45 replies to this topic

[Bench Racer]

Because someone's (me included) always looking for knowledge about rebuild/disassembly of the Miata transmission the below address is posted which has a real good write-up and pictures to be a work along with the FSM. I haven't been inside a transmission since my days with my Spec7/ITA Mazda RX7. Basically, similar transmissions. I'm in the process of total disassembly to all loose pieces. I'm at the point of fabing a long reach two jaw bearing puller to remove the main shaft bearing in front of 5th gear, then 5th gear will be removed . Will also be fabing a long reach socket to remove the nut hiding behind where 5th gear was. With Mr. Bennett's knowledge and videos my goal is to improve the syncro spring failure issue while generating an improved devise to keep syncro keys in place. This will be for use in a F production car. Mr. Bennett, if you have said devise or thoughts you'd care to share please forward.

 

 http://rotarycarclub...ead.php?t=17671

 

Moderators, I couldn't find any site info nearly as complete as this included thread copied from RotaryCarClub. Might this be a subject to be placed where all can easily find?

[Johnny D]

I like the idea along with video (maybe there's some YouTube already) so everyone gets a good idea of whats involved in doing a tranny.

 

So are we going to be following your trials and tribulations here ? Blog ?

 

I don't really like you not doing a SM tranny. I don't want anyone getting confused and doing something that's not SM legal.

And here we are with a RX7 tranny to run in F production ?

Just my opinion.

 

J~

[Bench Racer]

Couldn't find a video of a Miata transmission tare apart or rebuild.

 

Me no be a blogger. May be a tad of BS now and then.

 

Nope, the address write up/pictures are a Miata transmission. IIRC the RX7 transmission had a shorter input shaft and different ratios. In post 1 of this thread I made a comment why I've taken a transmission apart (to improve the syncro spring for an F production class car) and have no intentions of adding to this thread other than if from my experience I may be able to support other's potential questions for tare apart or rebuild. BUT there are others who do the tare apart or rebuild who could better answer questions. 

 

If a solid conclusion results from my investigation/improvement to hold the syncro keys in place for an F production car I may ask someone to post result picture. Learning experience.

 

Now off to World of OutLaw sprint car races at the 1/3 mile Angell Park Speedway at Sun Prairie, WI.

 

Have Fun

[Johnny D]

Thanks for sharing !!  Have fun 

 

J~

[Bench Racer]

Completed the long reach bearing puller as show in the write up/pictures. Slam bam thank you puller, came off real easy. One could make mods for a shorter reach puller by drilling some new holes closer to the jaws to position the jacking/screw head.

 

Now off to get a 41mm socket and tube to fab a super deep well socket to remove the nut from the main shaft. Cut the socket in half length wise and weld 2 socket halves and tube together. When reviewing the write up/pictures the author reference the nut being a 32mm. I measured the nut to be 1.6 inches which equals 40.6mm, so 41 mm will do the job. 32mm is 1.26 inches. The 32mm nut is the nut size for the counter shaft that may be removed with a normal 32mm socket.

 

Johnny, World of Outlaws was great, first time for them at this track and now they have their own track record which is better than the local and the announcer said the crowd was max ever in 70 years at the track. Professional racers do put on a GREAT show.  

[Johnny D]

Johnny, World of Outlaws was great, first time for them at this track and now they have their own track record which is better than the local and the announcer said the crowd was max ever in 70 years at the track. Professional racers do put on a GREAT show.

[Bench Racer]

Daryn Pittman #9 in a Kasey Kahne car with Donny Shatz #20 in a Tony Stewart car. They had it going cushion or down low. It appeared Shatz had the overall edge and maybe his past experience played a part in capturing the $10,000.00 to win.

[MotoFusi]

There is a reason that the Outlaw's slogan is "the greatest show on dirt" . They are without a doubt. I'm no Schatz fan as I've pitted next to him and he was a turd. His dad is a hoot though. Pittman is a super guy. Both great wheelmen.

[Bench Racer]

Special tools cost info.

 

Long Reach Puller:

 4 pcs. 1/8 x 1 1/4 x 18 inch cold rolled steel $15.00 assembled with two jaws of puller, jacking/screw head of puller and it worked great. 

 

 

Deep well socket:

41mm socket $11.00, 2 1/2 O.D. x 1/8 wall tube $21.00

Cut socket length wise in half, welded together with tube and it worked great.

 

Pretty easy to fab these tools, available as loaners.

[Johnny D]

TAKE IT OFF BABY !!!

