**VERY LONG POST WARNING** If you want the pictures, just skip the BS and go to bottom.
Sometimes the simplest minor miscalculation or two or three can really bust your balls, but we all know that right.
I was using a 26" tire on 16"x10 Bogarts on my stock IRS that I had made and was told to ask for the 03-04 Cobra backspace. I was told that particular wheel had a 6.5" backspace by someone else that got them, but what I had was actually 6.25". The 16" wheel would fit with no grinding, a 15 meant you would have to grind IRS knuckles, so I went with the 16's. I mounted 26x11.5 ET Streets on them and they worked great and when I switched to the 4.10 gear I was trapping 122-124 around 6200-6400 right at my shift light, just perfect. I got over 120 passes on those Streets before they started to act like they were toast, so I needed new tires to match my new setup.
Last winter I planned finishing the build up that was to add another 50 blower horses and 100 or more NOS ponies. I was worried that trapping 130-132 would run me out of gear. My calculator said 27" was better but I couldn't find much in that size for my wheels or for 15" for that matter. I talked to a couple of track Rats that were using 28" on big blower cars, I never got into the specifics of the backspace or how wide of a 28"x15 tire they were using, just that they worked with their solid converted 600+hp Cobras. I ordered a couple 28"x16x12.5 before my 9" was even installed, what a mistake.
My NOS is windowed into a second stage (4000+rpm) so my launch horsepower did NOT change enough (470 to about 510-520) to handle that tire because a 2" jump is HUGE, top speed really should have never been a concern of mine, just run out the backdoor on the limiter, if it will mean a better launch and the right gearing for a quicker 60ft!
The mistakes didn't end there. I swapped my IRS out for a totally built Moser 9" and I did some string measurements and as far as I could tell it seemed about 1/4" wider, so that didn't seem significant but I think it is closer to a 1/2" which is. Well my best 60ft with the old stock IRS setup was 1.60, I thought that was good but I knew when I could not get a better 60ft with the solid, something was up.
I was getting NO weight transfer out of my new rear suspension w/50-50 Lakewoods, a rule of thumb pinion angle and a custom made, under axle anti-roll system. I couldn't understand it, everything was just like it should be. Well I wasted 3 times to the track before I realized my only friggin problem was that my tires were hitting the back of the rocker area, below the side scoops in the fender well with my built for IRS wheels that were now sticking 1/2" farther out. They were not clearing it so it was like having a bump stop and would unload the rear spring and dead bog unless I had so much air in there I would start spinning before the weight transfer. I saw the rub after the very first pass with the 28"ers but it was such a flat area with no risk of cutting the tire, I didn't pay it much attention, until we started studying launch movies.
It doesn't stop there, none of my mistakes are solo, I like to Cluster my F-ups!
Because I tried to use my 16" wheels to begin the testing of my upgrades and wanted to wait and save a few pesos before getting 15" Bogart $$ replacements to use with the solid axle (15"= more tire choices and MORE SIDEWALL!) I ended up buying a set of tires I can't use. I knew I needed STIFF sidewall slicks to use with my heavy clutch, stick and 6K+ dumps but I had already dropped a bundle so I ordered 16" ET Streets, there were no choices for 16" other than soft compounds, so I figured maybe I would try another DOT slick like I before. Well they not only twisted on the wheel when I hit them, they would also fold the sidewalls, just look at the pictures below.
It was time to sack up, about $1400 worth of my nut sack to at least try to eliminate the possible tire issue before getting crazy with the suspension that seemed to be setup correctly ( I had other racers check out all my upper and lower lengths, pinion angle, etc.. ).
Well I measured up how much room I had behind the wheel with my 6.25 backspace wheels and decided that for my particular solid, I could run a 10.5" wheel with a 7.5" backspace in the bolted RT pattern (barrel clearance is also dependent on style wheel). That moved the inside of the wheel in a full 1.25" and the outside lip in .75" and I added another .5" in wheel width. I wanted to run a tire recommended for a 10" wheel on a wider 10.5 because that is another way to have a stiffen the sidewall. I then could run the 26x10x15 M/T Drag Slicks in the Super Stock Stiff Sidewall pattern. I also drilled them for screws and run 8 on each side. I think they tuck under much better and have about 1/2" clearance on the backside of the tires.
