ASK THE COACH
#92
Rennlist Member
Sounds like you might know what the problem is, based on GBox's Stan's suggestion, its the synchros.
There are ways to relieve some pressure on them and make them last longer should you rebuld. some of those ideas Ive posted. the main thing is to understnad the cause.
one of the posts deleted, was a point about why 1st gear was now notchy. as I mentioned, its because a lot of folks, reve the engine up, and put the clutch in and put the car into 1st. the is a huge force on the sychros to have to stop the entire mass of the drive shaft, layshaft and gears along with the clutch discs. since 1st is a very active gear in the paddock and certainly on the street, and this force is fairly substantial, it will wear the synchos. to prevent, wait a second or two to put the gear shft in 1st after the clutch is depressed. sometimes , i use 5th to stop the drivetrain before i stick it into 1st.
The other thing to keep in mind is that the 997 has a history of weak synchros and based on the materials used steel or carbon, depending on the gear, it will wear and could have problems if you dont take precautions during shifts.
The borg warner style synchros, although more durable, can be a "wall" if the rpm is not match correctly. old style gear boxes dont behave like this. Its part of the design. but, there is no substitute for good gear maching and timely clutching, as well as delaying the shift points to slower speed in the final gear to be selected on a downshift.
There are ways to relieve some pressure on them and make them last longer should you rebuld. some of those ideas Ive posted. the main thing is to understnad the cause.
one of the posts deleted, was a point about why 1st gear was now notchy. as I mentioned, its because a lot of folks, reve the engine up, and put the clutch in and put the car into 1st. the is a huge force on the sychros to have to stop the entire mass of the drive shaft, layshaft and gears along with the clutch discs. since 1st is a very active gear in the paddock and certainly on the street, and this force is fairly substantial, it will wear the synchos. to prevent, wait a second or two to put the gear shft in 1st after the clutch is depressed. sometimes , i use 5th to stop the drivetrain before i stick it into 1st.
The other thing to keep in mind is that the 997 has a history of weak synchros and based on the materials used steel or carbon, depending on the gear, it will wear and could have problems if you dont take precautions during shifts.
The borg warner style synchros, although more durable, can be a "wall" if the rpm is not match correctly. old style gear boxes dont behave like this. Its part of the design. but, there is no substitute for good gear maching and timely clutching, as well as delaying the shift points to slower speed in the final gear to be selected on a downshift.
Save the synchros (my new motto).
Had a great conversation with Stan Richardson of GBox (who really impresses me with his ability to communicate technical information to this former liberal arts student).
The transmission is in good shape except for worn out 3rd and 4th synchros and a toasted 1st synchro (interesting as its just a starting gear). Rest of the transmission is good.
The dog rings are a bit off (the cone taper isn't quite right, so its not engaging completely).
Looks like we will stay with the same ratios and work with tire diameter. I'll post about that later.
Had a great conversation with Stan Richardson of GBox (who really impresses me with his ability to communicate technical information to this former liberal arts student).
The transmission is in good shape except for worn out 3rd and 4th synchros and a toasted 1st synchro (interesting as its just a starting gear). Rest of the transmission is good.
The dog rings are a bit off (the cone taper isn't quite right, so its not engaging completely).
Looks like we will stay with the same ratios and work with tire diameter. I'll post about that later.
is it ctitical to do full pedal travel during double clutch or is it enough just to 'jerk' it back quickly down to usual point where clutch engages and push it full down again? or is it critical to allow it to travel all the way back? that is kinda slow.
I have issues with 2nd gear engaging at downshifting from third, imho issue always was there if I am threshold braking from about of redline on 3rd into mid-range of 2nd gear.
if braking is not that hard there are no issues usually, it goes in fine. when it does not go it feels like I hit a solid metal wall there, it simply does not go at all, like I am pressing something into a metal plate. not sure what is the cultrip - worn clutch, syncros or engine mounts but it looks like double clutch helps a little bit.
I have issues with 2nd gear engaging at downshifting from third, imho issue always was there if I am threshold braking from about of redline on 3rd into mid-range of 2nd gear.
if braking is not that hard there are no issues usually, it goes in fine. when it does not go it feels like I hit a solid metal wall there, it simply does not go at all, like I am pressing something into a metal plate. not sure what is the cultrip - worn clutch, syncros or engine mounts but it looks like double clutch helps a little bit.
