3.6 diff with 6 speed - any reviews?
 

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Drive a 5-speed/4.30 car. It has the same 1st and 2nd as a 6speed/3.63 car. 3/4/5 are slightly shorter (2-6mph per gear), with a "highway" 6th.

3.636 + 6sp - Would buy again.

My car used to be 5sp/4.3. The switch to 5sp/3.9 was perfect.

I have this set-up in my track car and love it so much that I'm going to put the same in my daily in the near future...but it's pretty hot.

Jason I have this combo and its very nice. I recommend it strongly for higher hp miatae. Stock or wussturbopower I would not. Note that I also have 8000rpm redline which makes an even larger difference than the gears. I'm only run 7400rpm limit on track events though. On the street though, 3rd gear ends at like 92mph FTW.


Note that I am going wide geared quaife though so if any of you track sluts want a 6speed with a juiced 2nd gear synchro for uh $300 shoot me a pm.

I have this combo from the factory and I love it. Having driven many other combos, I like it more than anything.

Jason, I had the 5 sp/4.3 combo as well but upgraded to the 6sp when the 5 went south. The 6/4.3 combo really makes 1/2 gears useless and considering either the 3.6 or 3.9 to remedy this. I'm curious as to why you're considering the 3.6 if you considered the 5/3.9 perfect.

6/3.6 yields a 1/2 that's the same as the 5/4.3.
In order to make the 6sp 1/2 the same as my 5/3.9, it needs a 3.3, which doesn't exist.

Higher redline!!!

I went from a 5/4.1 to this and so far have been somewhat underwhelmed. Track only, so I can't comment on dd or hiway..

I guess I was expecting so much after the research before the decision. That said, I've only 2 and 1/2 events to get used to it...it may grow on me.

This is with 15"/275 tires. When I put the 13" wheels on, It feels much better, so much that I'll likely be using a 13"/255 combo when the current tires need replacing.

I do feel better knowing it's a more robust setup than the old one..

Why are you so enamored with a usable 1st gear? If you want a usable 1st gear, why not use a 6-speed/4.30 combo and launch in 2nd? That's the most usable "1st" gear you'll find in any factory Miata, and since you don't seem to care about the consequences in the other 4 or 5 gears, the 6-speed/4.30 would probably be a perfect match for you.

Or, you could stop worrying about a 1st gear that isn't going to be usable no matter what rear end you run, and focus on the ratio split and versatility that make the 6-speed such a great gearbox.

Enlightenment is when your 6sp/3.909 car will spin 3rd gear from a 40mph roll - once that happens you can stop worrying about the stupid low gears and optimize the 3-4-5-6, which are the ratios that actually matter in the twisties.

Making 1st gear usable makes 6th gear nice and tall for cruising. The 6sp/4.3 combo would be nearly as bad as the stock car for cruising RPM.

I drove a 6sp/3.9 in the twisties and the 2-3-4 ratios seem too close. A 3.6 would make that feel better.

It looks to me like the 3.6 will be OK, and 3.3 ideal (if it exists).

The Aussie MSMs (badged as SEs here since badging that contains "speed" promotes reckless driving according to our regulators) came OEM with a 3.6 which is how they should have been delivered in the US too. As stated above, 6th is a VERY useful gear when driving long distances.

How many torq's do you make? You might want a 3.90 if you're not over 210wtq or so. If I didn't drive my car to and from the track I'd have a 3.90 in it.

That makes sense. I'm at 197. I guess if we ever get to run 3/4 of the oval at TWS I'll be able to stretch it's legs more. Like I said, still getting used to it. At MSR-C, on the 3.1, I was trying to learn the track "and" the new shift points (data showed I was even slower on the 1.7 bits).

On a plus side, with the old setup, there were a couple of places that required a shift at apex, now it's past the apex. But track dependant, as TWS introduced the opposite effect. Well see how Hallet is next month..

Time for megasquirt.

When I run my car at 210whp/200wtq I feel like the gears are too big and won't spin the tires in 3rd. When I run 242whp/230wtq it feels "right".

Are you guys getting these gears out of old 626's or through another source? I've really been wanting to go to a longer gear but I'm a little nervous about going through all that work just to drop in a 30 year old ring and pinion built for a 100hp family sedan. I'd love some confirmation on how they are holding up.

Yeah, it's sitting in a box with bigger injectors and COPS. My garage temps have been rivaling the surface of the sun for like 2 months now.

It's my new winter project.

All i know is that 238wtq on a 6spd/4.10 combo is friggin' stupid.

Got mine here, but holy shit the price is gone through the roof now?


http://www.corksport.com/index.php?s...earch&x=10&y=5

If it's an 88-92 626/MX6 Turbo (H-type trans), don't worry about the strength. It's way stronger than anything that ever came factory in a Miata.

Jeez, looking at the ratios, the 3.63/6-speed looks like a great option even for a stock-ish NA. I may have to further investigate this after Hallett... but right now I need to go buy tires.

You raised the 6500 redline at least right? lol.

Yeah, it's at 7200 i think (hard to tell without datalogging because the factory tach is so innaccurate). But it's still dumb. A car with torque doesn't need gearing like this. It'd be way faster with a longer 5 speed.

I don't need to feel like an F1 driver in traffic accelerating up to 40mph to cruise in 5th or 6th gear. (Don't get me wrong, i LIKE shifting, but it's not really the point.) It's geared like an S2000 with a 2000rpm lower redline, and twice the useable torque. DUMB. :giggle:

a 6/4.10 in your car would scream...but suck on the highway.

