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Author Topic:   need help
str8racing
Dirt Full Roller

Total posts: 65
posted April 02, 2005 05:14 PM  
i have a mustang mini stock that i run at a 1/3 rd. mile track and i need some help for more power. i need to run about 6800 rpms. i have a 5 speed tranny have 345 rear end ratio. how do i tell what the 2nd. gear ratio is in my tranny now and what do i need . to make it better. i'm still learning. thanks in advance for help.

FCRA
Dirt Roller

Total posts: 14
posted April 02, 2005 05:53 PM  
First you put your transmission into the gear you want to check. Then put a mark on the input shaft and the output shaft. Start turning the input shaft and have someone keep track of the number of rotations of the output shaft. To find the ratio you divide the number of rotation of the input shaft by the number of rotations of the output shaft. If you don't have a calculator handy, 10 rotations of the output shaft is the easiest, because all you'll have to do is stick a decimal point in your number. Having said that, the higher your numbers are the more accurate results will be, as long as you keep accurate count.

Now that you know how to do it, I'll tell you that my cheat sheet says that you probably have a 1.94 in 2nd and 1.34 in 3rd. You should still probably check it, though. It is good practice.

To figure out what you need, we will also need to know your tire circumferences. Personally, I hate guessing what gears people should run, because I never run the same as anyone else, but I'm sure someone will help you.

Nate Stevens
Four Cylinder Racing Alliance

racerman707
Dirt Freak

Total posts: 374
posted April 02, 2005 06:47 PM  
Depending how good the engine is (especially the head) I would shoot for 7200-8000 rpm. What's your rules?

str8racing
Dirt Full Roller

Total posts: 65
posted April 08, 2005 04:32 PM  
then what do you do with tire size? thanks.

str8racing
Dirt Full Roller

Total posts: 65
posted April 09, 2005 07:46 PM  
i have 60 series tires ontheir now. 77" or can switch to track tires which are about 81" thanks.

str8racing
Dirt Full Roller

Total posts: 65
posted April 10, 2005 07:14 PM  
please help me with the gearing, thanks.

b4racing
Dirt Forum Champ
Total posts: 626
posted April 10, 2005 11:38 PM  
for a 1/3 mile track I would try a a 2.14 and your 345. if that is too mucy go to a 214 and 327 or 197 and a 345. Good luck Bobby

str8racing
Dirt Full Roller

Total posts: 65
posted April 11, 2005 06:49 PM  
how do you change 2nd. gear in the trans. and where do you buy one? thanks.

racerman707
Dirt Freak

Total posts: 374
posted April 13, 2005 09:32 AM  
You don't change the gear, change to another trans. Chack the turns on the trans first to make sure what it is in all gears. Then find gears that come out close to the final B4 stated. Trans ratio x rear gear = final. Ex... 2.14 x 3.45 = 7.38 final

[This message has been edited by racerman707 (edited April 13, 2005).]

str8racing
Dirt Full Roller

Total posts: 65
posted April 13, 2005 07:09 PM  
i guess i'm still confused how do you determine what the final ratio should be? thanks for all you're patience.

racerman707
Dirt Freak

Total posts: 374
posted April 14, 2005 08:08 AM  
Ask somebody at the track you're going to run if they'll tell you the truth. We do it by trial and error. The track we run now we use a 6.24 1/2 mile. Another track we run we use a 6.50 1/2 mile. Depends on the motor, tire size, etc. Best to start with what Bobby said then tune to suit your car. The more experience you get you'll start to catch on pretty quick. Good luck.

str8racing
Dirt Full Roller

Total posts: 65
posted April 14, 2005 07:58 PM  
I'm trying to find a 4 speed trans. in my area but the older mustang supply is pretty well shot the only trans. i can find are 5 speeds, so do you think i can do any better with differant rear gears, thanks.

b4racing
Dirt Forum Champ
Total posts: 626
posted April 15, 2005 07:03 AM  
where are you located?

str8racing
Dirt Full Roller

Total posts: 65
posted April 15, 2005 01:51 PM  
upstate ny . anybody have one?

FCRA
Dirt Roller

Total posts: 14
posted April 15, 2005 03:41 PM  
I've got a few laying around. Not really even really sure what I've got. If you are anywhere near Newark Valley, NY, you can stop by and take a look at what I have. I'm not looking to get rid of everything, but I know I have a few duplicates. If you are interested give me a call or shoot me an e-mail.

Nate Stevens
Four Cylinder Racing Alliance
JALD Graphics
Nate@JALD.net
(607)642-3683

[This message has been edited by FCRA (edited April 15, 2005).]

str8racing
Dirt Full Roller

Total posts: 65
posted April 17, 2005 05:46 PM  
where is newark valley located? i'm near rochester ny

popeye14709
Dirt Forum Racer

Total posts: 86
posted April 17, 2005 06:40 PM  
str8racing what track are you running? We run Freedom and Mckean County really just wondering dont have a spare 4sp but if its a track that we have ran might be able to help out....

dirttracker98
Dirt Freak

Total posts: 284
posted April 18, 2005 09:02 AM  
quote:
Originally posted by str8racing:
i guess i'm still confused how do you determine what the final ratio should be? thanks for all you're patience.

you multiply the gear ratio{the gear you will race in} of the trans to the rear~end gear ratio,that will give you your final drive gearing.tire size{13"~14"~15" not the width} will alter the gearing some.
PS check out the formulas in the tool~box on this site.

[This message has been edited by dirttracker98 (edited April 18, 2005).]

str8racing
Dirt Full Roller

Total posts: 65
posted April 18, 2005 06:19 PM  
we run at batavia, thanks.

FCRA
Dirt Roller

Total posts: 14
posted April 18, 2005 07:03 PM  
Sorry, but I live a couple hours from you. You might try posting over on my forum at http://www.4cylinder.net/forum. I think that oilman, over there, lives a lot closer to you and would probably be willing to help. If he doesn't have any extra transmissions, he could probably tell you where to find some. Good luck!

Nate Stevens

[This message has been edited by FCRA (edited April 18, 2005).]

[This message has been edited by FCRA (edited April 20, 2005).]

popeye14709
Dirt Forum Racer

Total posts: 86
posted April 20, 2005 05:54 AM  
I belive if i am rememberin correctly that Jason hall runs a German 4sp with 3.45 rears when we ran Batavia we ran a German 4sp with 3.73's and did fine we finished 4th started last(we had never step a foot at that track before). alot of it has to do with your driving style and preference. we turned 7200 rpms at Batavia with that set-up also your runnin a hydrolic set-up(unless the rule was changed but not in there book)so you'll need to be carefull not to float the valves. Jason Hall ran a roller and we run solid of course that was legal last year. We did alot of our passing on the outside that night but once you get up towards the front you need to protect the bottom line...hope this helps some...

str8racing
Dirt Full Roller

Total posts: 65
posted April 20, 2005 03:43 PM  
i did some further testing and found that we have a 234 or 237 tranny. gear and a 327 rear gear. what could i do to improve?

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