#94
Rennlist Member
Thread Starter
Had the great pleasure to coach 2 very good drivers the last 2 days at Watkins Glen, under wonderful sunny skies. Yesterday afternoon, riding with one of them, we had a common but eye opening experience. I was alternating timing several laps followed by segment timing a segment where he had room for improvement. Anyway, we had just completed by far his quickest lap ever, when the car really stepped out climbing the Esses. It was apparent the tires were going away rapidly. So I changed to segment timing (not that segment) and he lowered his pace in all the other parts fo the track except our timed segment in order to cool the tires. After a lap, however, it was obvious the tires were still going away. The client made the correct call to park the car.
Sometimes it is important to realize & accept that there is literally no upside & lots of downside to staying out (it was an open track practice day, not a race) when the car is significantly going away. I see lots of drivers who don't make this call, just to not "give up" laps they "paid for"...and they often regret it, especially on a track with consequences like the Glen.
Matt...LMFAO!
#95
Rennlist Member
Had the great pleasure to coach 2 very good drivers the last 2 days at Watkins Glen, under wonderful sunny skies. Yesterday afternoon, riding with one of them, we had a common but eye opening experience. I was alternating timing several laps followed by segment timing a segment where he had room for improvement. Anyway, we had just completed by far his quickest lap ever, when the car really stepped out climbing the Esses. It was apparent the tires were going away rapidly. So I changed to segment timing (not that segment) and he lowered his pace in all the other parts fo the track except our timed segment in order to cool the tires. After a lap, however, it was obvious the tires were still going away. The client made the correct call to park the car.
Sometimes it is important to realize & accept that there is literally no upside & lots of downside to staying out (it was an open track practice day, not a race) when the car is significantly going away. I see lots of drivers who don't make this call, just to not "give up" laps they "paid for"...and they often regret it, especially on a track with consequences like the Glen.
Matt...LMFAO!
Sometimes it is important to realize & accept that there is literally no upside & lots of downside to staying out (it was an open track practice day, not a race) when the car is significantly going away. I see lots of drivers who don't make this call, just to not "give up" laps they "paid for"...and they often regret it, especially on a track with consequences like the Glen.
Matt...LMFAO!
#96
Rennlist Member
Thread Starter
Thanks, Bobby, as I said it was a real pleasure! And nothing you did, over 2 days, scared me. It was a slight surprise when the car went away on us so suddenly there, considering how hooked up it had been, but that was nothing you did. Congrats to both of you on some remarkable progress from your already-high baselines!
#97
Still plays with cars.
Lifetime Rennlist
Member
Folks,
Just a reminder, this thread is called "Ask the Coach". It is about driving and racing techniques. Pro coaches voluntarily contribute their expertise.
It is NOT a forum to discuss the weakness of synchros, nor to contradict the opinion of firms that rebuild gearboxes. One post is OK, multiple posts expressing the same opinion are unappreciated and have been deleted.
Regards,
Just a reminder, this thread is called "Ask the Coach". It is about driving and racing techniques. Pro coaches voluntarily contribute their expertise.
It is NOT a forum to discuss the weakness of synchros, nor to contradict the opinion of firms that rebuild gearboxes. One post is OK, multiple posts expressing the same opinion are unappreciated and have been deleted.
Regards,
#99
Three Wheelin'
Thx Bob for riding Sheriiff... This is a thread that should not get "lost" in minutia.
VR great idea and thread! Thx to you and the other coaches that have contributed.
You have spoken in the past of not forcing the car; rather, of guiding it and letting the car go where it wants. Can you expand a bit on that concept, please?
Am I right in thinking that the main idea here is to sense, or 'feel', the relative G loading on the tires and suspension? That is, develop enough feel to know when over-taxing same will result in a decrease in speed?
If I am not totally off, then; during a practice session (lapping), what exercises/techniques do you recommend to 'evolve' or 'progress' that 'feel'?
TIA
VR great idea and thread! Thx to you and the other coaches that have contributed.
You have spoken in the past of not forcing the car; rather, of guiding it and letting the car go where it wants. Can you expand a bit on that concept, please?
Am I right in thinking that the main idea here is to sense, or 'feel', the relative G loading on the tires and suspension? That is, develop enough feel to know when over-taxing same will result in a decrease in speed?
If I am not totally off, then; during a practice session (lapping), what exercises/techniques do you recommend to 'evolve' or 'progress' that 'feel'?
