MX-3.com

Why can't I downshift into 1st unless my car is near a dead stop? I've already switched out shifter and extension rod bushings. While my shift gates are tighter, and shifts more crisp I still have this problem of downshifting into 1st. Is this by design on the mx-3? A car like ours that relys on keeping revs high is a big handicap in autocross when you can't heel-toe down to 1st for a fast exit in a tight corner.

psh...u said it. probably by design

If you are doing yor heel-toe correctly it should drop right into first. This is probably old news but I'll run down the procedure just in case your not doing it right-

Clutch in
shift to neutral
clutch out
blip throttle- you need to bring the rpm's up pretty high
clutch in
shift into first
clutch out
go like hell!

In my experience, double clutching is unnecessary. A simple clutch in and blip of the throttle is all thats needed. If done properly it should slide into 1st nicely. Not that I'm knocking double clutching or anything. I've just always found it much more efficient to do it this way at full track speed. Especially for a corner that has a multiple gear downshift.

double clutching will spin the tranny input shaft up directly with the engine rpms. If you keep the clutch in the tranny does get spun up but you are relying on the small amount of drag the pilot bearing & disengaged clutch have to transfer the power into the input shaft. It may spin up, it will just be at a lesser rpm than what the engine was just revved to.

That is true. However, the point of heel and toe downshifting is to match engine speed to wheel speed. The input shaft is just along for the ride. As long as you get the engine up to the correct speed you should be good. I heel and toe in my car on a daily basis. It's just a habit of mine.

ive found that both methods work,
double clutching and

holding down and bliping

Originally posted by mazdubber:
That is true. However, the point of heel and toe downshifting is to match engine speed to wheel speed. The input shaft is just along for the ride. As long as you get the engine up to the correct speed you should be good. I heel and toe in my car on a daily basis. It's just a habit of mine.

Only partly true. The real purpose is to get the input shaft of the transmission spinning at the same speed as the output side of the transmission. This makes the gears you are about to engage together spin at the same speed and they mesh together more easily. The reason they mesh easier is that the relative speed to each is closer to zero. This makes the job of your synchros easier and the final result is it is easier to get your car into gear.

Only partly true. The real purpose is to get the input shaft of the transmission spinning at the same speed as the output side of the transmission. This makes the gears you are about to engage together spin at the same speed and they mesh together more easily. The reason they mesh easier is that the relative speed to each is closer to zero. This makes the job of your synchros easier and the final result is it is easier to get your car into gear.

I've rebuilt many transmissions on my own. I agree with you about of the physics and was not arguing that double clutching was wrong or bad. Just unnecessary. Because with a simple clutch in and blip of the throttle, it slides into gear smooth as silk. And my previous post is totally true as I was talking about heel and toe. With no double clutch involved.

I have no problem matching RPMs in any other gear on a downshift, but no matter how well I get them matched up it just won't go into 1st. I didn't mean for this to become a post on technique, but I was looking for something more technical as to why my car is doing this, and if anyone else has the same issue. The reason I asked if this was by mazda's design is because my friend's RX-7 is the same way.

I have the same problem.
Hard to shift into 1st and 2nd.

A friend of mine whos a mechanic said it might be the synchros.

nope-mx3

It the design. what you have to do during autocross, and I know this first hand, you have to force it. Don't play with it just push it, it won't hurt the car (I'm told this by Vetran Mazda Autocrossers) its a set up design cus if you running 85mph first gear cannot handle the downshift and will destroy your tranny, you can force it through the "lock" but it has to be a quike, steady, and force-full movement. I down shifted from 35mph in to first like that with no problems during my autocross this weekend. if you do it slow without power you will "lock out" and get a grinding sound.

If you've got the technique down then it's a worn synchro. There is only one way to properly fix it and thats a tranny rebuild. Changing the tranny fluid to something like redline MTL *might* help or even cure it. Your friends RX-7 has the same problem. I've owned more than half a dozen rx-7's. I can say for sure they will down shift into 1st.

His is a third gen which puts it about the same year as my mx-3.

It is not by design. It is just that synchros cant do it. Look at the parts diagram of a mazda tranny. See if you can find the 1st gear lock out mechanism.


You won't because it doesn't exist.