New Project called B9R Under Construction...at BBi
#451
08-05-2009, 09:57 PM
I just looked up the tranny ratio's and stock 6 speed and TIP ratio's.
We used the following gears from first thru sixth.
3.167:1, 1.938:1, 1.474:1, 1.174:1, 0.968:1 and 0.821:1
Stock gearing on the six speed is:
3.82:1, 2.05:1, 1.41:1, 1.12:1, 0.92:1 and 0.85:1
Stock TIP gears:
3.59:1, 2.19:1, 1.41:1, 1.00:1 and 0.83:1
We used the following gears from first thru sixth.
3.167:1, 1.938:1, 1.474:1, 1.174:1, 0.968:1 and 0.821:1
Stock gearing on the six speed is:
3.82:1, 2.05:1, 1.41:1, 1.12:1, 0.92:1 and 0.85:1
Stock TIP gears:
3.59:1, 2.19:1, 1.41:1, 1.00:1 and 0.83:1
#452
08-05-2009, 09:58 PM
The tranny had all six gear ratio changed. First and second were made longer, third, fourth, fifth and sixth were shortened. Don't remember all the gear ratio's off hand, but first was something like a 3.18-1 which with our redline takes first to about 72 mph. All gear ratios are listed in our thread in the Tuner/Modification section. All gears were made using the 28 mm width square cut teeth like the RSR tranny to add strength. One of the shafts was rifle drilled to provide additional oiling to the upper gears. All gears were friction coated and the shafts and case interior was coated to repel oil. Syncro's are steel and black carbon coated. The case was drilled for an external oil cooler and pump. A billet RSR LSD was utilized. Case was tapped for tranny oil temperature probe.
The tranny was built by Brian Copan.
The tranny was built by Brian Copan.
#453
08-06-2009, 07:30 AM
Joe and I have a concern about the cars becoming airborne. as in leaving the ground, after certain speeds and under less than perfect wind and road conditions.
These cars have the ability to do this before terminal velocity is attained.
#454
08-06-2009, 09:26 AM
Join Date: Nov 2007
Location: L.A.
Posts: 3,190
Rep Power: 274 
I hear you and I think it is a very critical component also. Just a little head wind and difficult condition would easily do that. How about placing a few sand bags in the front
#455
08-06-2009, 10:05 AM
you need to build more down force. Ruf or 9ff had a 996 turbo that hit 241 mph on a track. I am sure they worked on the down force to get it there and not fly away, but from what I remember it was not drastic. The teardrop shape of these cars is very efficient at high speed. Just increasing rake will give better downforce and something to consider.
#456
08-06-2009, 10:37 AM
Excellent advice!We are changing out the suspension and taking steps to do just that
#457
08-06-2009, 12:22 PM
Join Date: Nov 2007
Location: L.A.
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100% Agreed.
Great advice, we will look into this as well.
you need to build more down force. Ruf or 9ff had a 996 turbo that hit 241 mph on a track. I am sure they worked on the down force to get it there and not fly away, but from what I remember it was not drastic. The teardrop shape of these cars is very efficient at high speed. Just increasing rake will give better downforce and something to consider.
#459
08-06-2009, 01:41 PM
Join Date: Nov 2007
Location: L.A.
Posts: 3,190
Rep Power: 274
Nice Avatar Rob, why are you going so far? At BBi there are two of them parked (996 & 997), seen them in person, go check out the sequential shifter. Just the tranny alone on that car cost over $90K. Definately a beautiful car with all the specs you'll need on track. Thanks for sharing.
#460
08-06-2009, 02:55 PM
Joe, Art,
I think the factory std forward rake on these cars is 1 degree. not positive on this. But you guys running the mile don't have 1 degree of rake. I'd bet you are at 0 or higher because under acceleration the rear squats and the front lifts, so you have the worst of all possible conditions. At the rate your cars are accelerating that front end does not drop much.
I would be very careful about too much rake. If it was me I would drop the entire car maybe 4mm which increases downforce, then drop the front another 4mm. Doesn't seem like much, but it is at 200+mph. I do know that too much forward rake can cause the rear end to get loose and make it seem like it wants to come over and around you. I'd bet someone has done studies on this, maybe 9ff or Ruf. In fact their 241 mph 996 definitely looked forward rake to me. I'll see if I can find that article, it may talk about rake.
I have a friend who dropped the front on his viper by an inch and never installed the Racecar wing in the back, and at 215 mph he crapped his pants because he was sure his rear end was coming over him. But before he dropped the nose, his car almost got airborne. I think that if he would have dropped the nose by 10mm on his car and dropped the entire car by an additional 10, he would have been fine.
I think the factory std forward rake on these cars is 1 degree. not positive on this. But you guys running the mile don't have 1 degree of rake. I'd bet you are at 0 or higher because under acceleration the rear squats and the front lifts, so you have the worst of all possible conditions. At the rate your cars are accelerating that front end does not drop much.
