4A-GE to W5x Gearbox Adapter Kit

One year has passed since the last post and this is me right now:

Just like Goku there, i'm gathering my spirit bomb to work on The Dog again after neglecting her for a year. She has just got a new battery but i guess all the neglect warrants me the sulking that she is now. She failed to start and it has been three weekends since i've been trying to get the engine to run. I managed to narrow down the problem to somewhere between the EDIS crank sensor and the module itself (thanks to my own post about the EDIS conversion) and hoping that this weekend i can get her to start.

Meanwhile, i've been forcing myself to lurk the links on the right: Speedhunters, Driftworks, club4ag, etc just to get my car boner up again. During my lurking, i found something interesting:

That, my fellow petrol heads, is similar to what i have done in 2012: an adapter plate to mate W5x gearbox to 4A-GE engine. The above is fabricated and sold by SQ Engineering. I know some of us are itching to ditch that toothpick-like weak T50. Here's your solution! Head on to the SQ Engineering page for more info. Don't forget to get the modified clutch carrier.

Meanwhile, here's the cousin of our beloved Charmant as covered by Speedhunters, Carina AA63. A fellow Four Door AE86 that i won't hesitate to buy should one show up.

Hachirokuism

Awful post title, i know. Sorry but it's been a while since i updated this blog so my writing is a bit rusty. Apart from being transferred to another area of work (which is sadly getting me further from my hometown Jakarta), the bike is basically my main focus lately. Fear not, The Dog is still getting some love from the owner as you shall see in just a bit.

So far, The Dog is running AE86 LSD, a W58 gearbox conversion, RX7 front calipers and T3 bits which are all somewhat common in AE86 scene. Yesterday, my Charmant is getting even similar to a four-door Hachiroku with this finally reaching my doorsteps from Japan.

43-teeth ring gear and 10-teeth pinion for a T-series diff, giving me a 4.3 ratio. You know what car these gears come stock in? Exactly: AE86. Ever since i upgraded to a W58, i have wanted a final gear ratio increase to recoup the loss of acceleration from the box's taller ratio compared to T50. While a 4.778 ratio might give me even better acceleration, i don't think it's really necessary for a turbocharged daily driven car, hence a 4.3 was chosen. Besides, it's already quite an increase from the stock 3.909 ratio coming from 43:11 and much cheaper.

Here's the 10 teeth pinion..

and the ring gear..

Although both a 43-teeth 6.7 inch ring gear, the one from the 4.3 ratio has taller dimension compared to the 3.909 which is of course required to reach the smaller pinion gear diameter.

Here's the pinion gears side-by-side (commonly known as "gigi nanas" or "pineapple gear" here for obvious reason). The left one was the old 11 teeth pinion.

I had to replace one of the conical bearings and oil seal. Bearing number was M86610. Some shims with various thickness was needed as well to adjust the bearing's preload.

Last but not least is the backlash adjustment. There are some things better left to be handled by the expert and working on diff pumpkins are one of them. Seriously, i had no idea that gear to gear contact is such a delicate work!

After everything was put back together, a test drive was done and as expected, it accelerates much better and the rear wheels lock easier. Best of all, the whining is now gone. I guess the previous gear ratio was not adjusted properly and caused  the whining.

T50 No More - W58 Gearbox Conversion Pt.2

I can't sleep so i figured i might as well write the second part of my W58 gearbox conversion. In case you missed it, the first part is about fabricating the T50 bellhousing to W58 box adapter. By the way, i can't really be sure if mine's really W58.. it could be W57 which only differs on the shorter 5th gear. I thought it were only W58s that had steel sandwich plate like mine, but some googling got me to doubt that. Anyway, it shouldn't really matter.. I won't be using the 5th much and they both handle crazy torques.

Before i did the swap, i was prepared for a bit of customizing in getting the correct clutch disc. You see, W58 and T50 have different input shaft diameter and spline count. T50 is 24.1mm with 21 splines while W58 is approximately 28.6mm with the same spline count. A 4A-GZE clutch disc fits perfectly to W58. Now, since my clutch disc is 200mm or 8 inch (which i found out only later after i took off my T50 and actually strange since i should have the 212mm or 8.5 inch clutch with my smallport 4A-GE), i will have to find a clutch disc of the same diameter but with the bigger W58 shaft input diameter.

