What is the largest rear sprocket I should plan for?

[RussMcB]

When I design and build my rear subframe, space will be tight because I'm trying to retain the rear suspension without modifications. The RF94 rear shock and bell crank are competing for the same space as the sprocket.

I'd like to determine the largest rear sprocket circumference that I will want to run so I can plan for it.

Here are some bits of information that might affect it:
- Current stock front sprocket is 17 teeth (which I can change)
- I'll be running regular FC tires - Hoosiers (70.25"?)
- attached is a picture of the Kawasaki gear ratios
- Redline = 13,000? (my engine is stock 2005 ZX-10R)

Here is a dyno graph of the 2004 engine:
http://www.sportrider.com/features/1...yno-1-zoom.gif

I think I also need to determine the track(s) I will be running with the slowest top speed. I'm not sure what those answers might be. Maybe Nashville? 130 MPH?

Thanks in advance for suggestions and thoughts.

[RobLav]

You will need to reduce the sprocket size in the front, and we are figuring a 10.5" diameter max rear sprocket.

About 4 years ago, I downloaded a neat Excel spreadsheet from the SportsRacer site that will help you determine the sprocket sizess for max speed at a particular track. It was lost years ago in a hard drive crash. Ask around over there.

[RussMcB]

Thanks, Rob.

Ask around over there.

Yep, I'm tapping those great minds, too:

http://p081.ezboard.com/fdsrforumcar...icID=943.topic

[Garey Guzman]

An FF can go close to 130 mph at Nashville. Although Nashville has two really tight 180° turns, it has reasonably long "straight".

[stonebridge20]

I used a 16T crank and a 42T drive on most of my customers CSR's here in the Northeast. We use the 42 at Limerock,Watkins Glen,Summit Point. A 40T at Pocono (the longest strait you will EVER see). 44T at NHIS. This is all the gearing we used when I had Jeremy Treadway in one of the cars last year.

car specs: ZX12 10,500 shift point and a 22" rear tire

Agnif

[RobLav]

I had geared my Hayabusa at 16 tooth front and 46 tooth rear - was planning max speed somewhere around 150-155.

[Daryl DeArman]

I aplologize if this topic has been brought up in one of the other links.

One thing to be mindful of is final drive ratios and chain links that will result in rapid wear: Small counter shaft sprockets, chain link numbers that are evenly divisible by sprocket size. Don't use a 120 link chain on a 40 or 60 rear sprocket, or a 10, 12 or 15 tooth front. If you think you need a 12:60 final drive--go with a 13:66 with a 120 link chain.

[sidney]

I have added a little information to it for my own build, but the info can be input to reflect your car easy enough. Enjoy!

[carnut169]

I'd say for design purposes if a 48 will fit with adjustment you are good to go, and you are welcome to borrow my 48-49 or 50!