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Old 05-22-2007, 03:09 PM   #1
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Default experiences with final drive ratio

Ok, so looks like the 7" rear swap needs to happen. The one I have is assembled with a 4.10 r&p. I'm on the stock 4.30 now, and it's very short in 1 & 2, a bit short in 3, fine in 4 and 5 but I wouldn't mind spinning a bit less on the highway.

For you guys who have swapped your rear/r&p, what ratio did you put in, and are you happy with it?

I need to decide if I'm going 4.10 (free and easy) or 3.90 (not free and more work).
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Old 05-22-2007, 03:13 PM   #2
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I'm loving the 4.10, seems like a good compromise without going too tall. I noticed it right away, 1st is a bit more tame, however I can still light it up. anything taller at my power level would be a waste. Highway cruise is a lot better, right where it needs to be.
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Old 05-22-2007, 03:34 PM   #3
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where do i get a new speedo gear?
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Old 05-22-2007, 03:36 PM   #4
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where do i get a new speedo gear?
Dealer.
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Old 05-22-2007, 05:34 PM   #5
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I went with a 4.10 for the Torsen in my '92. I can still spin the tires (T1S) in first gear, they break loose at around 4,000RPM. This isn't a big change- only 4.6%. I did not change the speedo gear, and according to my GPS receiver my speedo is now less inaccurate than it was before.
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Old 05-22-2007, 05:49 PM   #6
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according to the 3 police speed signs I've passed since the swap, my speedo is dead on
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Old 05-22-2007, 05:56 PM   #7
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sounds like you guys are happy with the 4.10s. I was afraid that it wasn't enough of a difference to be meaningful. I would like to make 1&2 more useful and also calm the motor down on the interstate.

another thought I had was 410s w/ an rx7 5th gear in the miata tranny. i have the tools and help available to do it, but not the time or motivation.
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Old 05-22-2007, 06:00 PM   #8
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i hear that I dont even wanna finish wiring my knocksense and EBC, let alone rewire the LC-1 whenever is shows up.
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Old 05-22-2007, 06:18 PM   #9
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do cheap and easy, worry about the rest later... you'd rather be driving anyway
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Old 05-22-2007, 06:27 PM   #10
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since I'm probably getting my gearbox rebuilt, would it be worth swapping in the rx7 5th gear? (4.1 diff)
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Old 05-22-2007, 06:30 PM   #11
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If you do any interstate driving, hell yes.
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Old 05-22-2007, 06:40 PM   #12
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Quote:
Originally Posted by Ben View Post
sounds like you guys are happy with the 4.10s. I was afraid that it wasn't enough of a difference to be meaningful. I would like to make 1&2 more useful and also calm the motor down on the interstate.
Like I said, 4.30 to 4.10 is a very small change. You're not really going to notice it unless you're keeping notes. At 70 MPH and assuming a 22.6" tire we're talking about a reduction of 170 RPM (3643 to 3473).
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Old 05-23-2007, 06:53 AM   #13
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Default i'm a cheap-***... :)

went with 205/50x16 on the back ... about an 1.5" (6%) more diameter, and that all important slammed look

No noticeable performance difference, but yeah my speedo is closer to true now - very important for when you're passing police cars :gay:
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Old 05-23-2007, 10:37 AM   #14
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Mark just posted on m.net that the mazdaspeed/comp dropped the price on the 3.63 over $100 (now just over $300) - and somebody said that they bought the set two weeks ago for under $300. So you might just keep an eye on that after driving around with the 4.10. I went for it- especially since the R trans has an even shorter 1st gear than the Miata. I know there's one guy driving around with the 3.63 and the 5speed and he loves it (kmag?). Granted you're gonna lose some time on a standing start acceleration with that setup... but my guess is you'll be shopping a 6 speed soon anyway.
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Old 10-15-2007, 05:36 PM   #15
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Quote:
Originally Posted by m2cupcar View Post
Mark just posted on m.net that the mazdaspeed/comp dropped the price on the 3.63 over $100 (now just over $300) - and somebody said that they bought the set two weeks ago for under $300. So you might just keep an eye on that after driving around with the 4.10. I went for it- especially since the R trans has an even shorter 1st gear than the Miata. I know there's one guy driving around with the 3.63 and the 5speed and he loves it (kmag?). Granted you're gonna lose some time on a standing start acceleration with that setup... but my guess is you'll be shopping a 6 speed soon anyway.
Can I get a link on this ****? I was thinking about getting a 3.63 for my sister's msm, then taking her 3.90 and running that in my 5 speed...I have a 4.30 now and I doubt I'll be happy with that on the track or highway.

How much HP is enough to "be fun" with a 3.63 or a 3.90 in a 5-speed?

Sorry to resurrect.
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Old 10-15-2007, 05:38 PM   #16
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I don't think I'd be happy with a 3.90 in my car. The 4.10 seems perfect. An rx7 5th gear would probably make it even better.
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Old 10-15-2007, 05:44 PM   #17
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Quote:
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I don't think I'd be happy with a 3.90 in my car. The 4.10 seems perfect. An rx7 5th gear would probably make it even better.
too wide?
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Old 10-15-2007, 06:01 PM   #18
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I loved my car with 4.3 at 200whp. Maybe its just me. I'm gonna be using the ~4 from the rx7 diff swap with my 6speed once it goes in. My speedo will be off, but not by much.
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Old 10-15-2007, 06:03 PM   #19
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Quote:
Originally Posted by neogenesis2004 View Post
I loved my car with 4.3 at 200whp. Maybe its just me. I'm gonna be using the ~4 from the rx7 diff swap with my 6speed once it goes in. My speedo will be off, but not by much.
i bet those gears didn't last long from shift to shift.
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Old 10-15-2007, 06:07 PM   #20
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Whats the problem with accelerating quickly?
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