Hard tail dragster problem

Mike Hedger · 07-05-2007, 09:59 PM

I have been racing my HT dragster for about a year now and before the San Antonio nat. I decided to put a new set of tires on it. I had a 16.5X32.5 Hoosier on it but it was pretty strung at the finishline so I went to a 33X16.5 S Hoosier on it. (Farren at Hoosier put me on this tire) The tire I chose was designed for a HT car but this is where the problem started. The car has a 515" BBC in it that made 825 HP with a 1.80 low and 4.10 gear with an 8" ATI that stalls 5800 (the converter is directly out of my door car)

When you leave the car will wind up the tire and about 10-15 feet out it spins or skips the tires about one revolution. I talked to Farren and he told me to try lowering the tire pressure from 5.25 to 4.75 so I did and it got better, so I tried to go another .25 lb till the car started to handle bad and backed up a step. I am at 4.25 with a CSR gauge now. My problem is it has gotten better but never fixed. It will also do this off of the stop as well, I am wondering if I need to make a converter change etc. Let me know if anyone has any ideas. Thank you, Mike Hedger S/C Q/R 4600

sc1153 · 07-07-2007, 09:37 PM

did you try going UP in tire pressure? To me (not being able to see it) sounds like you are wrapping over the sidewall, and overlapping the tread. On my car (2000 mullis 4 link) i am running a 532bbc about 900 hp, 6500 stall 9" steal stator converter the car runs better at 6lbs of pressure on a 16x33 hoosier. I also had a friend with a hard tail car running 7.50s and ran about 7 lb of tire pressure in the same tires..

give it a shot when it spins go back down a little.....you really need to find a happy medium, dont forget a spin isnt always bad as long as it does it all the time (consistently)

Mike Hedger · 07-07-2007, 09:46 PM

I started with the same pressure I had in the old tires and when it did it the first time I was at a Nat event going into the last TT so I asked Farren from Hoosier for advice and went with it. I have not tried to go up on pressure yet I am going to try another converter a buddy has (the one I put in to try was my spare and after loaning it out it came back broken) So the trans has to come out anyway. I will try the tire pressure up a little at a time to see if it makes any diff. Yhank you, Mike

3993Schmidt · 07-08-2007, 01:26 AM

Sounds to me like the car is trying to dead hook initially, but because the wheel is spindling so far ahead of the tire due to low tire pressure, it has no choice but to loop the tire after the initial hit. I agree that raising the tire pressure would probably help. Launch rpm and convertor will also affect this situation.

Mike Hedger · 07-08-2007, 11:29 PM

I have a race to go to this weekend so we are going to test Friday and see what we can come up with I am going to try a different converter and play with tire press as well. I think I will start at 6.0 LBS and go from there.

Thank all of you that have helped out, Mike Hedger S/C Q/R 4600

SC1448 · 07-21-2007, 05:55 PM

Mike-
How did you make out with your tire pressure experimentation? Results??? I have a hard tail also and would be interested in what you came up with.
Thanks!
-Don

Mike Hedger · 07-23-2007, 10:23 AM

Quote:

Originally Posted by SC1448

Mike-
How did you make out with your tire pressure experimentation? Results??? I have a hard tail also and would be interested in what you came up with.
Thanks!
-Don

Don it has rained here every weekend I have had time to go and the ones it has not rained I have been to busy in the shop to do anything but work. I plan to go this Sat. and find out what a little more pressure will do. Mike

Jason Oldfield · 07-24-2007, 11:45 AM

Make sure you go high enough and then back the pressure back down to it's optimal setting! Ideally, you would like to have the pressure as high as possible without negatively affecting the performance of the vehicle.

I had been running mine between 5.5 - 6.0 psi, but when I switched to M/T and subsequently Hoosier, I found that I could run 8 psi no problem (it's a smaller tire on a 4-link car so I wouldn't necessarily expect the same pressure on a HT dragster with a bigger tire). I never would have thought that I could go that high, but I just decided to keep going up until I saw a dropoff in performance. My dropoff came at about 9 psi, so I settled on 8 psi as a safe pressure.

Anyway, good luck, and look forward to hearing the results...

Mike Hedger · 07-29-2007, 06:10 PM

Well I upped the tire pressure to 6.0 last night (it was night after the 2 hour rain delay) and the tire spin/wadind is better. I went out in the third round after putting the car in a little deep in the beams and going red. You know how you know you screwed up when you staged and now you are married to it? I am going to try 7psi the next time I go to the track and see if it works. Thank you for all the help, Mike

Mike Hedger · 09-16-2007, 11:35 PM

I tried 6.75 last time out and I now know what tire shake feels like. I am sticking with 6.0 and calling it fixed. Thank you for all the help, Mike

07-05-2007, 09:59 PM	#1
Mike Hedger Junior Member Join Date: Jul 2007 Location: Kemah TX Posts: 93 Likes: 0 Liked 1 Time in 1 Post	Hard tail dragster problem I have been racing my HT dragster for about a year now and before the San Antonio nat. I decided to put a new set of tires on it. I had a 16.5X32.5 Hoosier on it but it was pretty strung at the finishline so I went to a 33X16.5 S Hoosier on it. (Farren at Hoosier put me on this tire) The tire I chose was designed for a HT car but this is where the problem started. The car has a 515" BBC in it that made 825 HP with a 1.80 low and 4.10 gear with an 8" ATI that stalls 5800 (the converter is directly out of my door car) When you leave the car will wind up the tire and about 10-15 feet out it spins or skips the tires about one revolution. I talked to Farren and he told me to try lowering the tire pressure from 5.25 to 4.75 so I did and it got better, so I tried to go another .25 lb till the car started to handle bad and backed up a step. I am at 4.25 with a CSR gauge now. My problem is it has gotten better but never fixed. It will also do this off of the stop as well, I am wondering if I need to make a converter change etc. Let me know if anyone has any ideas. Thank you, Mike Hedger S/C Q/R 4600