TIA
#100
Rennlist Member
Thread Starter
Thank you!
Here is what I meant: generally, the car knows the proper trajectory thru a corner, providing the driver provides some "adult supervision" at entry. If you accept this premise, then you should do everything possible to not "fight" the car & force it where it doesn't want to go. For example, many folks don't begin opening up their steering at apex, and they kill a lot of exit speed with front tire scrub...in addition to introducing instability as the front tires load up instead of the rears. So yes, your summary is accurate IMO.
Exercises? Start opening up steering (slowly, a few degrees at a time) sooner than your comfort level suggests....see if you go off track at track out! See if you are adding steering angle at or even after apex. Things like that.
Here is what I meant: generally, the car knows the proper trajectory thru a corner, providing the driver provides some "adult supervision" at entry. If you accept this premise, then you should do everything possible to not "fight" the car & force it where it doesn't want to go. For example, many folks don't begin opening up their steering at apex, and they kill a lot of exit speed with front tire scrub...in addition to introducing instability as the front tires load up instead of the rears. So yes, your summary is accurate IMO.
Exercises? Start opening up steering (slowly, a few degrees at a time) sooner than your comfort level suggests....see if you go off track at track out! See if you are adding steering angle at or even after apex. Things like that.
#101
Rennlist
Basic Site Sponsor
Basic Site Sponsor
Thank you!
Here is what I meant: generally, the car knows the proper trajectory thru a corner, providing the driver provides some "adult supervision" at entry. If you accept this premise, then you should do everything possible to not "fight" the car & force it where it doesn't want to go. For example, many folks don't begin opening up their steering at apex, and they kill a lot of exit speed with front tire scrub...in addition to introducing instability as the front tires load up instead of the rears. So yes, your summary is accurate IMO.
Exercises? Start opening up steering (slowly, a few degrees at a time) sooner than your comfort level suggests....see if you go off track at track out! See if you are adding steering angle at or even after apex. Things like that.
Here is what I meant: generally, the car knows the proper trajectory thru a corner, providing the driver provides some "adult supervision" at entry. If you accept this premise, then you should do everything possible to not "fight" the car & force it where it doesn't want to go. For example, many folks don't begin opening up their steering at apex, and they kill a lot of exit speed with front tire scrub...in addition to introducing instability as the front tires load up instead of the rears. So yes, your summary is accurate IMO.
Exercises? Start opening up steering (slowly, a few degrees at a time) sooner than your comfort level suggests....see if you go off track at track out! See if you are adding steering angle at or even after apex. Things like that.
__________________
Larry Herman
2016 Ford Transit Connect Titanium LWB
2018 Tesla Model 3 - Electricity can be fun!
Retired Club Racer & National PCA Instructor
Past Flames:
1994 RS America Club Racer
2004 GT3 Track Car
1984 911 Carrera Club Racer
1974 914/4 2.0 Track Car
CLICK HERE to see some of my ancient racing videos.
Larry Herman
2016 Ford Transit Connect Titanium LWB
2018 Tesla Model 3 - Electricity can be fun!
Retired Club Racer & National PCA Instructor
Past Flames:
1994 RS America Club Racer
2004 GT3 Track Car
1984 911 Carrera Club Racer
1974 914/4 2.0 Track Car
CLICK HERE to see some of my ancient racing videos.
#102
Increasing speed in corner vs. time
Coaches,
I got a question. In a generic kind of way if one hit an apex 2 miles per hour faster than the time before is there any generic sense of how much that results in laptime? You know, kind of like that rule of thumb taking 100lbs out of a car is good for 0.1 seconds in 0-60mph time.
Thanks!
I got a question. In a generic kind of way if one hit an apex 2 miles per hour faster than the time before is there any generic sense of how much that results in laptime? You know, kind of like that rule of thumb taking 100lbs out of a car is good for 0.1 seconds in 0-60mph time.
Thanks!
#103
Having a go at him
Too many questions perhaps I'll get kicked off here.... So lets say you battle with a guy and you can feel you tires get greasy and you get hot and flustered over driving your car. Continuing a battle almost ensures he will get away.
