Tire Chatter/Racepak Graph Help

August 22, 2019, 07:43 AM

quote:
Originally posted by Mike Rietow:
You need a two way adjuster on the compression side of the damper/shock with as much down pinion angle as you can get away with and low tire pressures for wheel speed. Run the high speed stiff and low looser/normal so it's not like being on a pogo stick / bumpy tracks, as the rear end slows down.

What's the theory with misaligning the driveshaft?

August 22, 2019, 08:19 AM

Mike Rietow

quote:
Originally posted by Bucky:
quote:
Originally posted by Mike Rietow:
You need a two way adjuster on the compression side of the damper/shock with as much down pinion angle as you can get away with and low tire pressures for wheel speed. Run the high speed stiff and low looser/normal so it's not like being on a pogo stick / bumpy tracks, as the rear end slows down.

What's the theory with misaligning the driveshaft?

A larger rebound damping setting/adjustment window, based on the fundamental initial movement of the rear end.

September 04, 2019, 04:12 PM

Bucky

quote:
Originally posted by Mike Rietow:
quote:
Originally posted by TOP38:
quote:
Originally posted by Mike Rietow:
quote:
Originally posted by TOP38:
quote:
Originally posted by rradracer:
I had same issues this year 1.00 60ft 4.32 with tire shake starting around .15 into the run. my fix was 6 lbs air and tighten the compression on shocks

At .150 into the run is quick different that 0.9 plus or minus! Rear end is not moving at .9 out and the car should be up on the tire well before this point so shock settings won't fix this, air pressure may have some impact but I wouldn't bet on it.

In all due respect, You're looking at it from an aspect of an adequate damping system, when the cause of the shake is the result of a inadequate damping system, resulted by an out of phase imbalance between the two tires ,,,, tire shake. This is an objective fact anywhere the shake occurs early in the run.

A guess a shock travel sensor would answer the question..............

No sir, it's an objective fact shake is an out of phase imbalance between the two tires resulting in inadequate damping, high damper shaft speeds of 20-30 inches per second during shake, so we know the rear end is moving un-dampened/uncontrolled. This is an objective fact anywhere the shake occurs early in the run. .

What about mono shock cars with stiff antiroll bars? A shock can't distinguish one tire from the other in that case.

September 05, 2019, 01:42 AM

Mike Rietow

quote:
Originally posted by TOP38:
quote:
Originally posted by Mike Rietow:
quote:
Originally posted by TOP38:
quote:
Originally posted by Mike Rietow:
quote:
Originally posted by TOP38:
quote:
Originally posted by rradracer:
I had same issues this year 1.00 60ft 4.32 with tire shake starting around .15 into the run. my fix was 6 lbs air and tighten the compression on shocks

At .150 into the run is quick different that 0.9 plus or minus! Rear end is not moving at .9 out and the car should be up on the tire well before this point so shock settings won't fix this, air pressure may have some impact but I wouldn't bet on it.

In all due respect, You're looking at it from an aspect of an adequate damping system, when the cause of the shake is the result of a inadequate damping system, resulted by an out of phase imbalance between the two tires ,,,, tire shake. This is an objective fact anywhere the shake occurs early in the run.

A guess a shock travel sensor would answer the question..............

No sir, it's an objective fact shake is an out of phase imbalance between the two tires resulting in inadequate damping, high damper shaft speeds of 20-30 inches per second during shake, so we know the rear end is moving un-dampened/uncontrolled. This is an objective fact anywhere the shake occurs early in the run. .

Mike

Shake and chatter are two different animals. Once a car goes into real tire shake, all bets are off and the only option is to lift and try again. So under real tire shake, the kind that breaks chassis, I could believe your 10 to 20 IPS shock speeds.

But in this case, there is no way shock speeds are even close to 10 never mind 20 IPS. Not to mention that a car with this kind of power should even be able to "Shake" the tires,,, unless they try too with a crazy setup. Promod power levels can and do drive into tire shake this far out but not these deals. And yes, this is my opinion just like yours.

The track conditions where not good on the run shown, even the 1-2 gear shift upset the tires.

Based on the data presented and info listed here so far, I can tell you one thing for sure! There are way more questions than answers at this point!

50 plus IPS in extreme cases of shake on a Pro Mod. In a hypothetical race with the same shake in both lanes whatever the IPS may be as example. The damper/shock on the car that recovers quickest, in turn gets to the finish line first and is the superior damper/setup. The winner. For this reason and because a fairly high percentage of these races are decided in a similar fashion to some degree, no expense is spared. The difference between a high technology damper/shock and low, is it's capacity to build force at high frequencies/shaft speeds.

September 05, 2019, 08:44 AM

DragRaceResults

All this shock dampening technology and setting come into play 'IF' the spring is light enough that the shock actually moves during the run.

The problem is that the spring is so stiff it doesn't move in which the dampening is a mute point.

Needs a lighter spring before he can go any further. He has put a lighter spring on and been to Penske (he lives in Michigan), and has had the shock gone thru. Last I heard he has been real busy and hasn't been back to track with this car.

SL...

September 05, 2019, 09:16 AM

Bucky

I think we could all agree that the shock is at least one part of the equation, but certainly not the only part.

September 05, 2019, 09:57 AM

Mike Rietow

quote:

What about mono shock cars with stiff antiroll bars? A shock can't distinguish one tire from the other in that case.

In any scenario the energy created by the shake not absorbed by the damper is absorbed through the system of attachment, the same as a hard tail, no damper.

September 05, 2019, 11:40 AM

DragRaceResults

quote:
I think we could all agree that the shock is at least one part of the equation, but certainly not the only part.

Well he asked about the shock. I guarantee, like Casman a converter change could also be made to help this situation but it sounds like he wants to go fast and I guarantee he wouldn't like it.

He!! he has MTs on, from the internet they don't shake so I'm not really sure of the issue.

SL... just say'n

September 05, 2019, 12:16 PM

Bucky

September 09, 2019, 08:24 AM

Bucky

Anything new from this car?

September 09, 2019, 08:41 AM

DragRaceResults

I hope he will get on here and get us an updated. He won the $5k Shootout at the ACE Ohio event this weekend. I'd say the car must at least be better.

September 09, 2019, 11:55 AM

NC3x58

quote:
Originally posted by DragRaceResults:
I hope he will get on here and get us an updated. He won the $5k Shootout at the ACE Ohio event this weekend. I'd say the car must at least be better.

I know I watched the car Friday night and took a slo-mo, the car looked fantastic!!

September 09, 2019, 12:22 PM

Sparks3224

350# spring and some tuning from Eric at Penske did the trick! Car ran great all weekend. Still have some tuning to do when sun beating on track but overall significantly better! Graphs and feel are both better.