 

J~

[RWP80000]

Another handy "part" or "special tool" to keep around (not only for use while removing the transmission from the car) is a discarded propshaft slip yoke. In addition to keeping oil from leaking out the tailshaft during trans removal you will find it also slides onto the transmission input shaft. This makes it an excellent tool when used in conjunction with a bench vise to hold the transmission gear set assembly steady and secure while working with it on a work bench.  I even use it to hold the main-shaft in a vertical position for some tasks. 

 

I also found that sacrificing a 1-"5/8" -  3/4" drive socket (by grinding out the 3/4 square drive end with a 1/4" air grinder) so the socket is able to slide over the slip yoke end of the main-shaft, and when combined with a large pipe wrench, you have all that is needed to remove/install the large nut.

 

Rich Powers 

[Bench Racer]

Rich, thanks for the added tips.

 

For anal folks, assembly torque with the pipe wrench???

 

Now is the time for some wise a$$ to suggest using a fishing spring tension scale.   

[SaulSpeedwell]

 With Mr. Bennett's knowledge and videos my goal is to improve the syncro spring failure issue while generating an improved devise to keep syncro keys in place. This will be for use in a F production car. Mr. Bennett, if you have said devise or thoughts you'd care to share please forward.

 

 

Not sure what you mean about a device to keep synchro keys in place.  I sell the improved synchro springs shown in the videos to anyone that wants them, or are you talking about some kind of tool to keep the keys in place during assembly? 

[Bench Racer]

Mark, you have a pm. Will you be at the Runoffs? If so how about we compare notes. I'll be there Thur. thru Sun. with Kenny Kannard under the Advanced Auto Sports tent.

[davew]

Davey Dew, I sent parts home with Kenny last night.

 

WOW, 4 days with Dewhurst. Can't wait 

[Bench Racer]

Davey Dew, I sent parts home with Kenny last night.
 
WOW, 4 days with Dewhurst. Can't wait 

Kenny called, will pick up after this post. Thanks

Was going to come on the 16th to be there for test day and all Q. days, BUT with the Pro's doing the car/cars
it gets boring/to much empty time. Plus, I've lost some weight and sponging Ann's food for all those days
wouldn't be keeping with my goal of getting down to 200 pounds.

[SaulSpeedwell]

Mark, you have a pm. Will you be at the Runoffs? If so how about we compare notes. I'll be there Thur. thru Sun. with Kenny Kannard under the Advanced Auto Sports tent.

Dave, you have a PM. Why are we using PM for your Nancy Grace transmission rebuild thread, lol?

[Bench Racer]

Mark, I thought a pm was a personal message.

That aside when we have Miata 5 speed transmission Syncro springs and or syncro rings breaking there is logical reason for the breakage. Through Mark's investigation he found the cause to be brittle springs, he improved the springs and increase spring life 3 to 4 times.

With the transmission apart and examining hubs, sliders, keys, Syncro springs and syncro rings I'm saying to myself, in order for something to be damaged or break there is a force and for every force there is a
reaction force that is equal and in the opposite direction. Before measuring parts I did a parts color transfer similar to what Mark did in his videos and yes the color transferred.

In this case the cause of the reaction force is a parts (syncro ring, syncro spring,
clutch hub) design/dimension/manufacturing interference stack up of .0102 inch to a clearance of .0035. Two different spring material cross sections measured were .048 and .054 and I used the
.054 for the dimensional stack up. The hub anchor hole for the syncro spring in the clutch hub is per gauge pin .0975 inch diameter. The .0975 diameter spring anchor hole is up .0115 inches from the bottom of the clutch hub counter bore bottom surface. During forming of the 90* bend in the syncro spring a .006 inch bulge on each side seemed normal.
I could go through the stack up numbers to make the communication more cumbersome but Let's skip that.

Next with a hand file I shaped the bottom of the syncro spring anchor hole in the clutch hub so the side/bottom of the hole are as deep as the bottom of the clutch hub counter bore with square corners. Redid the color transfer and no colored transferred.

Conclusion, with no reaction force, syncro spring and syncro ring life will be extended way out there.

Another angle I'm working on is to find some syncro springs similar to those used in Jeep, Toyota, Muncie transmissions. These springs anchor on the first and third syncro keys, hence no reaction force.

Of course my investigation is for use in an F production transmission.

But then, one of the philosophies of Spec Miata is cost effectiveness of building and racing a car, correct.

[FTodaro]

you should post a picture of the modification. you know they say they are worth a thousand words.

[Johnny D]

Mark should come to the track with his bag/box of tricks/parts for you guys to review.