Once I tried to calm myself sort of Zen so to speak and got target fixated. He made a mistake which I could have capitalized on. Instead fixated on him while trying to calm down to gain composure to have another run at him, I followed his mistake and almost drove off the track! In every race I seem to find a few laps that are sweeter than the rest where the car seems to work best or I'm in best tune with it. I'm not sure which but I'd love to find those sweet laps when trying to get around a tough racer.
If you need to get by a person of similar talent what can be done with your driving so that you and your car so that you can be in a better position to make the pass and keep it?
Once I tried to calm myself sort of Zen so to speak and got target fixated. He made a mistake which I could have capitalized on. Instead fixated on him while trying to calm down to gain composure to have another run at him, I followed his mistake and almost drove off the track! In every race I seem to find a few laps that are sweeter than the rest where the car seems to work best or I'm in best tune with it. I'm not sure which but I'd love to find those sweet laps when trying to get around a tough racer.
If you need to get by a person of similar talent what can be done with your driving so that you and your car so that you can be in a better position to make the pass and keep it?
#104
Rennlist Member
This is generally the differnce of slicks vs DOTs. think about it, 2mph. thats the "walking away" from the competitor we often hear about.
If the turn is about 5 seconds, that might be a car length difference around the turn. one car length, depending on the speed. if you are going 50mph thats 75feet per second, so a car length of 15 feet, would be less than 1/4 second. multiply that by 6-7 turns, and add in the extra 2mph down each of the straights, and deeper in the brake zones, and it ends up to be a few seconds at least. I would guess that for every 1mph around an apex faster, that relates to 2 seconds a lap faster. Thats a guess. as was mentioned, there are quite a few factors to consider
Mk
If the turn is about 5 seconds, that might be a car length difference around the turn. one car length, depending on the speed. if you are going 50mph thats 75feet per second, so a car length of 15 feet, would be less than 1/4 second. multiply that by 6-7 turns, and add in the extra 2mph down each of the straights, and deeper in the brake zones, and it ends up to be a few seconds at least. I would guess that for every 1mph around an apex faster, that relates to 2 seconds a lap faster. Thats a guess. as was mentioned, there are quite a few factors to consider
Mk
Coaches,
I got a question. In a generic kind of way if one hit an apex 2 miles per hour faster than the time before is there any generic sense of how much that results in laptime? You know, kind of like that rule of thumb taking 100lbs out of a car is good for 0.1 seconds in 0-60mph time.
Thanks!
I got a question. In a generic kind of way if one hit an apex 2 miles per hour faster than the time before is there any generic sense of how much that results in laptime? You know, kind of like that rule of thumb taking 100lbs out of a car is good for 0.1 seconds in 0-60mph time.
Thanks!
Last edited by mark kibort; 05-15-2011 at 12:59 PM.
#105
Rennlist Member
Too many questions perhaps I'll get kicked off here.... So lets say you battle with a guy and you can feel you tires get greasy and you get hot and flustered over driving your car. Continuing a battle almost ensures he will get away.
Once I tried to calm myself sort of Zen so to speak and got target fixated. He made a mistake which I could have capitalized on. Instead fixated on him while trying to calm down to gain composure to have another run at him, I followed his mistake and almost drove off the track! In every race I seem to find a few laps that are sweeter than the rest where the car seems to work best or I'm in best tune with it. I'm not sure which but I'd love to find those sweet laps when trying to get around a tough racer.
If you need to get by a person of similar talent what can be done with your driving so that you and your car so that you can be in a better position to make the pass and keep it?
Once I tried to calm myself sort of Zen so to speak and got target fixated. He made a mistake which I could have capitalized on. Instead fixated on him while trying to calm down to gain composure to have another run at him, I followed his mistake and almost drove off the track! In every race I seem to find a few laps that are sweeter than the rest where the car seems to work best or I'm in best tune with it. I'm not sure which but I'd love to find those sweet laps when trying to get around a tough racer.
If you need to get by a person of similar talent what can be done with your driving so that you and your car so that you can be in a better position to make the pass and keep it?
We had a few seasons where all of us (about 4-5 cars) all would have the same exact lap times the races were determined by who qualified best, who got the best start advantage, (contrary to popular opinion, some races are determined by the first corner. ) However, i do remember having a slight aero /hp advantage and using that to make a dive into the following turn on occasion, as well as being the victum of a car with lighter, better handling out of a demanding off cambered turn exit, into a braking zone where I just couldnt defend. Its probably the best part of racing. it becomes a game of chess and/or golf. strategy and consistancy.