If any of you guys have them or have had them what kind of power do they give and what top speed could you expect ? thanks Bobby

 

That would be me.

IMO, 4.44 is about the best final drive ratio for use on the street. Any higher (numerically) than that and you start to suffer from bad fuel economy and high cruising rpm and any lower is too slugish.

Personally I noticed quite a big improvement in acceleration with the 4.44 compared to the stock 3.9 diff ratio.

Top speed will depend on how much power you have ie. how many rpm you can pull in fifth gear.

7500rpm equals about 140mph in fifth gear with a 4.44 rear end.

 

why did you go to 4.44
i was thinking about getting some 4.11 when i get a new rear end (with lsd ofcourse), but have not decided yet

 

Well, just from hearing other peoples comments and experience I felt 4.44's would be the best compromise gear for the street. Not too tall and not too short.

 

Did you get your 4.444 gears through Racing Beat? If not, where? How tough was installation? I have my LSD off right now and am kinda thinking about upgrading, but don't really want to spend $500 on new gears if there's a cheaper way. Thanks

 

Watch your transmission output bushing closely if you go with deeper gears, especially if you drive at high speeds a lot. The bushing isn't very well lubricated, and the higher speeds the driveshaft will spin at will eat the bushing rather quickly. There *is* a way to fix it permanently, but it's not cheap - the tailshaft housing must be removed, built-up with a TIG welder, bored out, and a needle bearing assembly pressed in. Then you replace your driveshaft yoke with a hardened one.

Or you could just replace the bushing every so often as a maintenance item. You can check it by trying to wobble the driveshaft up and down in the transmission. Usually when they're bad, the seal leaks big-time as well.

 

What's involved in replacing the bushing? Is it just a matter of dropping the tail-shaft?

 

Never done it on a Mazda (never had to) but a trans shop should have a tool to change it with the trans in-car.

I expect that I'll find out first-hand should I go ahead with my plans to put in 4.778 gears

 

Find a 4wd Mazda B-2000 series pickup from late 1980's in the scrapper... Front differential should be comaptible.

 

Don't you have to take the ring and pinion out and swap em into the Rx-7 diff?

That's what I did with mine, except they came out of a Mazda E-1600 van.

 

I do a lot of highway driving. I am at 4000rpm as it is on the highway at 75mph with the stock rear gears. What does your tach read at 75 with 4.444 gears?

 

i could swear the se's came with a higher gear already,
im gonna check.

yep sure do,
i'll just post all the gear ratios since i know someone will end up asking for them
here goes

GROUP1

rx2 1971-74---------------------------3.900
rx3 sp 1977-78-----------------------3.727
rx7 12a 1979-83 + late 84-85---------3.909
rx7 12a early 84----------------------3.933
rx7 1984-85 gsl-se-------------------4.076

GROUP2

rx3 1971-75--------------------------3.900
rx3 1976------------------------------3.727

GROUP3

rx4 1974-75----------------------------3.700
rx4 & cosmo 1976-77--------------------3.636

GROUP 4

rotary pickup 1974-75----------------4.625
rotary pickup 1976 manual------------4.375
rotary pickup 1976 auto--------------4.111
rotary pickup 1977--------------------3.900

GROUP 5

rx7 1986-92 nt auto-------------------3.909
rx7 1986-92 nt manual----------------4.100
rx7 1989-91 gtu------------------------4.375

GROUP 6

rx7 1987-91 turbo----------------------4.100

GROUP7

rx7 1993-95 manual-------------------4.100
rx7 1993-95 auto-----------------------3.909

 

if you still want to maintain a high top end spped then if you gonna swap your rear also swap the tranny,

here's why,
these are the specs on a 79-83 tranny

1st - 3.674
2nd - 2.217
3rd - 1.432
4th - 1.0
5th - .825

now a 84-85 tranny is a bit more tricky
here are the specs

1st - 3.622
2nd - 2.186
3rd - 1.419
4th - 1.0

5th
84 12a - .758
84 13b - .807
85 12a - .807
85 13b - .711

all this info is quoted from racing beat so i believe it is all very acurate.