Given that I'm prone to long road trips in the car, a decent highway gear would be good to have. Plus, one of these days I still plan to bolt a blower to it...

Just checked mazdaspeed site - looks like the price of the R&P has gone up about 40% since I picked mine up...

I blame Obama.

Well the deed is done. I now have a 6 speed with my 3.9.
Now, how to find a 626 rear end...

One nice side effect. My new 2nd gear is the perfect urban dorifto gear.

It would be very comparable to my current 5sp/4.1 with 13's. Great on the track but in 5th on the freeway I am over 4k at 75MPH.

You might already know this... but the 86 626 was what was mentioned earlier. You'll need an older car than that if you're looking for a rear end. ;) 86 is still GC chassis.

Oh right, stupid question time: Do certain FWD 626's have the 3.6 gears I want?

Gotta admit i'm not aware of a 626 off the top of my head with a 3.6 final drive.

Nor am i sure if they'll work with the Miata, but that's your job. I'm still a Miata noob. :laugh:

Let me look around, i have the spec readouts somewhere for the 88-92 626 at least, and the next generation's specs are everywhere on the internet. I'll have something for you by tomorrow afternoon if nobody else answers before then. :) (Are you sure you didn't get confused when you saw the 3.63? That's from an aussie SE)


I have a 4.39 final drive from an MX3 sitting at my garage, but that's not helping anything lol.

You've got to find a first gen 626 with a manual trans and then you need to get under it and roll rear tire while you count the drive shaft turns. After taking the time to do this one day I realized it was far cheaper for me to spend $400 and buy a new 3.6 r&p. :D

^Ok, that makes more sense.

In that case, good luck finding a 1st gen 626. I don't think i've EVER seen one in person. :P

FWD gears not compatible with Miata gears.

Well, except that thanks to Helicopter Ben, they're much more than $400 now.

What about gears from a RX-7?

Pinion is different.

You need a pre-83 RWD 626 R&P, as per Joe Perez:

https://www.miataturbo.net/suspension-brakes-drivetrain-49/scored-cheap-3-636-r-p-39012/

or you can buy one brand new from Mazda for $500.

You could do an 8.8 swap and use 3.73 or 3.55 gears.

The only problem is the cost:
-Ford 8.8 diff
-Axles
-Driveshaft
-Diff mount
-Refab exhaust to clear pumpkin
-fabricate transmission mount

This is from Mazdaspeed Motorsports Development? I can't find it in the competition parts catalog, they have a zillion other R&P ratios (5.12:1, anyone?) but no 3.63.

--Ian

Yes

its stock. not in comp parts

Where in stock parts? Those parts are all sorted by year/model, and the oldest 626 they have is 1986.

--Ian

I need to find a dealer around here for diff swapping. Can anyone explain to me why a 99 5 speed and a 3.63 is fail? Here pretty soon going to be doing a 45min commute each way on freeway alone for school and really want to lower the rpm's for highway use. Sitting at 4k in 5th now at about 80. Would love a 6spd but not in the budget, yet. Or would the 5spd w/3.63 make 1st gear tall as hell?

EDIT: Also is there a chart anywhere with what fits, ratios, and what cars they come from with years? Been searching but apparently my google skill need updating

FM has a gearing chart on their site somewhere that shows speed/gear. That should answer questions. Running the 5spd with the 3.63 would just put a damper on acceleration numbers- you'd still be able to get the car rolling. Definitely feasible given your commute if you can stand a slower car, but IMO with boost it's not a big deal.

I've driven a car with this, with a 260whp supercharger, and the gears are miserably long. It could reasonably take 15-minutes to wind-out 3rd in a stock car.

Don't forget that your tach is slow, so it's actually 4200rpm and you're open-loop, getting shitty MPG.

Johnwag and I are building them now, maybe you could send your pumpkin to us. Oh and by "Johnwag and I" I mean "john builds them while I drink and phonewhore".

I don't doubt that (specifically the spread on 2 & 3 - see attached), but his concern seems to be the rpm (or enduring it) on a long commute. That gear will definitely change the rpm in fifth at his speed. The other (preferred) option is swap in the rx7 5th gear- but I have no idea the cost difference.

Here's the FM link you guys were looking for: http://www.flyinmiata.com/tech/gearing.php

Are they all like that? My tach is fast, but i've got a late NB, don't know if that makes a difference... 7000rpm dyno pull was showing 7500-7600 on the stock tach.

Part number MA02-27-110, jeez I bought one a few years ago from mazda, was like $300.

https://www.miataturbo.net/attachmen...1&d=1312987868

Thanks to Helicopter Ben....

lol @ weak dollar

Guess I'll be stock pilling drivetrain parts in the garage. By building them you guys just need a carrier and the gear and you do the work. I'm down, don't trust myself enough to set the lash. Need to sell my 97 so I can afford to be baller. Used 6spd and new r&p here I come. Also curious why the tachometer is slow? Just always reads a percentage low or just lags behind on rev. Any cheap fix? It seams like no car has an accurate tachometer. Guess my question is should a autometer tach possibly solve it or is the tachometer pickup just scetchy. Or is it just the nature of the beast

If you've got a standalone, just don't worry about it. Just know where your true fuel cut is, and stop there.

I'm guessing on my tach, fuel cut will be showing somewhere around 8k, because it's rather optimistic.