How about the GX71 Cressida's clutch disc which came with the W58 box i bought? This is good news for smallport users: Cressida's 1G-E clutch is exactly 8.5 inch and should fit smallport's flywheel just fine. So, how about my 200mm disc? Armed with the knowledge that G and W boxes have many similarities (for example, they interchange bellhousing) and that G boxes are found under our beloved KF chassis Toyota Kijangs, i went to see if these local commercial vehicles have the disc i needed. And you know what? I got lucky!

That above is 200mm clutch disc that fits my W58 box and flywheel! It's stock clutch for 4K equipped KF40 Kijang. So, i guess i'm safe from having to customize every time i replace the clutch set later in the future. Also found on the pic above are bush sets for my W58 shifter stick, front and rear gearbox seal and a new clutch release bearing. All of them interchange with G boxes as well. Part number for the clutch disc is 31250-YD010 just in case you need it. Ignore the cable lugs you see.. They're to recondition my starter wire.

Bolting the gearbox to the engine was quick which means the adapter must be doing it's job. The gearbox was fitted to the engine and pulled out again to confirm whether the input shaft really mates with the pilot bearing. Once it's confirmed, the box was again fitted to the engine, the bellhousing to engine bolts were fastened and the gearbox end was lifted using a jack and we arrive to this minor problem.

Nothing to worry about.. An angle grinder was used to cut a bit off the tunnel to clear the shifter. Apparently i wasn't so lucky in getting the W58 with the wrong shifter position. There are four known shifter position for W5x gearbox based on the distance from the front and mine's the obviously the furthest which is why i had to cut a bit of the tunnel to clear.

Depending on the tilt you're after with the gearbox tail, you could use the W58 crossmember, drilled to fit the existing mounting holes and add some rings as spacers or you could use a pair of angle iron like Assassin1000. I use the earlier method.

In my case, this way gets the engine to tilt at near stock angle.

One thing that surprised me on the swap was that i had to shorten my driveshaft by 20mm. I was on the impression that this wasn't necessary based on my initial research on the net but apparently i was wrong. In total, now my driveshaft is approximately 40mm shorter than stock Charmant as converting from S to T-series diff demanded the same requirement as well.

Luckily, W58 driveshaft yoke fits my stock U-joint just fine.. so less headache there.

Finally, what to do with this ugly gap from the trans tunnel?

LOL, the solution was again the ever-useful chopping board.. Yet another use for this lovely kitchen inhabitant.

A bunch of measurements, drilling and cutting later.. Here's the final result, all done.

It took two days to complete the swap work with the biggest time waster being going back and forth the machine shop to finalize the pilot bearing spacer and to shorten the driveshaft but other than that, the work was pretty easy.

Stay tuned for Part 3 where i will explain the basic differences between T50 and W5x gearbox and my driving impression with the new box.

T50 No More - W58 Gearbox Conversion Pt.1

Ah.. the old T50s.. Words are not enough to express just how legendary they are.. These gearboxes come paired with any longitudinal 4A-GEs ever been produced by Toyota, making them just as renowned to any Toyota-head all across the globe.

Funny thing about T50s, though, Toyota seemed to deviate from their habit of over-engineering when they designed these boxes: they are notorious for blowing up at the wrong time and place. I should know that.. after 4 hours and just another 10 minutes of drive before i reach home, my first T50 decided to get stuck on 3rd gear. Mine was behind a turbocharged smallport.. if you lurk the internet forums like i do, you'll even find guys that break their T50s with just bone stock bigports!

Perhaps it's just bad maintenance on my side and that T50s don't suppose to break that easily, however, i'm not keen on finding out (again). That's why i'm ditching my T50 in favor of a stronger monster, the W58. W58s are commonly found in non-turbo Supras and, especially in Indonesia, Cressidas. They are said to withstand 300-400 HP easily, numbers i'm not planning to reach with my 4A-GTE, so hopefully it would last forever on The Dog. Besides, T50s worth more than W58s here in Indonesia. I'm hoping with the cost of the conversion would be covered by the cash i'll get for the T50.