now if im right the lower the gear number the higher the top end,like on a rear end,
although for quite a while i always thought it would be opisit,but then how do you explian a 2nd gen with a 2nd gear ratio of just 2.002 and a rear end of 4.100 and redlining at 60 mph in 2nd,
while my 1st gen redlines at 42 mph in 2nd,
it does red a grand higher but it shifting a grand under still is above 40mph

so your best bet would be a
1985 13b tranny

second best being a
1984 12a tranny,

lmk if im wrong

 

and dont forget tire and rim size make a diference as well,

some 16"s should help out the top end.

i just double checked it and i was right,
here is the formula,


(t.c.) x (rpm)
----------------------------- = Speed (mph)
(1056) x (a.r.) x (t.r.)


tc = the outside rear tire circumference measured in inches

ar = rear axle ratio (ring & pinion)

tr = transmission gear ratio in any gear you want to use

rpm = engine rpm

 

Ok, so in theroy, if you could redline a stock GSL-SE in 5th, you would be going 147.8834039920238 MPH? And then if you had the 4.444 gears, you would be going 135.63743354443943 MPH? Just wondering...So Im assuming that the lower (higher?) gearing would be for more torque? Ok that doesnt make sense...If the rear end is 4.076 stock, and you put in 4.444 gears, that would be putting in higher gears right? Because 4.444 is bigger than 4.076? But wouldnt higher gears make a car faster? Like 5th gear versus 4th gear? Im confused...Someone please help

~T.J.

Oh, and that was assuming that the outside tire diameter was 18". I dont know what it really is, I just kinda guessed...

 

Lower numerically is higher gears. 4.444 is lower than 4.076. You're thinking on the wrong end of the lever... 4.444 means the driveshaft must turn 4.444 times for every 1 turn of the wheels, which is more leverage than if the driveshaft only turned 4.076 times.

Outside tire dimater is roughly 23-25" depending on tire size and tread depth.

If you have an '84-85 rearend, you can just grab the 4.3 pumpkin out of a late model Miata. Should just bolt right in, don't know about the driveshaft flange though. Go to members.aol.com/solomiata and check out the drivetrain info.

 

Hells yeah.. No more searching for 4wd pickup trucks and building frankendiff. Just the pumpkin eh? Cool beans

So, which package Miatas have Torsen LSD's?

Whats the pinion flange on the RX-7?

From the Solo Miata web site:

"When Mazda upgraded the rear in 1994 they also had to change the driveshaft to fit the larger rear. It is 48mm shorter (L1= 1001mm vs 1049mm, 39.41/41.3" : L2= 864mm vs 816mm, 32.1/34.02) and used the larger 86-91 NA RX-7 pinion flange pattern of 4x67mm vs the 4x62mm pattern of the 1.6 rear. "

That could kill my idea cause I'm thinking of using a 1994-1997 Miata Torsen rear.

 

what would have to be changed to put an 84-85 rear end into a SA?

 

The whole rear.. And if you get a disc brake rear, the master cylinder and proportining valve...

Then you'll need custom brake hoses for the thread pitch...

 

sorry, should have phrazed that a little different.
i know that you would need all of those parts, but my real question was would it bolt straight up like an 81-82 rear will. or will there be custom work necessary??

i think you would have to switch to an 84-85 drive shaft, but anything beyond that?

 

It'll bolt straight up but you'll either need the driveshaft, or swap pinion flange.

Pele - according to one site i know, the Miata rear is a bolt-in to '84-85 rears - the axle splines for '84-up solid axles are the same as the splines on the Miata output yokes.

 

thanks peejay.. that was what i was hoping to hear..
when i get around to it, i think i will go ahead and look for an 84-85 gsl rear end instead of aa 81-82gsl

 

V8Killr,

Do you happen to have the gear ratios for the 2nd gen tranny's? Both Turbo and NA?

