42% front and %58 rear weight bias
09-22-2009, 08:25 AM
#1
Team Owner
Thread Starter
42% front and %58 rear weight bias
I just thought that I would post a picture of changing my street tires over to slicks at the race track. All I have to do is place my jack about 6 inches behind my cross member and it lifts the tires nearly equally off the ground.
My street tires are Kumhos 275/17 and 335/17 rears. They rear hug the turns during every day screwing off.
My slicks in this day were 295/35/17 fronts and 12 width X27 dia rear Hoosier R6 road racing slicks. Road racing with big slicks makes all the difference. I've looped my Vette on the way home from the track because I was so used to driving at full potential and street tires break away at much lower "G's"
My street tires are Kumhos 275/17 and 335/17 rears. They rear hug the turns during every day screwing off.
My slicks in this day were 295/35/17 fronts and 12 width X27 dia rear Hoosier R6 road racing slicks. Road racing with big slicks makes all the difference. I've looped my Vette on the way home from the track because I was so used to driving at full potential and street tires break away at much lower "G's"
09-22-2009, 07:37 PM
#2
Melting Slicks
Thats one heck of a spacer on the rear...guess that allows you to run the wider tire without switching to an offset trailing arm.
You ever have any issues with your rear bearings being that you're running that thick spacer on the track at high speed and heavy G's?
You ever have any issues with your rear bearings being that you're running that thick spacer on the track at high speed and heavy G's?
09-22-2009, 08:04 PM
#4
Team Owner
Thread Starter
That is a two inch adapter with all 1/2 inch studs. They must be over 10 years old because I had them before the forum existed. No bearing problems. Everything has been upgraded over the years. Those are 12 inch wheels with 7 inch BS Racing wheel manufacturers like to keep the wheel strong also by nearly centering the bolt on point.
09-22-2009, 09:10 PM
#5
Team Owner
That is a two inch adapter with all 1/2 inch studs. They must be over 10 years old because I had them before the forum existed. No bearing problems. Everything has been upgraded over the years. Those are 12 inch wheels with 7 inch BS Racing wheel manufacturers like to keep the wheel strong also by nearly centering the bolt on point.
I have 2.5" adaptors, but using '89 vette wheels, used to be '92 wheels...
09-23-2009, 11:42 AM
#6
Team Owner
Thread Starter
78 &79 Vettes have a bad weight disadvantage. Even with everything I removed to lighten my Vette. But then I also added a very heavy roll cage, fire system, the interior was done in flame proof aluminum matting and then covered with short pile flame retardant carpet, and blow proof bell housing. The Motown 434 ci small block is heavy. When it adds up the four corner scales with a full 25 gallons of gas it is a porky 3167 pounds. It is the big heavy frame that I gusseted and seam welded. I really can’t think of anything to get it lighter unless I gut the doors and go lexan windows. For racing I pull out the monster 900 CC amp battery and put in a tiny racepack battery. I also try to only have 5-6 gallons of fuel in the tank and I pull out the stock passenger seat. Even with all that it probably only comes down to 3000 pounds
Some guy on here posted a 74 down to 2780# or some number. I can only wish of ever getting down to the SCCA class minimum of 2850#
As for safety. That big long nose and motor are pretty tough. Side impact your dead even with the late C-3 steel guard rail in the doors. I really feel safe in my roll cage.
I removed all the heavy steel and the opening head lights. I replaced it with aluminum round and square tubing to re support the front end. I work at a race shop so I had the chassis fabricator guy make it. Excellent aluminum welding and fabricating the ecklers fixed head lights. I'm a motor and race car setup person. I leave painting a fabrication to the pro's
Some guy on here posted a 74 down to 2780# or some number. I can only wish of ever getting down to the SCCA class minimum of 2850#
As for safety. That big long nose and motor are pretty tough. Side impact your dead even with the late C-3 steel guard rail in the doors. I really feel safe in my roll cage.
I removed all the heavy steel and the opening head lights. I replaced it with aluminum round and square tubing to re support the front end. I work at a race shop so I had the chassis fabricator guy make it. Excellent aluminum welding and fabricating the ecklers fixed head lights. I'm a motor and race car setup person. I leave painting a fabrication to the pro's
09-23-2009, 11:53 AM
#7
Tech Contributor
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78 &79 Vettes have a bad weight disadvantage. Even with everything I removed to lighten my Vette. But then I also added a very heavy roll cage, fire system, the interior was done in flame proof aluminum matting and then covered with short pile flame retardant carpet, and blow proof bell housing. The Motown 434 ci small block is heavy. When it adds up the four corner scales with a full 25 gallons of gas it is a porky 3167 pounds. It is the big heavy frame that I gusseted and seam welded. I really can’t think of anything to get it lighter unless I gut the doors and go lexan windows. For racing I pull out the monster 900 CC amp battery and put in a tiny racepack battery. I also try to only have 5-6 gallons of fuel in the tank and I pull out the stock passenger seat. Even with all that it probably only comes down to 3000 pounds
Some guy on here posted a 74 down to 2780# or some number. I can only wish of ever getting down to the SCCA class minimum of 2850#
As for safety. That big long nose and motor are pretty tough. Side impact your dead even with the late C-3 steel guard rail in the doors. I really feel safe in my roll cage.
I removed all the heavy steel and the opening head lights. I replaced it with aluminum round and square tubing to re support the front end. I work at a race shop so I had the chassis fabricator guy make it. Excellent aluminum welding and fabricating the ecklers fixed head lights. I'm a motor and race car setup person. I leave painting a fabrication to the pro's
Some guy on here posted a 74 down to 2780# or some number. I can only wish of ever getting down to the SCCA class minimum of 2850#
As for safety. That big long nose and motor are pretty tough. Side impact your dead even with the late C-3 steel guard rail in the doors. I really feel safe in my roll cage.