07-07-2007, 09:37 PM	#2
sc1153 Member Join Date: Jun 2005 Location: Parlin, NJ Posts: 420 Likes: 0 Liked 0 Times in 0 Posts	Re: Hard tail dragster problem did you try going UP in tire pressure? To me (not being able to see it) sounds like you are wrapping over the sidewall, and overlapping the tread. On my car (2000 mullis 4 link) i am running a 532bbc about 900 hp, 6500 stall 9" steal stator converter the car runs better at 6lbs of pressure on a 16x33 hoosier. I also had a friend with a hard tail car running 7.50s and ran about 7 lb of tire pressure in the same tires.. give it a shot when it spins go back down a little.....you really need to find a happy medium, dont forget a spin isnt always bad as long as it does it all the time (consistently) __________________ Chris DePascale S/ST 1531 & S/C 1153....Addicted Racing Jad153@aol.com

07-07-2007, 09:46 PM	#3
Mike Hedger Junior Member Join Date: Jul 2007 Location: Kemah TX Posts: 93 Likes: 0 Liked 1 Time in 1 Post	Re: Hard tail dragster problem I started with the same pressure I had in the old tires and when it did it the first time I was at a Nat event going into the last TT so I asked Farren from Hoosier for advice and went with it. I have not tried to go up on pressure yet I am going to try another converter a buddy has (the one I put in to try was my spare and after loaning it out it came back broken) So the trans has to come out anyway. I will try the tire pressure up a little at a time to see if it makes any diff. Yhank you, Mike __________________ Mike Hedger S/C 4646 MPH Racing and Fabrication

07-08-2007, 01:26 AM	#4
3993Schmidt Junior Member Join Date: Jun 2006 Location: Indy Posts: 41 Likes: 0 Liked 0 Times in 0 Posts	Re: Hard tail dragster problem Sounds to me like the car is trying to dead hook initially, but because the wheel is spindling so far ahead of the tire due to low tire pressure, it has no choice but to loop the tire after the initial hit. I agree that raising the tire pressure would probably help. Launch rpm and convertor will also affect this situation.

07-08-2007, 11:29 PM	#5
Mike Hedger Junior Member Join Date: Jul 2007 Location: Kemah TX Posts: 93 Likes: 0 Liked 1 Time in 1 Post	Re: Hard tail dragster problem I have a race to go to this weekend so we are going to test Friday and see what we can come up with I am going to try a different converter and play with tire press as well. I think I will start at 6.0 LBS and go from there. Thank all of you that have helped out, Mike Hedger S/C Q/R 4600 __________________ Mike Hedger S/C 4646 MPH Racing and Fabrication

07-21-2007, 05:55 PM	#6
SC1448 Member Join Date: Jun 2003 Location: Southampton, PA Posts: 226 Likes: 5 Liked 2 Times in 2 Posts	Re: Hard tail dragster problem Mike- How did you make out with your tire pressure experimentation? Results??? I have a hard tail also and would be interested in what you came up with. Thanks! -Don

07-24-2007, 11:45 AM	#8
Jason Oldfield Senior Member Join Date: Jun 2007 Location: Rochester, NY Posts: 619 Likes: 1 Liked 10 Times in 4 Posts	Re: Hard tail dragster problem Make sure you go high enough and then back the pressure back down to it's optimal setting! Ideally, you would like to have the pressure as high as possible without negatively affecting the performance of the vehicle. I had been running mine between 5.5 - 6.0 psi, but when I switched to M/T and subsequently Hoosier, I found that I could run 8 psi no problem (it's a smaller tire on a 4-link car so I wouldn't necessarily expect the same pressure on a HT dragster with a bigger tire). I never would have thought that I could go that high, but I just decided to keep going up until I saw a dropoff in performance. My dropoff came at about 9 psi, so I settled on 8 psi as a safe pressure. Anyway, good luck, and look forward to hearing the results... __________________ Jason Oldfield S/G & S/St 1838

07-29-2007, 06:10 PM	#9
Mike Hedger Junior Member Join Date: Jul 2007 Location: Kemah TX Posts: 93 Likes: 0 Liked 1 Time in 1 Post	Re: Hard tail dragster problem Well I upped the tire pressure to 6.0 last night (it was night after the 2 hour rain delay) and the tire spin/wadind is better. I went out in the third round after putting the car in a little deep in the beams and going red. You know how you know you screwed up when you staged and now you are married to it? I am going to try 7psi the next time I go to the track and see if it works. Thank you for all the help, Mike __________________ Mike Hedger S/C 4646 MPH Racing and Fabrication

09-16-2007, 11:35 PM	#10
Mike Hedger Junior Member Join Date: Jul 2007 Location: Kemah TX Posts: 93 Likes: 0 Liked 1 Time in 1 Post	Re: Hard tail dragster problem I tried 6.75 last time out and I now know what tire shake feels like. I am sticking with 6.0 and calling it fixed. Thank you for all the help, Mike __________________ Mike Hedger S/C 4646 MPH Racing and Fabrication