infernosg's S5 N/A Build

[tweiss3]

Looks like a great weekend of work. You have more guts than I do, transmissions scare me.

[infernosg]

Originally Posted by tweiss3

Looks like a great weekend of work. You have more guts than I do, transmissions scare me.

Maybe other transmissions are different but the Mazda "Type M" really isn't all that bad. The hardest part is having the right tools and keeping track of everything. Speaking of keeping track of everything, here's the entire gear set exploded:




Something interesting to note; the Miata 2nd gear is double-synchro'd:



Another odd difference is the RX-7 reverse gear is straight cut whereas the Miata is helicall.

I've also got the housings mostly clean.



If the weather ever warms up I'll finish scrubbing these and slap on a few coats of paint.

The input shaft is with a machine shop to be modified (also modifying my RX-8 rear stationary gear). While I wait for that I'm debating swapping the RX-7 5th gear over to achieve a taller 5th for highway driving. Because of the Miata input and countershaft differences the ratio bumps up from .697:1 to something like .75x:1, which is still better than the .814:1 of the Miata. It's not like I'll ever go into 5th on the track anyway.

Shine body parts will arrive tomorrow as well. It's going to be a busy couple weeks

[RETed]

Originally Posted by infernosg

Something interesting to note; the Miata 2nd gear is double-synchro'd:

Is the ratios like the FC ratios?
If so, this makes sense...
If the ratios from 1st to 2nd are pretty wide, then the double syncho would make for a smoother shift between the two, especially at high revs.
FC's are known to scratch the 1st -> 2nd gear shift when getting close to redline.
Also, trying to downshift and rev match is a royal PITA from 2nd -> 1st, although most people don't need to, but some really low speed autocross course might...

Another odd difference is the RX-7 reverse gear is straight cut whereas the Miata is helicall.

This makes sense too...
FC's tend to scratch going into reverse gear...
A band-aid procedure is to shift into 1st (or 2nd) first and then into reverse on the FC.
This seems to help.

Kudos and documenting this and posting the info!


-Ted

[diabolical1]

Originally Posted by tweiss3

Looks like a great weekend of work. You have more guts than I do, transmissions scare me.

this ...

Originally Posted by RETed

Kudos and documenting this and posting the info!

... and this.

[infernosg]

Originally Posted by RETed

Is the ratios like the FC ratios?
If so, this makes sense...
If the ratios from 1st to 2nd are pretty wide, then the double syncho would make for a smoother shift between the two, especially at high revs.
FC's are known to scratch the 1st -> 2nd gear shift when getting close to redline.
Also, trying to downshift and rev match is a royal PITA from 2nd -> 1st, although most people don't need to, but some really low speed autocross course might...

Everything I've read about the Miata gear ratios has 1-3 being taller, but closer together than the RX-7 ratios. 2nd gear gets slammed quite a bit both up from 1st and down from 3rd so I can see why Mazda added the second synchronizer. I can see this being even more advantageous in an RX-7 application due to the higher engine speeds. It's a more complicated design, which means more points of failure so I'm curious how it'll hold up. It's a completely different transmission, but does anyone know if Mazda made this same change to the Type R transmission in the FD?

Originally Posted by RETed

This makes sense too...
FC's tend to scratch going into reverse gear...
A band-aid procedure is to shift into 1st (or 2nd) first and then into reverse on the FC.
This seems to help.

I recall having this issue. Fortunately I spend very little time in reverse. It was just something interesting to note. These transmissions are all fundamentally the same so it's interesting to see all the little internal revisions Mazda did throughout the years. My transmission came out of a '96 Miata so it's possible other years are different. I've heard the latest ('04?) Type M's are the best to get because they have the most amount of improvements.

Originally Posted by RETed

Kudos and documenting this and posting the info!


-Ted

I'm going to try to take more pictures during the reassembly process. My goal is to use them in reverse in a "how-to" thread. There are many other small differences between the transmissions (e.g. snap rings, bearings, etc.) and I'll try to reference them all there.

In other news the input shaft modification is supposedly done so I'm going to pick that up after work today. I gave them the dimensions from Mazdatrix's website but I'm still a little worried it won't turn out right. Just an annoying trust issue I have I guess...

[Fidelity101]

Originally Posted by infernosg

Maybe other transmissions are different but the Mazda "Type M" really isn't all that bad. The hardest part is having the right tools and keeping track of everything. Speaking of keeping track of everything, here's the entire gear set exploded:




Something interesting to note; the Miata 2nd gear is double-synchro'd:



Another odd difference is the RX-7 reverse gear is straight cut whereas the Miata is helicall.

I've also got the housings mostly clean.



If the weather ever warms up I'll finish scrubbing these and slap on a few coats of paint.

The input shaft is with a machine shop to be modified (also modifying my RX-8 rear stationary gear). While I wait for that I'm debating swapping the RX-7 5th gear over to achieve a taller 5th for highway driving. Because of the Miata input and countershaft differences the ratio bumps up from .697:1 to something like .75x:1, which is still better than the .814:1 of the Miata. It's not like I'll ever go into 5th on the track anyway.

Shine body parts will arrive tomorrow as well. It's going to be a busy couple weeks

Let me know when you are doing that because I need to get my rx8 stat gear machined too, prob couldn't hurt to have them both done at the same time, maybe help split the cost. Do you have a stock rear stat gear for them to setup the chuck/mockup the bit for?

[infernosg]

Originally Posted by Fidelity101

Let me know when you are doing that because I need to get my rx8 stat gear machined too, prob couldn't hurt to have them both done at the same time, maybe help split the cost. Do you have a stock rear stat gear for them to setup the chuck/mockup the bit for?

I already had the machining done and picked up the parts yesterday. I found a local machine and die shop the seemed competent enough to do the job. Groove put in the rear stationary gear:



I wasn't able to get good measurements of the groove myself so I left them the stock stationary gear to use as a setup. The groove is approximately .100" wide by .060" deep. I plan on using a little RTV in addition to the o-ring so a little error shouldn't be that big of a deal.

I also picked up the input shaft. Fortunately it looks like the turned out correctly. Modified Miata input shaft on bottom, stock RX-7 on top:



A quick check shows the overall length and spline length to be a little longer than the RX-7 shaft but I verified the dimensions with Mazdatrix's recommendations and I trust they know what they're doing so everything should work.

The fiberglass body parts were delivered yesterday too (busy day).

Shine Auto vented hood:



The hood is latched in above picture but not bolted to the car. It lines up fairly well but I'm going to have to lower the latch quite a bit it seems. I'll be picking up some hood pins somewhere along the way. It's a true vented hood:



I'll be tying the vent into some kind of post-radiator fan ducting eventually.

Shine Auto Fenders:



It's a pretty subtle flare but should be enough to cover the wider wheels and tires:



I've got family visiting this weekend so I won't be able to work on the car too much. The immediate plans are to reassemble the transmission and to mock up the body parts to verify fitment. I'll leave the final fitting and painting to the professionals. I'll be picking up a fender roller early next week to work on the rears.