MurfDogg Motor Works Discussion thread
10-28-2010, 11:31 AM
#647
WOW...they are geared WAY different than my B4/T4's are then. I mean if I understand it all correctly (found an article on how to calculate rollout) my B4 should have an approximate tire diameter of 3.5 inches and a final drive ratio of 5.35 (72 spur / 35t pinion x 2.6) giving me a rollout of 0.6542056 inches or 16.616822239982053 mm. Quite a bit different indeed!
10-28-2010, 11:34 AM
#648
WOW...they are geared WAY different than my B4/T4's are then. I mean if I understand it all correctly (found an article on how to calculate rollout) my B4 should have an approximate tire diameter of 3.5 inches and a final drive ratio of 5.35 (72 spur / 35t pinion x 2.6) giving me a rollout of 0.6542056 inches or 16.616822239982053 mm. Quite a bit different indeed!
The mathematical equation for ROLLOUT is-
Tire size (I like to use millimeters) X PI (3.14) X pinion / spur
41.10mm X 3.14 X 51(pinion) divided by 72(spur) = 91.41mm
We use rollout (NOT FDR) with FOAM tires because of our tires changing size from run to run.
Last edited by JayBee; 10-28-2010 at 11:48 AM.
10-28-2010, 11:38 AM
#650
WOW...they are geared WAY different than my B4/T4's are then. I mean if I understand it all correctly (found an article on how to calculate rollout) my B4 should have an approximate tire diameter of 3.5 inches and a final drive ratio of 5.35 (72 spur / 35t pinion x 2.6) giving me a rollout of 0.6542056 inches or 16.616822239982053 mm. Quite a bit different indeed!
I believe most on-road cars fdr's are in the three's
10-28-2010, 11:53 AM
#653
And what you calculated above is exactly right...that's why you were way off. But why are you trying to use this formula with RUBBER tires? Rubber tires don't have the wear that FOAM tires do. Plus camber and caster changes the 'shape' of our tires on our 1/12th & 1/10th scale pancars. Most of us 're-true' (shave down) our tires, so the tire size changes and to maintain the same speed (rollout) pinion size has to increase. A couple of other factors are involved but this is it basically....
Still confused?
10-28-2010, 11:57 AM
#654
Make sense now? So I take it you are saying that I shouldn't be concerned with rollout at all then?
10-28-2010, 12:03 PM
#655
Brah...calm ya nerves. Nothing that I've said and how I've type it should have came across as demeaning. If it has, I apologize. But whether your new or not....I'm explaining.
And yes....If you are running offroad w/RUBBER tires, ROLLOUT doesn't apply to that application.
(I'm smiling at you)
And yes....If you are running offroad w/RUBBER tires, ROLLOUT doesn't apply to that application.
(I'm smiling at you)
10-28-2010, 01:09 PM
#658
Brah...calm ya nerves. Nothing that I've said and how I've type it should have came across as demeaning. If it has, I apologize. But whether your new or not....I'm explaining.
And yes....If you are running offroad w/RUBBER tires, ROLLOUT doesn't apply to that application.
(I'm smiling at you)
And yes....If you are running offroad w/RUBBER tires, ROLLOUT doesn't apply to that application.
(I'm smiling at you) (I'm smiling back). From MY perspective your statement that you were trying to figure out why I was trying to figure rollout on an offroad car with rubber tires wasn't really explaining...it was confusing. So I felt the need to explain myself.
Sorry...text can be taken in so many different ways...I like to use caps and bolds and stuff to infasize things I think are important..it's not yelling or me being pissed or anything. If I was mad or insulted you would have no doubt in your mind, plus I'd probably use the RED smilies!
