T50 to AZ6..... At the CNC....

[oldeskewltoy]

A brief overview... the AE86 GTS is going on 20+ years old. It is rear wheel drive. It was originally equipped with the 4AGE twin cam 4 cylinder, a 5 speed transmission, and a solid rear axle. In recent years the AE86 has garnered "collectors status" as well as becoming a cult "drifter". The AE86's popularity is VERY strong!

The 5 speed transmission is known as the T50. The 5 speed T50 evolved from the earlier T40 4 speed. The T40/T50 was originally designed for engines producing 40 to 100 hp. The stock power of the AE86 4AGE is 112 horsepower. The T50 in stock form tends to have 2nd gear difficulties as it has aged. Cost to rebuild a STOCK T50 (complete rebuild) are quite expensive, parts can cost $900+ and the labor would add another $450. There are TRD performance gearsets for the T50, they would add somewhere between $1200 and $1900 to the rebuild cost. The TRD gear set is more substantial but overall the T50 remains fragile. (( all $$ figures are US dollars))

Besides its fragility, the stock gearing is VERY poor. So poor that when it was originally tested by Road & Track in February 1985, they commented,

The GT-S was a fraction slower... ...there were times and places when the engines power couldn't be used... ...the jump from 2nd to 3rd is too wide and the jump from 4th to 5th isn't wide enough

adding a TRD gear set improves the gear spacing, but because the TRD gear set's 1st is so much tighter (2.6 or 2.3 to 1 as opposed to 3.5 to 1) it makes use on the street MUCH tougher.

Move ahead in time 15 years... The Miata is introduced with the AZ6 6 speed transmission. In essences the AZ6 is a close ratio 5 speed(gears 2 through 6), with a taller 1st gear. This in essence gives you the advantage of a close ratio transmission WITHOUT sacrificing the ease of use that a tall 1st gear offers. The AZ6 was originally designed for the Altezza, the Miata and the RX8, its power capability is well over 250 horsepower. The AZ6 is capable of running just about ANY type 4AG - n/a, s/c, turbo. The gearing is just about perfect for the 4AGE AE86 - placing redline shifts at or above 4500 rpm(TVIS engagement) for each successive gear


The problems to overcome:
1) Toyota gearbox is a self contained unit, the bell housing isn't intregal to sealing the gearbox itself, the Miata bell housing is also the front of the gear box case. This is the biggest problem to overcome. Doing research I've found that this isn't an unknown swap (AZ6 into AE86) but it is VERY RARE, but it has been done a handfull of times, but in all previous cases the Toyota bell was welded to the AZ6 bell and a clutch mixture has been used. The problem with this is the engineering involved with the clutch working range was never taken into consideration. The reliability of this is unknown. "We"* decided that the most reliable way to do this was to use the entire Toyota clutch... complete bellhousing, hydralics, disc and pressure plate, all Toyotas engineering. To do this we needed to cast an adapter. This adapter would closee up the AZ6 gear box, support the output shaft bearing, and have a flange to bolt on the Toyota bell housing.
2) Since we decided to use an adapter, the input shaft becomes too short. Also, to use the Toyota clutch, the splines are wrong anyway. The Toyota input shaft will be grafted on to the Miata input shaft. this will extend the length needed, and fit the Toyota clutch
3) The AZ6 is physically larger than the T50, a bit wider(no so wide to be a concern) and quite a bit longer. The length on the AZ6 will be compensated by shortening the stock 2 piece drive shaft. The front section will be shortened and the AZ6 output shaft will be added. This will keep the driveshaft support bearing in the stock place, thus keeping the driveshaft to axle angles all intact from the stock driveline.
4) As stated above the AZ6 is larger, one of the issues in this swap is the shifter would come through the floor in the AE86 about 9" behind where it does originally. Now if this was a racing example, this would not be an issue, just move the parking brake and cut a hole, BUT I don't want to do that, so the shifter section is going to be shortened so the shifter will come through the floor in the correct location. This will require shortening the top of the AZ6 case and shortening all the shift linkage.
5) The AZ6 as fitted to the Miata does NOT have a rear transmount as is conventionally known... the AZ6 in the Miata has a link to the rear this link holds up the back of the AZ6. This link section needs to be modified to hold a conventional cross type transmission mount.
6) The last problem to overcome is speedometer drive. The Miata uses a digital signal, the AE86 uses a mechanical cable. For now... we are looking at fitting a mechanical drive to the AZ6.

Now.... there are a lot of VERY intricate details that seem to be "over engineered" for a one of a kind swap. Now some of this is because I want a fully useable car when I'm done, but there is a second larger over riding purpose... go back... look above....

T50 remains fragile AND The AZ6 is capable of running just about ANY type 4AG - n/a, s/c, turbo. soooo.....

