Transmission issues, please help!
 

Ok Is just bought this 2001 miata base model last week and I've been have some issues with it.

1. At 60mph in 5th gear I'm at 3600rpm. that seems a little High to me. the gears are really short. not sure if that's a normal Miata thing.

2. at 1/3 throttle or more in gear I get a strange buzzing noise coming from the trans tunnel. very consistant and loud.

3. 5th gear grinds every so slightly when going into gear. Now this car has 50,000 miles on the clock, and usually 2nd or 3rd is the first to start going.

Any help would be graetly appreciated.

has it been modified at all

you have a 4.30 final. it's about time for a fluid change. and change the turret oil as well.

high rpms is normal

Turret oil? Is that like headlight fluid or exhaust bearings?

jking! What is turret oil? I've never heard of it before.

the oil in the area where the shifter sits. Dunno about the NBs, but the NAs are filled with oil and it goes away after a while...some people stuff it with grease.

put new fluids in. You can't really do anything about gear ratios.

On a side note, I have a guy who works for me who keeps taking his wife's SUV in because "it runs too many rpm's on the highway." They keep trying to explain the concept of ratios to him, and he keeps getting angry and thinks the dealership is trying to screw him. ...this is what I have to work with.

I'm sorry about that. I know that there is nothing that can be done about gear ratios (except for changing the gears themselves) but I've had so many pleasant surprises so far on this thing, I wouldn't be the least bit surprised if the previous owner had put in a different gearset. (i.e. didn't know until after we bought it that there was a methanol tank in the trunk! And the full aquamist kit to go with it.

The buzzing is what really worries many, any idea on what that might be?

Buzzing noise from a transmission...could be anything. There happens to be a lot of moving parts in transmissions.

What kind of buzzing? What pitch? Increases with car speed or with RPM? At what RPM do you notice it begin? At what RPM does it disappear, if at all? Does it increase in pitch of volume in certain gears? Does it quiet down/disappear when you're in the 1:1 gear (4th)? Does the noise increase, decrease or disappear when revving the car in neutral? What kind of work has been done to the car with regard to aftermarket parts? What happens if you put a thicker tranny oil in it (Redline MT-90)?

It has almost nothing to do with RPM, Gear, or speed. Only throttle position. it sound like a mono-tone tractor whenever I depress the throttle more than 1/3 of the way down, and only when it's in gear. could be the methanol pump?

load based buzz could very well be the heat shield on the down pipe. You can hear mine from a mile away :(

I don't know if there is a heat sheild on the DP. It's and aftermarket DP for a turbo.

It. does sound like a heat sheild of some sort rattling, yet it is so abrupt and consistant.

So, what kind of aftermarket turbo do you have? I mean, there are so many variables, and you haven't even really told us about the car.

If it were a stock car, maybe, MAYBE, we could help you pinpoint the problem, but you've added so many variables...

he has an external fuel pump and WI...i bet it's one of the pumps.

external inline-fuel pumps can be very buzzy.

For that matter some of the high flow in-tank pumps can be buzzy...

Happens right around 2500-4000 rpm? If so I'd say exhaust... that seems to be the resonate frequency or something because mine has always buzzed in that range even after 3 catback designs and various hanger changes.

That's true...mine's always had some resonant exhaust noises in that RPM range, too.

As you can see, lots of things could be the culprit.

Definitely sounds like a load noise, which would indicate something loose. Almost always a heat shield (not to be the 10th guy to mention it).

My 99 has the same 5th gear issue. It's just the synchro going bad. Just spend a little more time in the staging point just before you actually put it into 5th gear which will give 5th gear time to catch up to engine rpm (or rpm to fall more likely). This will save you some synchro life, but eventually it will need replacement if you can't take the grind.

I really don't mind the 5th gear grind that much, guess I'll just live with it for now.

Ok, so here is a list of aftermarket parts (that I know of)

GT2560r turbo
Magnaflow single tip exhaust
(looks like) custom Turbo maniufold and DP
South Florida Performance IC piping
Spearco IC
Aquamist WI kit
Aeromotive Billet Digital FMU, P/N 16303
Hard Dog view roll bar
JR shift knob and e-brake handle

(in glove box)
HKS type I turbo timer
Autometer boost and EGT gauges

and that's all I've found so far. The buzzing sound is not rpm snesitive, it's only throttle sensitive. anything past 1/3 throttle and the buzzing kicks in.