Blown Auto-Slicks -Stiff or Soft sidewalls

G'Day, I was after other racers experience with slicks on Altereds/FC running blown autos. I am running a 125'' altered with a blown SBF with powerglide standard 1.76 1st and 4.11 diif gears. I have been having issues with tyre shake when I step up the tune.

I was running M/T 33x16.5x15 (3804) and tried them with tubes and without tubes. I found that I was suffering aloy of shake with this tyre no matter what pressures I tried from 4.5lbs to 8.5lbs. I then put a set of Hoosier 32.5x16.5 (18300) and did not have the shake issues as much as the M/Ts. The car runs alot better with the Hoosiers but I have started to get tyre shake back as I step up the tune.

I noticed when I changed the tyres that the Hoosiers where alot stiffer in the side wall than the M/Ts. M/T make a stiif wall tyre in the 33x16.5x15 which I am thinking of trying with back to back passes to see how it changes the car in regards to shaking the tyres. I was also going to change to 4.3 gears in the diff to see what that does also.

Car has run as fast as 7.001 @ 195 mph weighing 1990lbs. What are other racers running for tyres with blown P/G combos. All replies would be much appreciated.

Thanks Lyle.

 

I run BBC with 1.80 first gear, 7,000 stall, leave at 4,000 no throttle controller 5.25 lbs of air with a 36x17x16 Good Year D2 beadlocks 6.70's 2200lb altered.

 

Mickys like beadlocks, they have a soft/flimsy sidewall and beadlocks stiffen it. I heard that Mickys were designed to run with beadlocks, the 34.5 size anyway. Do you run beadlocks? You may have to hop it up till it blows the tires off and then back it down, most tire shake is from lack of wheel speed, which is another way of saying you don't have enough HP ( Or gearing). When you run 7.00 sec. and slower tire shake is not an issue because not only do you not have enough HP to spin the tires you don't have enough to make them shake. Thats why bracket racers never have tire shake no matter what size tire they run..... no big HP. (I also bracket race and have never shook a tire at 7.00sec and slower and I've run just about every combo out there) So hop it up some more, there's no such thing as to much HP. LOL Hope this helps.

 

roar... what rear gear ratio are you using? what stall in the converter?

 

Just changed rear end ratio from 4.11 to 4.30. Converter is just over 6000 rpm according to playback from taco. Leave the line at 2000rpm.
Lyle.

 

May want to try leaving harder, at 2000 rpm's it just flashes the converter more and makes it more violent. Like the other post said 4000 rpm's should be about right. In my blown dragster with a glide I leave at 3800 to 4000 rpm's.

 

Roar the other thing you have to watch for with the Mickey Thompson tires is they make two versions. One for a converter car and one for a clutch car. Like Jody said use the converter tires on bead locks and leave harder. I leave around 4200-4700 rpm and flash my converter to around 6100 rpm. This is in a 511" blown hemi with a 3 speed Lencodrive.

 

gotta agree with jody on this... man if you really have a 7,000 stall and you are leaving at 2,000 (basically idle on a blown motor) then you are giving the engine a huge 'run' at that converter... couple that multiplication with the gearing you already have and i would imagine the thing is trying to shake/smoke the tires/leave the earth/etc... am i close? and in that scenario moving the pressure up and down just makes it seem even more unpredictable? just a guess

on a deal like this i would highly recommend two things for sure: one is a basic pneumatic throttle controller. it'll allow you to consistently set the engine at a stage rpm that won't flash the converter (4,500?) and it will allow you to control blade opening speed to suit the track/conditions. two would be a suggestion in the gear department... and this is totally dependant on how aggressive your motor combo is... you might be happier with the 4.11 (and possibly even higher)? i only say this because 33/32" tires tend to make your overall first gear ratio pretty damn aggressive

just my opinions here bro... hope it helps

fwiw... i have a 125" altered, bbc, mike's glide, 3.90 ratio, 3,000 stall, throttle controller and i run the goodyear d2072 (which is a softwall/high growth tire) and i've run it with both blown alcohol and 90% nitro set-ups...

on a converter car the throttle controller will be your friend

 

yeah right JT... kinda like a left and right handed hammer?? i've fallen for that one before!! like we're supposed to believe your BS?!

only kidding bro... see what this winter shit is doing to me!! i'm going crazy... cuz heslink's hot rod hauls the mail!!