Rob and I decided that most of the T50s are now junk, and for nearly the same cost as a rebuilt T50 with a TRD gear set you can have an AZ6! The final costs will be set once the engineering is done, but as of now the total cost for a complete AE86 AZ6 swap would come in UNDER $3000 That might seem like a lot, but once you compare it to rebuilding an inferior trans...(or purchasing a Quaife for $6g!) it makes PERFECT sense!

* - "We" are Rob Golden owner of Pineapple Racing http://www.pineappleracing.com/ - renown Mazda builder....
and me

Why.... bet that is running through some brains.... simple really... T50 sucks. W box is fine... but could used better ratios... AND one more gear(for use with a 4AGE). In essence(for 4AGE use) look at the AZ6 as a 6 speed W box.....

But why?.... well in my case, the one part of the puzzle that isn't there... is the addition of a 4.10 Richmond Racing rear diff. The slightly taller 1st gear of the AZ6, matched to the 4.10 offers me nearly identical starts.... as the T50 and the 4.30... and between the 4.10 and the .843 6th gear I should lower highway rpm by over 700... which I'm expecting a 10% boost in mileage... In other peoples case(yours?) they may want to run this option so they can run more power down the driveline.


Ratios for those that want them.......
Original Transmission T50

gear ratio
1st 3.587
2nd 2.022
3rd 1.384
4th 1.000
5th 0.861

Final Gear Ratio
4.300

TRD set#1 For T50

1st 2.630
2nd 1.891
3rd 1.384
4th 1.000
5th 0.861

TRD set#2 For T50

1st 2.341
2nd 1.607
3rd 1.195
4th 1.000
5th 0.886


AZ6 from 1999-05 MX5

1st 3.760
2nd 2.269
3rd 1.645
4th 1.257
5th 1.000
6th 0.843

The 1st pattern - what the casting will look like once poured


The poured aluminum pattern - prior to machining


There has been an EXTENSIVE delay in this... without going into detail, the aluminum pieces are now at a different pattern maker and progress is expected VERY soon!!!!

[Wiggles]

Wow. Just, wow.
That's a hell of a task you've set for yourself there.

$3000 for what is basically re-engineering a whole gearbox sounds pretty cheap. Are you doing most of the labour yourself? Or paying for a fabricator//machinist?
Is this a one-off conversion, or are you/pineapple racing producing casts for a conversion kit
?
Good luck with it, i'll be really interested to see the progression of this.

P.S. The T50 isn't THAT bad is it?

[Hiro]

The AZ6 was originally designed for the Altezza, the Miata and the RX8,

I think you mean the Atenza, aka the Mazda6. I highly doubt Mazda made a gearbox for Toyota vehicles, especially one like the Altezza which already has an excellent gearbox

[oldcorollas]

i am concerned about "your step 2"
grafting toyota input shaft onto mazda input shaft to extend it's length? sounds like a world of hurt

what about the Altezza 6 speed, or the silvia? 6 speed? or are they the same box?
as for 250hp....
with 4AGTE's regularly getting aorund 250-270hp at the wheels, this is a bit more than 250 at the crank. will this be an issue? (then again you can break any box with any engine.. almost.. with enough abuse)

[Hiro]

Also remember guys that this is in the US (first post states $$ values are US), so $3000 really turns into around $4000 here, and probably more if shipping is required (as opposed to sourcing parts locally)

[-GT-]

Hiro, he's correct, same box in the mx5 and altezza. Mazda don't make gearboxes, they buy them from gearbox manufacturers and put them in their cars, like toyota do (generally!) In this case both companies are using the same gearbox, known as the J160 in the altezza (&IS200) and AZ6 in the mx5, built by Aisin i believe?

And stu, i *think* it might be also in the S15, i remember hearing that somewhere. I know i've heard the S15 box is somewhat fragile, people are busting them and retrofitting the S14 5 speed (i know 2 mates who have done just that), so that would indicate a similar strength to the mx5 and altezza boxes, kind of?

By fragile etc i mean only compared to what nissan fans are accustomed to after the S14.

This does look like a hell of a project, good on you for taking it on. In regards to this boxes suitability behind 4agte's, i remember someone on here trialing the J160 to a 4A (one of the CCG guys??) and them saying they thought it would be a great box for an NA 4A, but would recommend W5x for 4agte's.

Then again, gixer has an AE86 with a 20V + GT28RS(?) running through an Aisin 6 speed, if i recall his sig correctly.

[-GT-]

I have fitted an MX5 6 speed to my 4age (better ratio spread) but the gear box is made by the same people and many internal parts are interchangable with the Altezza one, I made up a custom adaptor plate to bolt the gearbox to the motor, and had to use an RX8 extension housing to move the gearlever forward, a custom rear crossmember had to also be made as in an MX5 they use the Power Plant Frame to locate the rear of the gearbox to the diff. What I like about it is I have nice close ratios BUT with a first gear I don't have to slip the clutch with, like a conventional style close ratio box (due to first gear normally being taller!) the ratios are 3.73, 2.265, 1.645, 1.254, 1.00, 0.843 as you can see 2-6 work nice with a turbo 4AGE.