This conversion will be detailed into three parts. This first part covers the adapter plate fabrication, the second part will cover the details found during the swap process and final part will give some comparison between the T50 and W58. Apparently, W58 conversion is quite popular among AE86 owners so you'll find a lot of info on this on the web.

The conversion was started with these..

A spare bellhousing from my 1st T50, the W58 gearbox and a driveshaft with front yoke that fits W58 output splines. You don't need the whole drive-shaft as i found out later the yoke will replace Charmant's easily. Also, if you have a spare 4A engine, that would be great as it will be explained later, you'll save some swap process down time.

I got the idea from Andrew a.k.a Assassin10000's thread on Toymods forum.. so my steps will be very similar to his with just some minor differences. His method is the most cost effective and feasible for me. The idea is to make an adapter plate that sits between the W58 gearbox and T50 bellhousing. Why bother when you can buy custom bellhousing that couples W58 to 4A engine (or any W5x series, as they share common bolt pattern)? First, they're hard to find with decent quality and second, spending some 400 bucks for them and another nearly the same amount getting it past customs seems unjustifiable for me. Another way to get W5x behind your 4A would be to cut both T50 and W58 bellhousing somewhere in the middle and weld them together.. As these bellhousings are aluminum, welding them together can be tricky. I can't find any decent aluminum welder close-by so obviously i'm left with the adapter plate method.

Before i start detailing my conversion process, i'd like to point out something..

Bellhousings from T50 and W58 are placed next to each other and a driveshaft is laid on top. The gap found above T50 bell proves that they're NOT of the same height. I've read somewhere saying otherwise so this just disproves it.

First, take off W58's clutch release bearing carrier guide and draw the outline on 20mm thick steel plate with a chalk. This plate will be your adapter. Drain the oil first before you do this as it will spill when you take the guide off from the gearbox. Then cut the plate using a welding torch.

Next, refit the bearing carrier guide and drill the holes for the dowel pins on the gearbox so that your adapter plate can sit flat. I found out the best way to do this is to dab some paint on the dowel pins and place the adapter on top of them so that you have the marks to drill.

To drill the holes for the bolts to hold the adapter to the gearbox, make some dowel pins for the W58 bell. This way, you can secure the bell on top of your adapter and drill out following the bellhousing holes. Accuracy is important here, as redrilling a massive chunk of steel is no fun.

There're nine holes to drill but for reason to be explained later, you may want to leave one out. Anyway, i drilled all nine holes.

The adapter will be secured to the box using hex bolts so the next step is to enlarge the holes so the bolt head will fit, allowing the T50 box to sit flat on the adapter. Take care not to drill all the way through the holes..

As i have mentioned before and will explain later, you may want to leave the top left hole un-drilled. Eight out nine is still strong enough, i believe.

Next is to drill the holes for the T50 bellhousing bolts. First you need to make sure the T50 bell is centered to the W58 input shaft. For this purpose, a centering tool is machined out on a lathe by opening up an inner diameter the size of W58 bearing guide and reducing the outer diameter to T50's center opening.

You need to know how to align the T50 bell to the W58 box so that later on the car, the shifter stick will sit upright and not tilt to the side. The part of the T50 bell that you need to align to W58's shifter stick center line is the part exactly across the bellhousing drain hole. This is what you'll see when your bellhousing is aligned to the box.

Be very cafeful on this part as mistake here will be costly to fix later.

Once the bellhousing is aligned, drill and tap one hole first to hold the bellhousing firmly to the adapter. Once it sits firmly, you can drill and tap the other holes.

Remember when i said that you may want to leave one gearbox bolt hole not drilled? Here's why..

The bellhousing bolt hole sits on top of the gearbox side of the adapter's bolt hole so you can't drill and tap there. If you leave that particular hole not drilled, you still have eight bolts to fix the adapter to the gearbox AND are able to drill and tap the holes for the bellhousing side. Andrew and I decided to just oblong the hole and use long bolt to fix the bellhousing directly to the gearbox. Here's after i oblong the hole.

and that concludes the adapter plate part of the conversion.. Here's the end result after the outer side is trimmed.

