Bernhard

herkguy

Great vid, daily vs racing tire…what a difference.

anoldsman

Amazing setup!

OLDSter Ralph

While the "tire prep" can make a difference in traction, it takes more than tire prep to pop wheelies.

I do find it interesting that he does a couple short dry burnouts when competing and not spinning the tires in the "water box". The metal screws in the rim, low tire pressure, using inner tubes and short, dry burnouts is "old school" stuff that still works. Tire compounds have changed over the last 50 years too.
.....Just my two cents worth.

Bernhard

Notice the wheel screws were all on the inside of the rim. I'm sure they have removed all the stiction from the suspension and the spring rates and shocks are dialed in.
There is major money involved in that operation.

OLDSter Ralph

Yes, but I thought I saw one tire in the video that had them on both sides. If the rules permitted, I would have them on the inside and the outside. I used a lot fewer screws.

Whats "stiction" ?

Yes, there is major money involved. But, you need "major power" to pop the front wheels.

Rallye469

Wish I had that kinda of time to JUST deal with tire set up.
Its obvious this is his full time hobby.

Still…fun to watch.

Bernhard

Stiction is friction in motion, in this case I was referring to the control arms travel. Most likely these cars can be push with one hand in the lanes. I'm quite sure that the rim screws have to be kept on the inside of the rim to stay in the spirit of stock appearing. There is one build going together right now that is running large as in massive dome pistons, it will be interesting to see what that engine produces.


[QUOTE=OLDSter Ralph;1555751]Yes, but I thought I saw one tire in the video that had them on both sides.

You right watched the video again and the Vette has screws on both sides of the rim. I agree I would rather have screws on both sides and fewer of them, just like the way we used to run them. Why they were on only one side of the Camaro ?

New2oldsw30

Ya Pennyington's sure have the Vette stuff figured out. I'm actively looking for a '69 Vette to put my F.A.S.T. style ZL1 in and was thinking to send the chasses to them to do the suspension stuff. Not sure if Lane or Dave, being leaf spring guys, would help people out with there suspension stuff, or know where one with leafs could send there car to get the chassis sorted and baselined?

Bernhard

Have you joined the stock appearing Facebook group?

Good luck with your new project the times that the cars are running on small tires are impressive.
Did you see the posts about the 69 Vette that went sideways in the top end and ended up in the barrier. The one positive is that car was well built with all the safety upgrades, so driver was able to walk away. He has already started a new build, you have to admire the perseverance in racers.

New2oldsw30

Bernard, I don't do facebook, so no. My car won't "fit" there rules as I used headers and the intake is a '72. I believe the "parts" had tp be within 1 yr of the claimed yr your running.

83hurstguy

It's actually the opposite. Stiction = static (starting) friction. If the suspension is stuck in place and won't articulate, you don't have a chance in hell of getting it to articulate and work.

83hurstguy

I don't think you'll get much out of Lane or Dave unless you're sending a Mopar to Dave to get work done.

The ZL1 camaro had springs from Landrum in it, I think. Landrum has a lot of GM options, but weren't going to work for the Mopars we have. I have my own homebrew leaf spring setup made with extra parts from the local driveline shop and homemade clamps. I actually had a shock start leaking from the bending forces from spring wrap when I was using stock leaf springs to try a "softer" setup to absorb the hit.

Bernhard

Thanks for the correct explanation of the term.

CANADIANOLDS

I had to look up what stiction means…and I found out, nobody has a clue.

it sounds sexy…but in true technical and engineering terms, the word is hotly debated.

the best and most realistic use of the word means the breakaway force needed to overcome static at rest friction. it’s used most to describe the breakaway force needed to move the front forks on a motorcycle….when i googled stiction, that came up the most. the seals in the front forks of a motorcycle need to seal the fluid,, the friction from the seal on the shaft itself needs more force to move than they do to keep moving once the breakaway (stiction) force is overcome.

another thing that came up a lot was the force to break free a valve to get movement. they called it static or kinetic breakaway force..we’ve all experienced it…trying to break something free,?/‘s then, bang, the force drops dramatically once broken loose.

so I don’t know what stiction has to do with these types of cars? for one, all the automatic cars are brake torque’d to preload the suspension..you can’t shock these type of tires…they’ll go up in smoke. they need to have to TQ applied gradually…the stick cards are no different…no way is dumping the clutch gonna work…they are ridding the clutch the best they can to make sure the tires don’t break free..if they do, it’s over. that’s why the majority are automatic.