From here;
http://www.toymods.net/forums/showpo...56&postcount=7

[-GT-]

Here's what i was looking for, it was chuck landwehr;

http://forums.toymods.org.au/index.p...t=0#msg_799349

Also from that thread;

The gear lever position, has caused a few drama's. The engine now sits a little further forward than I had hoped for. The tunnel hole has been cut all the way back to the cross body support web. The strange cradle for the shifter, also meant the tunnel had to "massaged".

My opinion for what is is worth, I would probably stick with a W58. The 6 speed just means you will always be in the torque/power zone. But with a properly sized turbo, a couple of hundred revs here or there will not make any difference. So yeah unless you are dead set on the six speed box, just use Bill Sherwoods bellhousing, and a W55/57/58.

Cheers Chuck.

Sorry Chuck for stealing all your thunder! Make sure you rep him for this info, i'm just searching and linking... Hopefully he'll pop up in here soon.

170bhp in that thread (who i think may be gixer here these days?) mentions the rx8 extension housing helps fix the shifter position issue (extension brings it forward? ), and that the gearbox is also used in the RX8.

Good thread that one.

[Gavatron]

It is gixer on here who has a MX5 six speed with RX8 extension housing in his Sprinter track car with 20v Turbo 4AGE.

[-GT-]

Yeah, that's what i said isn't it? Twice?

[Gavatron]

Yeah, I was just confirming. You had a few question marks...

[oldeskewltoy]

I'll try to answer what I can....

the idea came from 170BHP(from Club4AG)... he had made a plate to adapt the trans to the 4A engine... Problems with this are you then need some mixture of clutch/flywheel/hydralics to pull it off... AND it requires fabrication by someone. The other way is to cut a 4A bell and weld it to the gearbox...




As I stated the BEST way(in my opinion) is to make the adapter we are... using all 4A clutch/flywheel/hydralics and then use the AZ6.

The RX8 tail housing does shorten the whole thing... but not enough to fit through the OEM shifter hole. So you either still have to cut the box... or cut the transmission tunnel. As I mention if it was a one off... or a racing car.. who tf cares if you have to cut the floor. BUT... our cars are becoming something of value these days... a direct fit gearbox option would make retro fitting the T50 a none issue since the car doesn't get molested.

What I and Rob Golden decided is to make a complete bolt in kit! As of now... we are expecting you'll get a trans with adapter AND CORRECTLY shortened tailhousing, a shortened driveshaft with proper output yoke, and a trans mount. That should all cost $3000 US. For the people who only want the adapter, it will be for sale once demand for the whole kit has subsided or run out.

The AZ6 is built by Aisan Industries - http://www.aisin-ai.co.jp/english/products/fr.html it is used in the MX5, the RX8, the S15 and the Altezza (SXE10).

I've emailed Chuck... he already described what he is doing, and it is closer to what 170BHP did then what we are doing.

Concerning "grafting" .... welding was given a though, but too much chance of changing temper and overheating causing warpage. What is currently planned is close to a "dado" in woodworking... imagine if you will the BMW logo... now each shaft will be cut to appear to be either the blue, or white in the BMW logo. These will be made to zero tolerance... along with a zero tolerance fit, a set screw will be added to bind all the parts together. We did discuss adding a "compression" sleeve around the spliced shafts.... but we don't think its required. This has changed.... the current thought is to make a shortened shaft... exterior splined to fit the toyota clutch, interior splined to fit the Miata input shaft. They will be made to zero tolerance... the adapter will be heated to about 400 degrees and then "tapped" on with a mallet and let to cool. Since there is a spigot(input shaft) bearing in the back of the crank there will be no way these could come apart by accident

Interestingly enough Rob Golden is expecting the speedo drive to be the next most difficult part... there is a correct placement that needs to be considered... proper teeth alignment too.

Here is Rob Goldens shop... Pineapple Racing
http://www.pineappleracing.com/

We are expecting a finished adapter within 2 weeks - say before the end of April! We've had delay after dealy on this.... first it took nearly 2 months to find an MX5 AZ6, now it has taken this first pattern maker over 6 months to get us a finished pattern. Rob has taken the aluminum castings from the current slow pattern maker to another guy he uses to make his custom parts already... the guy has looked it over and expects to have the pattern finished by Aprils end... with luck and patience... it will be done!

[Mr Revhead]

very interesting.
although the prices quoted for t50 parts is waaaaay over the top.

now, if my KP had more power i could think about fitting one of those! lol

[oldeskewltoy]

NOW available!!!

[floody]

So you're saying everyone who has attempted the swap didn't consider making the clutch work, and bolting an adaptor on the front is no good so you're cutting it up and bolting an adaptor behind the toyota housing....No offence but it comes off a bit arrogant.

Don't T50s have input shaft issues? So you're going to a 2 piece input shaft? righto....