Author Topic: Gear Ratio vs RPM?  (Read 12830 times)

Offline Racinjj

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Gear Ratio vs RPM?
« on: June 16, 2008, 09:33:20 am »
Right now I am using a 3.73 rear gear in 4th gear and running 10,400RPM if I switch to 3.58 rear gear still in 4th how many RPM will I drop?  I know that with my late model a rear gear change of 0.1 was equal to about 100rpm.  Is that close to the same with the legend car?  That would be a final gear ratio change from 8.43 (3.73) to 8.09 (3.58) , would my RPM's go down 400 to about 10,000?  A bunch of the guys I race with use the 3.58 already with much success.  I like the pull off the corner with the 3.73 but I think I could get more straightaway speed with the 3.58.  Also this past weekend I was running about 3 feet off the wall all the way around the track and the motor was just screaming and never really got a break, oil temp was 280-290 after the race.


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Racecar spelled backwards is racecar. Racecar upside down is expensive.


Offline djracing

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Re: Gear Ratio vs RPM?
« Reply #1 on: June 18, 2008, 11:31:18 am »
It would drop you aprox. 400-450 rpms. According to the setup notes I have from the previous owner, he was hitting about 10.2k-10.3k with the 3.73. And only 9,900-10000 rpm with the 3.58 thats in the car now.


Offline VMS Motorsports

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Re: Gear Ratio vs RPM?
« Reply #2 on: June 18, 2008, 11:42:44 am »
Hey Jeff,
It really all depends on your driving style as to what to use. Alot of the guys are using the 3.73 in 4th -vs- the 3.58 at Charter. I started out with the 3.73 and spin the wheels all the way around the track (see the "spinning my wheels" post on this forum for some info), so I finally broke down and switched to the 3.58...yet to try it at Charter yet, but it was NOT the right gear for Chilton. I bought my 3.58 from Kevin Brill, who just went back up to the 3.73, and you see how well he's doing. I guess, in my inexperienced opinion, do what you're most comfortable with. From talking to alot of different people, the 3.73 is the way to go, but they recommended I go to the 3.58 until I get my driving ability up to the cars ability, then go back to the 3.73.

My 2 cents

Jim
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Offline Racinjj

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Re: Gear Ratio vs RPM?
« Reply #3 on: June 18, 2008, 12:58:24 pm »
I am thinking about going to the 4.10 for Chilton because I was only turning 9,000RPM with my 3.73.    I think I may do some calling before I make the switch though. 

The only reason I was thinking of changing at Charter is for running the high side the 3.73 is a bit much.  It works great for the bottom though which makes me not want to change.  I dont really have a tire spinning issue, I would maybe change the RR spring to fix that if I where you.
www.JeffSteenbergen.com

Racecar spelled backwards is racecar. Racecar upside down is expensive.

Offline VMS Motorsports

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Re: Gear Ratio vs RPM?
« Reply #4 on: June 18, 2008, 04:48:49 pm »
were you running 3rd or 4th at Chilton? 3.73 in 3rd should get the job done there...not that I can talk, I was just driving around there anyway  :)
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Offline Racinjj

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Re: Gear Ratio vs RPM?
« Reply #5 on: June 18, 2008, 09:27:35 pm »
I was in 4th gear.
www.JeffSteenbergen.com

Racecar spelled backwards is racecar. Racecar upside down is expensive.


Offline VMS Motorsports

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Re: Gear Ratio vs RPM?
« Reply #6 on: June 19, 2008, 01:27:33 pm »
Try 3rd tomorrow...thats what I was in until until I had a valve stem/someone elses bumper issue and had the left rear start going down...then I put it in 4th and just drove around...darn cheap wheels   :D
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Offline Racinjj

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Re: Gear Ratio vs RPM?
« Reply #7 on: June 19, 2008, 01:42:28 pm »
Yeah, I will give 3rd a shot.  I bought the 3z car last night for my buddy to race/my backup car.  He will start racing with us next Saturday.
www.JeffSteenbergen.com

Racecar spelled backwards is racecar. Racecar upside down is expensive.


Offline VMS Motorsports

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Re: Gear Ratio vs RPM?
« Reply #8 on: June 19, 2008, 01:46:15 pm »
Hell of a back-up car...i was wishing I had a couple more closings coming up when I saw Loren was selling. Was it his knee?
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