Keep in mind that there's one hole on below right for the bellhousing that you can't drill on the adapter as it sits just on top of the hex bolt head beneath it so you end up using only six out of seven holes on the bellhousing.

One disadvantage from using adapter plate is that your input shaft will be shifted back the same amount as the adapter's thickness. There are two problems raised from this fact.

First problem is that the gearbox input shaft will be floating in the air as it no longer reach the pilot bearing. Leaving it this way is a bad idea as you may risk breaking the shaft later. To solve this problem, you need to make a spacer for the pilot bearing. This spacer will shift the bearing back about the same amount as the shaft offset. Here's the design for the spacer.

Notice the tapered sides? That's to clear the flywheel bolts. The problem with this spacer is that you can't space it out too much as you'll hit the clutch disc but if you space it too little, the gearbox shaft will not reach the bearing. I started with numbers:

a = 36 mm

b = 8 mm

c = 4 mm

d = 12 mm

i then try fitting it in and reduce as necessary so that i have about 2-3mm of space between the pilot bearing and clutch disc. The clutch disc will wear and gets thinner so you need that space. Keep in mind that the pilot bearing is #6001 having 12mm ID x 28mm OD x 8mm T. I didn't have a spare 4A so i had to go back to the machine shop a few times to get it to the right size. A spare engine will save you some time during the swap process.

The second problem is the risk of the clutch release bearing carrier falling off the guide because now the carrier has to sit further forward to engage the clutch. Solution? Lengthen the rear tail of the bearing carrier the same amount as the adapter's thickness.

Here's Before VS After shot..

That concludes this part. Head on to Part 2 for the swap process details.

Today I Learned: Turbo'd Carb & Dizzy Relocation

On the last post, i mentioned about Nico, a friend i met in Lampung. Nico rides a KE20 but this one is not your ordinary "humpback" Corolla.

Here's why:

That's a 4A-GE (rough guessing from the spark plug leads, bigports) converted to carb and turbo. This being the my first time to see a running carb turbo engine in person, to say i'm amazed was an understatement. I have always wondered how can carburetor work with positive air pressure coming from a turbo and now i get the chance to learn how it's tackled.

After seeing Nico's engine in detail, i learned that the key in allowing turbo carb is this (see arrow):

That is called a rising rate fuel pressure regulator. This is what's stopping you from pushing pressurized air into the carb jets and subsequently pushing those fuels out of the float chamber. This works by sensing the air pressure on the charge pipe and via some membrane and spring system, ensures that the fuel pressure from the pump is always above the air pressure coming to the carb. Typically it's set to 3-4 psi above the air pressure. Here's a short yet good writing about rising rate FPRs.

That's not the only thing i learned from Nico's 4A-GE. Notice where the dizzy is on the engine? Since the engine's converted to carb, the stock distributor is useless since it's designed to work with the ECU. One way to solve this is to use a point-and-condenser dizzy. I don't know what engine's distributor is usually used but i think this one's from a K-series engine. Correct me if i'm wrong. Anyway, that's not my focus now. I'm more interested on where the dizzy is.

Although usually dizzy relocation is more of a 20V RWD conversion thingy as this will keep you from ruining the firewall, it's a good idea also for turbo application as you're now moving the melt-prone dizzy cap away from the turbo heat. You'll also be spared from leaky distributor oil seal.

Seeing it in person, it looks simple. The most complicated work i believe is modding the dizzy shaft so that it'd match the slot you that you machined on the cam sprocket bolt. I think Nico's slot was too wide as i still see a small gap that would allow a small play on the dizzy. This is not ideal as your ignition timing won't be firm but since you're already using a mechanical point dizzy, i guess precision ignition timing is not really what you're after, now is it?

So, imagining myself doing the same work, here's, in order, how i would do it :

1. Make a slot the cam sprocket bolt.

2. Mock up the placement of the dizzy mounting plate. This is so that you can measure how much you need to cut the dizzy shaft.

