Green_Streak

i was just looking through the sticky at the top of the section and it said the 'verts and auto's came with 3.9x gears out back while all the other sticks came with 4.10's. anyone know why the verts got stuck with the sucky auto gears out back?

kiyoshi

I think because Mazda targeted vert for people who prefer low rpm cruising on highway.

Green_Streak

well that kinda sucks, it's got more pork, and they give it taller gears. i'm not sure i could think of a better combination to make a car slower, other than dropping HP and torque

George84

The only 2nd gen RX-7 with 3.90 rear stock is with an auto trans because they only have 4 gears, I have a vert (5 speed) and I have a 4.10 rear.

George84

I found what you were talking about, it looks like only 1988 verts were like that. Thats strange, all that could do is slow them down.

ajsuper7

yeah, im not sure why mazda did that to the verts, they changed back to all 4.10 gears in the s5 verts but the 88 verts got the shaft. wernt the auto s5's 3.90 as well?

Green_Streak

well, looks like i got the shaft. at least i didn't get stuck with an auto(thank god). and yup, mine's an '88

George84

Yes, all auto trans FC's had 3.909 rear end. That must be one real good reason verts got such a "slow car" rap when Mazda brought them out in 88 with only 3.90 rears. The critics never came to rate the performance again so verts were always thought of as the slowest RX-7 ever (which I don't belive is the case with the s5 verts).

Icemark

The 3.9 rear end gear (only in the 88 vert) was for gas mileage. Mazda was just skirting having the vert get a gas guzzler tax.

In 89 the gas mileage restrictions eased, so mazda was able to import the auto tranny verts and change the rear ends to 4.1 as found on the manual tranny coupes.

And the 90-91 verts were slower than the 88. The auto tranny non turbo 90-91 vert is the slowest RX-7 ever made.

Green_Streak

how are the S5 verts slower than the S4??? the S5's not only have more HP and torque, but they have better gearing? how are they slower?

Green_Streak

oh yeah, that and the S5's rev higher, making better use of the already better gearing

George84

Why is that? What about 89 verts also. Wouldn’t a 3.90 rear end in a car with 146hp and a curb weight of 3003 lbs. be slower than a 160hp car with a 4.10 rear and a curb weight of 3045lbs? It’s a 14hp gain, geared better, and only weighs 42 pounds more and has a higher redline also. Oh yeah and one more thing, why is the weight the exact same for an 89 and 90-91 when 89s did not have any kind of air bag system yet?

gonzz

I just did a 5 speed swap in my 90 cert. I need to change out the diff. The gearing sux

Icemark

okay guys...(sadly shakes head) sorry you are not reading correctly. I'll re-say it.

I didn't say S5 verts, I said 90-91 auto tranny verts.

But lets start with the basics (that prehaps are eluding some of the above posters).

The 90 and 91 US spec verts came with the SRS (air bag system) as well as considerable extra weight from the S5 dash subframes. While the 89 used the same dash subframe as a 88 vert.

The S5 engine while, yes does have more horsepower, has no real more torque than the S4 motor. So what does this mean... well since torque is what really moves the car from a stop to go fast, no more torque means no more speed when starting out.

So add it up. No real additional power (until 5500 RPM) and 200lbs heavier than a non P package 88 vert. As a note, the non P package 88 vert only weighed 2860 lbs. Almost 200 lbs lighter than a 89 and 250 lbs lighter than a 90-91 manual tranny vert (or 300lbs light than a 90-91 auto tranny vert).

And the 89-92 non turbo manual tranny verts all use the same M50 tranny that the 88 came with, so there is no better tranny gearing.

Do you really think now that the 90-91 vert is going to be faster???

Now the 89 vert is faster than the 88 vert. The additional weight is offset by the slight bit of extra power, but the 4.1 final gearing helps as well. But the 90-91... well they are just slow as dogs and very very heavy.

George84

Thanks for the info Icemark. I know this is off topic but I know you are a genius when it comes to electronics that also works on Lexus electronics. I got some heated seat pads and the switches out of a 95 Lexus GS 300, I want to put them in my vert. Can you tell me what color wires go to what? When I got them out I had to cut the wire between the switches and the heat pads, there are allot of wires going to the switches and I am not sure what I need to hook them all up to. (high/off/low type switches)

~George