PART2
Can you tell which one is the Stiff Sided? You can almost see where it was bottoming out.
problem solved. 1st launch at a conservative 5K and with 12lbs which was too much air, I got a 1.56 60ft. Even though the NOS didn't spray more than 1/2 of one gear (another problem, don't ask that is another post) I ran a pig rich pass with 4 degrees of timing pulled for nothing, but still ran an 11.02 best, all because of that 60ft. I then put the blower only tune in, dropped down to 11lbs air. I got really psyched in the lanes to get my 1st 10, so launched like a man at my 6500 rpm 2step. This was the 10th or so pass on my new but broken in RAM race clutch so when I dumped on a set of tires that behaved, it came up so hard it freaking caught me by surprise. I was looking up and grinning so wide I missed my shiftpoint, it comes fast with 4.11's, I have to start to shift into 1st BEFORE the 6400 shiftlight! So I thought I would fix that by then missing the gear completely, good thing I was granny shifting, instead of power shifting like I normally do or I would have missed that opportunity to spike the fuel pressure and blow my first FRPS in over 2 years. I bailed on the pass soon after that, because it started to run like sheeit but not before my upgraded BAP-> FPDM-> GT pumps-> fiore hat-> 8AN-> CPR modded rails-> 60lbers drowned my serpent so bad it stalled and wouldn't start before I could get back on the return road. It was flooded so bad it was belching gas back out the intake so the 04Snake got to ride the winch onto my trailer.
Just another day in paradise, oh and that was after waiting until 4:15pm to get that 2nd pass of the day so I was going to pack it in anyway. I have had a FRPS (Ford's fuel rail pressure sensor) in my toolbox for 2 years that I finally got to use and was already going to change the oil after that track day. That last disaster did net a 1.52 60ft so I was on my way to my first 10, but apparently I haven't passed the "test" yet.
I ordered 2 more FRPS and the Kenny Bell disc to dampen the spikes and will be back at a rental in a little over a week. Maybe I will have a little better luck, I'm due.
Sometimes the simplest minor miscalculation or two or three can really bust your balls, but we all know that right.
I was using a 26" tire on 16"x10 Bogarts on my stock IRS that I had made and was told to ask for the 03-04 Cobra backspace. I was told that particular wheel had a 6.5" backspace by someone else that got them, but what I had was actually 6.25". The 16" wheel would fit with no grinding, a 15 meant you would have to grind IRS knuckles, so I went with the 16's. I mounted 26x11.5 ET Streets on them and they worked great and when I switched to the 4.10 gear I was trapping 122-124 around 6200-6400 right at my shift light, just perfect. I got over 120 passes on those Streets before they started to act like they were toast, so I needed new tires to match my new setup.
Last winter I planned finishing the build up that was to add another 50 blower horses and 100 or more NOS ponies. I was worried that trapping 130-132 would run me out of gear. My calculator said 27" was better but I couldn't find much in that size for my wheels or for 15" for that matter. I talked to a couple of track Rats that were using 28" on big blower cars, I never got into the specifics of the backspace or how wide of a 28"x15 tire they were using, just that they worked with their solid converted 600+hp Cobras. I ordered a couple 28"x16x12.5 before my 9" was even installed, what a mistake.
My NOS is windowed into a second stage (4000+rpm) so my launch horsepower did NOT change enough (470 to about 510-520) to handle that tire because a 2" jump is HUGE, top speed really should have never been a concern of mine, just run out the backdoor on the limiter, if it will mean a better launch and the right gearing for a quicker 60ft!
The mistakes didn't end there. I swapped my IRS out for a totally built Moser 9" and I did some string measurements and as far as I could tell it seemed about 1/4" wider, so that didn't seem significant but I think it is closer to a 1/2" which is. Well my best 60ft with the old stock IRS setup was 1.60, I thought that was good but I knew when I could not get a better 60ft with the solid, something was up.