 

I was going to ask if anyone thinks he went the wrong way when they moved from a 4.11 to a 4.30. I would of thought they should drop down to at least a 3.90 maybe even more??

 

Actually Sean they do make two tires and I got stuck with the clutch tire last spring. Couldn't get 60 feet with them. Put the other tire on the car and went 4.12 at 143.

 

is the sidewall the difference? damn that could be a costly lesson for a guy to learn... cause i know if it was me i'd want to make a bunch of runs to try to figure the set-up out. i mean typically it's hard to blame new tires as being bad. although i have seen it a few times.

i'm sure there are horror stories about the chilean goodyears several years back?

 

The converter stall is 6100, and yes when I have had it shake hard it gets all 4 wheels of the ground. I have never tried leaving the line any higher than 2800. I am going to try leaving at 4000 next meeting and I will keep you informed. I do have a printed grahp from the playback taco that I could email you from last meeting. Thanks for the advice.
My email : gilmoreroars@iprimus.com.au

Thanks Lyle.

 

I agree with J.T. .....had same problem at the columbus points meet...m/t switched them and have been running low 6.10's or 4.10 in the 1/8 since then....125"altered lencodrive 4:30 rear,450ci hemi,beadlocs 34.5,leaving at 4000rpm...

 

Big B no offense to you but , I'm not so quick to think he is going the wrong way with the gear.
Lyle did say that this is a smallblock car , He doesn't make the torque that a hemi does . I would think that the 4.30 rear gear might help him get up on the tire quicker and I think the 3.90 with a 1.76 first gear powerglide would drag the motor down too much on the shift.
Lyle if you have a air throttle on the car , you can play with the opening speed ,I would start out by trying to snap the blades open quicker.
This might be apples to oranges because I m talking about a dragster but: when I ran my smallblock 235" "dragster" ,I Had a 4.30 rear gear a 1.80 powerglide and the same size hoosier tires without beadlocks.I would shake the tires when we tried launching at 2200rpm with a 4000rpm stall converter and having the air throttle slowed way down thinking it would help hook the car WRONG! , after that we tried more starting line rpm a 6000rpm stall converter and opening the throttle as fast as it would open and... shazzzam !!! the car hit the tires and left with the front wheels a foot and a half in the air and went 1.03 60 ft. , I know thats not really a great 60ft unless you consider it that I was riding the wheelie bar and breaking the 60ft beams with the rear tires and obviously it did not shake the tires ! If I could give you the video I have of my old car ,you could slow it down and see the car instantly turn the tires one revolution then get up on the tire and hike the front end and go.

 

Altered boy I am still having these shake issues when I hot up the tune,can you give me some more information on where to get and setting up a air control for the throttle.

My email is gilmoreroars@iprimus.com.au

Thanks Lyle.

 

Happy,

G'day mate, good to meet you in Sydney, and thanks for your help with finding parts for my glide..

I think you and i , have very simular power...
Same cubes ,i got 358 but sbc , but we have 'hairdry'ers.."

I run hoosier 34.5-17-16 in the C2055 compound , screwed rims
they 'rattle" abit when down around 5.5 psi, 6.5-7.0 they just 'turn a bit" on the start line,like a pro car, then hook up... it slows the 60ft down a bit ( .05 slower) but doesnot rattle the tyres...

5.5 psi tyres went 7.1 @ 198.8 ... tyre shake
6.75 psi tyres went 6.8 @ 200.29 .... no shake..
C2055 hoosier tyres

3.7 rear end, and "used to" run same 1.76 1 st gear.....
1.03-1.04 60fts
i had a quick look @ your plugs , when you where ringing around on Saturday morning, and yes, your pretty keen on the tune up...

i wonder if you try several things..

loosen the converter ,
taller rear gears,
richen the bottom section of the fuel curve , and then lean it out a bit up top ??

Ken Lowe makes a air cylinder deal, but that isn't legal for comp....

cheers
Ash
BB/AA 75

"Doof Doof " altered....

 

can you get a video of this start line rpm for me please...

 

Hiya Lyle, say hello to Your mum & dad for me. Good to see you here,

 

Lyle, my car came with a throttle controller when l bought it. Should still have all the bits. Pretty sure it is a Bill Mitchell Hardcore set up. Give me a call if your interested and l'll see what l can find.
Damien Scully. 0410 221 272.