TRANSMISSION SOLUTION 

The Tick Performance bronze bushing.

Running 205 on a dyno is of course quite different than on the asphalt. The oft rumored inability of the T56 to shift at high rpm was debunked as on my first launch I found my motor was at 9000 before i could shift. The upshift was zero problem as was the 9000 exchange into third. I finally coralled the engine in third at 8800.

I had sheared the speedo needle on the dyno and was limited on my first run (rookie) to 166. Since i had no speedometer needle i figured 160 ish was about 6900 in fifth. When i shifted into fifth i looked at the tach and it was slightly over 6000 and climbing quickly. I literally lifted my foot off the accelerator. Then looked up to see the 3/8 mile marker ahead of me. 

On the second run (limited to 199) i melted a fuel pump fuse which collapsed the corner seal springs and was all done for the event. After returning from the event i replaced the corner seal springs and sort of became busy doing engines. After doing about 160 13 BREWs to my spec i decided to shift gears a bit and only build from new blocks. This allowed me to get back to my FD and another shot at the Texas Mile. 

Fortunately the stars started to align as we moved from Wisconsin to the mountains of NE Georgia. The concept of being able to drive/engineer my FD 12 months a year is mind blowing.  I had a pretty interesting year in Wisconsin in 2018 as i tested a number of turbos and did a huge amount of road tuning. However, being able to work on my car pretty much full time in Georgia has it in another zipcode. This year, among many other things i completely evaluated four intercoolers. ( watch for a new Section on the site) 


Of course, being a racer, the Texas Mile is always the elephant in the room. 200 mph is calling and here we get back on topic. After an unsatisfactory initial outcome, the plan was to get the ducks in a row. I didn't race for 22 seasons without learning the most important lesson... you don't do any work less than 100%. If you do a job 95% the other 5% will bite you bad. As i considered prep for another (Oct 2021) attempt the stars aligned and Tremec rolled out the Magnum F. Thank you Tremec.

I never liked the idea of finishing the Mile at 8600. Around 200 acceleration is quite modest and the idea of the motor almost at a steady state at 8600/575 hp was not appealing from so many apsects. The Magnum F really super fixes gearing after 4th. Not ony is fifth closer (-20%) to fourth but 6th is 21% from fifth. Awesome!  Instead of holding my breath at 8600 i will be shifting to sixth and if all goes well will buzz through the timer at engine friendlier 7000. Sign me up.


So I did sign up and bought a Magnum F ($3400) at the end of June. The Magnum F, unlike the T56, uses a larger yoke. The yoke is unique to the Magnum F. They were in short supply but i was able to source a really high quality chromoly forged Sonnax yoke through D&D Performance. D&D is a top tier Tremec distributor out of Michigan and was quite helpful as to tech info.

                                                                                                                                                          Sonnax P/N T3-3-24915

  

It is possible to have a perfect transmission but if you have the wrong clutch package you will hate driving your car. I am always always about dual purpose with my FD. Any clutch package must be completely at home in stop and go driving as well as holding the engine torque. A few years ago that would be a tall order for the rotary. Since the engine is so small, 13 X 13 X 13 inches, for the shortblock the flywheel/frictional surface is small. Small flywheel requires either tons of spring pressure (goodby dual purpose) or a double disc. Double disc equals more frictional area and therefore less spring pressure and a friendlier situation for the left leg. Take up, or the (crucial) ability to feather, relates significantly to the type of disc material. 

Say hello to the clutch package solution: 

The Mcleod RST organic double disc was designed to hold 800 hp/800 ft pounds of torque in 3900/4400 pound Mustangs and Camaros.  It is perfect for a dual purpose single turbo FD. Mcleod fabbed a billet aluminum flywheel and then removed 6 additional pounds and presto, the ultimate FD clutch package. Shockingly easy on the leg. I really don't believe it can hold that much torque given the friendly nature of the pedal and takeup but won't ever be making that kind of power. Here's the backside of my flywheel where they removed additional weight. Talk to Lee in Tech if you want such a package.

The yoke requires a slightly larger U-joint than the T56. My Quartermaster aluminum driveshaft had the smaller 1310 yoke so i sourced a Spicer 1350/1310 U-joint. I did not have to change the length of my T56 driveshaft nor change my rear transmission mount. I did not have to change the three electrical connections either. I do use a Dakota Digital module to correct the speedometer.

Of course on any transmission swap shifter location can be a challenge. When I swapped in my T56 i added a (Pontiac 2004-2006 GTO) external shifter mechanism. The GTO item re-locates the shifter dead center for the FD. I did have reverse issues with the shifter in the last few years. The problem was not with the transmission but with the plastic cup that fits between the shifter ball and selector rod well. Other than the reverse problem the T56 shifted perfectly. 

I did some research re external shifters  for the Magnum F and found the Sikky shifter. I also replaced the plastic shift bushing with a bronze shifter cup from Tick Performance P/N 95B. There is a special GTO cast piece that must be swapped onto the end of the T56 or Magnum F shift rod that enables the use of the external GTO/Sikky shifter.  GM P/N 92147292. BTW, I like Tick and they are a Tremec dealer.

Of all the items that i swapped into my FD for the Texas Mile i was probably most nervous about the shifter. It turned out to be one of the favorite things on my car! Totally love it, shifting is almost like having a sequential gearbox and there are zero problems with reverse. I think both the shifter and the bronze bushing contribute.

 

Other than adding up dollarwise this all sounds pretty good. What's the catch? The catch is mating the transmission to the motor. 

