Rotational weight

[bobtile]

Is it true that 1x static weight is = to about 10x in rotational weight?

Maybe I phrased that wrong.
example:
If I took 5 lbs of wheel/ tire combo off the car, would that equate to 50 lbs. or .05 on the track?

 

[Cranky]

Don't know what the equation is but yeah, taking off 5 lbs from each wheel can make a difference. Also, a car that's heavy on the ends reacts slower than when some of that same weight is more towards the center of the car. I've heard it called the bar bell effect. Move the weight to the center, and the bar becomes easier to rotate. Why would you want the car to rotate on the launch? That's simple.....

 

[bobtile]

React how? wheel speed?

 

[SUPERSTOCKRACER]

I go slower running tubes over tubeless by .07
does that help?

 

[Cranky]

Usually when a car pitch rotates quickly, it's going to plant the rear tires quickly also. Heavy wheels or not, quicker pitch rotation is usually better than a car that has a slower pitch rotation.

 

[bobtile]

I go slower running tubes over tubeless by .07
does that help?

NO

 

[Cranky]

I go slower running tubes over tubeless by .07
does that help?

What do tubes weigh? About 5 lbs per slick?

 

[dvw]

I took 7lbs of rotating weight out of the trans this spring and picked up about .10 & 1 mph in the 1/8th. No mph gain in the 1/4 though.
Doug

 

[SUPERSTOCKRACER]

I took 7lbs of rotating weight out of the trans this spring and picked up about .10 & 1 mph in the 1/8th. No mph gain in the 1/4 though.
Doug

I thought it was from the modified accelerator rod on the carb? lol
What did you take out of the trans. to lose 7lbs.

 

[bobtile]

I thought it was from the modified accelerator rod on the carb? lol
What did you take out of the trans. to lose 7lbs.

Trans fluid.

 

[Badvert65]

I went from a 7 blade clutch cooling fan to a 5 blade clutch fan because it was 2.2 lbs lighter.

 

[bobtile]

I took 7lbs of rotating weight out of the trans this spring and picked up about .10 & 1 mph in the 1/8th. No mph gain in the 1/4 though.
Doug

With that in mind, if I go to a 235 rear dr as opposed to the 275, I would be 10lbs. rotational weight less which should gain me .10 in et. As long as I don't have a traction issue. Interesting to say the least.

- - - Updated - - -

Aluminum drive shaft perhaps?

 

[SUPERSTOCKRACER]

With that in mind, if I go to a 235 rear dr as opposed to the 275,

- - - Updated - - -

Aluminum drive shaft perhaps?

Are you talking 1st gear. Stock is 2.45.
that A &A piece I got you was 2.45

 

[bobtile]

Are you talking 1st gear. Stock is 2.45.
that A &A piece I got you was 2.45

No, I'm talking about tire size. My 275's weigh33 lbs and 235's weigh 28. 10 lbs rotational weight total

 

[Cranky]

Lighter small diameter parts help but it's the larger diameter lighter parts that help the most so an aluminum DS might not do much but it will help in unsprung weight.....at least the back half of it will the most.

 

[dvw]

Had an A&A billet drum. Replaced it with aluminum. Also put the sun shell on the mill and got just over 1lb off it, just over 7lb total. I've done shocks, ladder bar, accel pump, timing, air pan, trans stuff since last year. Started out 1.36/6.10@114,9.42@143+. Now 1.29/5.77@118.4,9.12@147.6. By far the two biggest gains were the air pan and the trans stuff. Haven't touched the engine valve lash or cam timing, yet.
Doug

 

[Cranky]

Had an A&A billet drum. Replaced it with aluminum. Also put the sun shell on the mill and got just over 1lb off it, just over 7lb total. I've done shocks, ladder bar, accel pump, timing, air pan, trans stuff since last year. Started out 1.36/6.10@114,9.42@143+. Now 1.29/5.77@118.4,9.12@147.6. By far the two biggest gains were the air pan and the trans stuff. Haven't touched the engine valve lash or cam timing, yet.
Doug

Good info! How much does the car weigh?

 

[Budnicks]

any rotating mass that's lighter will help,
overall weight loss 1st off & ease of getting to power quicker/easier,
less wear & tear too...

I don't remember the ratio or formula,
it might be as high as 5:1, doesn't matter really,
rule of thumb
any rotating part it seems the lighter the better/quicker it will run,
mph is effected more from HP increases, more than ET is most effected by/in weight...
if that makes any sense ?

 

[bobtile]

Yep, makes perfect sense.

 

[Canyon707]

Someone had mentioned to me about setting up some better air flow on the front of my 68rr. I think some better air flow under thr front end may help. He also mentioned the wheel wells also. Looking at that but thats a tough one not sure just how to get that to flow smoother. I am doing disc brakes in the front as we speak and that should save a good amount of weight. On my 04 viper the whole bottom is an al. sheet.