I removed all the heavy steel and the opening head lights. I replaced it with aluminum round and square tubing to re support the front end. I work at a race shop so I had the chassis fabricator guy make it. Excellent aluminum welding and fabricating the ecklers fixed head lights. I'm a motor and race car setup person. I leave painting a fabrication to the pro's
09-23-2009, 12:01 PM
#8
Team Owner
Thread Starter
09-23-2009, 02:03 PM
#9
Melting Slicks
09-23-2009, 02:11 PM
#10
Team Owner
Thread Starter
I bet that the late 70's 24 would fit right in. Our frames in the back have similar dimensions
09-23-2009, 05:16 PM
#11
Melting Slicks
I must have missed this at some point, but why do you run the slicks (bias I assume) in the rear with DOT R6's in front? Why not run the same tire (model or compound, not necessarily size) all the way around?
09-23-2009, 06:21 PM
#13
Safety Car
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Bee Jay
09-23-2009, 06:51 PM
#14
Melting Slicks
We had a Grand Sport in the shop one day and I commented to my buddy about how massive the gas tank was (32) gallons. That was an optional tank back then and used on all the race cars for endurance racing.
I bet that the late 70's 24 would fit right in. Our frames in the back have similar dimensions
I bet that the late 70's 24 would fit right in. Our frames in the back have similar dimensions
I've actually been looking to put a 30 gallon tank in mine but can't find a fuel cell or poly tank that would fit without modifying the frame or fiberglass compartment. Yes I'm aware how heavy a 30 gallon tank is full of gas.
Any idea where I could find the 32 gallon you mentioned in the GS or the 24 gallon in the late 70's? I'd like to find out the dimensions and if they're available for sale. Otherwise I'll be drawing up a custom tank over the winter and sending it out to Ricks Hot Rod shop, Rock Valley or some other capable shop. Wish I could afford a TIG that could do alluminum and I'd give it a go.
09-23-2009, 08:10 PM
#15
Team Owner
Thread Starter
It was the last race day of the year and I was just out to burn up my front 295's and these rears. I usually run 335/18 R6's on the rear so it is radials all the way around. I'm done racing my Vette. So I wasn't going to spend an additional $800 for one day. Lap times mixed is right on with all radials which was just about the same as 4 bias. I just take out or add a few clicks of compression between side wall stiffness.
09-24-2009, 06:56 AM
#16
Le Mans Master
I read your comments on the weight and it got me thinking after looking at your pictures about ways to reduce that number, which I am sure you have thought of already but most likely due to dollars have not done. I do not race my 78 but was wondering about the weight of your motor, which you mentioned. How about an aluminum small block V8? Aluminum upper and lower control arms? Aluminum rear differential carrier and trailing arms? Aluminum racing calipers and lighter weight rims? I am sure that you have thought of all this and the dollars it would involve but do you think changing some of these items would get you into the 2700-2900 lb range?
09-24-2009, 08:02 AM
#17
Team Owner
Thread Starter
I've actually been looking to put a 30 gallon tank in mine but can't find a fuel cell or poly tank that would fit without modifying the frame or fiberglass compartment. Yes I'm aware how heavy a 30 gallon tank is full of gas.
Any idea where I could find the 32 gallon you mentioned in the GS or the 24 gallon in the late 70's? I'd like to find out the dimensions and if they're available for sale. Otherwise I'll be drawing up a custom tank over the winter and sending it out to Ricks Hot Rod shop, Rock Valley or some other capable shop. Wish I could afford a TIG that could do alluminum and I'd give it a go.
Any idea where I could find the 32 gallon you mentioned in the GS or the 24 gallon in the late 70's? I'd like to find out the dimensions and if they're available for sale. Otherwise I'll be drawing up a custom tank over the winter and sending it out to Ricks Hot Rod shop, Rock Valley or some other capable shop. Wish I could afford a TIG that could do alluminum and I'd give it a go.
09-24-2009, 08:15 AM
#18
Team Owner
Thread Starter
I read your comments on the weight and it got me thinking after looking at your pictures about ways to reduce that number, which I am sure you have thought of already but most likely due to dollars have not done. I do not race my 78 but was wondering about the weight of your motor, which you mentioned. How about an aluminum small block V8? Aluminum upper and lower control arms? Aluminum rear differential carrier and trailing arms? Aluminum racing calipers and lighter weight rims? I am sure that you have thought of all this and the dollars it would involve but do you think changing some of these items would get you into the 2700-2900 lb range?
As to allot of aluminum. You are better off having a street rod Vette and a dedicated race car for what ever kind of racing you do. For drag racing sub 8 second vehicles are fun. For road racing you will never beat the open wheeled cars with wings.
So I'm going to race an older real open wheel F2 March chassis which can do 3 "G" turnes. It has bigger better wings than what it was raced with back in the day. Sub 4 pounds per HP
09-24-2009, 03:03 PM
#19
Melting Slicks
I've searched everywhere for a fuel cell that would fit within the length and width of the vette without cutting anything and its either 0.5 to 1.5" to big. I don't care about the height b/c I'd build some brackets to whatever height it needed to be to run the 30 gallons of fuel. I'd also build a steel box like the GT1 vette had to protect a poly fuel cell if needed.
10-03-2009, 10:28 AM
#20
Melting Slicks
It was the last race day of the year and I was just out to burn up my front 295's and these rears. I usually run 335/18 R6's on the rear so it is radials all the way around. I'm done racing my Vette. So I wasn't going to spend an additional $800 for one day. Lap times mixed is right on with all radials which was just about the same as 4 bias. I just take out or add a few clicks of compression between side wall stiffness.
