(i posted most of this in another section... given the many excellent trans swap threads in this section i thought it would be good to re-post here)

a combination of 28 years service and turbo system upgrades (often also due to 28 years service) place great strains on our transmissions. there are many threads throughout rotary land as to finding a fix, and as usual, there are many options.

in 2013 i switched gears, literally and figuratively, so as to run the Texas Mile. my objective was/is to run over 200 with a 13BREW fixtured as a dual purpose, street and track. wastegated into the downpipe. i figured about 575 would get it done as another club member did 196 with a 550 swapped in V8. one of the issues was a weak 5th gear in the stock trans. i did not want to shred a gearbox anywhere near 200. another trans issue for me has always been the gearing... a really short first gear and pretty wide spacing after first..

just like spring rate is the trump card in coil overs, gear ratios is the number one factor when considering transmission options.

i zeroed in on the Tremec T56. a club member had mated it to his 20 B which gave me much of the initial info.

before we get to that let's compare ratios:

assume we shift at 8800:

FD 1st gear 3.483, 2nd gear 2.015 5104 rpm, 3rd 1.391 6072, 4th 1.0 6336, 5th 6336

T56 1st gear 2.66, 2nd gear 1.78 5896, 3rd 1.3 6424, 4th 1.0 6776, 5th .74 6512 6th .5 (forget it)

obviously the T56 wins the race. combine the better gearing with 450 ft pounds of torque capacity and newer design syncros at an attractive price and you have a viable trans option. there was lots of internet scuttlebut that the trans wouldn't shift at higher rpms but the 20b swapped setup had no problem. i bought a 50,000 mile 1999 trans from a boneyard for a grand. i added an automatic rear iron to my motor and acquired an auto bellhousing and starter.

the reason for the automatic items is that since the Mazda auto trans is wider than the manual trans the starter is mounted towards the front to eliminate a clearance issue.

i worked with an large industrial metal shop in Milwaukee and created a simple adapter plate with 18 drilled and tapped holes. simple yet precise as the input shaft needs to be dead center to the pilot bearing. i called my friends at Quartermaster and they delivered a very nice aluminum driveshaft. a huge bonus here is that i am scrapping the Mazda driveshaft that has U joints that are NOT replaceable. if you ever have your driveshaft out of your car rotate the U joints and you will very quickly realise they are fully amortised. i ditched the PPF and swapped in (a 30 minute install) Samberg's rear diff subframe. i used a 2004 Pontiac GTO external shift mechanism which located the shifter in exactly the correct position. back in 2013 my clutch options were a bit limited but this has turned around and my clutch is one of the most pleasing aspects of the project. Mcleod's RST double disc is organic sprung and can hold 800 ft pounds. it is also very easy on the leg with a Tilton short 7/8 master cyclinder amd a Tilton 6000 release bearing. amazing!

i found my T56 shifts fine at nine/9000. in prep for the 2013 Texas Mile we did a dyno run to 205 mph which was 8604 rpm in 5th. i wasn't crazy about not being able to use 6th as at the end of the course as you are close to steady state (not much acceleration at 200) and having the motor and clutch at that rpm could be a bit dicey. perhaps fortunately i melted a fuel pump fuse on the second run so never found out.

i enjoyed the T56 in my FD from 2013 til 2021 when in prep for my second TM attempt i decided to jump on Tremec's newest 6 speed offering, the Magnum F. the Magnum F has the same exterior dimensions as the older T56 but has all of Tremec's 2021 engineering. 700 ft pounds, really advanced syncros and is a bolt in replacement for the aging T56s. the big thing for me is that it has a .80 5th and a .63 6th. which means 200 is 7000 in 6th. Perfect.

i was having just a slight reverse engagement issue with my T56 and believed it was the aging external GTO shift mechanism. after doing some research i discovered what appeared to be a 21st century replacement from Sikky. i also discovered a bronze insert from Tick Performance that replaces the plastic fantastic OE insert. executive summary: it shifts like a sequential. night and day better than the GTO setup. almost my favorite thingy on my car.

probably the biggest impediment for the swap is finding an auto rear iron (no longer being made by Mazda) as well as an auto bellhousing and,starter. i believe Grannis may offer another option where they use the manual iron, bellhousing and machine away a part of the trans case. worth a look. i think there may be another more simple solution and will be exploring it when i am at the PRI next week.

i just want to make a pitch for the Magnum F here.... perfect gearing, fabulous syncros, fairly inexpensive for what it is around $3400. quiet, smooth, fits in the tunnel like it was made for the FD. unlike other recent Tremecs, the Magnum F places the reverse lockout solenoid a bit forward which makes it fit the tunnel without interference. i expect to see 7000 in 6th come March in Texas. i almost made it to the TM this October but ruptured a fuel line getting my car on the trailer...

the Magnum F is an excellent trans solution. maybe Tremec should rename it the Magnum FD.

here's the trans with a Spicer 1350 to 1310 U joint and Sonnax yoke that is unique to the Magnum F


ready to install with a Mazda auto setup


awesome Sikky shifter



Mcleod rotary flywheel for RST clutch package custom lightened by 6 pounds for me


Mcleod RST clutch. easy driving in stop and go traffic



Samberg subframe... locks down diff