141 replies to this topic

[Michael Novak]

I must not have any feeling in my hand. The aluminum one last forever or the nylon doesnt and requires regular changes..  Maybe I will wrap the shift lever in gel and call it good....

 

It took mine one full weekend of racing to loosen up. 

 

 

Thanks you for answering.

[SaulSpeedwell]

I must not have any feeling in my hand. The aluminum one last forever or the nylon doesnt and requires regular changes..  Maybe I will wrap the shift lever in gel and call it good....

 

It took mine one full weekend of racing to loosen up. 

 

 

Thanks you for answering.

 

I'm not sure I follow what you are saying - are you saying you have used the aluminum bushing and you don't have a problem with the feel?  Which bushing are you talking about needing a weekend to loosen up?

[Michael Novak]

I'm not sure I follow what you are saying - are you saying you have used the aluminum bushing and you don't have a problem with the feel?  Which bushing are you talking about needing a weekend to loosen up?

Sorry. I have been using the aluminum one and thought it worked fine. It took about 1-2 hours to loosen up. Replacing the regular one all the time seems like a pain. I will put a plastic one in and compare

[SaulSpeedwell]

Just for documentation and reference purposes, below are shaky, grainy, stuffy-nose iPhone videos of my audit testing for the 4th batch of improved synchro springs.
 
For anyone that breaks these springs, I want them back.  I will gladly replace them free of charge.
 

[AW33COM]

Hmm, so how many miles you get out of these springs vs regular springs? 

[SaulSpeedwell]

Hmm, so how many miles you get out of these springs vs regular springs? 

 

It isn't a miles issue, it is a "how many shifts" issue.  I've tried to demonstrate in the videos that we have spring that will take MANY TIMES more stress/strain and impact trauma than the stock springs.

 

The world's most abusive shifting person may only get 2-10 terrible shifts out of these compared to 1 truly worst case shift with the stock ones, but in any case, after the spring breaks it is somewhat random as to how long it takes for the spring to walk out of place and cause a synchro to get jammed/cracked.

 

In contrast, my goal is for the vast majority of drivers to NEVER break a spring as the cause of a DNF or rebuild. 

[SaulSpeedwell]

Public Service Announcement:  3-4 Shift Forks

 

https://picasaweb.go...feat=directlink

 

Some of you may have noticed a change in appearance and processing to Mazda's 3-4 Shift Forks ever since the "D" revision of that part came out.  (Pic link above, but it may take me some time after I post this to get it working and displaying just right - and I now realize I have some pics to add later)

 

As one of the most frequently operated/worn out/ and replaced components in the transmission, I have been meaning to get around to testing and measuring these parts versus the "C" Revision that we have used for most of the time the SM class has been around. 

 

Results:

"C" Revision: 

Base Material hardness:  15 HRc

Pad Hardness at wear surface:  19 HRc

Pad thickness:  0.271"

 

"D" Revision:

Base Material hardness: 24 HRc

Pad Hardness at wear surface: 28 HRc

Pad thickness: 0.278"

 

Conclusion:  Although arguably "uglier" than the old "C" revision forks, the newer "D" revision forks are significantly "harder" and 0.008" thicker at the unmachined pad surface.  The unmachined surface will "polish down" rapidly during break-in.

 

Bottom line:   Compared to a machined "C" revision, these forks are expected to last longer, but with increased chance of wearing the mating hardened hub sleeve (~ 57 HRc at the wear surface).

 

-MB

[FTodaro]

Mark how many different forks in the D version did you test. I am still wondering about the consistency of the Mazda parts in a given run with all the issues that have cropped up in transmission parts over the last few years.

[SaulSpeedwell]

I tested two "new" forks.  The worst looking one with the voids shown - interestingly, it bears a "family resemblance" to some older forks that I have.  Meaning the voids are in the same place as what an older fork showed as only "minor acne".  It seems these parts are cast out of more than one mold cavity, but it also appears the "D" revisions is coming out of the same mold as before. 

 

I don't want to suggest Mazda is making "bad" parts here - I'm just trying to understand the differences and whether/how they matter to our little world here - I've got to believe we are rebuilding more 90-05 Miata transmissions here in our little SM niche market than anyone else on the planet is. 

[Qik Nip]

Reflecting the origional spirit of this two year old thread, I am today annoucing that I'll soon be offering a sequential shift SM transmission constructed of 100% unobtanium, weighing in at six pounds capable of executing gear changes in three micro seconds. The target price will be about the same as a set of Saul's springs.

Rick

[Jim Drago]

Reflecting the origional spirit of this two year old thread, I am today annoucing that I'll soon be offering a sequential shift SM transmission constructed of 100% unobtanium, weighing in at six pounds capable of executing gear changes in three micro seconds. The target price will be about the same as a set of Saul's springs.
Rick

We have been running those for two seasons

[Bench Racer]

We have been running those for two seasons

Are you using the 360* flat wire (same cross section as todays flat spring wire) diagonal gap with no bent tab syncro spring in your Qik Nip three micro second sequential shift SM transmission? 

[DrDomm]

Ironic how some of these comments came together as my rebuilt transmission just showed up from Mark, and is now in the same garage that houses a GT2 car that just got a sequential box to replace the old PBS.  Of course I've been looking at the sequential, wishing it was in my car.  Pretty cool stuff.

[Bench Racer]

, and is now in the same garage that houses a GT2 car that just got a sequential box to replace the old PBS. 

Would the garage mate GT2 car be the same color as your car and a skid of PBS's get shipped to Wisconsin?

[SaulSpeedwell]

Spec Miata Transmission Insomnia Mystery Science Theater 2000:  Twisted Countershaft Splines

 

(And I have no idea why it sounds like I am saying "counterSHIFT" 50% of the time???!!!)

 

[DrDomm]

Would the garage mate GT2 car be the same color as your car and a skid of PBS's get shipped to Wisconsin?

 

That would be correct.  I stole the paint scheme.  The garage belongs to my father-in-law.  The owner of the GT2 Nissan (my wife's uncle) has my old SM (painted the same, as well) in Houston.  It's a big happy (racing) family. 

[DrDomm]

Spec Miata Transmission Insomnia Mystery Science Theater 2000:  Twisted Countershaft Splines

 

(And I have no idea why it sounds like I am saying "counterSHIFT" 50% of the time???!!!)

 

 

I bet that goes viral.

[Jim Drago]

It's a big happy (racing) family.
[/quote]

This guy related?

[Bench Racer]

Saul, you mentioned the twisted countershaft. I have an early transmission rebuilt by a pro shop, in an emergency situation installed in an E production car. As the story was told, during it's first race the driver looped the car in 5th gear with the end result being a twisted countershaft. Transmission rebuilt and never used to date. Your thoughts???

[FTodaro]

I could not hear the audio of the vid on my work computer, but by the title, I have rebuilt one transmission that had a twisted counter shaft I could get it apart but it was a real PITA. it still worked fine but not much fun to rebuild. It could just be the result of the extra stresses we put on the box that are above its design limits. 5th gear pulls on that part of the shaft so it must be something to do with the stresses in 5th. What did you say on the video. I will read it before i go to bed to put me to sleep.