These types of tires need to lose rubber as they go down the track. the loss of rubber means they are bitting into the track , putting down rubber (losing it from the tire) while moving forward….there is no other way to move the car forward without losing rubber from the tire and putting it into the surface of the track…the narrower the tire, the more rubber loss there needs to be to move the car.

the suspension is critical..it needs to have the instant centre perfect which forces the rear axle into the track…that’s my theory. 😂😂😂

CANADIANOLDS

Stiction is a new word which was invented in the 40’s by someone.

it’s not really an engineering term…you’ll find engineers arguing about what it is online. just ask,,you’ll get torn to shreds.

the word is a combination of STatic and frICTION ... it’s the difference between no movement and movement…I think?

I’m not an engineer..thank God for that

CANADIANOLDS

You dont want the tire to breakaway…a perfect run down the track would have the tire roll the exact amount of its circumference to equal the length of the track..zero slip or spin.

that’s called perfect traction…but we all know that’s not gonna happen. in todays world we have driveshaft sensors and wheel sensors that tell us the amount the wheel/ driveline rotation relative to the track…we can reduce power from the engine to be just on the edge of breaking traction/contact with the surface of the track…

it’s the same with breaking ..to get maximum breaking traction to produce the minimum stopping distance…there needs to be no loss of traction ..no lock up..if the tire locks, or is just past the breakaway/traction point..it’s game over

Bernhard

Bernhard wrote:
One place the word is used is in the class racing world when describing the force required to move the control arms. You have the initial force to get the arms to move stiction. There is increased friction through out the control arms travel when using stock unmodified bushings. Some class cars are running Del-a-lum bushings. The old school method is to grind off the serrations on the upper control arm bushings. The control arms bushings are run with out side pre-load to allow the arm to move freely. The reason they do this is to allow the front end to move freely aiding in weight transfer and planting of the rear tires. Dale you already know this. The word might be new to the hobby, but the practice of lowering it goes back to the late 60's.

CANADIANOLDS

Dp

CANADIANOLDS

the del’s are still bushings with a lot of contact area. needle bearing inserts are way better. These lubed with oil, not grease. Stiction gone

83hurstguy

Static friction is pretty well defined. For the friction force calculation, there's a different coefficient that is used to define the friction force between two surfaces not moving, compared to dynamic friction which occurs once the objects are sliding. We dealt with stiction a lot more on cars that handle compared to drag racing, because every time you go through a suspension transient, it's present at the start, which can upset the car's balance.

Just because the car is preloaded on the converter, stiction is still there because the suspension isn't moving, and sometimes the force applied through the rear links could make it worse (like pushing down on a sanding block before it's moving). What matters is the motion as soon as you release the brakes and want the suspension to start planting. If the rear doesn't want to separate or the front to come up, you get no benefit from the transfer, unless you're lucky enough to have more than enough tire for the power level or great track prep.

Bernhard

Nice!
Do they fit GM A body control arms? I know that you have to run the pre 69 lower if you run the Del-a-lum as well as other lower friction bushings.

Bernhard

Luke thanks for the engineering term lesson and there proper application.
How did you have your 68 Hurst set up to run on the stock tire?

CANADIANOLDS

the TQ converter being loaded isn’t the same as the rear suspension being preloaded. These cars don’t leave off a trans brake . The automatic cars leave off a stutter box and a foot brake or a combination of that and timing retard that is gradually put back in as the car accelerates.

the tires can’t be hit without suspension preload or they’ll break the tires loose. one of the fastest cars has no rear body separation at all..infact, it actually squats a bit in the rear ..the front does rise and transfer to the rear.

here’s three pics and a vid of the Camaro leaving. Pre stage no suspension preload, staged with rear suspension preloaded you can see the suspension get pre loaded and the rpm’s change with slight body separation , and third the leave. watch the vid from about 19.00 min point , there’s a secondary vid of the leave.

the rear is already at max travel and does not separate any further as it leaves..watch top of wheel well.