I'm sure there is something already out three about this, but.........

what-if any-are the performance differences in a small vs a large spur gear on an oval?

Thanks,
Al

Every few months someone asks this question, if you use the search there will be few threads already talking about this.

A gear ratio is a gear ratio is a gear ratio. That being said, changing the spur size can have tuning benefits such as where the motor sits in the pod @ a certain roll out. Smaller spur means smaller pinion and that means less rotating mass. Big spurs and pinions have a better gear mesh. Smaller spurs are less likely to be damaged in a rear end collision and less likely to hit the track and be damaged.

I believe if you

increase the spur teeth = more acceleration/less top end
decrease the spur teeth = less acceleration/ more top end
increase clutch bell teeth = less acceleration/more top end
decrease clutch bell teeth = more acceleration/less top end

I think thats how it works

http://www.hobbytalk.com/bbs1/showthread.php?t=244008

This thread has every opinion (or fact if I posted it :p) you could ever want on the subject.

LOL, we all know this one could get messy...HAHAHA.

Some will say a ratio is a ratio.

IMO smaller spur more top end. Bigger spur more out of the corner. This is just my opinion with track and dyno testing. And all the Trinity team guys back in the day said to run a big spur. They all ran 128's, and kicked everyones but...

Joel White

as long as you use a PRS spur and pinnion you can't go wrong! i love these threads!

Just like everything NEW and GOOD - reruns are a part of life.

Don't bash on the new guys for asking what is a NEW question to THEM!

You ever try to search for things here? Sometimes it's a PAIN in the BUTT!

It's much easier to ask all the EXPERTS that will give you 2 dozen different answers!

Just like everything NEW and GOOD - reruns are a part of life.

Don't bash on the new guys for asking what is a NEW question to THEM!

You ever try to search for things here? Sometimes it's a PAIN in the BUTT!

It's much easier to ask all the EXPERTS that will give you 2 dozen different answers!

:thumbsup:

Just like everything NEW and GOOD - reruns are a part of life.

Don't bash on the new guys for asking what is a NEW question to THEM!
You ever try to search for things here? Sometimes it's a PAIN in the BUTT!

It's much easier to ask all the EXPERTS that will give you 2 dozen different answers!
That's right.

Old problems never die. They just get rediscovered by people without the experience to solve them.

I found this to be helpful.

http://www.hpiracing.com/graphics/instr/savagegears.jpg

It isn't extensive but it has enough info. to help get the point?
Just look at what happens when the spur gear changes and the clutch bell changes. (yes, i know it's for a savage, but it should still apply)
Hope it helps.

LOL, we all know this one could get messy...HAHAHA.

Some will say a ratio is a ratio.

IMO smaller spur more top end. Bigger spur more out of the corner. This is just my opinion with track and dyno testing. And all the Trinity team guys back in the day said to run a big spur. They all ran 128's, and kicked everyones but...

Joel White



+1 for joel.. bigger spur quicker out of the corner smaller spur faster top end

-1 for both of you actually :p

http://thenastyboys.files.wordpress.com/2008/11/train-wreck.jpg

Was that train running small gears?

I'm trying to figure out what spur gears and train wrecks have in common! :confused:

I'm trying to figure out what spur gears and train wrecks have in common! :confused:

Keep following this discussion...it always ends up looking the same. Well, at least the last 10 or 20 times it was brought up anyway. How about a useful thread on roll centers or something that will actually make you faster?

.... How about a useful thread on roll centers or something that will actually make you faster?

well.... go ahead :rolleyes:

well.... go ahead :rolleyes:
You can lead a horse to water...

You can lead a horse to water...

....But a pencil must be lead...

http://home.scarlet.be/~be067749/58/

....But a pencil must be lead...

led :p

Keep following this discussion...it always ends up looking the same. Well, at least the last 10 or 20 times it was brought up anyway. How about a useful thread on roll centers or something that will actually make you faster?

I'm just going to do testing at our next club race.

I adjust the Associated front-end to lower the roll center.
Front CGH is .291
Should be interesting.

Any man can lead a horse to water,but,if you can make him lie on his back and float,then you've done something:thumbsup::thumbsup:

I'm just going to do testing at our next club race.

I adjust the Associated front-end to lower the roll center.
Front CGH is .291
Should be interesting.

ROSS WHAT ARE YOU TALKING ABOUT??? AND HOW DID YOU COME UP WITH THAT MEASUREMENT AND WHAT DOES IT MEAN???? PLEASE EXPLAIN I GUESS WE WILL SEE ON SUNDAY IF IT HELPS YOU.. BUT I AM SURE YOU WILL SEE 2-3 KSG CARS IN THE TOP 3... THATS HOW ITS BEEN FOR THE LAST 2 MONTHS..... KSG IS WHERE ITS AT.... JUST BUSTIN YOU DIFF BALLS BUT REALLY WHAT IS THAT MEASUREMENT AND HOW DID YOU COME UP WITH IT......

Dave Front Roll Center is relatively easy to calculate it's the intersection of extended lines drawn along your left/right upper and lower a-frames. Rear roll center on a T-plate style pan car requires a fully charged and peaked calculator.
Center of gravity is completely different and requires several more complex calculations, maybe Ross can show us the formula/technique he used.

I use a formula to find CGH of the car using four scales.
Two part formula.

E is center height of rear wheel in inches
WB is wheel base in inches

Im working on putting this and other formulas in the Excel program.
Testing it out and see if I find any patterns or changes in the cars handling.

omg

I just shut one eye and tilt my head side to side and when it looks right I throw it on the track no wonder I am so slow!