1991 miata stang sound when decelerating

If the noise is gear specific, it's likely coming from the transmission. A 91 is old enough, and may have enough milage or hard use to cause a transmission problems. Generally, a used transmission is the least expensive solution.

Are there any differences between the 5-speed used in 1991 and the one used in 1996 on the miata?

Pat

Check miata.net, go to 'garage' then click on 'compatibility' it should be there. I'm thinking that trannys for 1.6 and 1.8 liter engines are the same.

Chris

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i just put in a stage one racing clutch and new drive shaft and replaces the seals is there anything else in the transmission that would do oit? my dad says its a rattle but i dont know

They are definitely compatible, I have a 1991 transmission hooked to a

2001 differential, 2001 driveshaft and a 1994 engine with a '99 head. The transmission has 142,000 miles on it and was one of the only things that wasn't replaced just because there was nothing wrong with it.

Still, I am thinking that I heard that they had done something to make the 1994+ tranny stronger, I could be wrong.

I guess the reason that I am asking is because I have the 1996 tranny with 75K miles that I can either sell or use as a donor part in the future when the original one finally goes out. It is, however, kind of a big thing to store and move around. I'll probably let it go.

Pat

Your description isn't entirely clear - in the subject line you say you get the sound when decelerating, but in the body of your e-mail you say it happens when you ease off the clutch. If the noise appears when you're decelerating (i.e. easing off the accelerator rather than the clutch), this may be your exhaust system somewhere along the line; I've had a rattling noise on my '91 for a while now when decelerating, and that's what it is (a point apparently where two parts of the exhaust system meet, or not quite properly meet anymore). My mechanic has put a ring around the join and tightens it whenever I bring it in for a service or whatever. Not a proper fix but until I can afford to replace the whole exhaust system it'll do.

In my case, though, the noise appears when decelerating in any gear, not just fourth as in your case, so it might be a different problem.

Eric

I do think some more specifics about the noise might be helpful...I have to tell you though, your description does make it sound an awful lot like a loose catalytic converter heatshield...whether it happens when you decellerate or let off the clutch. I had this happen on my old

95 Civic, my sister's 94 Civic, two of my friend's cars, and I know it's a common problem in Miata's as well. My mechanic says it's a problem with all Japanese cars but that it is quite alright to just rip it off and toss it away. Is it a buzzing noise? A loud RAT TAT TAT? Get graphic and mayhaps we can give you a good starting place.

Two good sounding methods for under the car:

Start the car, lie on your stomach and look under the car. Have someone (sounds like maybe your dad?) sit in the driver's seat and...in neutral!...slowly push the throttle in. If, as you say, there's a rattle as you're letting off things--clutch or throttle, you're not clear--then it's likely that part will vibrate at a certain frequency, which you can replicate with the revving of the engine. Just make sure the driver doesn't redline under no load! If this method works, it probably won't take much throttle.

Another method I came across over on the ineffable

is to jack the car up and start tapping things (exhaust, chassis, transmission, clutch assembly, etc.) with a rubber mallet. Eventually, you can track down what system is making the noise, and then where in the system the noise is.

Also, do you have any aftermarket (or OE) bracing that might be coming loose? Now's a good chance to torque those bolts...and heck, change the oil filter while you're down there...

Best of luck, keep us posted.

Cheers,

-r0ll

ok guys, lets start here,

i have a stage 1 racing clutch and just replaces all seals and pressure plate. i dont have a catalytic converter i just put in a test pipe. i guess it could be and exaust rattle cause i had to take out my exaust from the headers back. the test pipe didnt line up perfectly before tightening it but it pulled itself together. its a hard sounnd to explain its like a rattle but alsoo sounds like a grind but i doupt its a grinding. if im drivingg down the road and am in 4th gear and a light turns red ill ease off the gas and not press in the clutch that is when it happens. i guess it happens when i let the engine/clutch slow me dow instead of using the breaks. its a 5 speed manual. i think that covers it.

Ya, it's sounding more and more like an exhaust system rattle. That misalignment has probably put some twisting pressure (torque) on the system and your engine tends to shift around as you get on and off the loud pedal. The flexing of the motor mounts allows this and that little movement is probably allowing two metal parts to touch / rattle / grind as you mention. One other thing you can keep an eye out for while underneath is a shiny spot on an otherwise dingy part. That might give you a clue as to the contact point. Keep in mind though that these parts are probably very close together even when not making contact. Take a really good light under there and poke around.

Chris

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