13 replies to this topic

[Ken Wilkinson]

On the diff, just behind the flange which bolts up to the drive shaft, there is a piece of metal which resembles a 4 leaf clover or iron cross.
I have been told that this is a counterbalance weight and rotates with the spinning driveshaft.
On my car, this weight will rotate independant of the drive shaft. I can turn it with my hand without moving the drive shaft. I understand that it is actually connected to the diff by way of a rubber bushing and with age, that rubber fails and the connection breaks away.
I lost my transmission at my last event and it has been suggested that the failure of this fixed weight lead to a vibration which transferred up the drive shaft and detonated the gears.
Questions:
- does this weight need to be replaced
- can this weight be removed and left off
- is this common
- have others had this same outcome
Any thoughts or ideas are appreciated.

[Bench Racer]

Ken, the part you talk of is actually called a pinion damper. It is found on 1.8 Torsen differentials, not on 1.8 automatic trans cars, also not on 1.6 cars. Being that it's a damper I will presume that the rubber attacher to the pinion flange MUST keep the damper from rotating. Similar to a crankshaft damper. If you were to open miatanet you would find a "Differental Spoters Guide" that talks/shows pictures of the different Miata differentals.

[Glenn]

On the diff, just behind the flange which bolts up to the drive shaft, there is a piece of metal which resembles a 4 leaf clover or iron cross.
I have been told that this is a counterbalance weight and rotates with the spinning driveshaft.
On my car, this weight will rotate independant of the drive shaft. I can turn it with my hand without moving the drive shaft. I understand that it is actually connected to the diff by way of a rubber bushing and with age, that rubber fails and the connection breaks away.
I lost my transmission at my last event and it has been suggested that the failure of this fixed weight lead to a vibration which transferred up the drive shaft and detonated the gears.
Questions:
- does this weight need to be replaced
- can this weight be removed and left off
- is this common
- have others had this same outcome
Any thoughts or ideas are appreciated.

Common failure! Also makes some very odd noises at different RPMs as the damper just spins independently. Trans failure not sure I have seen the cause/effect on that one. Usual trans failure comes from meat fisted drivers

[FTodaro]

What kind of transmission failure are you talking about? did the car have a noticeable high speed vibration or anything like that?

[Glenn]

What kind of transmission failure are you talking about? did the car have a noticeable high speed vibration or anything like that?

Id buy maybe a driveshaft or rear trans seal, but not gearbox failure. Again most of those are driver induced.....

[davew]

On the diff, just behind the flange which bolts up to the drive shaft, there is a piece of metal which resembles a 4 leaf clover or iron cross.
I have been told that this is a counterbalance weight and rotates with the spinning driveshaft.
On my car, this weight will rotate independant of the drive shaft. I can turn it with my hand without moving the drive shaft. I understand that it is actually connected to the diff by way of a rubber bushing and with age, that rubber fails and the connection breaks away.
I lost my transmission at my last event and it has been suggested that the failure of this fixed weight lead to a vibration which transferred up the drive shaft and detonated the gears.
Questions:
- does this weight need to be replaced
- can this weight be removed and left off
- is this common
- have others had this same outcome
Any thoughts or ideas are appreciated.

Legally, the weight needs to be replaced. I have heard of many people running without one. I never have.

At a minimum you must remove the pinion flange and discard the damper.

yes it will cause a trans to break. Sets up some really weird harmonics that destroy the gears.

I would not call it a common failure, but not unheard of. I usually see a couple each year in my 25 weekends with 10 cars each weekend.

I disagree with Dave, the only diffs I have seen without a damper are automatic car or 1.6. Stick shifts all have them regardless of Torsen/open, 4.1/4.3, 94-05. To the best of my knowledge. A flange from any 1.8 car should be usable.

Dave

[Bench Racer]

I disagree with Dave, the only diffs I have seen without a damper are automatic car or 1.6. Stick shifts all have them regardless of Torsen/open, 4.1/4.3, 94-05. To the best of my knowledge. A flange from any 1.8 car should be usable.

Dave

Dave, all is good. Your user friendly response has me thinking a bit more about this pinion damper. If this damper is used on the stick shift cars we presume it's harmonics from the diff, or could it be from the harmonics/diff/drive shaft angle, but then why doesn't the automatic trans have a damper?

Anybody???

[Glenn]

Dave, all is good. Your user friendly response has me thinking a bit more about this pinion damper. If this damper is used on the stick shift cars we presume it's harmonics from the diff, or could it be from the harmonics/diff/drive shaft angle, but then why doesn't the automatic trans have a damper?

Anybody???

Cause Mazda engineers figured out they didnt need one.....

[Bench Racer]

Cause Mazda engineers figured out they didnt need one.....

Not good enough.

[Ken Wilkinson]

Prior to failure, I had not noticed any vibrations or other seemingly serious changes. I did occasionly hear a metalic clunk when letting the clutch out while in a turn.
The current gearbox is a rebuilt unit I installed earlier this year. The gearbox it replaced was the originial unit and since I bought the car brand new off the showroom lot in March 2000. The car had just over 50k on it when I changed it out and probably 40k of that was on track over 8 years. While I don't think of myself as a heavy handed shifter, I am smart enough to never say never.
So do I just remove it or do I replace it and if so, is it a part you can get from Mazdaspeed?

[Adam Molaver]

looks to me like its probaby 27-020 / MA03-27-120B per the attached mazdacomp exploded diagram. if that's the right part, looks to be $100.

ahm

Attached Files

•  99diff.jpg   263.37KB   22 downloads

[FTodaro]

looks to me like its probaby 27-020 / MA03-27-120B per the attached mazdacomp exploded diagram. if that's the right part, looks to be $100.

ahm

How did you attach that thumb nail I tried doing it and could not get it to go?

[Adam Molaver]

hit the more reply options at the bottom of the thread. next page got the typing area, and below it an 'attach files' field. hit the browse button, find the jpg you want to attach (not sure what formats are supported), and hit ok in the browse window. then hit the 'attach this file' button under the browse field. click add reply after typing your response.

or it was magic pixie dust. one or the other...

ahm

Attached Files

•  how.attach.jpg   16.53KB   10 downloads

[Ken Wilkinson]

Frank, I know Adam all too well and the first part of his exlanation is an attempt to confuse and lead you away from the truth...the pixie dust is the right answer...same thing he uses when he drives!