I would be very careful about too much rake. If it was me I would drop the entire car maybe 4mm which increases downforce, then drop the front another 4mm. Doesn't seem like much, but it is at 200+mph. I do know that too much forward rake can cause the rear end to get loose and make it seem like it wants to come over and around you. I'd bet someone has done studies on this, maybe 9ff or Ruf. In fact their 241 mph 996 definitely looked forward rake to me. I'll see if I can find that article, it may talk about rake.
I have a friend who dropped the front on his viper by an inch and never installed the Racecar wing in the back, and at 215 mph he crapped his pants because he was sure his rear end was coming over him. But before he dropped the nose, his car almost got airborne. I think that if he would have dropped the nose by 10mm on his car and dropped the entire car by an additional 10, he would have been fine.
#461
08-06-2009, 04:33 PM
Join Date: Nov 2007
Location: L.A.
Posts: 3,190
Rep Power: 274
Thanks for all the info Dennis, we do appreciate it. Anything above 170mph is all in aero and engineering just like you stated. Betim and I have looked at the 9ff design already and are working on it as we speak. I will have a write up on this when we get close to that point. For now, let's get that damn engine in there......
#463
08-06-2009, 06:41 PM
you need to build more down force. Ruf or 9ff had a 996 turbo that hit 241 mph on a track. I am sure they worked on the down force to get it there and not fly away, but from what I remember it was not drastic. The teardrop shape of these cars is very efficient at high speed. Just increasing rake will give better downforce and something to consider.
I addition the track 9ff used is banked just right.
#464
08-06-2009, 06:59 PM
Joe, Art,
I think the factory std forward rake on these cars is 1 degree. not positive on this. But you guys running the mile don't have 1 degree of rake. I'd bet you are at 0 or higher because under acceleration the rear squats and the front lifts, so you have the worst of all possible conditions. At the rate your cars are accelerating that front end does not drop much.
I would be very careful about too much rake. If it was me I would drop the entire car maybe 4mm which increases downforce, then drop the front another 4mm. Doesn't seem like much, but it is at 200+mph. I do know that too much forward rake can cause the rear end to get loose and make it seem like it wants to come over and around you. I'd bet someone has done studies on this, maybe 9ff or Ruf. In fact their 241 mph 996 definitely looked forward rake to me. I'll see if I can find that article, it may talk about rake.
I have a friend who dropped the front on his viper by an inch and never installed the Racecar wing in the back, and at 215 mph he crapped his pants because he was sure his rear end was coming over him. But before he dropped the nose, his car almost got airborne. I think that if he would have dropped the nose by 10mm on his car and dropped the entire car by an additional 10, he would have been fine.
I think the factory std forward rake on these cars is 1 degree. not positive on this. But you guys running the mile don't have 1 degree of rake. I'd bet you are at 0 or higher because under acceleration the rear squats and the front lifts, so you have the worst of all possible conditions. At the rate your cars are accelerating that front end does not drop much.
I would be very careful about too much rake. If it was me I would drop the entire car maybe 4mm which increases downforce, then drop the front another 4mm. Doesn't seem like much, but it is at 200+mph. I do know that too much forward rake can cause the rear end to get loose and make it seem like it wants to come over and around you. I'd bet someone has done studies on this, maybe 9ff or Ruf. In fact their 241 mph 996 definitely looked forward rake to me. I'll see if I can find that article, it may talk about rake.
I have a friend who dropped the front on his viper by an inch and never installed the Racecar wing in the back, and at 215 mph he crapped his pants because he was sure his rear end was coming over him. But before he dropped the nose, his car almost got airborne. I think that if he would have dropped the nose by 10mm on his car and dropped the entire car by an additional 10, he would have been fine.
Don't get me wrong ,on my first pass in the car (221)I noticed the car was wandering around a little up to speeds of about 180mph,which after further thought was probably due to it being in "squat " position from being under power.Nothing uncontrollable but it did require some steering input something I had never felt in the car before.After 180 it did hunker down and become planted resulting in a much more stable feeling.Todd Z and myself compared notes after his first pass in the car and his expierience was the same.My car's suspension was lowered 1" all around for the event on H&R springs.Now driving Todds 997 tt 850 was a totally different experience.Although it wasn't lowered and was at a stock ride height it was very stable throughout the entire mile,in fact,you could damn near set the presets on the radio while making a pass 
.Both were on the same tires.The question becomes where(mph) does the car become front end light over 230mph.Todd did say it was just as stable at 230 as it was at 220 ,so hpoefully it doesn't become unstable at 232
.Considering the stock bodied Supra ran 246 without really any aero mods,i think we are ok,but we are looking to stiffen the suspension(to help with the wandering)and giving it a slight rake as you mentioned earlier.This time I will have to make a few passes to check the operation of the chute to see how the car reacts(since i have never run a car with a chute) and will be able to gradually gradually work up to the terminal speed .
#465
08-06-2009, 09:00 PM
Chad, who's ignoring the underside. Lowering the car decreases the amount of air under the car which increases the air over the car ratio to air under the car which increases downforce, and I mentioned that. I agree that the underside is important. But all aspects are. I just want everyone to be safe.
Joe, if you look at the supra, take a look at it's rake. It is definitely raked more than stock. Whether it was done with suspension or larger tires in back I don't know but it has that dragster look to it.
Dennis