I will probably be looking at picking up a 3.63 ring and pinion very soon and was wondering at what whp level would putting it in make most sense so it doesn't make my miata a dog. I will have roughly 230whp shortly when I get my ms2 and put my injectors, intake, and larger intercooler on the car. Would this still be too low? I just hate first and second gear with the 4.3 that is in there now and I am probably only putting down 180whp. I know the torque is really what makes the difference but my torque should be roughly the same as my whp with my setup.

 

If you want a nice highway cruiser, do it now. If you want to wait until it will make the car faster on track, you need a minimum of 300whp and 250+wtq before you can pull 3.63s.

 

How would the 6 speed change that hp figure?

 

It is a street car so I guess I might do it now. I would love to track it and do some auto cross too, however, I don't have too much time for that currently. The car will be getting further power upgrades later so it would be necessary down the road anyway.

 

if you are still on the 5sp keep in mind this will put a lot more load on your gears and they will break faster/easier.

 

5/3.63 is an awful idea.

6/3.63 is pretty sweet. Basically, 1-5 are a touch tighter than a 5/4.30 and you have 6th on top. It's geared "right" in my car from 230whp on up. I will also put this combo in my daily soon.

 

I have a mazdaspeed like the sig says so its a 6 speed

 

sigs disabled lol.

in that case yes, get the 3.6. msm gears are stupid short

 

I am getting a deal on my ring and pinion from a guy who is selling it still in a 1.8 diff. He said it is a high mileage unit. The ring and pinion are in good shape but he said he recommends changing the pinion bearing and seals and the unit also doesn't have the billet bearing caps. I have no idea about diffs and am having him send me pictures tomorrow of the teeth on the ring and pinion to verify the condition. Is there anything I should look for? When I install it should I just switch out the ring and pinion into my known good diff or repair the already assembled diff? which way will be cheaper? which way will be more reliable?

Thanks for the quick answers to my questions

 

I am also assuming I should have a good shop do the swap or repair the other diff since I am inexperienced and could ---- it up

 

If your auto crossing the 3.636 will help immensely. As you can achieve a reasonable speed without going to 3rd. The track guys with the 6 speeds pretty much never use second. So they like to gear to get out of the sharpest corner in third.

The stock Masdaspeed gearing is stupid for autocross. Tops out at ~50 mph in second pretty much garenteeing 2nd -3rd shifts at bad spots on most autocross courses. It usually turns out what works best for autocross works out best for street driving as well. Your 0 to 60 time will go down without the extra shift.

Bob

 

I tried 3.63s in Theseus at ~240whp and 5th was really doggy. At 320whp it felt right. At 350+whp I am out of gear in 5th and 6th in too many places, so I am going back to 3.63s.

3rd has very little to do with it - I really want the 3.63s in my car because I want the extra speed in 5th and 6th.

 

I non mazdaspeed diff will not bolt into that car. You just need the ring gear I believe.

 

Okay so I will just cannibalize the ring and pinion. The rest of the diff will just get trashed. The deal is really good. I am getting pictures today of the teeth on the ring and pinion to make sure everything looks good. Anything else I need to find out to make sure it is in good shape?

 

You guys just saved me a few bucks. I was about ready to swap gears since I roll about 80-85, (along with traffic in Detroit), in preparation for a turbo swap. But it looks like I need to wait until I go 6 speed and/or big horsepower.

 

I'm running 3.63's in a 5 speed.......

 

Never has the argument against running a 5-speed with 3.63s been stronger.

 

I bet my 5 speed lasts longer than your 6-speed

 

He's got a queef.

 

This.