3. Once you shorten the dizzy shaft, make the key on the shaft that match the slot on the sprocket bolt.

4. Mount the dizzy, done. Make sure the mounting plate is thick enough and firm to withstand the vibration.

Last but not least, Nico also took me to my new playground here in Lampung. I've been looking for a junkyard here and finally i found one! Here's one view of the junkyard..

This is a great find for me.. Why? See the pic above. Hint: this will solve my gearbox problem. Got it? Well, this junkyard have some W58 gearboxes! Now i don't have to hunt one in Jakarta!

Toothpick T50

I've been to online forums many times and read that T50 gearboxes as "strong" as toothpicks and will break even with a bit of harsh treatment behind a stock 4A-GE. Never really believed that.. until just recently. A few days ago, i went to Jakarta to attend my sister's wedding. It was about 250 km of driving with the 4A-GE boosted on stock TD04H actuator. This was The Dog's first long ride after the turbo was running.  At first, everything went smooth. I shifted at moderate to high RPMs under full boost, enjoying how easy it was to overtake slow trucks and old-men drivers. Hell yeah, turbo FTW!

Then, after about two hours, the gearbox started to sound funny.. whining and popping occasionally. Gears would suddenly turn neutral when decelerating. Three hours in and it just got worse, there was horrible gear grinding sound and shifting gears got even more difficult. Finally, just 10 about more minutes left before i reach home, the gear was stuck on 4th! There was no way i can get home now. Called dad and he helped me tow the car to the nearest autoshop. It was 4AM in the morning so the shop was still closed. I left The Dog in front of the shop and left a note.

At 8AM the shop called me. I lazily woke up of bed and took my spare T50 gearbox (Oh yes, i have one. Everybody should have a spare gearbox lying on their front yard, right?) and head to the shop. Explained what happened and they started the swap.

Here's the spare already in.

Here's the KIA box. Resting in pieces.

With me having no more spare T50, mini-project W5X series gearbox conversion has officially started. These W55-W58 gearboxes are much stronger than T50. The input shaft are about 50% bigger and best of all, they're cheaper here than T50s! I'm now on the phase of gathering ideas from online forums to find the best way to tackle this.

Nearly There

Got the engine running again finally. Since pictures worth more than thousands of words (or i'm too lazy to write), here are some progress shots with minimum amount of words in between.

ARP flywheel bolts

Turbo oil drain flange on sump

ARP head studs and 4A-GZE 8.9 CR slugs

ARP head stud protrusion. This is why some need to shave one of the studs as it fouls the distributor shaft. Obviously not this one as i took photo of the wrong side.

Considered leaving the timing belt cover off but put it back on to be safe.

Last shot before turbo conversion the next day. Notice the oil drain line is only ziptied near the strut tower.

The next day, after running the engine for a day and ensuring the rebuild was successful, turbo conversion was started. Oil sandwich adapter went in first. Only one out of four outlets was used.

HKS copy cast iron manifold with gasket cut out from a soda can. Cheap and refreshing, indeed.

The very minimum space at the back of the turbo with downpipe flange off. Gotta move some wiring to protect them from the heat.

Oil lines plugged in and this is the final shot of the day.

The next day which was yesterday, exhaust was fully redone. The initial plan was only to fabricate the downpipe and connect it to the existing exhaust but after quick reconsider, decided to ditch the whole system and put 2-inch pipes front to rear. Only 2-inch? Well, the turbo downpipe flange output is that diameter, i'm merely following. No use in going bigger, yes? The flexible joint was welded to the downpipe and only one tiny muffler was used. The rest of it was 2-inch piping and elbow joints to allow going over-axle. Oxygen sensor bung was installed on the same location as the original piping. Didn't take many photos that day, sorry.

Finally, just today, i installed an SPST switch on the bootloader jumper header on my Megasquirt. I did this to ease flashing firmwares later without having to open the MS case anymore. I'm currently focusing on finding the correct values to go into the kpafactor and barofactor inc files as i'm going to use the 4A-GZE map sensor which is not directly supported by the original MS1-Extra firmware i'm using.