I was getting NO weight transfer out of my new rear suspension w/50-50 Lakewoods, a rule of thumb pinion angle and a custom made, under axle anti-roll system. I couldn't understand it, everything was just like it should be. Well I wasted 3 times to the track before I realized my only friggin problem was that my tires were hitting the back of the rocker area, below the side scoops in the fender well with my built for IRS wheels that were now sticking 1/2" farther out. They were not clearing it so it was like having a bump stop and would unload the rear spring and dead bog unless I had so much air in there I would start spinning before the weight transfer. I saw the rub after the very first pass with the 28"ers but it was such a flat area with no risk of cutting the tire, I didn't pay it much attention, until we started studying launch movies.
It doesn't stop there, none of my mistakes are solo, I like to Cluster my F-ups!
Because I tried to use my 16" wheels to begin the testing of my upgrades and wanted to wait and save a few pesos before getting 15" Bogart $$ replacements to use with the solid axle (15"= more tire choices and MORE SIDEWALL!) I ended up buying a set of tires I can't use. I knew I needed STIFF sidewall slicks to use with my heavy clutch, stick and 6K+ dumps but I had already dropped a bundle so I ordered 16" ET Streets, there were no choices for 16" other than soft compounds, so I figured maybe I would try another DOT slick like I before. Well they not only twisted on the wheel when I hit them, they would also fold the sidewalls, just look at the pictures below.
It was time to sack up, about $1400 worth of my nut sack to at least try to eliminate the possible tire issue before getting crazy with the suspension that seemed to be setup correctly ( I had other racers check out all my upper and lower lengths, pinion angle, etc.. ).
Well I measured up how much room I had behind the wheel with my 6.25 backspace wheels and decided that for my particular solid, I could run a 10.5" wheel with a 7.5" backspace in the bolted RT pattern (barrel clearance is also dependent on style wheel). That moved the inside of the wheel in a full 1.25" and the outside lip in .75" and I added another .5" in wheel width. I wanted to run a tire recommended for a 10" wheel on a wider 10.5 because that is another way to have a stiffen the sidewall. I then could run the 26x10x15 M/T Drag Slicks in the Super Stock Stiff Sidewall pattern. I also drilled them for screws and run 8 on each side. I think they tuck under much better and have about 1/2" clearance on the backside of the tires.
PART2
Can you tell which one is the Stiff Sided? You can almost see where it was bottoming out.
problem solved. 1st launch at a conservative 5K and with 12lbs which was too much air, I got a 1.56 60ft. Even though the NOS didn't spray more than 1/2 of one gear (another problem, don't ask that is another post) I ran a pig rich pass with 4 degrees of timing pulled for nothing, but still ran an 11.02 best, all because of that 60ft. I then put the blower only tune in, dropped down to 11lbs air. I got really psyched in the lanes to get my 1st 10, so launched like a man at my 6500 rpm 2step. This was the 10th or so pass on my new but broken in RAM race clutch so when I dumped on a set of tires that behaved, it came up so hard it freaking caught me by surprise. I was looking up and grinning so wide I missed my shiftpoint, it comes fast with 4.11's, I have to start to shift into 1st BEFORE the 6400 shiftlight! So I thought I would fix that by then missing the gear completely, good thing I was granny shifting, instead of power shifting like I normally do or I would have missed that opportunity to spike the fuel pressure and blow my first FRPS in over 2 years. I bailed on the pass soon after that, because it started to run like sheeit but not before my upgraded BAP-> FPDM-> GT pumps-> fiore hat-> 8AN-> CPR modded rails-> 60lbers drowned my serpent so bad it stalled and wouldn't start before I could get back on the return road. It was flooded so bad it was belching gas back out the intake so the 04Snake got to ride the winch onto my trailer.
Just another day in paradise, oh and that was after waiting until 4:15pm to get that 2nd pass of the day so I was going to pack it in anyway. I have had a FRPS (Ford's fuel rail pressure sensor) in my toolbox for 2 years that I finally got to use and was already going to change the oil after that track day. That last disaster did net a 1.52 60ft so I was on my way to my first 10, but apparently I haven't passed the "test" yet.
I ordered 2 more FRPS and the Kenny Bell disc to dampen the spikes and will be back at a rental in a little over a week. Maybe I will have a little better luck, I'm due.