Given the racecar suspension, weight, and aero the FD is literally a supercar in sheepscar clothing. While it was offered with 217 rwhp, the motor begs to have the unfortunately designed 28 year old turbo system discarded and replaced with a 21st century turbocharger. Modestly fixtured and tuned, rwhp doubles and the nature of the car switches from a peppy Miata to a full fledged supercar. Of course to make the proper transformation most everything needs to be uprated. Brakes, tires, wheels, springs/shocks, swaybars, bushings ad infinitum.

Often overlooked is the transmission. While it works fairly well with the stock power output, it has a useless first gear, wide ratios, crude syncros and needs to eat a lot of spinach. Crank up the power with a single turbo and you will soon be looking for another transmission. The primary reason most modded FDs still retain the stock transmission is because there hasn't been a logical replacement.

Until now.

A number of years ago Borg Warner spun off their transmission division. the new company company, Transmission Engineering Corp or Tremec, has gone on to not only maintain Borg Warner's esteemed reputation in the market but to build upon it.  Corvette, Viper, Camaro, Mustang and Challenger manual 6 speeds are Tremec. Even the new mid engine Corvette sports a Tremec 8 speed transmission. During the 20 plus years that Tremec has offered high performance 6 speeds engineering has moved ahead in virtually every area. Way better syncros, wider faced gears, tighter clearances, better bearings, better shift forks, better materials... every year, every area:  enhanced engineering, enhanced performance. 

Positioned at the very top of this engineering process is Tremec's newest aftermarket offering, the Magnum F.
















While the "Magnum" tag is not new to the Tremec line, the "F" is. "F" refers to F body GM cars... Camaro/Firebird. It was the "F" body that first offered Tremec's ground breaking T56. The T56 was the first 6 speed that was engineered to mate with the higher hp "muscle" cars. Proof of the fact that Tremec has been busy re-engineering is that the Magnum F handles 700 ft pounds of torque, up from 400!

Likewise, ratios have been improved to perfect. Fifth is closer to fourth and sixth is now a scant 21% from fifth making it very usable. 

In 2013, as i was engineering my FD for a 200 mph run at the Texas Mile, i concluded i needed a better tranmission. I would be running around the 575 rwhp range, needed closer gear spacing and was greatly concerned about the especially weak 5th gear. I did not want to shred fifth in the 200 neighborhood. I also didn't want to have to generally pussy foot around driving my car in 500 land. The idea of constantly having to replace broken FD transmissions was not appealing.  After a close examination of my transmission options i settled on a T56. I bought a 1999 T56 that came out of a Camaro and had approximately 50,000 mile of usage.  

Just like spring rate is the most important factor in choosing coil overs, GEARING is the most important factor as to transmission selection. The T56 scored bigtime here....

Compared to the FD box and shifting at 8800:

FD

1st 3.483, 2nd 2.015 5104 rpm, 3rd 1.391 6072, 4th 1 6336, 5th .719 6336

T56

1st 2.66, 2nd 1.78 5896, 3rd 1.3 6424, 4th 1 6776, 5th .74 6512, 6th .5 5945 (too long)

Sure easy to see who wins the race.

I did run the October 2013 Texas Mile. Since the spacing from fifth into sixth was a bit wide my plan was to finish the Mile in fifth, around 8600. The week prior to the event we did a run in fifth on the dyno to 8604 which was 330.1 KPH/205 mph.   

As you may know, the FD was offered in small quantites with an automatic transmission. Because the auto trans was wider than the manual trans the rear facing starter would not clear the transmission body. Mazda cast an auto bellhousing that positioned the starter toward the front solving the problem.  A slightly different rear iron was needed to properly anchor the starter. The Tremec is a bit wider and if mated to a manual bellhousing the starter interferes with the transmission case. I picked up an auto rear iron, auto bellhousing and auto starter. I had an adapter plate made that bolts to the rear of the Mazda auto bellhousing and the Tremec transmission. 18 bolt holes drilled and tapped and they must position the input shaft in the (dead) center of the Mazda pilot bearing.

Here's my T56 adapter plate:


















I found that it would not fit the Magnum F as the newer transmission has various items protruding from the front face. After much whittling i ended up with this:



















It looks better after paint and works perfectly.

So the whole Magnum F sounds like it is do-able, just source the 3 parts and talk me into calling the shop with the pattern for a plate. Except for... Mazda no longer makes 13BREW auto rear irons, there are no auto starters in the U S (according to Ray Crowe) and i don't know about belllhousings. (although i have two sitting around.)

Many wouldn't want to open their engines for a rear iron swap. I did just that in July. I decided to build a new block motor for myself for the Texas Mile. I sold my motor and then realised that it had an auto iron on it so i took the new rear iron from the motor i had just bought and swapped it into the motor i had sold. My brand new block motor has my old auto rear iron on it.

I do think all the auto items are around gathering dust after the owner swapped in a manual so could probably be found with the help of the net and the RX7club. But for most, the auto swap deal is an uphill battle.

I just returned from the Performance Racing Industry tradeshow in Indianapolis. I did find an answer to the mating challenge.

The answer is Browell Bellhousing.com.

Browell makes bellhousings of all kinds for all kinds of frontline racing customers. They have made numerous bellhousings that adapt our (!) motors to any transmission you wish. Browell has a 3/8 inch thick adapter plate that bolts directly to the rear (manual) iron and then adapts rearward to an assortment of bellhousings. I spoke with Scott who is a design engineer for Browell. He mentioned using a Chevrolet aluminum BH that mates with a forward facing starter. They also are capable of making a hydroformed BH which would offer increased safety.  I am very impressed with Browell. If i hadn't already fabbed my setup together i would be giving them a call. They are located in Indiana. 



views better on a laptop. all pics

are here but some out of sequence

on mobil.

TUET16362

A Tilton 6000 hydraulic clutch release bearing and a Tilton (or Wilwood) shorty 7/8 clutch master cylinder complete the swap. Only Tilton on the release bearing. Trust me on this.