Could you post em?


I looked at the Racingbrat site but I couldn't find it.

 

directfreak - go to solomiata! it's all there. members.aol.com/solomiata

 

Thanks!

US Spec Mazda Driveline Ratios


20:55 Rear Net Tire RPM @ -Countershaft & Mainshaft Gear Teeth--
Vehicle Year 1st 2nd 3rd 4th 5th Axle Final Tire Size RPM 60 MPH C1 C2 C3 C4 C5 M1 M2 M3 M4 M5 Tooth Count Certainty or Notes
626 79-82 3.214 1.818 1.296 1.000 0.860 3.636 3.128 185/70-13 894 2796 14 22 27 30 31 27 24 21 18 16
B2000 82-84 4.359 2.519 1.507 1.000 0.875 3.308 2.894
B2000 Auto 82-84 4.359 2.519 1.507 1.000 0.875 3.900 3.413
B2200 82-84 4.359 2.519 1.507 1.000 0.875 3.900 3.413
B2x00 85-up 3.622 2.186 1.419 1.000 0.859 13 20 32 37 47 28 26 27 22 24
B2x00 Man4WD 87-88 Part # M054-27-110A ----> 4.444 fits RX-2, RX-3*, RX-7, RWD 626 thru 1985; Miata '94-up
Cosmo 76 3.683 2.263 1.397 1.000 0.862 3.636 3.134 185/70-14 855 2680 14 22 28 32 33 29 28 22 18 16 100%
Cosmo 77-78 3.380 2.002 1.390 1.000 0.791 3.636 2.877 185/70-14 855 2460 14 22 27 31 33 29 27 23 19 16 100%
Cosmo 78.5 3.380 2.077 1.390 1.000 0.791 3.636 2.877 185/70-14 855 2460 14 22 27 31 33 29 28 23 19 16 100%
R-100 70-72
REPU 74 3.683 2.263 1.397 1.000 4.625 4.625 7.35-14 792 3663 14 22 28 32 33 29 28 22 18 16 TRPM Estimated
REPU Auto 74 3.683 2.263 1.397 1.000 4.375 4.375 7.35-14 792 3465 14 22 28 32 33 29 28 22 18 16 TRPM Estimated
REPU 75 3.683 2.263 1.397 1.000 4.375 4.375 7.35-14 792 3465 14 22 28 32 33 29 28 22 18 16 TRPM Estimated
REPU Auto 75 3.683 2.263 1.397 1.000 4.111 4.111 7.35-14 792 3256 14 22 28 32 33 29 28 22 18 16 TRPM Estimated
REPU 76 3.683 2.263 1.397 1.000 0.862 4.111 3.544 7.35-14 792 2807 14 22 28 32 33 29 28 22 18 16 TRPM Estimated
REPU 77-78 3.380 2.002 1.390 1.000 0.791 3.900 3.085 7.35-14 792 2443 14 22 27 31 33 29 27 23 19 16 TRPM Estimated
RX-2 71-74 3.683 2.263 1.397 1.000 3.900 3.900 165-13 894 3487 14 22 28 32 33 29 28 22 18 16 TRPM Estimated
RX-3 72-75 3.683 2.263 1.397 1.000 3.700 3.700 155-13 904 3345 14 22 28 32 33 29 28 22 18 16 TRPM Estimated
RX-3 76 3.683 2.263 1.397 1.000 0.862 3.727 3.213 175/70-13 904 2904 14 22 28 32 33 29 28 22 18 16
RX-3 77-78 3.380 2.002 1.390 1.000 0.791 3.727 2.949 175/70-13 904 2665 14 22 27 31 33 29 27 23 19 16
RX-3 78.5 3.380 2.077 1.390 1.000 0.791 3.727 2.949 175/70-13 904 2665 14 22 27 31 33 29 28 23 19 16
RX-4 73-75 3.683 2.263 1.397 1.000 3.900 3.900 BR70-13 873 3405 14 22 28 32 33 29 28 22 18 16 TRPM Estimated
RX-4 76 3.683 2.263 1.397 1.000 0.862 3.636 3.134 BR70-13 873 2736 14 22 28 32 33 29 28 22 18 16 TRPM Estimated
RX-4 77-78 3.380 2.002 1.390 1.000 0.791 3.636 2.877 BR70-13 873 2511 14 22 27 31 33 29 27 23 19 16 TRPM Estimated


