Sebring transmission, What gears for me? Options

[Jetsetsurfshop]

Ok Guys, what do you think....
Want to get a racing tranny for my track car with Sebring in mind. What's the best set-up? Is a LSD a good idea? Quaife? How about a cooler? What's an intermediate plate?
Thanks for the all the help, I'm really green with trannys. (IMG:style_emoticons/default/biggrin.gif)

[brant]

Shane,

I didn't do a good job at providing you an answer
like everyone replied, there are lots of ways to do what you are after
and also diminishing returns at some point..

there is perfect, optimum, expensive

and option #2, less expensive, not perfect and better than stock


picking out gears often becomes a compromise
for example the chart might show that a "W" gear would be perfect, but that is an $800 gear and you can often get away with a different ratio that is not quite as good, but only $100

so for my first race trans, I think I was similar to you and trying to learn about transmissions/gearing without breaking the bank

take your longest track or most frequent track.. it sounds like sebring is already the track you've picked. gear for red line at sebring in 5th

I'm guessing that sebring may be your longest track also?

then depending on your current motor state of wear.. you may want to pick ratio's for your current motor redline and power, or for your not yet built.... next motor redline and hp.

usually the 4cylinder has a much lower redline than a 6, which gives you cheaper gear selection usually.

also you can probably get away with only changing the top 3 gears that you mostly use on the track.. that can save you a few dimes too. you can pick 2nd gear also but there are only 3 ways to do it... stock, GA not too bad, and 904= very expensive
So if stock F will work great.. and if not try to see if a GA 2nd will be acceptable for your needs?

you need to pick your 5th gear first and then plan the lower ratio's from there
Ideally the rpm drop between gears will get lower as you shift up... as the torque of the next gear is reduced due to higher speed and wind resistance you want the rpm drops to tighten

so off the top of my head,... my 4th to 5th gear rpm drop is currently only 900rpm
but my 3rd to 4th is slightly more... maybe 1200rpm (I can't remember)

the 4cylinder redline makes this less touchy than a high rpm of a -6. The pro's dyno each motor and pick gears using a dyno result... We aren't pro's so pick redline in 5th and go from there.

once you pick your 5th gear optimum.. then see if there is an affordable alternative and keep doing the same for 4th and 3rd.

I don't know sebring, but people commonly use M-S-X for 4cylinders with close to stock redlines... and a cheap version of MSX is Ka-S-X

my first race box was Ka-S-X with a locked diff, no cooler.

of course differentials, and cooling are more money and a whole-nother topic
and add a lot of money to the basic race transmission
you can likely get away with out them unless you want to spend that much money all at once. differentials add heat... (a locked diff wears out your tires but does not add heat)


brant