Caution: No value statement follows!!!

Yep, this time I'm really done.

 

Worn synchros simply don't get the shafts spinning at the the same rate by the time your shift lever passes through neutral and the dog gears are either going too fast or two slow for the next selected gear. Crunch.

You can shift up the gearbox with worn synchros without a problem, but down the gearbox is another story.

Case in point, you can drive an H pattern gearbox clutchless. You just have to be patient on upshifts and rev in neutral to match gearbox shaft revs on downshifts (the job of synchros ordinarilly). No rev, you will never get into gear.

 

somone posted this , after the experts stared to discuss this topic. to my point:

art of this also can depend on how the clutch is used. Is the clutch being fully depressed to the point where there is absolutely no interaction between the flywheel / pressure plate combination and the clutch disk? If so then the syncro probably is doing all of the work when downshifting. If the clutch is only being depressed far enough to remove the majority of the friction, but not enough to completely separate all the clutch components and prevent all energy transfer, then rev-matching would probably have a tangible impact on syncro wear and shifting. Depending on how a specific combination of clutch parts actually fit together and are adjusted, there may end up being some amount of energy transfer regardless of how the clutch pedal is depressed.
i think this is happening in most clean downshifts.


yep, i agree. decelerating friction doing the work on upshifts, so not an issue.....but , im thinking residual friction of the clutch and engine/driveline, that is enough to spin things up, but not enough to effect gear change and selection.

but you do have such value here, until you dont!