03/12/01


US Spec Mazda Driveline Ratios


20:55 Rear Net Tire RPM @ -Countershaft & Mainshaft Gear Teeth--
Vehicle Year 1st 2nd 3rd 4th 5th Axle Final Tire Size RPM 60 MPH C1 C2 C3 C4 C5 M1 M2 M3 M4 M5 Tooth Count Certainty or Notes
RX-4 78.5 3.380 2.077 1.390 1.000 0.791 3.636 2.877 195/70-13 873 2511 14 22 27 31 33 29 28 23 19 16
RX-7 79-83 3.674 2.218 1.433 1.000 0.825 3.909 3.227 185/70-13 892 2878 13 20 25 29 31 28 26 21 17 15
RX-7 83 3.674 2.218 1.433 1.000 0.825 3.909 3.227 195/60-14 891 2875 13 20 25 29 31 28 26 21 17 15
RX-7 auto 84 2.458 1.458 1.000 0.720 3.909 3.909 185/70-13 892 3487
RX-7 GSL-SE 84 3.622 2.186 1.419 1.000 0.758 4.083 3.097 205/60-14 878 2719 13 20 32 37 51 28 26 27 22 23
RX-7 84p 3.622 2.186 1.419 1.000 0.807 3.933 3.175 185/70-13 892 2832 13 20 32 37 50 28 26 27 22 24
RX-7 85 3.622 2.186 1.419 1.000 0.807 3.909 3.156 185/70-13 892 2815 13 20 32 37 50 28 26 27 22 24
RX-7 GSL-SE 85 3.622 2.186 1.419 1.000 0.715 4.077 2.914 205/60-14 851 2480 13 20 32 37 40 28 26 27 22 17
RX-7 mixed 85 3.622 2.186 1.419 1.000 0.697 4.444 3.099 205/55-14 910 2820 13 20 32 37 41 28 26 27 22 17
RX-7 Base 86-91 3.476 2.002 1.366 1.000 0.711 4.100 2.917 185/70-14 855 2494 15 21 32 37 52 31 25 26 22 22
RX-7 GXL 87-91 3.476 2.002 1.366 1.000 0.697 4.100 2.859 205/60-15 841 2404 15 21 32 37 41 31 25 26 22 17
RX-7 Turbo 87-91 3.483 2.015 1.391 1.000 0.719 4.100 2.948 205/55-16 828 2441
RX-7 Conv 88
RX-7 GTUs 89 3.476 2.002 1.366 1.000 0.758 4.300 3.261 205/55-16 828 2700 15 21 32 37 51 31 25 26 22 23
RX-7 93-95 3.483 2.015 1.391 1.000 0.719 4.100 2.948 225/50-16 829 2444
Miata 1.6L 90-93 3.137 1.888 1.331 1.000 0.814 4.300 3.501 185/60-14 910 3186 15 23 34 38 40 26 24 25 21 18
Miata 1.8L 90-97 3.137 1.888 1.331 1.000 0.750 4.100 3.076 185/60-14 910 2799 15 23 34 38 41 26 24 25 21 17
Miata 5-spd 99- 3.136 1.888 1.330 1.000 0.814 4.300 3.500 185/60-14 910 3185
Miata 6-spd 99- 3.760 2.269 1.645 1.257 1.000 3.909 3.295 195/50-15 913 3009 6th .843****
Miata auto 00- 4.100 185/60-14
I would be happy to include non-US models if anyone would submit that info.