Does size matter ?.
 

Now that i have your attention :lol:.

My ? is about spur gear size inrelation to pinion size . To get the ratio i need i have to use a 66t or 60t spur with a larger pinion . The car comes stock with a 72t spur . I cant use the 72t spur & get the ratio i need . So how does the size of the pinion in relation to the size of the spur affect torque & top end ?.

A smaller spur, or larger pinion will increase top speed. A smallre pinion or larger spur will decrease top speed and increase torque via gear multiplication.

On a side note, I always think it is best to use the smallest spur and largest pinion to achieve the correct ratio. That way you will see less pinion wear, and the gear mesh is greater at any point due to better engagement of the teeth. Anyone who has run a very small pinion with a large spur can attest to the fact that is does not feel as smooth as a larger pinion with a smaller spur.

This mainly applies when you have different diff and tranny ratios to choose from. I noticed it quite a bit when I put my slayer together. Because I am using a revo tranny, which has more reduction than the slayer tranny, I had to run a much larger pinion. I currently have a 20t pinion with a 36t spur, and it runs very smooth and can be set up with very little backlash in the gears.

It is all about the end-to-end drive ratio for torque & top end... Size doesn't matter Linc will be glad to hear

I believe Mod1 tooth shapes do slightly change with smaller pinions to get a good mesh and hence agree with linc that 16+ pinions tend to have a nicer mesh....

What i did'nt know was if the torque or top end was affected if a larger spur & small pinion were resversed & it was a larger pinion & smaller spur . But bill at associated jsut told me if the ratio is the same it doe's not matter if it's a large spur & small pinion or the other way around . Also im talking about 48p gear in my tc4 .

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thank's chris i just saw you repliy :smile:.