so i bought an underdrive pulley awhile back but haven't put it on yet because i have no clue what belt size i need.

when i bought it i just bought the pulley, and that was it so i was wondering what size belt i need if any of you guys know?

 

go to the pettit racing site they have the belts to go with underdrive pulleys im not sure if they have the sizes posted though www.pettitracing.com

 

are all the underdrive pulleys the same size? i'd think so..

 

cf. http://www.banzai-racing.com/

They have a belt size guide for FDs.

 

i didnt see a belt size guide on there, and i have no clue what kind of underdrive pulley i have all i know is that its aftermarket so i dont know if the sizes are the same for all aftermarket underdrive pulleys or not

 

alright just found out its an unorthadox pulley if that helps. not sure if i found the right belt size, will this pulley work with factory hardware or am i going to have to fandangle something

 

Put the pulley on. Then with a string, trace around the routes of the belts. Measure the string to find the length belt(s) you require.

 

good idea

 

i found out what length i needed by mocking up the original belt to the new setup and estimating how much longer i would need to get around the last pulley. and just get the shortest one that will fiton , the alt adjustment will take out whatever slack is there. rcc also has a thread on this with belt sizes listed for different setups but im too lazy to look it up

 

http://www.banzai-racing.com/products_FD_belts.htm